Idle Stalling - Help Needed Please!
Discussion
Picture the scene ... a glorious sunny Sunday with an opportunity to meets friends for lunch at a New Forest pub.
The perfect excuse to dust off the Chimaera, remove the roof and have some fun, or so I thought!
Having been laid up for the winter, I went out to the garage and thankfully, she started first time, left idling for 10 minutes or so and went back in the get ready to leave. 15 minutes later we were ready to leave, then disaster!
Got about 20 yards up the road and the car splutters and stalls. Restarted and reversed back onto the drive. Went to open garage and she stalls again and won’t restart, but does turn over.
Managed to push her back into the garage with the help of a rather annoyed wife and had to leave in other car.
Thinking it maybe stale fuel, I popped to the local garage with a couple of petrol cans and filled tank with 97 unleaded adding some Redex for good measure.
Again she started first time but after 15 minutes started to idle badly. And stalled again. When I turned the ignition off and on I noticed a rapid ticking noise which was coming from the stepper motor. So I connected my ECU Mate and tried to extend and retract the stepper motor manually. Nothing, just more ticking but value stayed on 114. Hey presto! That must be the issue so ordered and new one from RaceTech (The one manufactured in Mexico, not a cheap one!) and fitted with a nice seal of Hylomar. Also replaced the Fuel Pump& ECU relays as been meaning to do so for a while.
Decided to hook up RoverGauge this time so I could record some data and started her up and crossed everything!
Got to 15 minutes and all looking good, Lamda’s started when water temperature at 78 degrees (11 minutes in), idle matching target idle nicely, passed 20 minutes with the fans coming on several times.
Then, got to about 24 minutes and suddenly revs drop (919, 875, 727, 517, 223, 223, 0) all within 5 seconds. Tried to restart and after a few turns, catches but stalls again after a 30 seconds again revs dropping (917, 833, 550, 236, 236, 236, 0) in 5 seconds. Tried to restart and just turned over without starting.
Decided to try again the next day after car cooled down.
Before starting checked HT cables all tight etc, relays all seated etc.
Tried again, she started first time, got to 25 minutes and revs suddenly drop (908, 788, 855, 551, 293, 219, 219, 0) again within 5 seconds. RoverGauge was showing Fuel Relay indicator light as green.
Last year I had both Lamdba’s replaced, new coil, ignition amp, HT leads, distributer cap, rotor arm, spark plugs and fuel filter replaced.
None of the above has caused any faults to be registered on ECU.
It seems like a sudden fuel pressure loss possibly caused by incorrect sensor information (heat induced?) being sent to ECU?
Just wondered if I’m missing something obvious, does the RoverGauge data look ok or should I get the car transported to a TVR specialist?
Many thanks, Paul.
The perfect excuse to dust off the Chimaera, remove the roof and have some fun, or so I thought!
Having been laid up for the winter, I went out to the garage and thankfully, she started first time, left idling for 10 minutes or so and went back in the get ready to leave. 15 minutes later we were ready to leave, then disaster!
Got about 20 yards up the road and the car splutters and stalls. Restarted and reversed back onto the drive. Went to open garage and she stalls again and won’t restart, but does turn over.
Managed to push her back into the garage with the help of a rather annoyed wife and had to leave in other car.
Thinking it maybe stale fuel, I popped to the local garage with a couple of petrol cans and filled tank with 97 unleaded adding some Redex for good measure.
Again she started first time but after 15 minutes started to idle badly. And stalled again. When I turned the ignition off and on I noticed a rapid ticking noise which was coming from the stepper motor. So I connected my ECU Mate and tried to extend and retract the stepper motor manually. Nothing, just more ticking but value stayed on 114. Hey presto! That must be the issue so ordered and new one from RaceTech (The one manufactured in Mexico, not a cheap one!) and fitted with a nice seal of Hylomar. Also replaced the Fuel Pump& ECU relays as been meaning to do so for a while.
Decided to hook up RoverGauge this time so I could record some data and started her up and crossed everything!
Got to 15 minutes and all looking good, Lamda’s started when water temperature at 78 degrees (11 minutes in), idle matching target idle nicely, passed 20 minutes with the fans coming on several times.
Then, got to about 24 minutes and suddenly revs drop (919, 875, 727, 517, 223, 223, 0) all within 5 seconds. Tried to restart and after a few turns, catches but stalls again after a 30 seconds again revs dropping (917, 833, 550, 236, 236, 236, 0) in 5 seconds. Tried to restart and just turned over without starting.
Decided to try again the next day after car cooled down.
Before starting checked HT cables all tight etc, relays all seated etc.
Tried again, she started first time, got to 25 minutes and revs suddenly drop (908, 788, 855, 551, 293, 219, 219, 0) again within 5 seconds. RoverGauge was showing Fuel Relay indicator light as green.
Last year I had both Lamdba’s replaced, new coil, ignition amp, HT leads, distributer cap, rotor arm, spark plugs and fuel filter replaced.
None of the above has caused any faults to be registered on ECU.
It seems like a sudden fuel pressure loss possibly caused by incorrect sensor information (heat induced?) being sent to ECU?
Just wondered if I’m missing something obvious, does the RoverGauge data look ok or should I get the car transported to a TVR specialist?
Many thanks, Paul.
Sorry can't read the figures very well.
Just try starting the engine and opening the boot, listen for air at the fuel cap, leave cap on and when engine falters quickly remove fuel cap.
Sounds a bit like a vacuum causing fuel starvation to me.
Fuel regulator failing or blocked filter could cause similar issues.
When engine stalls I'd check a spark plug for colour.
Just try starting the engine and opening the boot, listen for air at the fuel cap, leave cap on and when engine falters quickly remove fuel cap.
Sounds a bit like a vacuum causing fuel starvation to me.
Fuel regulator failing or blocked filter could cause similar issues.
When engine stalls I'd check a spark plug for colour.
Nothing obvious ECU wise there- but try disconnecting the stepper when its warm and idling nicely (engine on when you do this) - if it still dies its nothing to do with stepper control.. It could be crap in the fuel tank getting drawn into the exit and blocking it, that then drops away when the engine dies, so it will run again normally for a while. Unfortunately the lambda cycling seems to be stopping at idle, so we cant rely on its value, so you would need to connect a test meter to the lambda outputs between the black and white wires to get a live reading, and if the voltage sticks at zero ( it should cycle around 1 volt ) you know its fuel starvation. What Rovergauge wont really show here is if its ignition or coil failing on you. Otherwise its a mechanical fuel pressure gauge in the fuel rail to see if the pressure is holding up.
Firstly, apologies for not replying sooner, for last few days PH blocking replies for new members due to some sort of abuse!
And secondly, many thanks for all your replies, it is very much appreciated.
ClassicChimera, I sort of tried your fuel cap check, I didn't manage to get the cap off when it stalls as happens within a few seconds. I did undo cap and try to restart but didn't make any difference.
Hughesie, I have a couple of new 100amp fuses arriving today, so will jack car and replace (assuming I can find it!). While I'm there I'm going to look at fuel pump connections.
Blitzracing, I disconnected the stepper motor once the fans had kicked in for the first time but the car still stalled several minutes later.
It definitely seems to be temperature / time related as I've now tried several times and she has stalled after 24.5, 25.25, 25.5, 24.0 and 25.5 minutes all having started perfectly on cold start. I can get her to restart but will stall after less than a minute and then won't start at all.
Yesterday, however, I did get a ECU fault code showing on ECUMate "23 low fuel pressure" directly following the stall, which disappeared after I re-ran the "Get ECU fault codes" function a few minutes later! But at least I got something!
And secondly, many thanks for all your replies, it is very much appreciated.
ClassicChimera, I sort of tried your fuel cap check, I didn't manage to get the cap off when it stalls as happens within a few seconds. I did undo cap and try to restart but didn't make any difference.
Hughesie, I have a couple of new 100amp fuses arriving today, so will jack car and replace (assuming I can find it!). While I'm there I'm going to look at fuel pump connections.
Blitzracing, I disconnected the stepper motor once the fans had kicked in for the first time but the car still stalled several minutes later.
It definitely seems to be temperature / time related as I've now tried several times and she has stalled after 24.5, 25.25, 25.5, 24.0 and 25.5 minutes all having started perfectly on cold start. I can get her to restart but will stall after less than a minute and then won't start at all.
Yesterday, however, I did get a ECU fault code showing on ECUMate "23 low fuel pressure" directly following the stall, which disappeared after I re-ran the "Get ECU fault codes" function a few minutes later! But at least I got something!
Again, many thanks for your input.
Latest update ... tonight I've cleaned the contacts on the fuel pump, replaced the 100 amp fuse (having disconnected battery first!).
At bit more optimistic, I started her up, 10 minutes of idling later she stalls!
Brilliant!!
I've made it worse!!!
Unsure what to do next I remembered a post where someone mentioned about disconnecting the AFM connector. What the hell, I'll try anything now ...
Started her up again and after 50 minutes of idling (750 - 950 rpm) I'm thinking this definitely means something! My ECUMate was showing 0.03v on the AFM which I presume is a default setting and a AFM fault on the ECU. She was never going to pass an emissions test based on the exhaust smell!
Both lambda's were showing default values and not changing (A = OK, B = Lean) which again I presume is a result of no AFM input.
So after stopping her on 50 minutes, reconnected the AFM and 3 minutes later she stalls again. Both Lambda's now switching.
I had both lambda's changed last year and only done a couple of hundred miles since.
The lamdba's could still be the reason (if they were faulty) but I presume the AFM is the most likely candidate?
Latest update ... tonight I've cleaned the contacts on the fuel pump, replaced the 100 amp fuse (having disconnected battery first!).
At bit more optimistic, I started her up, 10 minutes of idling later she stalls!
Brilliant!!
I've made it worse!!!
Unsure what to do next I remembered a post where someone mentioned about disconnecting the AFM connector. What the hell, I'll try anything now ...
Started her up again and after 50 minutes of idling (750 - 950 rpm) I'm thinking this definitely means something! My ECUMate was showing 0.03v on the AFM which I presume is a default setting and a AFM fault on the ECU. She was never going to pass an emissions test based on the exhaust smell!
Both lambda's were showing default values and not changing (A = OK, B = Lean) which again I presume is a result of no AFM input.
So after stopping her on 50 minutes, reconnected the AFM and 3 minutes later she stalls again. Both Lambda's now switching.
I had both lambda's changed last year and only done a couple of hundred miles since.
The lamdba's could still be the reason (if they were faulty) but I presume the AFM is the most likely candidate?
Edited by Byte5ize on Wednesday 19th April 22:26
Did it stall when approaching a junction; i.e. coming off the revs and in neutral/idle? That happened to me a few months back, and it turned out I had inadvertently disconnected the speed sensor under the whale tail (just aft of the hand brake). Worth a look. If that connection comes free, then the ECU gets all confused and stalls you.
You said this all began after the car was started after a lay up over the winter, did you try to start the car on old fuel by any chance?
Modern fuels only have a 6 week life before they've degraded to the extent they can cause serious problems, BP advises petrol actual begins to degrade after just one week and state it will only last for 3 weeks at a temperature of around 20 deg C before fresh petrol should be added. The problem is worse on injected engines because the injectors themselves have very fine internal tolerances that are extremely sensitive to the waxy deposits in stale petrol. These deposits can either block the injector nozzles stopping fuel flow or gum up the injector internals stopping it from closing fully, being a constant pressure system if the injector is partially stick open over fueling is inevitable.
Often you can have a mix of conditions with some injectors working perfectly, some partially blocked and some that can't quite close fully so don't underestimate the effects of stale fuel, modern fuels have a much shorter tank life than the petrol we all grew up with. Modern fuels also contain a percentage of ethanol, ethanol has a number of undesirable characteristics but the one that affects the fuel over time is the fact it's very hygroscopic, meaning it's extremely effective at absorbing water from the atmosphere.
So there are lots of things going on as modern fuels degrade, firstly as the lighter active elements are the first to evaporate off the fuel rapidly becomes less volatile, this reduction in volatility reduces the level of octane making cold starts more difficult and reducing performance, it also makes engine damaging detonation far more likely. Whats left are the waxy heavy ends which cause the injector issues outlined above, combine this with the accumulation of water the ethanol element in the fuel has absorbed from the atmosphere and the liquid you end up with in your tank is a long way off being petrol, issues become inevitable if the fuel is six weeks old and gets rapidly worse from there on.
A car being laid up over the winter should first be left with a low tank, when you come to start the vehicle in the spring you should put at least two gallons of new fresh fuel in the tank before you attempt the start, it may also be helpful to run the fuel pump continuously for a minute to fully circulate and mix the old fuel with the new before starting the engine. You should then make your first trip a run to closest petrol station where it's best to brim the tank with new fresh fuel. If you stated the car on stale fuel the damage may already have been done, at this point you should get as much fresh petrol in the tank as you can and use a good injector cleaner to remove any waxy heavy end deposits in your injectors, the best injector cleaner you can get is BG 44K which you can buy at Kwick Fit tyre centres of all places.
Don't underestimate the effects of stale petrol, it's a very real problem and one that should not be ignored!
http://www.bp.com/content/dam/bp-country/en_au/med...
Modern fuels only have a 6 week life before they've degraded to the extent they can cause serious problems, BP advises petrol actual begins to degrade after just one week and state it will only last for 3 weeks at a temperature of around 20 deg C before fresh petrol should be added. The problem is worse on injected engines because the injectors themselves have very fine internal tolerances that are extremely sensitive to the waxy deposits in stale petrol. These deposits can either block the injector nozzles stopping fuel flow or gum up the injector internals stopping it from closing fully, being a constant pressure system if the injector is partially stick open over fueling is inevitable.
Often you can have a mix of conditions with some injectors working perfectly, some partially blocked and some that can't quite close fully so don't underestimate the effects of stale fuel, modern fuels have a much shorter tank life than the petrol we all grew up with. Modern fuels also contain a percentage of ethanol, ethanol has a number of undesirable characteristics but the one that affects the fuel over time is the fact it's very hygroscopic, meaning it's extremely effective at absorbing water from the atmosphere.
So there are lots of things going on as modern fuels degrade, firstly as the lighter active elements are the first to evaporate off the fuel rapidly becomes less volatile, this reduction in volatility reduces the level of octane making cold starts more difficult and reducing performance, it also makes engine damaging detonation far more likely. Whats left are the waxy heavy ends which cause the injector issues outlined above, combine this with the accumulation of water the ethanol element in the fuel has absorbed from the atmosphere and the liquid you end up with in your tank is a long way off being petrol, issues become inevitable if the fuel is six weeks old and gets rapidly worse from there on.
A car being laid up over the winter should first be left with a low tank, when you come to start the vehicle in the spring you should put at least two gallons of new fresh fuel in the tank before you attempt the start, it may also be helpful to run the fuel pump continuously for a minute to fully circulate and mix the old fuel with the new before starting the engine. You should then make your first trip a run to closest petrol station where it's best to brim the tank with new fresh fuel. If you stated the car on stale fuel the damage may already have been done, at this point you should get as much fresh petrol in the tank as you can and use a good injector cleaner to remove any waxy heavy end deposits in your injectors, the best injector cleaner you can get is BG 44K which you can buy at Kwick Fit tyre centres of all places.
Don't underestimate the effects of stale petrol, it's a very real problem and one that should not be ignored!
http://www.bp.com/content/dam/bp-country/en_au/med...
If the ECU has tripped a low fuel pressure code, both lambda outputs must have been low for a period and stopped switching. The fault code points at pump for fuel pressure regulator. Worth wiring a test meter across one of the lambda probes, and see if it stops switching as the car dies, keep an eye on the short term trim on ECUmate- Id expect to see a +255 reading as it tried to richen the mixture if the fuel pressure drops.
Chimp871 said:
He got it running for 50 mins so not sure had petrol is causing problems.
You can often start a car on stale petrol, it's just it won't run very well and may stall after a period just as the OP describes because all the time you're running on stale petrol you're putting that bad fuel through your injectors leaving waxy deposits behind not to mention the inevitable idle issues associated with a fuel that's lost most of it's volatility.Stale petrol won't cause any noticeable issues until you try to run the engine on it, so running the car for 50 minutes on stale petrol is not proof the petrol isn't stale it's just potentially 50 minutes running on stale petrol and will likely be accompanied by poor running and the stalling the OP is complaining about.
The long layup and stalling are two pieces of evidence that combined point to the possibility of stale fuel and lead me to ask him how old the fuel was when he started his engine, the problem of stale petrol is a very real one and is often overlooked. While its tempting to go straight to the laptop to solve all your poor running frustrations the truth is you are much better off going back to basics first... IE spark, fuel, compression
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