350i misfire - the return....
Discussion
Hi Mark, yes misfire from early in the year was traced to a knackered coil. Replaced that and it ran without issues until Millbrook. I followed my mate in his S2 over to the Shuttleworth collection on the Saturday for 140 miles, at pretty much full revs in every gear and it ran perfectly. It was as we left Millbrook on the Sunday that it started playing up although it did splutter a bit on the second flat out run down the 1 mile straight earlier in the day.
Misfire does not occur when the engine is cold. As the engine warms up it occasionally and randomly "coughs" for a split second. It coughs more regularly the hotter the engine gets. It feels as if all power is dying and then instantly is fine again. It is very random, not rev or load related or cornering related. I could drive for a couple of miles and nothing and then a cough, and then it could be 100 yards or 2 miles before the next time.
I've checked all electrical contacts and cleaned them with pukka electrical contact cleaner. It's had a new fuel pump and pressure does not vary when engine coughs, instruments do not appear to twitch, cough is there with old and new HT leads, with old and new ignition amp, with old and new coil, with old and new CTS, thermo time, and no difference with remade section of wiring loom.
The interesting fact is that when the new PowerSpark dissy went in, all was good for about 3 weeks and then the misfire came back. As I know it's not the ignition amp then maybe it is the dissy pick up? More head scratching needed. Cheers.
Misfire does not occur when the engine is cold. As the engine warms up it occasionally and randomly "coughs" for a split second. It coughs more regularly the hotter the engine gets. It feels as if all power is dying and then instantly is fine again. It is very random, not rev or load related or cornering related. I could drive for a couple of miles and nothing and then a cough, and then it could be 100 yards or 2 miles before the next time.
I've checked all electrical contacts and cleaned them with pukka electrical contact cleaner. It's had a new fuel pump and pressure does not vary when engine coughs, instruments do not appear to twitch, cough is there with old and new HT leads, with old and new ignition amp, with old and new coil, with old and new CTS, thermo time, and no difference with remade section of wiring loom.
The interesting fact is that when the new PowerSpark dissy went in, all was good for about 3 weeks and then the misfire came back. As I know it's not the ignition amp then maybe it is the dissy pick up? More head scratching needed. Cheers.
mrzigazaga said:
Does it happen at a particular rev range and does it rev passed it or is it like a wall?..
Quite - mine has a slight cough or murmur when cruising at 1500 rpm - maybe 1 in 20 or 30 beats. And not enough to shake to propshaft or anything. But because it goes away on full chat WOT I ignore it. Life's too short, as they say.Keith...Do you have a new distributor or just a pick up in the old unit....There is a lot of difference in quality between the original units and the powerspark ones available, I guess components are sourced cheaply from cheapville but we still pay a premium...Thus causing parts to fail more often due to incompatibility with the existing components, Which are of better quality and the use of shyte materials...
I generally use land rover sites and companies like Britpart for my bits..ANG are okay but there is a lot of poo out there unfortunately...I wonder what TVR parts have in their stocks...Looks like a powerspark unit...A friend of mine changed the pick up in the old dizzy but after buying a complete dizzy kit with coil..Amp and rotor arm he never got round to testing it...I might give it a go on mine but do not want to start introducing potential problems...
I generally use land rover sites and companies like Britpart for my bits..ANG are okay but there is a lot of poo out there unfortunately...I wonder what TVR parts have in their stocks...Looks like a powerspark unit...A friend of mine changed the pick up in the old dizzy but after buying a complete dizzy kit with coil..Amp and rotor arm he never got round to testing it...I might give it a go on mine but do not want to start introducing potential problems...
Hi Keith...Just spoke to a mate who had a headache of a mis-fire when his got up to temp...Cold it was fine...Turned out his ECU needed rebuilding...My guess is that this could be your issue too...
Not sure that putting in another borrowed ECU is worth doing unless its a known good one...There is a company called BBA-Reman, Okay they are in my neck of the woods but they can test it first to see if its faulty, They are not the type of firm who would say it is nadgered just to get the work...
I do remember reading a Range Rover bulletin that stated one of the main components that will fail on the efi system over time IS the ECU...AND it is recommended to have it rebuilt...My friends 350i is now hard to keep up with...He said he is using less fuel but has more power and it drives faultlessly...
It cost £200 plus postage and has been totally rebuilt and has a 25 year guarantee ...Whats not to like......
Might be worth a call
https://www.google.co.uk/url?sa=t&rct=j&q=...
Not sure that putting in another borrowed ECU is worth doing unless its a known good one...There is a company called BBA-Reman, Okay they are in my neck of the woods but they can test it first to see if its faulty, They are not the type of firm who would say it is nadgered just to get the work...
I do remember reading a Range Rover bulletin that stated one of the main components that will fail on the efi system over time IS the ECU...AND it is recommended to have it rebuilt...My friends 350i is now hard to keep up with...He said he is using less fuel but has more power and it drives faultlessly...
It cost £200 plus postage and has been totally rebuilt and has a 25 year guarantee ...Whats not to like......
Might be worth a call
https://www.google.co.uk/url?sa=t&rct=j&q=...
Hi Mark, yesterday I picked up a known good ECU from a guy with a Rover 3.5V8 EFi mounted in a Stag. He's rebuilt an original Triumph engine so is putting that back in. I got the AFM and ECU off him.
Swapped the ECU tonight and I've been for a 30 minute blast down the lanes and no difference. Random cough is still there every few miles. Tomorrow night I'll swap the AFM out of curiosity.
Would the TPS potentially cause this sort of issue? If the carbon track is worn and the actual circuit is broken as the throttle moves about would this give a signal to the ECU that could result in a soplit second shutdown of power? Just a straw to clutch at? I've got a spare over with the 390SE so I could give that a try also?
Swapped the ECU tonight and I've been for a 30 minute blast down the lanes and no difference. Random cough is still there every few miles. Tomorrow night I'll swap the AFM out of curiosity.
Would the TPS potentially cause this sort of issue? If the carbon track is worn and the actual circuit is broken as the throttle moves about would this give a signal to the ECU that could result in a soplit second shutdown of power? Just a straw to clutch at? I've got a spare over with the 390SE so I could give that a try also?
Its possible but realistically its best to test the TPS across the range of operation, Not sure of the values but someone will know them.. ...If you have a spare then give it a try...Failing that i have a good working spare you could borrow.
However looking at your post from February i would have a closer look at the dizzy as the internals are probably sourced from Korea or China and most of the original parts on ours are Lucas or Bosch genuine parts which are obviously better quality which can cause an incompatibility in some cases with new inferior parts...Lets be honest here most of the components on our cars have lasted nearly 30 years...Some of the new parts that people have fitted have lasted all but 2...Some only a week!...
Just seems strange that you had a mis-fire...Changed the distributor as it was made of jelly...Mis-fire goes...Happy days....6 months or so later back to where you were 6 or so months ago....My thought finger would be pointing in that direction......Possibly......
However looking at your post from February i would have a closer look at the dizzy as the internals are probably sourced from Korea or China and most of the original parts on ours are Lucas or Bosch genuine parts which are obviously better quality which can cause an incompatibility in some cases with new inferior parts...Lets be honest here most of the components on our cars have lasted nearly 30 years...Some of the new parts that people have fitted have lasted all but 2...Some only a week!...
Just seems strange that you had a mis-fire...Changed the distributor as it was made of jelly...Mis-fire goes...Happy days....6 months or so later back to where you were 6 or so months ago....My thought finger would be pointing in that direction......Possibly......
mrzigazaga said:
Its possible but realistically its best to test the TPS across the range of operation, Not sure of the values but someone will know them.. ...If you have a spare then give it a try...Failing that i have a good working spare you could borrow.
However looking at your post from February i would have a closer look at the dizzy as the internals are probably sourced from Korea or China and most of the original parts on ours are Lucas or Bosch genuine parts which are obviously better quality which can cause an incompatibility in some cases with new inferior parts...Lets be honest here most of the components on our cars have lasted nearly 30 years...Some of the new parts that people have fitted have lasted all but 2...Some only a week!...
Just seems strange that you had a mis-fire...Changed the distributor as it was made of jelly...Mis-fire goes...Happy days....6 months or so later back to where you were 6 or so months ago....My thought finger would be pointing in that direction......Possibly......
Mark, yes agree with you. I've got the spare TPS and AFM so it's a 10 minute swap when I get in from work tomorrow, after I've dropped off the new camshaft kit to the garage for the 390SE! I've got a couple of older dissys so will pull them apart to try and get a decent spare one and I'll give it a test powered up but not installed in-situ by spinning the end drive to check the spark. If it looks like it's behaving them I'll drop it in to see if any difference.However looking at your post from February i would have a closer look at the dizzy as the internals are probably sourced from Korea or China and most of the original parts on ours are Lucas or Bosch genuine parts which are obviously better quality which can cause an incompatibility in some cases with new inferior parts...Lets be honest here most of the components on our cars have lasted nearly 30 years...Some of the new parts that people have fitted have lasted all but 2...Some only a week!...
Just seems strange that you had a mis-fire...Changed the distributor as it was made of jelly...Mis-fire goes...Happy days....6 months or so later back to where you were 6 or so months ago....My thought finger would be pointing in that direction......Possibly......
Right, a positive update:
Good AFM fitted - no change still misfiring.
Good TPS fitted - also no change.
Then spent an hour dissecting three broken dissys to make one okay one. Took the good pick up from my old one, plus a three pin amp from a second and managed to bolt them in a third dissy with good bearings but blown electronics. Swapped the almost new PowerSpark dissy out with the cobbled together unit and guess what - no bloody misfire! I've thrashed it around the lanes for 30 minutes and all is good, apart from the timing being a little out. I'll take it to the office for a good run tomorrow but it certainly feels back to normal. I may well give Simon at PowerSpark a call in the morning.........
I'm now on the hunt for a GOOD original second hand unit. Anyone got one going spare?
Good AFM fitted - no change still misfiring.
Good TPS fitted - also no change.
Then spent an hour dissecting three broken dissys to make one okay one. Took the good pick up from my old one, plus a three pin amp from a second and managed to bolt them in a third dissy with good bearings but blown electronics. Swapped the almost new PowerSpark dissy out with the cobbled together unit and guess what - no bloody misfire! I've thrashed it around the lanes for 30 minutes and all is good, apart from the timing being a little out. I'll take it to the office for a good run tomorrow but it certainly feels back to normal. I may well give Simon at PowerSpark a call in the morning.........
I'm now on the hunt for a GOOD original second hand unit. Anyone got one going spare?
Hi Keith...As i suspected...It won't be Simons fault...The distributor that we have originally was a points type which had electronic pick ups put into it..You will have a job finding one...This is why i was hoping that my friend would fit the old dizzy that he fitted a new pick up in as i wanted to know the outcome....He bought a kit off of Simon..Dizzy...Rotor arm...Cap...Coil and all is fine so never bothered.
The components inside the new ones are cheap....Same issue with a lot of things these days....Like i always say.."False economy"...I bet that the amount of returns that companies get selling these parts outweighs their satisfied sales...They may be cheap on the manufacturing but all the money they save goes on wasted postage and replacements...When will this country learn...FFS!!!
Glad you have a positive post...And a silly grin again....
The components inside the new ones are cheap....Same issue with a lot of things these days....Like i always say.."False economy"...I bet that the amount of returns that companies get selling these parts outweighs their satisfied sales...They may be cheap on the manufacturing but all the money they save goes on wasted postage and replacements...When will this country learn...FFS!!!
Glad you have a positive post...And a silly grin again....
Problem we seem to have these days is there is no middle ground, its either cheap rubbish normally made in china. of mega expensive and over engineered.
Its a shame as the cheap stuff is normally just a fraction too cheap, and just a few extra $$ and a little attention to detail would make it great.
problem if there is a copy for $45 and one for $50 your buy the $45 as your assume they are both just the same thing.
2nd problem someone else make one for $44 to undercut and cut another corner. and before you know it they are $20 and only last as long as it take to pass the CC test.
What I end up doing is buy the cheapest, and then remove the important parts and then replace them with high quality ones. like the bearing etc. so you end up with a hybird part.
Its a shame as the cheap stuff is normally just a fraction too cheap, and just a few extra $$ and a little attention to detail would make it great.
problem if there is a copy for $45 and one for $50 your buy the $45 as your assume they are both just the same thing.
2nd problem someone else make one for $44 to undercut and cut another corner. and before you know it they are $20 and only last as long as it take to pass the CC test.
What I end up doing is buy the cheapest, and then remove the important parts and then replace them with high quality ones. like the bearing etc. so you end up with a hybird part.
Trouble is mate even the expensive parts contain shyte nowadays...I always buy the best i can but thats no guarantee...I just hope TVR parts do not go this route of cheap innards for OEM parts...I would rather pay a premium and have peace of mind..And a reliable car....
This place might be useful...
https://www.google.co.uk/url?sa=t&rct=j&q=...
This place might be useful...
https://www.google.co.uk/url?sa=t&rct=j&q=...
Edited by mrzigazaga on Friday 25th September 00:14
mrzigazaga said:
Trouble is mate even the expensive parts contain shyte nowadays...I always buy the best i can but thats no guarantee...I just hope TVR parts do not go this route of cheap innards for OEM parts...I would rather pay a premium and have peace of mind..And a reliable car....
This place might be useful...
https://www.google.co.uk/url?sa=t&rct=j&q=...
Yea some times paying more just means paying more but getting the same sThis place might be useful...
https://www.google.co.uk/url?sa=t&rct=j&q=...
Edited by mrzigazaga on Friday 25th September 00:14
t, as you would if you bought it from china, that's why the hybrid way is best, but its not possible for 95% of the people.Well after last nights success all hope is lost this morning. Wedge started okay, went a mile up the road and engine started continually coughing, misfiring and ran like a bag of nails. I'm hoping that it's just the cobbled together Frankenstein of the temporary distributor. I'll get a good second hand one sorted and take it from them.
nails. I'm hoping that it's just the cobbled together Frankenstein of the temporary distributor. I'll get a good second hand one sorted and take it from them.Keith...It could be the new amp failing...I think you are on the right track...This might help...
http://www.vintagemodelairplane.com/pages/Rover_Te...
Just out of interest what is your fuel pressure set to and have you checked the vacuum hoses and the N/S rocker breather...Have you tried it with the cold start disconnected....Have you checked the bullet connector near the AFM from the amp that goes to the ECU?....I wouldn't rule out a dodgy earth or connection...Im absolutely crud with a multimeter but testing the voltages and resistances of the amp and coil might shed some light on it...Ideally when cranked.
http://www.vintagemodelairplane.com/pages/Rover_Te...
Just out of interest what is your fuel pressure set to and have you checked the vacuum hoses and the N/S rocker breather...Have you tried it with the cold start disconnected....Have you checked the bullet connector near the AFM from the amp that goes to the ECU?....I wouldn't rule out a dodgy earth or connection...Im absolutely crud with a multimeter but testing the voltages and resistances of the amp and coil might shed some light on it...Ideally when cranked.
Edited by mrzigazaga on Friday 25th September 09:21
Spoke to PowerSpark and to be honest they couldn't have been more helpful. Full set of dissy electronics and base plate FOC posted today so I should have the package Monday. You never know - by next weekend I might have two Wedges up and running! Hope I haven't spoken too soon.........
These intermittent faults are a right bugger aren't they? It seems like you've replaced everything usual - and with the ECU loom - a bit more besides.
If it did it on command in the garage it would be much simpler to diagnose. Sometimes you just have to wait for it to get worse and more frequent until it's so obvious the fault jumps out at you.
Let's assume for now that it isn't mechanical - the valves are all going up and down OK and so are the pistons. The engine needs three things - air, fuel, spark (at the correct time). If the mechanical bit is OK we can assume it gets the air.
So this leaves fuel and spark.
So what can you do to check this on the car? The fuelling is mainly controlled by the pulses from the ECU. I have had some success attaching LED's to the injector wires so you can see the pulses while you drive. Quick and dirty is to trap the LED's under the windscreen wiper and run the wires straight up from the bonnet.
If you still get the coughing but the injector LED's are constant (they flicker but don't cut out) then you might want to move onto the spark. If you get an inductive pickup you can monitor the spark but you'll need an oscilloscope to look for dropouts. For this a portable one would be best, or a USB one with a laptop. Start with the pickup on the king lead and them move on to the individual plug leads.
Once you have an oscilloscope you can double-check the injector pulses too.
Once you've identified whether it's intermittent fuelling or intermittent ignition then you're half way there.
If it did it on command in the garage it would be much simpler to diagnose. Sometimes you just have to wait for it to get worse and more frequent until it's so obvious the fault jumps out at you.
Let's assume for now that it isn't mechanical - the valves are all going up and down OK and so are the pistons. The engine needs three things - air, fuel, spark (at the correct time). If the mechanical bit is OK we can assume it gets the air.
So this leaves fuel and spark.
So what can you do to check this on the car? The fuelling is mainly controlled by the pulses from the ECU. I have had some success attaching LED's to the injector wires so you can see the pulses while you drive. Quick and dirty is to trap the LED's under the windscreen wiper and run the wires straight up from the bonnet.
If you still get the coughing but the injector LED's are constant (they flicker but don't cut out) then you might want to move onto the spark. If you get an inductive pickup you can monitor the spark but you'll need an oscilloscope to look for dropouts. For this a portable one would be best, or a USB one with a laptop. Start with the pickup on the king lead and them move on to the individual plug leads.
Once you have an oscilloscope you can double-check the injector pulses too.
Once you've identified whether it's intermittent fuelling or intermittent ignition then you're half way there.
Thanks Adam. I've watched the fuel regulator gauge while the car is sat there occasionally "coughing" and there's not a blip on the pressure. There is absolutely not a twitch on the instruments. I have gone through the lot.
The dissy was definitely the original cause. New dissy and misfire immediately disappears. Comes back 3 weeks later. As the dissy was new I didnt think it could be the issue so changed about everything I could until last night when I swapped the dissy out again (with slightly ropey botched one) and no misfire again.
Still I'm not quite there yet so fingers crossed! Tonight when I got home I had a good look at the temporary dissy and guess what - the rotor arm again looked as if it had overheated and distorted slightly. Spare rotor arm in and all good again. I'm suspicious that these new plastic rotor arms are too sensitive to heat under the bonnets of our Wedges and the good old "bakelite" style ones are way more robust.
The dissy was definitely the original cause. New dissy and misfire immediately disappears. Comes back 3 weeks later. As the dissy was new I didnt think it could be the issue so changed about everything I could until last night when I swapped the dissy out again (with slightly ropey botched one) and no misfire again.
Still I'm not quite there yet so fingers crossed! Tonight when I got home I had a good look at the temporary dissy and guess what - the rotor arm again looked as if it had overheated and distorted slightly. Spare rotor arm in and all good again. I'm suspicious that these new plastic rotor arms are too sensitive to heat under the bonnets of our Wedges and the good old "bakelite" style ones are way more robust.
Keith...What colour rotor arms are you buying...These should be fine...
https://www.google.co.uk/url?sa=i&rct=j&q=...
https://www.google.co.uk/url?sa=i&rct=j&q=...
Sounds like you have duff parts mate...So frigging annoying....
https://www.google.co.uk/url?sa=i&rct=j&q=...
https://www.google.co.uk/url?sa=i&rct=j&q=...
Sounds like you have duff parts mate...So frigging annoying....
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