Various running problems - what to try next?
Discussion
My car is showing a number of engine running problems at the moment, two of which I've raised threads about before, but I'm beginning to think they're all inter-related so I thought I'd raise a new thread to bring all the symptoms together.
Issues I've got:
1) "Dead throttle syndrome". Engine abruptly and randomly loses all power for a second or two and doesn't respond to the throttle, then abruptly resumes pulling normally.
2) Misfiring after the car has been stationary. This seems to be heat related - on a warm day, if I stop for 10 to 20 seconds and then pull away, the engine is misfiring until I get back up to speed, then it returns to normal.
3) Stalling after stopping and switching engine off, e.g. refuelling. I sometimes have to keep the throttle open with my foot to stop it stalling, and it is misfiring. Again, this seems to be heat related because the problem disappears once I get on the move again. It's as if something is getting heat-soaked while the car is stopped.
4) Terrible running when starting from cold, as if running on only 6 or 7. The engine runs normally for about 10-15 seconds, then starts misfiring very badly, and then abruptly starts running okay after maybe a minute or two.
Here's what I've tried so far:
Everything I've tried so far has had a definite positive effect, but in some cases only temporary and in other cases leaving other aspects of the problems still there. It's as if several parts of the ignition system were a bit tired, and replacing them has helped, but there's still something else wrong.
So what should I try next, assuming the new coil doesn't cure things (which I suspect it won't)? I'm wondering about lambda sensor(s), but they're not cheap. I've read that I should be able to see their voltage flip-flopping, but how quickly? Will my cheapo digital multimeter be able to show it?
Any suggestions gratefully received!
Issues I've got:
1) "Dead throttle syndrome". Engine abruptly and randomly loses all power for a second or two and doesn't respond to the throttle, then abruptly resumes pulling normally.
2) Misfiring after the car has been stationary. This seems to be heat related - on a warm day, if I stop for 10 to 20 seconds and then pull away, the engine is misfiring until I get back up to speed, then it returns to normal.
3) Stalling after stopping and switching engine off, e.g. refuelling. I sometimes have to keep the throttle open with my foot to stop it stalling, and it is misfiring. Again, this seems to be heat related because the problem disappears once I get on the move again. It's as if something is getting heat-soaked while the car is stopped.
4) Terrible running when starting from cold, as if running on only 6 or 7. The engine runs normally for about 10-15 seconds, then starts misfiring very badly, and then abruptly starts running okay after maybe a minute or two.
Here's what I've tried so far:
- New HT leads. This instantly cured the "dead throttle syndrome", although exactly why I'm not sure. The problem disappeared for about 6 weeks, but unfortunately it is now back with a vengeance, sometimes happening every few hundred yards. Again, this seems to be heat related, because if I stop and lift the bonnet it'll go away temporarily.
- New coolant temperature sensor. This seemed to cure the rough running on start-up, but it has come back recently.
- New ignition amp module. I did this just yesterday, and it has also instantly cured the rough running on cold start-up.
- New coil on order, but not yet fitted. However, the car had a new Bosch coil about 3 years ago when I broke down in France, so it really shouldn't be this - but I can't rule it out.
Everything I've tried so far has had a definite positive effect, but in some cases only temporary and in other cases leaving other aspects of the problems still there. It's as if several parts of the ignition system were a bit tired, and replacing them has helped, but there's still something else wrong.
So what should I try next, assuming the new coil doesn't cure things (which I suspect it won't)? I'm wondering about lambda sensor(s), but they're not cheap. I've read that I should be able to see their voltage flip-flopping, but how quickly? Will my cheapo digital multimeter be able to show it?
Any suggestions gratefully received!
Edited by Dr Mike Oxgreen on Monday 7th September 13:28
Follow-up question:
If I do test the lambdas with my multimeter, should I do this from a cold start, and if so what would I expect to see as the engine warms up?
I've read somewhere that the ECU doesn't use the lambda readings until the coolant temperature is up to 70 - is that correct? If so, should I only bother checking them when the engine is warm?
How should I check the lambda voltage - at idle, or with the throttle partly open?
Many thanks for any help you can offer!
If I do test the lambdas with my multimeter, should I do this from a cold start, and if so what would I expect to see as the engine warms up?
I've read somewhere that the ECU doesn't use the lambda readings until the coolant temperature is up to 70 - is that correct? If so, should I only bother checking them when the engine is warm?
How should I check the lambda voltage - at idle, or with the throttle partly open?
Many thanks for any help you can offer!
Everything here points at HT or ignition. If the revcounter is steady when its misfing, Id be looking at coil, dizzy cap or rotor, or possibly rotor position if the dizzy has been out at any time. Sorry for the bit of a plug here, but Ive just put HT testers up for sale in the PH classified- they are the dogs nuts that allow you to read the HT voltage flowing down the plug leads (should be around 18KV )on a stock engine. Open circuits show up as higher voltages - up to 30 k- where as die-ing coils will show much lower. Its also worth strapping a strobe lamp to each plug lead and see if the flashing is even- a misfire will be quite visible when the strobe does not flash as it misfires.
http://www.pistonheads.com/classifieds/parts-and-p...
You can ignore lambda probes- they just trim the mixture, and would never shift the mixture far enough to cause the sort of symptoms you have.
http://www.pistonheads.com/classifieds/parts-and-p...
You can ignore lambda probes- they just trim the mixture, and would never shift the mixture far enough to cause the sort of symptoms you have.
blitzracing said:
Everything here points at HT or ignition. If the revcounter is steady when its misfing, Id be looking at coil, dizzy cap or rotor, or possibly rotor position if the dizzy has been out at any time. Sorry for the bit of a plug here, but Ive just put HT testers up for sale in the PH classified- they are the dogs nuts that allow you to read the HT voltage flowing down the plug leads (should be around 18KV )on a stock engine. Open circuits show up as higher voltages - up to 30 k- where as die-ing coils will show much lower. Its also worth strapping a strobe lamp to each plug lead and see if the flashing is even- a misfire will be quite visible when the strobe does not flash as it misfires.
http://www.pistonheads.com/classifieds/parts-and-p...
You can ignore lambda probes- they just trim the mixture, and would never shift the mixture far enough to cause the sort of symptoms you have.
The fact that it clears above 3500-4000rpm would indicate the missfire is caused under lambda control? I have had probes fail or go lazy in such a way it has made the ecu go full rich to the point of wetting the plugs http://www.pistonheads.com/classifieds/parts-and-p...
You can ignore lambda probes- they just trim the mixture, and would never shift the mixture far enough to cause the sort of symptoms you have.
Cant say Ive ever seen that happen, even with the probes unplugged, but its worth dropping a plug out and seeing if they are badly sooted.- you could try unplugging the lambdas and see if the engine runs any better- but dont try it for long as it dumps more fuel into the catalyst. You have so many variables when you open the throttle, like ignition timing, compression, and the amount of fuel, and all these things affect the way the HT voltages rise in the leads- so its simply a case of eliminating the unknowns. The problem with measuring Lambda output is the un burnt fuel reads as a very lean mixture, that can also cause a misfire, but you have a chicken and egg situation- is it a mis fire or lean mixture?
Thanks guys!
Yes, I'm pretty sure that I've seen the RPM gauge remain steady while the engine is in "dead throttle syndrome". Does the RPM gauge count the pulses coming out of the amp module?
The coil is next to try - I've just received a text telling me that it's been delivered, and I have a day off on Friday so will try fitting it then. If that doesn't work then at least I have a spare coil (and a spare amp module, and a spare set of HT leads!). I'll add the rotor arm to the list of parts to replace, and on the basis of blitz's comment I'll relegate the lambdas to the bottom of the list (which is a good thing - £100 each???). Plug extenders will have to go on the list as well.
At least this all means that I will have done a fairly complete refresh of the ignition system components, which is no bad thing.
Edited to add: That looks like a useful tool, blitz - I think I'll have one of those if the coil doesn't fix things, because I could easily waste a lot more money on other stuff.
Edited again: I might decide to have one anyway, cos it's a tool with lights on!
Yes, I'm pretty sure that I've seen the RPM gauge remain steady while the engine is in "dead throttle syndrome". Does the RPM gauge count the pulses coming out of the amp module?
The coil is next to try - I've just received a text telling me that it's been delivered, and I have a day off on Friday so will try fitting it then. If that doesn't work then at least I have a spare coil (and a spare amp module, and a spare set of HT leads!). I'll add the rotor arm to the list of parts to replace, and on the basis of blitz's comment I'll relegate the lambdas to the bottom of the list (which is a good thing - £100 each???). Plug extenders will have to go on the list as well.
At least this all means that I will have done a fairly complete refresh of the ignition system components, which is no bad thing.
Edited to add: That looks like a useful tool, blitz - I think I'll have one of those if the coil doesn't fix things, because I could easily waste a lot more money on other stuff.
Edited again: I might decide to have one anyway, cos it's a tool with lights on!
Edited by Dr Mike Oxgreen on Tuesday 8th September 12:07
I've been having all sorts of stalling and misfire issues over a period of years and although better still got problems. I'm currently replacing the leads with Moroso leads, a fire braid/heat wrapper extending about 10 inches up the lead from the plug and then Vulcan lava boots over the top (plug end) to do away completely with the extenders. I already have NGK BPR6ES plugs which are the right colour as opposed to the original 7ECS which were always black. I've done 3 yesterday and will do the rest hopefully this week but the leads are in component parts so its does take time to heat shrink the numbers on, cut them and build them up. I'm changing the plugs while I'm at it but they've only done c1,000 miles. I'll check how the leads go and then I've also got a dizzy/rotor arm, ignition amp and coil to swap next but only doing one item at a time so see if I can highlight what is causing the issue. I've got some new injectors and looking at the injector cabling later in the year/early next year to see if that cures by engine power dying problem (seems like an injector sticks and kicks neat fuel out the back).
Its a 430BV Griff by the way.
Will report how it goes with leads as due to be going to Wales on Sunday for fish and chips! (about a 270 mile round trip)
FFG
Its a 430BV Griff by the way.
Will report how it goes with leads as due to be going to Wales on Sunday for fish and chips! (about a 270 mile round trip)
FFG
I changed the coil today, but it doesn't seem to have made a difference. I also noticed that the vacuum assembly on the side of the distributor was very loose, so I tightened its screws up.
Unfortunately the traffic around Woking has been too congested to test it properly, but it still seems that when I stop or get stuck in a slow-moving queue the car is then lumpy and hesitant in the mid-range for the next half a mile or so, and on the rare occasions when I can keep moving at a moderate speed for a while it seems to smooth out and pull normally. I wasn't really able to tell how well it was pulling at the top end - too much traffic. I'll try again in the morning.
I've now replaced the two ignition components that I know can be sensitive to under-bonnet heat: the coil, and the ignition amp. Are there any other things under the bonnet that might react to heat and cause lumpy running? I do have a rotor arm and distributor cap on order; hopefully those might arrive on Monday when I have another day off.
I suppose there is another potential explanation: what if it's running rich and fouling its plugs when idling? Then perhaps after a short while of running at normal speeds it burns the fouling off?
I might pull the plugs out tomorrow and have a look. Traditionally you expect plugs to have a nice tan brown colour; does that hold true for the RV8 as well? What if I were to let the engine idle for a few minutes and then look at the plugs? Would you expect them to be clean, or does the RV8 habitually foul its plugs a bit at idle?
At least I haven't had "dead throttle syndrome", or the rough running after a cold start, or the tendency to stall. It's now only showing the lumpy, hesitant running in the mid-range. If I can just cure that it'll be great!
Unfortunately the traffic around Woking has been too congested to test it properly, but it still seems that when I stop or get stuck in a slow-moving queue the car is then lumpy and hesitant in the mid-range for the next half a mile or so, and on the rare occasions when I can keep moving at a moderate speed for a while it seems to smooth out and pull normally. I wasn't really able to tell how well it was pulling at the top end - too much traffic. I'll try again in the morning.
I've now replaced the two ignition components that I know can be sensitive to under-bonnet heat: the coil, and the ignition amp. Are there any other things under the bonnet that might react to heat and cause lumpy running? I do have a rotor arm and distributor cap on order; hopefully those might arrive on Monday when I have another day off.
I suppose there is another potential explanation: what if it's running rich and fouling its plugs when idling? Then perhaps after a short while of running at normal speeds it burns the fouling off?
I might pull the plugs out tomorrow and have a look. Traditionally you expect plugs to have a nice tan brown colour; does that hold true for the RV8 as well? What if I were to let the engine idle for a few minutes and then look at the plugs? Would you expect them to be clean, or does the RV8 habitually foul its plugs a bit at idle?
At least I haven't had "dead throttle syndrome", or the rough running after a cold start, or the tendency to stall. It's now only showing the lumpy, hesitant running in the mid-range. If I can just cure that it'll be great!
Edited by Dr Mike Oxgreen on Friday 11th September 17:02
Supplementary numpty question:
When I fitted the new coil, before bolting it onto the mounting bracket I connected it up and tried a test-firing of the engine. It cranked, but didn't even try to start. So I connected the old coil back temporarily - again, it didn't even try to start.
Only once I'd reconnected the new coil and bolted it to the bracket did the engine start - albeit slightly reluctantly, probably because it was slightly flooded.
So does the coil earth itself through the bracket, or something like that?
When I fitted the new coil, before bolting it onto the mounting bracket I connected it up and tried a test-firing of the engine. It cranked, but didn't even try to start. So I connected the old coil back temporarily - again, it didn't even try to start.
Only once I'd reconnected the new coil and bolted it to the bracket did the engine start - albeit slightly reluctantly, probably because it was slightly flooded.
So does the coil earth itself through the bracket, or something like that?
Hi.
I had the same problem last year while on the Hants TVR Easter in France. Tried all obvious things. It tuned out to be plug extenders, after I removed them it drove perfectly. No supplier had any new ones so I fitted some of those heat proof sock things until I could fit the correct items. After some months TVRParts had some new ones in so I purchased and fitted in February this year. All was well for about five months and then the fault reoccurred. Checked all usual things, even bought new Magnicore leads when I found all eight of the plug extenders had split from the top of the plug lead end to the metal surround. TVRParts sent replacements and I am now keeping an eye on them to see how the new ones fair. They did admit that some other customers had the same issue although never all eight. Makes you wonder what quality Genuine Replacements are????
Steve
I had the same problem last year while on the Hants TVR Easter in France. Tried all obvious things. It tuned out to be plug extenders, after I removed them it drove perfectly. No supplier had any new ones so I fitted some of those heat proof sock things until I could fit the correct items. After some months TVRParts had some new ones in so I purchased and fitted in February this year. All was well for about five months and then the fault reoccurred. Checked all usual things, even bought new Magnicore leads when I found all eight of the plug extenders had split from the top of the plug lead end to the metal surround. TVRParts sent replacements and I am now keeping an eye on them to see how the new ones fair. They did admit that some other customers had the same issue although never all eight. Makes you wonder what quality Genuine Replacements are????
Steve
FlipFlopGriff said:
What do the plugs look like?
What are your leads, extenders, dizzy cap and rotor arm like?
FFG
Don't know yet - will remove and inspect the plugs today when the engine is cold.What are your leads, extenders, dizzy cap and rotor arm like?
FFG
Leads were replaced about 8 weeks ago. At that time, "dead throttle syndrome" was happening almost every time I drove the car, though usually only in isolated incidents. After the new leads, it stopped for at least a month - but the problem returned with a vengeance whilst on holiday a few weeks ago.
I have a new cap and rotor arm on order - should arrive shortly.
The extenders looked okay when I had them off while replacing the HT leads - but you're right, I shouldn't discount them as a possibility, particularly in light of venus' experience with them.
Would I get away with doing a test drive without the extenders, and without socks - or would the heat quickly damage the leads?
Edited by Dr Mike Oxgreen on Saturday 12th September 03:31
My plug extenders were fine and my car was, and now is again, running beautifully.
But back in the spring my TVR guy, at the annual service, thought my plug extenders looked tired, so got a new batch of the correct ones from a major supplier. It took me about three months to work out where all my misfiring was coming from - two faulty extenders (one electrically dead, one that wouldn't stay clipped on to the plug) and one replacement for one of the failed ones that also wouldn't stay clipped on!!!
A number of other owners had similar problems with new extenders at the time, so I am just saying that if you invest £100 in new extenders, don't assume that the if problems don't go away, it cannot be the extenders.
However, my only problems were misfiring under load, so your issues don't sound similar.....
But back in the spring my TVR guy, at the annual service, thought my plug extenders looked tired, so got a new batch of the correct ones from a major supplier. It took me about three months to work out where all my misfiring was coming from - two faulty extenders (one electrically dead, one that wouldn't stay clipped on to the plug) and one replacement for one of the failed ones that also wouldn't stay clipped on!!!
A number of other owners had similar problems with new extenders at the time, so I am just saying that if you invest £100 in new extenders, don't assume that the if problems don't go away, it cannot be the extenders.
However, my only problems were misfiring under load, so your issues don't sound similar.....
Yes you could try them without the extenders for a test drive but make sure the leads don't touch the exhaust manifold or the leads in question will melt pretty quickly. I'm about to get rid of my extenders as they often turn on their own and cause the leads to touch exhaust,,,
I'm going to just go for some socks that protect the effected part of the leads.
I'm going to just go for some socks that protect the effected part of the leads.
Dr Mike Oxgreen said:
Supplementary numpty question:
When I fitted the new coil, before bolting it onto the mounting bracket I connected it up and tried a test-firing of the engine. It cranked, but didn't even try to start. So I connected the old coil back temporarily - again, it didn't even try to start.
Only once I'd reconnected the new coil and bolted it to the bracket did the engine start - albeit slightly reluctantly, probably because it was slightly flooded.
So does the coil earth itself through the bracket, or something like that?
When I fitted the new coil, before bolting it onto the mounting bracket I connected it up and tried a test-firing of the engine. It cranked, but didn't even try to start. So I connected the old coil back temporarily - again, it didn't even try to start.
Only once I'd reconnected the new coil and bolted it to the bracket did the engine start - albeit slightly reluctantly, probably because it was slightly flooded.
So does the coil earth itself through the bracket, or something like that?
for the HT sideAha! That would explain why it wouldn't start with the coil dangling freely. Every day's a school day!
So, here's what the plugs look like. To my eyes they look rather sooty, and they all look much the same although number 3 is maybe slightly greyer and the porcelain is not quite as sooty - but there's not much in it. Bear in mind, though, that the last drive I did was a frustrating test-drive in Friday afternoon traffic, so a fair amount of idling in queues.
And here's a close-up of number 4, which is fairly typical. The electrodes and the porcelain are sooty but dry:
The gaps all look quite big - well over a millimetre. What should they be?
So, here's what the plugs look like. To my eyes they look rather sooty, and they all look much the same although number 3 is maybe slightly greyer and the porcelain is not quite as sooty - but there's not much in it. Bear in mind, though, that the last drive I did was a frustrating test-drive in Friday afternoon traffic, so a fair amount of idling in queues.
And here's a close-up of number 4, which is fairly typical. The electrodes and the porcelain are sooty but dry:
The gaps all look quite big - well over a millimetre. What should they be?
Well, that was a very interesting test-drive!
I put the plugs back in exactly as they were, deliberately without cleaning them. But I left off all 8 plug extenders and simply wrapped a bit of tinfoil around a couple of the leads that were particularly close to the exhaust.
I drove a good 20 miles, including a mixture of urban main roads and some slightly faster roads.
The engine is now pulling keenly, with none of the hesitation I have been seeing. I even stopped and idled in a pub car park for a couple of minutes, then accelerated away briskly - and again there was no lumpiness or hesitation, it just pulled hard.
So, I might be converted to the anti-extender school of thought.
Once it has cooled down I might pull one or two of the plugs and see if they've cleaned themselves up after a slightly more spirited drive. If not, is it worth cleaning them?
I put the plugs back in exactly as they were, deliberately without cleaning them. But I left off all 8 plug extenders and simply wrapped a bit of tinfoil around a couple of the leads that were particularly close to the exhaust.
I drove a good 20 miles, including a mixture of urban main roads and some slightly faster roads.
The engine is now pulling keenly, with none of the hesitation I have been seeing. I even stopped and idled in a pub car park for a couple of minutes, then accelerated away briskly - and again there was no lumpiness or hesitation, it just pulled hard.
So, I might be converted to the anti-extender school of thought.
Once it has cooled down I might pull one or two of the plugs and see if they've cleaned themselves up after a slightly more spirited drive. If not, is it worth cleaning them?
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