Yet another rv8 rich idle headache..
Discussion
Hi people,
I’m nearly at the pulling my hair out stage with my freshly built engine and am hoping some of you may have some ideas to help me fix it..
Firstly it’s not in a tvr but my much loved rrc lse.
Symptoms are it’s running rich at idle (1.8% co) from cold start to fully hot and I can’t seem to effect a change.
It starts/runs/ drives ok and I’ve managed to do 500 miles in it to run it in. once off idle it drives fine if a little lacklustre considering the spec but that’s probably the standard fuel map/ auto box combination.
I am certain the cam timing is spot on after treble checking it before the engine went into the car, piper vernier camchain set to cam makers timing.
Using my old fashioned ears it sounds and feels just a tiny bit off/ lumpy at idle but I can’t detect why.
Ignition system is all good, new lucas bits, magnecore leads and new bpr6es plugs (rather black..)
Fuel pressure as it should be and all ecu side tests seemed fine, the only exception being the afm overshooting to .58 volts with ignition on and taking five or so seconds to settle where it should, substituted it for a newer one which doesn’t misbehave.
I’ve had a look in rovergauge, no faults but once warm the stepper motor seems out of spec with it being only a few percent and at one point 0%, long term fuel trim is at max with original afm and came down to 75% with better one, still no change.
I am a total newbie to rovergauge but after looking at other people’s screenshots my fuelling seems to be really rich with both on the lambdas and with pulse widtharound 3.8 at warm idle?
I’ve yet to confirm both compression and vacuum tests.
I did just for the hell of it thinking this might be a vacuum/ inlet air leak try blowing smoke down the inlet.. of course I didn’t get a nice steady stream of smoke from anywhere useful but while blowing something inside the motor made a click kind of sound similar to a tin plate/ glass jar test button popping and again on releasing pressure and I can’t for the life of me think what might do that?...
any advice would be really welcome!
I’m nearly at the pulling my hair out stage with my freshly built engine and am hoping some of you may have some ideas to help me fix it..
Firstly it’s not in a tvr but my much loved rrc lse.
Symptoms are it’s running rich at idle (1.8% co) from cold start to fully hot and I can’t seem to effect a change.
It starts/runs/ drives ok and I’ve managed to do 500 miles in it to run it in. once off idle it drives fine if a little lacklustre considering the spec but that’s probably the standard fuel map/ auto box combination.
I am certain the cam timing is spot on after treble checking it before the engine went into the car, piper vernier camchain set to cam makers timing.
Using my old fashioned ears it sounds and feels just a tiny bit off/ lumpy at idle but I can’t detect why.
Ignition system is all good, new lucas bits, magnecore leads and new bpr6es plugs (rather black..)
Fuel pressure as it should be and all ecu side tests seemed fine, the only exception being the afm overshooting to .58 volts with ignition on and taking five or so seconds to settle where it should, substituted it for a newer one which doesn’t misbehave.
I’ve had a look in rovergauge, no faults but once warm the stepper motor seems out of spec with it being only a few percent and at one point 0%, long term fuel trim is at max with original afm and came down to 75% with better one, still no change.
I am a total newbie to rovergauge but after looking at other people’s screenshots my fuelling seems to be really rich with both on the lambdas and with pulse widtharound 3.8 at warm idle?
I’ve yet to confirm both compression and vacuum tests.
I did just for the hell of it thinking this might be a vacuum/ inlet air leak try blowing smoke down the inlet.. of course I didn’t get a nice steady stream of smoke from anywhere useful but while blowing something inside the motor made a click kind of sound similar to a tin plate/ glass jar test button popping and again on releasing pressure and I can’t for the life of me think what might do that?...
any advice would be really welcome!
Thanks classic chim,
I thought that too so second time I blocked off the stepper motor pipe, held butterfly open with same weird click sound present..
method was simple, laughable and wasn’t really expecting a result but an excuse to light up in frustration. I simply took off the hose clip for the air flow meter, formed a good seal around the rubber inlet pipe with my mouth and blew a face full of smoke down it..
I’ve had the ram housing back off to double check and can’t see what it could be or any obvious sign of a problem although the butterfly seems properly closed when closed as in when cleaning it off the car no carb cleaner would pass it so there’s no tiny gap as per spec.
Chip and ECU are correct for the car and original engine spec but not the new engine spec. I get that I’ll probably have to seek out an affordable genius to get the fuelling right later but I’d assumed it would still idle and run ok ish for now?
It’s now on bigger (than rr) valves, ported and flowed heads, tubular manifold &stainless system without cats but with lambdas (was used with the previous now coffee table engine)
and a real steel cyclone cam.
I’ve tried on on the original ecu with ‘correct’ blue resistor and green no cat resistor. Also tried a second identical ecu with no change and just for laughs a 92’ 3.9 ecu (using blue resistor)
When I tried the non cat resistor I couldn’t effect any change in emissions even if I pulled the maf trim down to 0.8v?
I’m thinking it’s an air leak (although the above with the non cat tune confuses me)but god knows where and having only just built it I’m sure everything is spot on but obvs something isn’t..
I thought that too so second time I blocked off the stepper motor pipe, held butterfly open with same weird click sound present..
method was simple, laughable and wasn’t really expecting a result but an excuse to light up in frustration. I simply took off the hose clip for the air flow meter, formed a good seal around the rubber inlet pipe with my mouth and blew a face full of smoke down it..
I’ve had the ram housing back off to double check and can’t see what it could be or any obvious sign of a problem although the butterfly seems properly closed when closed as in when cleaning it off the car no carb cleaner would pass it so there’s no tiny gap as per spec.
Chip and ECU are correct for the car and original engine spec but not the new engine spec. I get that I’ll probably have to seek out an affordable genius to get the fuelling right later but I’d assumed it would still idle and run ok ish for now?
It’s now on bigger (than rr) valves, ported and flowed heads, tubular manifold &stainless system without cats but with lambdas (was used with the previous now coffee table engine)
and a real steel cyclone cam.
I’ve tried on on the original ecu with ‘correct’ blue resistor and green no cat resistor. Also tried a second identical ecu with no change and just for laughs a 92’ 3.9 ecu (using blue resistor)
When I tried the non cat resistor I couldn’t effect any change in emissions even if I pulled the maf trim down to 0.8v?
I’m thinking it’s an air leak (although the above with the non cat tune confuses me)but god knows where and having only just built it I’m sure everything is spot on but obvs something isn’t..
Wise words mr classic!
If I had the time and funds I’d probably enjoy getting stuck in to a different fuelling and spark system but I have all too many vehicles to divide my time between and was hoping that the cux would do a reasonable job especially as the car isn’t a tvr but a load hauling adventure car. The engine I removed due to split liner/ block was an incorrect for my lse 3.9 and ran just fine with mot happy emissions for 8 years running on the 4.2 with cat ecu set up although when I split it to keep the block I was shocked at how much carbon had built up in it!.
I did try to talk my daughter into letting me sell it and buy a chim but she said ‘how would we go camping in that?!’ We are planning on doing the nc500 soon and a run to the Le Mans classic if I can get it running properly.
Will wait in hope of any other ideas and look up the recommended cux genius for a later date
If I had the time and funds I’d probably enjoy getting stuck in to a different fuelling and spark system but I have all too many vehicles to divide my time between and was hoping that the cux would do a reasonable job especially as the car isn’t a tvr but a load hauling adventure car. The engine I removed due to split liner/ block was an incorrect for my lse 3.9 and ran just fine with mot happy emissions for 8 years running on the 4.2 with cat ecu set up although when I split it to keep the block I was shocked at how much carbon had built up in it!.
I did try to talk my daughter into letting me sell it and buy a chim but she said ‘how would we go camping in that?!’ We are planning on doing the nc500 soon and a run to the Le Mans classic if I can get it running properly.
Will wait in hope of any other ideas and look up the recommended cux genius for a later date
Hi Mark,
Thank you ever so much for that info. I’ll digest it later. On the 4.2 lr ecu it runs blue resistor for cats or yellow for Saudi/ not cat. As you say the 3.9 runs green or white I believe. I don’t have a yellow but have ordered the correct resistors so I can knock one up just to try it without the lambda control.
I’ll try the easy start idea. As much as I don’t want it to be an air leak it just seems odd that it seems so nearly closed yet Is running over rich..
I have a vacuum gauge on its way in the post too.
I have your g33 site to blame, in a good way for the current engine spec as it was reading it years ago that inspired me to build the current head spec rather than just slapping on a refreshed stock pair..
Thank you ever so much for that info. I’ll digest it later. On the 4.2 lr ecu it runs blue resistor for cats or yellow for Saudi/ not cat. As you say the 3.9 runs green or white I believe. I don’t have a yellow but have ordered the correct resistors so I can knock one up just to try it without the lambda control.
I’ll try the easy start idea. As much as I don’t want it to be an air leak it just seems odd that it seems so nearly closed yet Is running over rich..
I have a vacuum gauge on its way in the post too.
I have your g33 site to blame, in a good way for the current engine spec as it was reading it years ago that inspired me to build the current head spec rather than just slapping on a refreshed stock pair..
I agree, confused myself hence hoping some good ph people may have some ideas.its only an engine and a few sensors but it has me beat at the moment.
The car drives ok and on its first run out for 250 miles returned 19 mpg so i doubt its over fuelling above idle but is idling very rich, 1.8% at idle and just over 1% at fast lambda test idle on an mot test machine.
The idle sounds and feels just a little off and unsteady, a partial misfire that I can’t find.
Roverguage shows temps working fine, maf is at around 4% linear and throttle pot at 4% absolute. Stepper at around 10% at cold idle and drops off to a few % or 0 once hot. That was the reason for me thinking air leak? Also the weird clack noise when I blew down the inlet and also only from the maf/ inlet pipe work while running it’s making a strange noisy metallic sucking noise that I don’t ever remember it making before that sounds almost mechanical (or possibly a leak?)
On checking the base idle with a meter I couldn’t get a steady 500 rpm, the meter kept swinging around 500/630, I guess because of the miss?
All sensors checked with a meter and read and scale ok.
Lambdas checked with a meter both are cycling voltage wise and show to cycle on roverguage. On hot idle they show an average of -25% short term trim but showed +100% long term? The only change that affected that was swapping the maf for a good one which showed the same short term trim but altered the long term trim to around+75% ?
The car drives ok and on its first run out for 250 miles returned 19 mpg so i doubt its over fuelling above idle but is idling very rich, 1.8% at idle and just over 1% at fast lambda test idle on an mot test machine.
The idle sounds and feels just a little off and unsteady, a partial misfire that I can’t find.
Roverguage shows temps working fine, maf is at around 4% linear and throttle pot at 4% absolute. Stepper at around 10% at cold idle and drops off to a few % or 0 once hot. That was the reason for me thinking air leak? Also the weird clack noise when I blew down the inlet and also only from the maf/ inlet pipe work while running it’s making a strange noisy metallic sucking noise that I don’t ever remember it making before that sounds almost mechanical (or possibly a leak?)
On checking the base idle with a meter I couldn’t get a steady 500 rpm, the meter kept swinging around 500/630, I guess because of the miss?
All sensors checked with a meter and read and scale ok.
Lambdas checked with a meter both are cycling voltage wise and show to cycle on roverguage. On hot idle they show an average of -25% short term trim but showed +100% long term? The only change that affected that was swapping the maf for a good one which showed the same short term trim but altered the long term trim to around+75% ?
Thank you guys for your continued help
I’m stuck on a project at work for a few days but will go back through everything starting with the basics and see if I can find the issue.
I can’t tell if the slight misfire is engine related or just a result of it idling so rich, it doesn’t sound cyclic so I’d assumed it was the rich running. It’s chucking out so much co that it fills up the drain in my co meter and makes eyes water of anyone who dares get too close.. It starts on the button and there’s no sign of ignition hesitation above idle so I’m sure it’s not spark related.
I’m new to using roverguage having only bought the cable from mark last week but I just thought as an additional diagnostic tool it may help and I guess it has as I wouldn’t have known what position the stepper motor was working at without it.
Having thought about it I think I answered my own daft question about the strange noise though. While attempting the daft diy smoke test I didn’t block off the flame trap pipe so I’m fairly sure the noise was just me pressuring the valley gasket..
will update as soon as I have any news.
I’m stuck on a project at work for a few days but will go back through everything starting with the basics and see if I can find the issue.
I can’t tell if the slight misfire is engine related or just a result of it idling so rich, it doesn’t sound cyclic so I’d assumed it was the rich running. It’s chucking out so much co that it fills up the drain in my co meter and makes eyes water of anyone who dares get too close.. It starts on the button and there’s no sign of ignition hesitation above idle so I’m sure it’s not spark related.
I’m new to using roverguage having only bought the cable from mark last week but I just thought as an additional diagnostic tool it may help and I guess it has as I wouldn’t have known what position the stepper motor was working at without it.
Having thought about it I think I answered my own daft question about the strange noise though. While attempting the daft diy smoke test I didn’t block off the flame trap pipe so I’m fairly sure the noise was just me pressuring the valley gasket..
will update as soon as I have any news.
Hi guys,
I found some time to start digging around and other than miserable bottom end news I haven’t discovered the cause of the misfire problem yet.
The plugs were all too lean with exception of no. 3&4 which were perfect colour..
A compression test and leak down test revealed the heads are good but too much leakage past rings in all cylinders, around 20%.. i took a gamble on new rings and a hone as oversize pistons aren’t available for the 4.2 and looks like I now need new stock cylinders.
Compression test showed 6 cyls at 150-160 psi and one high at 170, one low at 145. Not good
A vacuum test connected to a stub on the plenum shows 12 ins hg at idle and rising to 20 at 2500rpm but I’ve no idea what it should be?.
I rigged up the correct ohm tune resistor for non cat map to eliminate the lambdas and it ran much the same but with even more co & hc
I still need to test the inlet area for air leaks but don’t like the idea of spraying easy start everywhere so I’m going to pull the ram housing and make up an air fitting that I can ram down each trumpet to check for a leak that way.
Other than pulling it apart again for a bottom end any ideas?.
I found some time to start digging around and other than miserable bottom end news I haven’t discovered the cause of the misfire problem yet.
The plugs were all too lean with exception of no. 3&4 which were perfect colour..
A compression test and leak down test revealed the heads are good but too much leakage past rings in all cylinders, around 20%.. i took a gamble on new rings and a hone as oversize pistons aren’t available for the 4.2 and looks like I now need new stock cylinders.
Compression test showed 6 cyls at 150-160 psi and one high at 170, one low at 145. Not good
A vacuum test connected to a stub on the plenum shows 12 ins hg at idle and rising to 20 at 2500rpm but I’ve no idea what it should be?.
I rigged up the correct ohm tune resistor for non cat map to eliminate the lambdas and it ran much the same but with even more co & hc
I still need to test the inlet area for air leaks but don’t like the idea of spraying easy start everywhere so I’m going to pull the ram housing and make up an air fitting that I can ram down each trumpet to check for a leak that way.
Other than pulling it apart again for a bottom end any ideas?.
I could affect a change in co, taking it down to .5v still had the co at 1.6% and eye watering hydrocarbons, turning it up to 1v or more sent co climbing.
Another strange thing I couldn’t fathom, while fiddling with the maf (also tried good substitute) engine idling I took the filter housing off so I could lift it up a little to get to the plug leads and every time I lifted it more than 10 degrees up or more it had an incremental negative effect on the idle and made it stutter. Wiring all seems fine and giving the maf wiring connector a good wiggle didn’t cause it.
I’m going to do the double check for inlet air leaks, put it back to non cat map and do a plug chop to see if it changes how the plugs look and swap dizzy just for the hell of although I’m sure it’s not an ignition problem as i’m pretty much out of ideas now.
When doing the previous checks I checked the exhaust header temps while warming up and the two cylinders with happier looking plugs were 80-100 degrees c cooler than the other six which were up near 400 degrees c
Another strange thing I couldn’t fathom, while fiddling with the maf (also tried good substitute) engine idling I took the filter housing off so I could lift it up a little to get to the plug leads and every time I lifted it more than 10 degrees up or more it had an incremental negative effect on the idle and made it stutter. Wiring all seems fine and giving the maf wiring connector a good wiggle didn’t cause it.
I’m going to do the double check for inlet air leaks, put it back to non cat map and do a plug chop to see if it changes how the plugs look and swap dizzy just for the hell of although I’m sure it’s not an ignition problem as i’m pretty much out of ideas now.
When doing the previous checks I checked the exhaust header temps while warming up and the two cylinders with happier looking plugs were 80-100 degrees c cooler than the other six which were up near 400 degrees c
So I’ve skipped off to the barn to swear at the car some more. I’ve got myself geared up with a selection of pipes and bits to see if I can provoke a vacuum leak anywhere before doing anything else.
I figured using a regulated 15psi supply from the compressor should be plenty to see if I can hear any leaks. First port of call was to rig up a funnel that handily fitted into the rubber plenum inlet pipe, discovered a hiss but no idea where from so again I introduced a puff of cigarette smoke into it, slipped the air gun back on and with a quick squirt I seem to have smoke coming from the back of the throttle spindle, I assume that shouldn’t leak?..
it’s rather hard to see exactly where it’s coming from but I’m sure it’s not coming from anywhere lower, now going to pull ram housing and check each inlet runner in turn and swap the injectors for the sake of it while it’s apart as I have a good known set.
I figured using a regulated 15psi supply from the compressor should be plenty to see if I can hear any leaks. First port of call was to rig up a funnel that handily fitted into the rubber plenum inlet pipe, discovered a hiss but no idea where from so again I introduced a puff of cigarette smoke into it, slipped the air gun back on and with a quick squirt I seem to have smoke coming from the back of the throttle spindle, I assume that shouldn’t leak?..
it’s rather hard to see exactly where it’s coming from but I’m sure it’s not coming from anywhere lower, now going to pull ram housing and check each inlet runner in turn and swap the injectors for the sake of it while it’s apart as I have a good known set.
I imagine it’s a problem with most ageing engines that still use a throttle, my van has a similar issue with a leaking egr valve spindle that blows crappy old oil out all over the place. One day I’ll try to see if I can get it bushed.
I imagine there would still be a market for a run of new twin inlet plenum covers should anyone be brave enough to make them!
I did a basic leakage test on the throttle spindle-
Held it vertically and sprayed carb cleaner on the outside and watched it dribble down through the bush onto the butterfly inside..
I then similarly checked the 3.9 one that came off the outgoing engine (which ran perfectly save for a cracked block) and another spare 4.2 one and they all seem to leak about the same amount. Not scientific by any means but all three ram covers (including the one I’m using on this engine) have their base idle screws set within a mm or so of each other too.
So, I managed to rig up some pipe work to the air line, removed plenum and checked for leaking inlet gasket down each inlet port with each at tdc in turn, nothing, no detectable leaks anywhere! I’d rather there was as I’m now all but stumped as to what can be causing the lean condition!.
Plugs still look the same after it's last run (on a cat map) no. 2&3 have a little colour the other six are lean white on one side of the insulator and black on the other (probably from me not cleaning them thoroughly after the engines first start up)
I didn’t get to swap the injectors as I damaged one of the o-rings taking them out so I gave up at that point and left the engine unceremoniously covered with a rag of shame..
I can’t seem to find the cause of this lean condition, no leaks, spot on ignition, fuel pressure correct, no fault codes. If I hadn’t owned this car for 12 years I’d be very tempted to send it to auction..
I imagine there would still be a market for a run of new twin inlet plenum covers should anyone be brave enough to make them!
I did a basic leakage test on the throttle spindle-
Held it vertically and sprayed carb cleaner on the outside and watched it dribble down through the bush onto the butterfly inside..
I then similarly checked the 3.9 one that came off the outgoing engine (which ran perfectly save for a cracked block) and another spare 4.2 one and they all seem to leak about the same amount. Not scientific by any means but all three ram covers (including the one I’m using on this engine) have their base idle screws set within a mm or so of each other too.
So, I managed to rig up some pipe work to the air line, removed plenum and checked for leaking inlet gasket down each inlet port with each at tdc in turn, nothing, no detectable leaks anywhere! I’d rather there was as I’m now all but stumped as to what can be causing the lean condition!.
Plugs still look the same after it's last run (on a cat map) no. 2&3 have a little colour the other six are lean white on one side of the insulator and black on the other (probably from me not cleaning them thoroughly after the engines first start up)
I didn’t get to swap the injectors as I damaged one of the o-rings taking them out so I gave up at that point and left the engine unceremoniously covered with a rag of shame..
I can’t seem to find the cause of this lean condition, no leaks, spot on ignition, fuel pressure correct, no fault codes. If I hadn’t owned this car for 12 years I’d be very tempted to send it to auction..
Thanks for that Mark, as you can imagine I’m confused myself.
I only have a co tester at home, the previous hc Reading was while plugged into a garage machine but judging purely on the toxic level of what’s coming out the tailpipe and using my co machine I can’t seem to effect much of a change. Even on a hot engine its chuffing out clouds of vapour and I can’t see any way of getting it down to a cat mot pass level!.
I haven’t had time to play with the maf again yet as I need to get the injectors/ plenum back together.
I’m going to change over the injectors and dizzy at the weekend although I’m fairly sure neither are at fault but it ticks off just about the last thing I can think of?!
I’m absolutely sure I timed the cam to real steels spec, spot on with a vernier chainset but if I had it a couple of degrees out would it cause this? I’d rather not pull it all apart to check if I don’t need to..
surely with a mild cam and not extreme cyl head changes it should still behave itself fairly well?
If I can’t find the fault at the weekend I’ll be saving up and looking for someone who can find the fault and make my much loved old landy purr like it should. Recommendations much appreciated!
I only have a co tester at home, the previous hc Reading was while plugged into a garage machine but judging purely on the toxic level of what’s coming out the tailpipe and using my co machine I can’t seem to effect much of a change. Even on a hot engine its chuffing out clouds of vapour and I can’t see any way of getting it down to a cat mot pass level!.
I haven’t had time to play with the maf again yet as I need to get the injectors/ plenum back together.
I’m going to change over the injectors and dizzy at the weekend although I’m fairly sure neither are at fault but it ticks off just about the last thing I can think of?!
I’m absolutely sure I timed the cam to real steels spec, spot on with a vernier chainset but if I had it a couple of degrees out would it cause this? I’d rather not pull it all apart to check if I don’t need to..
surely with a mild cam and not extreme cyl head changes it should still behave itself fairly well?
If I can’t find the fault at the weekend I’ll be saving up and looking for someone who can find the fault and make my much loved old landy purr like it should. Recommendations much appreciated!
Thanks Mark,
You are quite right that the co machine results can vary and I’m only using an old trusty Gunson gastester but I’ve found it to be fairly accurate across all the cars I’ve used it on but usually over reads by about 10% it isn’t liking the huge amount of vapour it’s ingesting on this car right now and goes out of calibration after a few minutes til I’ve dried it out..
There’s no black at tailpipe just co vapour and hc’s And plugs are showing lean
I’m certain the cam timing is right as I spent a long time dialling it in as I didn’t want a hiccup later..
I’ve tried ignition timing between 6-12 degrees and it makes little difference, timing mark doesn’t stray with the strobe at all so leads me to believe ignition must be ok as I’d expect wandering or a rich condition if it were spark side? The old engine had so much slack in its camchain that the timing wandered about 6degrees!
I checked the tdc marker and crank pulley mark while building the engine and was surprised that it’s actully spot on!
Do the lambdas still cycle if I run it on a non cat map so I can see what they are reading?
While doing the leak down test I checked for bubbles in the coolant and none were detected, I don’t have an hc coolant sniffer but my nose says it doesn’t smell of combustion gases and it’s not used any water in the 400 miles the engine has done although it does strangely seem to keep pressure at the expansion bottle even after a week of sitting (poss duff cap?) plugs although white from lean condition don’t show and sign of burning coolant and the tops of all the pistons have colour, none steam cleaned.
I’ve taken today off work to take a look as I have a horrid man flu, so I’m at the car, just cleaning the injectors then going to fit a spare plenum cover, fit a spare dizzy and hope..
Main concerns are-
Plugs look lean but I’ve no idea if it’s running lean all over or just at idle
On cold start there is a slight misfire, not like a whole cylinder down but fluffy which almost vanishes once warm
Weird sucking noise from maf/ inlet pipe
Way high emissions
Why the ecu isn’t throwing any codes on a cat map if it’s clealy not running right?
The car idles ok with a ‘very slight’ off beat, drives and accelerates ok but I’d hoped it would be a bit better with the new engine
I’m in Woking Surrey
All of the injection/ ignition components were used on the previous 3.9 engine and that ran rich no matter what I did..
You are quite right that the co machine results can vary and I’m only using an old trusty Gunson gastester but I’ve found it to be fairly accurate across all the cars I’ve used it on but usually over reads by about 10% it isn’t liking the huge amount of vapour it’s ingesting on this car right now and goes out of calibration after a few minutes til I’ve dried it out..
There’s no black at tailpipe just co vapour and hc’s And plugs are showing lean
I’m certain the cam timing is right as I spent a long time dialling it in as I didn’t want a hiccup later..
I’ve tried ignition timing between 6-12 degrees and it makes little difference, timing mark doesn’t stray with the strobe at all so leads me to believe ignition must be ok as I’d expect wandering or a rich condition if it were spark side? The old engine had so much slack in its camchain that the timing wandered about 6degrees!
I checked the tdc marker and crank pulley mark while building the engine and was surprised that it’s actully spot on!
Do the lambdas still cycle if I run it on a non cat map so I can see what they are reading?
While doing the leak down test I checked for bubbles in the coolant and none were detected, I don’t have an hc coolant sniffer but my nose says it doesn’t smell of combustion gases and it’s not used any water in the 400 miles the engine has done although it does strangely seem to keep pressure at the expansion bottle even after a week of sitting (poss duff cap?) plugs although white from lean condition don’t show and sign of burning coolant and the tops of all the pistons have colour, none steam cleaned.
I’ve taken today off work to take a look as I have a horrid man flu, so I’m at the car, just cleaning the injectors then going to fit a spare plenum cover, fit a spare dizzy and hope..
Main concerns are-
Plugs look lean but I’ve no idea if it’s running lean all over or just at idle
On cold start there is a slight misfire, not like a whole cylinder down but fluffy which almost vanishes once warm
Weird sucking noise from maf/ inlet pipe
Way high emissions
Why the ecu isn’t throwing any codes on a cat map if it’s clealy not running right?
The car idles ok with a ‘very slight’ off beat, drives and accelerates ok but I’d hoped it would be a bit better with the new engine
I’m in Woking Surrey
All of the injection/ ignition components were used on the previous 3.9 engine and that ran rich no matter what I did..
Thank you!
I didn’t quite get as far as testing the lambda signals.
I fitted a set of cleaned injectors with new filters and seals, a spare rather grubby looking plenum, yet another set of new plugs and it still seemed to run much the same but I decided to use it for the weekend and see what happened. Drove 7 miles home, weird sucking noise from inlet is gone, filled up with fuel, came out to take my daughter to youth club an hour later and it refused to start, backfiring and wouldn’t run... had to walk the 7miles back to my tools on sat, after a dig about I diagnosed a dead ignition amp, swapped it for a new lucas one and all good. Went out yesterday and it drove 15 miles still with a very slight miss at idle but really nicely once moving and enough power to hit a naughty top speed! Went to drive home and after a few miles it nearly died. Bad misses, backfire, no power and coolant level warning flashing... left it to cool down and coolant level was above where it should be but bubbles and gurgled a lot when I slowly opened the cap, managed to get it home but running sporadically good/rough to find it’s blown a hole in the rad. I’m waiting for a combustion leak tester to arrive but it seems I may well be on my second cracked block!....
I didn’t quite get as far as testing the lambda signals.
I fitted a set of cleaned injectors with new filters and seals, a spare rather grubby looking plenum, yet another set of new plugs and it still seemed to run much the same but I decided to use it for the weekend and see what happened. Drove 7 miles home, weird sucking noise from inlet is gone, filled up with fuel, came out to take my daughter to youth club an hour later and it refused to start, backfiring and wouldn’t run... had to walk the 7miles back to my tools on sat, after a dig about I diagnosed a dead ignition amp, swapped it for a new lucas one and all good. Went out yesterday and it drove 15 miles still with a very slight miss at idle but really nicely once moving and enough power to hit a naughty top speed! Went to drive home and after a few miles it nearly died. Bad misses, backfire, no power and coolant level warning flashing... left it to cool down and coolant level was above where it should be but bubbles and gurgled a lot when I slowly opened the cap, managed to get it home but running sporadically good/rough to find it’s blown a hole in the rad. I’m waiting for a combustion leak tester to arrive but it seems I may well be on my second cracked block!....
Indeed, a big ouch..
Block tester arrived yesterday and confirmed my fears, I tested it three times to be sure. First time at warming up idle, the fluid stayed blue, let it get fully up to temp then have it some revs for a few seconds and the next two tests turned the fluid yellow within a few seconds..
now wishing I’d had the block top hatted before I built it!.
I’d just like to thank everyone who took the time to impart me with their ideas and knowledge on the poor running symptoms and hopefully when it’s up and running again all will be well.
Block tester arrived yesterday and confirmed my fears, I tested it three times to be sure. First time at warming up idle, the fluid stayed blue, let it get fully up to temp then have it some revs for a few seconds and the next two tests turned the fluid yellow within a few seconds..
now wishing I’d had the block top hatted before I built it!.
I’d just like to thank everyone who took the time to impart me with their ideas and knowledge on the poor running symptoms and hopefully when it’s up and running again all will be well.
Thanks, from what I have read megasquirt is a good system but maybe all a bit too much fuss for me as I am not very good with any kind of technology and as the car is a 2.5 tonne range rover rather than a tvr I doubt I’ll see as much benefit.
Block is booked in at turner engineering to be top hat linered in a few weeks and will hopefully run properly when I get it all back together again!..
Block is booked in at turner engineering to be top hat linered in a few weeks and will hopefully run properly when I get it all back together again!..
Hi guys,
Just in case any of you nice people who tried to help were wondering I thought I should give you an update on the situation.
Thanks to covid it’s taken an eternity to get the block top hatted, built again and back in the car..
Mr Turner showed me a photo of the gaping crack in the block he discovered behind no.4 sleeve.
While apart I double checked the cam which seemed ok, heads also looked spot on although needed a clean as there was a lot of black carbon build up from its 500 mile run in period.
It’s all up and running again and other than it no longer has any coolant issues it’s still running just as sick as it was!.
It still has an obvious misfire from cold that quietens down after about 40 secs but even once fully warm still has an off beat miss and high emissions and un burnt fuel out the tail pipe.
The idle still shoots up to 2k from cold and takes longer than it should to settle to a steady idle and also when warm on the over run just below auto box lock up when I let my foot fully off the gas the revs drop quickly as I’d expect but after around 3 secs they bounce back up by 300rpm and it feels like it’s revving too high and pushing the car along?
Still feels like an air leak to me but I’m flummoxed for wherebit could be from!!
It drives ok with good midrange and (for an old rangie) flies up to 5.5k given a foot full.
The header temps checked from cold start up are around 350 degrees c for all cyls except 3&4 which seem to stay around 50% of the others until fully warm.
I’ve tested (and swapped for good measure) the fuel rail and injectors, tested ignition and swapped cap/ leads.
Plugs look very rich on the plug body with approx half the circumference of the white insulator on each plug black and the other half white?
I’ve tried 3 fuel maps- the cars correct 4.2 cat map, the 3.9 non cat map and the 4.2 non cat map with 2 separate ecus, used a spare air flow meter for the non cat map tests which I adjusted while running and none altered the misfire or emissions.
On all maps in rover gauge the idle valve shows fully closed or thereabouts until fully warm when it creeps up to 10% at most, air flow shows around 30% and throttle 5% lambdas show to be cycling although I forgot to look at the long term trim, short when hot had one bank adding 30% the other taking away 10%.
I’m something is causing a misfire which is throwing out the lambdas but I had hoped running the non cat map might make diagnosis simpler..
I’m now at my wits end and about to tear the damn thing apart and fit a different cam because I can’t think of anything else. Genuine 4.2 cams are NLA so I’m stuck with a choice of a crappy cheap one or attempting to choose another performance one in the hope it works with the engine spec.
if anyone can come up with any good ideas I’d really appreciate it!
Just in case any of you nice people who tried to help were wondering I thought I should give you an update on the situation.
Thanks to covid it’s taken an eternity to get the block top hatted, built again and back in the car..
Mr Turner showed me a photo of the gaping crack in the block he discovered behind no.4 sleeve.
While apart I double checked the cam which seemed ok, heads also looked spot on although needed a clean as there was a lot of black carbon build up from its 500 mile run in period.
It’s all up and running again and other than it no longer has any coolant issues it’s still running just as sick as it was!.
It still has an obvious misfire from cold that quietens down after about 40 secs but even once fully warm still has an off beat miss and high emissions and un burnt fuel out the tail pipe.
The idle still shoots up to 2k from cold and takes longer than it should to settle to a steady idle and also when warm on the over run just below auto box lock up when I let my foot fully off the gas the revs drop quickly as I’d expect but after around 3 secs they bounce back up by 300rpm and it feels like it’s revving too high and pushing the car along?
Still feels like an air leak to me but I’m flummoxed for wherebit could be from!!
It drives ok with good midrange and (for an old rangie) flies up to 5.5k given a foot full.
The header temps checked from cold start up are around 350 degrees c for all cyls except 3&4 which seem to stay around 50% of the others until fully warm.
I’ve tested (and swapped for good measure) the fuel rail and injectors, tested ignition and swapped cap/ leads.
Plugs look very rich on the plug body with approx half the circumference of the white insulator on each plug black and the other half white?
I’ve tried 3 fuel maps- the cars correct 4.2 cat map, the 3.9 non cat map and the 4.2 non cat map with 2 separate ecus, used a spare air flow meter for the non cat map tests which I adjusted while running and none altered the misfire or emissions.
On all maps in rover gauge the idle valve shows fully closed or thereabouts until fully warm when it creeps up to 10% at most, air flow shows around 30% and throttle 5% lambdas show to be cycling although I forgot to look at the long term trim, short when hot had one bank adding 30% the other taking away 10%.
I’m something is causing a misfire which is throwing out the lambdas but I had hoped running the non cat map might make diagnosis simpler..
I’m now at my wits end and about to tear the damn thing apart and fit a different cam because I can’t think of anything else. Genuine 4.2 cams are NLA so I’m stuck with a choice of a crappy cheap one or attempting to choose another performance one in the hope it works with the engine spec.
if anyone can come up with any good ideas I’d really appreciate it!
I forgot to say- I also checked the base idle which if done slowly I could get down to around 400 before it stalled but I set it to around 550, twas a little bouncy due to the miss but what surprised me was that It only had a gnats cock more than one turn left before the screw bottomed out. That seems like a tiny amount of air for an engine to run on??
I also pulled the throttle plate apart and fitted a new rubber seal on the shaft behind the linkage to cure the leak that the smoke test had shown and checked throttle plate closure.
I also read something on the web about blocking the afm flow to see if it affected idle so I slowly slid my hand across the front of it and at half way across the engine stalled, not entirely sure what that proves though..
I also pulled the throttle plate apart and fitted a new rubber seal on the shaft behind the linkage to cure the leak that the smoke test had shown and checked throttle plate closure.
I also read something on the web about blocking the afm flow to see if it affected idle so I slowly slid my hand across the front of it and at half way across the engine stalled, not entirely sure what that proves though..
Thanks guys.
Your input is appreciated!
I did try some neon spark testers and while I doubt they will show any variation in intensity they do show all pots getting a spark. The fact it runs worse cold and sounds very nearly right once warm led me away from a spark problem but knowing my luck it could just as well be..
All 8 plugs look much the same with only no. 7 looking ever so slightly red?
I’ll have a look around for colour tunes. I used to have one 30 years ago.
I did a compression test again and annoyingly there’s a bit of variation between cylinders but the two suspect ones are showing 170 psi so surely it can’t be a compression/ valve problem?
The one test I didn’t do on the fuel side was a flow rate check but I have some calibrated vessels now so I’ll try to rig them up in some kind of splash proof way at the weekend and check their flow and see what their spray pattern looks like.
I’ve taken the inlet manifold back off in the hope of finding signs of an air leak but other than slicing my index finger open on it there it looks to have been equally compressed with no obvious leak. In fact after the head/ block work I half expected the manifold to not fit properly but the bolts line up perfectly dead center to the holes which they never did before, they were a real cow to get in last time!
I’ll try to upload a pic of the plugs
Thanks again!
Your input is appreciated!
I did try some neon spark testers and while I doubt they will show any variation in intensity they do show all pots getting a spark. The fact it runs worse cold and sounds very nearly right once warm led me away from a spark problem but knowing my luck it could just as well be..
All 8 plugs look much the same with only no. 7 looking ever so slightly red?
I’ll have a look around for colour tunes. I used to have one 30 years ago.
I did a compression test again and annoyingly there’s a bit of variation between cylinders but the two suspect ones are showing 170 psi so surely it can’t be a compression/ valve problem?
The one test I didn’t do on the fuel side was a flow rate check but I have some calibrated vessels now so I’ll try to rig them up in some kind of splash proof way at the weekend and check their flow and see what their spray pattern looks like.
I’ve taken the inlet manifold back off in the hope of finding signs of an air leak but other than slicing my index finger open on it there it looks to have been equally compressed with no obvious leak. In fact after the head/ block work I half expected the manifold to not fit properly but the bolts line up perfectly dead center to the holes which they never did before, they were a real cow to get in last time!
I’ll try to upload a pic of the plugs
Thanks again!
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