Its not a happy engine
Discussion
Really need some help.
I've roller bearing'd the throttle bodies. Easy enough. All nicely operational without any of the previous slack or play. Am using the same throttle pots as before. Have tried a new set and have switched back to the old ones while i'm tinkering and struggling. Rest of setup is the same as before except cleaner of course.
Have connected the air temp sensor while I balance it (or try to
)
So after lots of messing around and resetting throttles via s/w and resetting maps, i'm at the point of wondering if something is wrong (so are my neigbours)
Engine is hot (raher too hot for my liking...dont think the cats are happy they smell hot). I start it with no throttle having set a "best guess" idle and adjusted the butterflies so they are nominally the same...i.e. *just* open. Revs jump right up to 1500 to 2000 or so, sit there for 5 secs then on their own, drop back to 1000 or so.
Then it gets lumpy and starts popping through the throttle bodies quite regularly. If I blip the throttle it picks up quickly but it sounds pretty rough (sort of a gruff sound and exhaust note sounds wrong)
Then, idle stabilises but then tends to die away until almost stalling, then suddenly picks up to around 1000 and sits for while sounding sort of horrible but not terminal, then slowly dies again.
All the time there are numerous pops from the throttles. Seems to come from all of them at random, although at one point I had it mostly on cyl 4 to 6.
On diags, throttles are about 15% each (within a %) and adaptives are still at 0.4% each bank I guess because the adaptives take a while to adapt. Lambdas both seem to be outputting values at idle I recall 0.11V ish both sides.
Using a synchrometer when it staying fairly steady it seems to be reasonably balanced, pulling around 18-20 on all cyls at 1000rpm.
Have crudely tried the balance adjustment sequence, but the balance seems close enough and the idle is so erratic that its hard to know what to do next. They seem close, and each time I reset the throttles in the s/w just to make sure, but i'm not converging on a nice running engine.
So, i'm baffled ! Why does it sound so rough, why does it idle up after I start and have I broken something ?
BTW: Was "fine" before I fiddled...except some good candidate symptoms for worn throttles like stutter on light throttle and slight high-end misfire under load.
BTW BTW: One thing I did do differently...I used a paper gasket under each body where before there was none (cut on a plot-cutter using thin "car spares shop" gasket material perhaps 0.2mm thick or so)
Is it time to panic or does it all just need to cool off and be tried again ?
I've roller bearing'd the throttle bodies. Easy enough. All nicely operational without any of the previous slack or play. Am using the same throttle pots as before. Have tried a new set and have switched back to the old ones while i'm tinkering and struggling. Rest of setup is the same as before except cleaner of course.
Have connected the air temp sensor while I balance it (or try to
)So after lots of messing around and resetting throttles via s/w and resetting maps, i'm at the point of wondering if something is wrong (so are my neigbours)
Engine is hot (raher too hot for my liking...dont think the cats are happy they smell hot). I start it with no throttle having set a "best guess" idle and adjusted the butterflies so they are nominally the same...i.e. *just* open. Revs jump right up to 1500 to 2000 or so, sit there for 5 secs then on their own, drop back to 1000 or so.
Then it gets lumpy and starts popping through the throttle bodies quite regularly. If I blip the throttle it picks up quickly but it sounds pretty rough (sort of a gruff sound and exhaust note sounds wrong)
Then, idle stabilises but then tends to die away until almost stalling, then suddenly picks up to around 1000 and sits for while sounding sort of horrible but not terminal, then slowly dies again.
All the time there are numerous pops from the throttles. Seems to come from all of them at random, although at one point I had it mostly on cyl 4 to 6.
On diags, throttles are about 15% each (within a %) and adaptives are still at 0.4% each bank I guess because the adaptives take a while to adapt. Lambdas both seem to be outputting values at idle I recall 0.11V ish both sides.
Using a synchrometer when it staying fairly steady it seems to be reasonably balanced, pulling around 18-20 on all cyls at 1000rpm.
Have crudely tried the balance adjustment sequence, but the balance seems close enough and the idle is so erratic that its hard to know what to do next. They seem close, and each time I reset the throttles in the s/w just to make sure, but i'm not converging on a nice running engine.
So, i'm baffled ! Why does it sound so rough, why does it idle up after I start and have I broken something ?
BTW: Was "fine" before I fiddled...except some good candidate symptoms for worn throttles like stutter on light throttle and slight high-end misfire under load.
BTW BTW: One thing I did do differently...I used a paper gasket under each body where before there was none (cut on a plot-cutter using thin "car spares shop" gasket material perhaps 0.2mm thick or so)
Is it time to panic or does it all just need to cool off and be tried again ?
You've done nothing wrong. I had the same probs with mine, 5 & 6 were the problem two. No matter what I did with the adjusters it made no difference. Persist with the tune starting with the centre (3) pot, make sure you have fitted the small springs between the adjusters. The popping is just the bodies being out of sync, even after adjusting, manually accelerate with the sync meter on the individual pot and note when it increases. Mine balanced fine but I found when I accelerated the outer pots were a bit lazy through the linkages so a little tweaking was necessary. Remember, if say 5 can’t be brought down or up, adjusting 6 or 4 will have some effect on 5. It's hard to explain but quite easy to do when you know how.
Rob
Rob
OK, thanks I think it must be "fixable" I'm just so puzzled by how far out it all seems.
One other complication...when I started out this morning I had a flat battery...had forogtten to switch my charger on for several weeks of non-use
I seem to recall that this can play havoc with the ECU and idle quality even if you give it a bit of charge up.
One other complication...when I started out this morning I had a flat battery...had forogtten to switch my charger on for several weeks of non-use
I seem to recall that this can play havoc with the ECU and idle quality even if you give it a bit of charge up.
Had the same problems dont worry 
Scares the sh!t out of you when you see popping under the throttle bodies.
You get yourself into a loop and end up resetting throttle body positions, then adjusting again and you end up with the wrong AFR. Your pulling too much air.
Close the throttles right back down, you should hardly be able to see a gap at all. Reset throttle pots and adaptives. Start up, revs will shot up, then come back down - a result of the reset. You should then go through the balancing, should be pulling 6-8 through the synchrometer.
It can be disheartening and unnerving but you will get there.
Took me about 4 hours running on the drive. I was close to giving up at a few points until i realised what i was doing. it all comes with experience i guess....and im far from experienced!!
Hope it goes better tomorrow...
edited to say do it in order, starting at the one with the throttle linkage on, then no 2, towards the front of the engine, then no 1. Then do no 4, then 5, lastly 6.
Then adjust the idle, but remembering the air should be arouns 6-8 ish.
Im sure someone has a better explanation on this but my engine seems to be running very well now.
Scares the sh!t out of you when you see popping under the throttle bodies.
You get yourself into a loop and end up resetting throttle body positions, then adjusting again and you end up with the wrong AFR. Your pulling too much air.
Close the throttles right back down, you should hardly be able to see a gap at all. Reset throttle pots and adaptives. Start up, revs will shot up, then come back down - a result of the reset. You should then go through the balancing, should be pulling 6-8 through the synchrometer.
It can be disheartening and unnerving but you will get there.
Took me about 4 hours running on the drive. I was close to giving up at a few points until i realised what i was doing. it all comes with experience i guess....and im far from experienced!!
Hope it goes better tomorrow...
edited to say do it in order, starting at the one with the throttle linkage on, then no 2, towards the front of the engine, then no 1. Then do no 4, then 5, lastly 6.
Then adjust the idle, but remembering the air should be arouns 6-8 ish.
Im sure someone has a better explanation on this but my engine seems to be running very well now.
Edited by Robertjp on Saturday 13th February 18:02
The more air your pulling the less sensive the syncrometer is. As Rob says you should be seeing around 7-8 with the idle set correctly (900-950). The number does not really matter its just that they are all the same. aim for +-0! Keep resetting tps and adaptives each time you do a throttle working from the middle out. Always ref back to the number 3 throttle.
Just been having a play with the diagnostic sw ready for next onslought on sat
Noticed that injector timing for the two banks are pretty different to each other even with adaptives at zero after reset
If I log while slowly opening throttle I can see the inj timings and they are same profile just one is a scaled version of the other
Normal ?
Also with 'sensible' amount of butterfly opening i see about 11% on both banks
Again...normal ?
Noticed that injector timing for the two banks are pretty different to each other even with adaptives at zero after reset
If I log while slowly opening throttle I can see the inj timings and they are same profile just one is a scaled version of the other
Normal ?
Also with 'sensible' amount of butterfly opening i see about 11% on both banks
Again...normal ?
Today's update...still not great
Played a bit this morning and reached the conclusion no amount of fooling was going to get it right.
BANK123 definately not happy...cat gets visibly hot. Not letting it run for too long as a result.
Even revving it a bit and holding at 2K sounds grim with throttles reasonable close to same value. All sort of angry and rough.
One interesting thing I noticed...the throttle pot reading with engine off bears no resemblance to the reading with the engine running but with no throttle applied. Answers to why greatfully received.
Spoke to SRT8SIX (thanks for advice guys). They gave me some check points but all are OK. They did however advise against the paper gasket under the throttle faces. Blue Hylomar apparantly. I'd used no sealant at all, just the gaskets.
So have just stripped it all down again, removed the gaskets and refitted with Blue Hylomar.
All back togther now.
Just fired it up to see it is any different. Gut feel was it sounded a little happier (pre tuning). Perhaps I had some air leak around the gaskets. They were wet with petrol on removal...not a good sign me thinks.
Tomorrow I'll have a proper stab at setting it up.
This is turning into a bit of mare ! I have visions of sticking it on a transporter and handing to RG to let them sort it out. But not quite beaten yet.
Played a bit this morning and reached the conclusion no amount of fooling was going to get it right.
BANK123 definately not happy...cat gets visibly hot. Not letting it run for too long as a result.
Even revving it a bit and holding at 2K sounds grim with throttles reasonable close to same value. All sort of angry and rough.
One interesting thing I noticed...the throttle pot reading with engine off bears no resemblance to the reading with the engine running but with no throttle applied. Answers to why greatfully received.
Spoke to SRT8SIX (thanks for advice guys). They gave me some check points but all are OK. They did however advise against the paper gasket under the throttle faces. Blue Hylomar apparantly. I'd used no sealant at all, just the gaskets.
So have just stripped it all down again, removed the gaskets and refitted with Blue Hylomar.
All back togther now.
Just fired it up to see it is any different. Gut feel was it sounded a little happier (pre tuning). Perhaps I had some air leak around the gaskets. They were wet with petrol on removal...not a good sign me thinks.
Tomorrow I'll have a proper stab at setting it up.
This is turning into a bit of mare ! I have visions of sticking it on a transporter and handing to RG to let them sort it out. But not quite beaten yet.
Well, kept at it and didnt need to call that number (thanks anyway SP6Animal).
Here's what I found
Remebered Robertjp's advice "to close them right down". So I did, literally. Manually balanced them so no slack in the pickup of all adjuster screws, but almost all closed to the point where a 2thou feeler gage *just* catches under the bufferfly bottom edge...and I mean just...you cant actually pass it underneath. I also "joggled" the various butterflies to ensure they are nicely centralised and no stick at the point of fully closed (if the butterfly is marginally off centre it can tend to catch the aluminium (very slight, but figured I dont want any more unknowns).
BIG difference. After starting it just sounded better and I'm within a spit of 7 KG/h on each throttle. Progress !
So I get it warm and keep playing. I eventually find that I can get it close but never quite right...cyl456 always pulling a more air (perhaps 9ish). And the screws on 456 are all "off the end" so no more adjustment range left to let them close under the action of the springs. Sure, I can get them all back in range by adjusting the main idle stop, but then I have all cyls pulling more like 10-ish...too high. Pops and grumpyness are back.
A closer inspection shows the reason. Its a bit of a design flaw I guess. The balance spring on cyl4 pushes against the main throttle arm trying to push butterfly 4 shut. No prob. If you take out the balance springs in 5 and 6 then butterfly 4 closes fully. Even the 2thou guage wont even catch. Put back the springs in 5 & 6 and now its not quite shut, 2 thou will easily go underneath...because cyl6 bufferfly is fully closed (return spring in throttle pot) and hence these last 2 springs are effectively pushing "back" and beating the one spring on 4. On the other bank of course there is no prob...there's no spring for cyl3, its right on the arm.
So I get my adventurous head on and find just the right dia spring but lots stiffer. Pop that into 4. Use the original in 5 and slightly weaker spring in 6 (good job I have a supply of useful stuff from previous jobs!). Hey preseto. All butterflies nicely closed.
Off we go again. Now we're talking. All cyls pulling about 7.5 to 8. Idles pretty smooth. Keep resetting the adaptives and pots. It'll sit at 850-900 no problem. Very occasional "twitch" from engine but nothing significant IMO.
Check the throttle balance at 2-3K...within 1 to 2%.
Here's the interesting thing. At light throttle, perhaps 20% on readout...still well matched BUT there are loads of little pops and flashes in the bodies. Almost like its overfueling. Wonder if this is root cause of the "light throttle stutter"
So now to drive it and see if the adaptives settle it down over time.
Edited to say:
Hmmm...not great. Throttle is rather on-off. Coughs a bit if you apply sudden throttle. Pulls hard under limited test. Idle now seems to want to sit at nearly 1200 :-( If I reset the throttles it drops to 850 then slowly creeps back to 1200. Weird ! Also can hear a few tell-tale "chuffs" from under the bonnet...a hint of popping. As expect light throttle is quite lumpy.
Logged a bit of data. All looks quite sensible. See below.
Here's what I found
Remebered Robertjp's advice "to close them right down". So I did, literally. Manually balanced them so no slack in the pickup of all adjuster screws, but almost all closed to the point where a 2thou feeler gage *just* catches under the bufferfly bottom edge...and I mean just...you cant actually pass it underneath. I also "joggled" the various butterflies to ensure they are nicely centralised and no stick at the point of fully closed (if the butterfly is marginally off centre it can tend to catch the aluminium (very slight, but figured I dont want any more unknowns).
BIG difference. After starting it just sounded better and I'm within a spit of 7 KG/h on each throttle. Progress !
So I get it warm and keep playing. I eventually find that I can get it close but never quite right...cyl456 always pulling a more air (perhaps 9ish). And the screws on 456 are all "off the end" so no more adjustment range left to let them close under the action of the springs. Sure, I can get them all back in range by adjusting the main idle stop, but then I have all cyls pulling more like 10-ish...too high. Pops and grumpyness are back.
A closer inspection shows the reason. Its a bit of a design flaw I guess. The balance spring on cyl4 pushes against the main throttle arm trying to push butterfly 4 shut. No prob. If you take out the balance springs in 5 and 6 then butterfly 4 closes fully. Even the 2thou guage wont even catch. Put back the springs in 5 & 6 and now its not quite shut, 2 thou will easily go underneath...because cyl6 bufferfly is fully closed (return spring in throttle pot) and hence these last 2 springs are effectively pushing "back" and beating the one spring on 4. On the other bank of course there is no prob...there's no spring for cyl3, its right on the arm.
So I get my adventurous head on and find just the right dia spring but lots stiffer. Pop that into 4. Use the original in 5 and slightly weaker spring in 6 (good job I have a supply of useful stuff from previous jobs!). Hey preseto. All butterflies nicely closed.
Off we go again. Now we're talking. All cyls pulling about 7.5 to 8. Idles pretty smooth. Keep resetting the adaptives and pots. It'll sit at 850-900 no problem. Very occasional "twitch" from engine but nothing significant IMO.
Check the throttle balance at 2-3K...within 1 to 2%.
Here's the interesting thing. At light throttle, perhaps 20% on readout...still well matched BUT there are loads of little pops and flashes in the bodies. Almost like its overfueling. Wonder if this is root cause of the "light throttle stutter"
So now to drive it and see if the adaptives settle it down over time.
Edited to say:
Hmmm...not great. Throttle is rather on-off. Coughs a bit if you apply sudden throttle. Pulls hard under limited test. Idle now seems to want to sit at nearly 1200 :-( If I reset the throttles it drops to 850 then slowly creeps back to 1200. Weird ! Also can hear a few tell-tale "chuffs" from under the bonnet...a hint of popping. As expect light throttle is quite lumpy.
Logged a bit of data. All looks quite sensible. See below.
Edited by PetrolHeadPete on Sunday 21st February 14:54
Did your throttle pots need a reset when you got back from your drive? Maybe they need replacing if they did?
My idle changes as she gets hot, settles at 900 when warm, slightly less 750 ish when cold.
Otherwise im all out of ideas! Would recommend Str8 six over RG, personal opinion from experience
My idle changes as she gets hot, settles at 900 when warm, slightly less 750 ish when cold.
Otherwise im all out of ideas! Would recommend Str8 six over RG, personal opinion from experience
If it's stumbling when you open the throttle and popping it sounds like too much air getting in for the measured throttle opening, so your adaptives are increasing to compensate and your idle is going up. Are you sure you've got all the vacuum hoses etc properly attached, and all your injector O rings etc are sealing?
Have you had a look at the plugs at all?
Have you had a look at the plugs at all?
My current theory is i've gone too far the other way and the throttles are all virtually closed, not really controlled by the idle speed screw, more resting closed hence subject to expansion effects as they heat up. If I bias them all open a tad using the main screw and then reset throttles and adaptives, I wonder if it will all settle back down to a proper operating point with about the right airflow ? BTW: When I reset the adaptives the revs drop back immediately to 850 but then slowly climb back to 1100-1200. Also on starting from hot, the revs seem to come right up to 1100, then drop down to "normal" but then slowly creep back up.
Thoughts on this theory ? Has anyone got their throttles in view at the moment so they could feeler guage the bottom edge of a butterfly to see just how open they should be.
Guess there's not much else left. All the vac pipe are in place, the balance/scavenge pipes are there and I checked there are no blockages etc. When it idles its fine. The tendency for step between off throttle and on throttle also imples to me that the butterflies at resting "shut" and dont cleanly and smoothly open for exactly this reason, they need to be biased a little more open.
Checked the butterfly closures again last night and I'd reckon the bottom edge of them is no more than 1thou, if that. They're virtually shut.
Thoughts on this theory ? Has anyone got their throttles in view at the moment so they could feeler guage the bottom edge of a butterfly to see just how open they should be.
Guess there's not much else left. All the vac pipe are in place, the balance/scavenge pipes are there and I checked there are no blockages etc. When it idles its fine. The tendency for step between off throttle and on throttle also imples to me that the butterflies at resting "shut" and dont cleanly and smoothly open for exactly this reason, they need to be biased a little more open.
Checked the butterfly closures again last night and I'd reckon the bottom edge of them is no more than 1thou, if that. They're virtually shut.
PetrolHeadPete said:
My current theory is i've gone too far the other way and the throttles are all virtually closed, not really controlled by the idle speed screw, more resting closed hence subject to expansion effects as they heat up. If I bias them all open a tad using the main screw and then reset throttles and adaptives, I wonder if it will all settle back down to a proper operating point with about the right airflow ? BTW: When I reset the adaptives the revs drop back immediately to 850 but then slowly climb back to 1100-1200. Also on starting from hot, the revs seem to come right up to 1100, then drop down to "normal" but then slowly creep back up.
Thoughts on this theory ? Has anyone got their throttles in view at the moment so they could feeler guage the bottom edge of a butterfly to see just how open they should be.
Guess there's not much else left. All the vac pipe are in place, the balance/scavenge pipes are there and I checked there are no blockages etc. When it idles its fine. The tendency for step between off throttle and on throttle also imples to me that the butterflies at resting "shut" and dont cleanly and smoothly open for exactly this reason, they need to be biased a little more open.
Checked the butterfly closures again last night and I'd reckon the bottom edge of them is no more than 1thou, if that. They're virtually shut.
That would hold true with the 'on-off' phenomenom with the throttle - maybe they are sticking slightly? If they are balanced i dont think opening it up a little on the idle screw makes that much difference, there should be an AFR range in which it will run well. Im afraid i cant get to mine to check - all under the bonnet and in the garage. As i said, my idle does change but not something i am worried about cause my change is from 700 to 900 - not the kind of change you have here. But, hey maybe mine are a little too closed as well. Thoughts on this theory ? Has anyone got their throttles in view at the moment so they could feeler guage the bottom edge of a butterfly to see just how open they should be.
Guess there's not much else left. All the vac pipe are in place, the balance/scavenge pipes are there and I checked there are no blockages etc. When it idles its fine. The tendency for step between off throttle and on throttle also imples to me that the butterflies at resting "shut" and dont cleanly and smoothly open for exactly this reason, they need to be biased a little more open.
Checked the butterfly closures again last night and I'd reckon the bottom edge of them is no more than 1thou, if that. They're virtually shut.
Are your adaptives still getting up to the +26 values shown on the screen above? If so and resetting your adaptives whilst not changing anything else causes your idle to drop then I reckon it's getting too much air at idle from somewhere. The adaptives are then coming back up based on the Lambda readings compensating for the weak mixture and bringing your idle back up.
If they are not then please ignore this.
If they are not then please ignore this.
Basil Brush said:
Are your adaptives still getting up to the +26 values shown on the screen above? If so and resetting your adaptives whilst not changing anything else causes your idle to drop then I reckon it's getting too much air at idle from somewhere. The adaptives are then coming back up based on the Lambda readings compensating for the weak mixture and bringing your idle back up.
If they are not then please ignore this.
So the two adaptive maps both look very similar on each bank and the adaptives are only non-zero for idle speeds that are above 1000 rpm or so.If they are not then please ignore this.
Sounds like pops and flashes are generally over-lean mixture ? Guess that makes sense...too hot and causes ignition in the throttles.
Having slept on it (not literally) I think I changed my mind. Pops and flashed must surely come from over rich mixture. That would tend to leave unburnt fuel in the exhaust, explaining the hot cat, the stink of petrolly exhaust, and the reason why the excess fuel can tend to ignite around the inlet valves as the "wasted" 2nd spark during exhaust cycle.
Overfuelling would explain a lot. And during the first attempt at tuning when it was really grumpy, the plugs were black fouled and wet.
Thoughts ?
Overfuelling would explain a lot. And during the first attempt at tuning when it was really grumpy, the plugs were black fouled and wet.
Thoughts ?
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