V8S stalling when cold
Discussion
Help! My V8S always starts perfectly no matter how cold it is but after about 1 minute it frequently stalls and cannot be restarted for half an hour at least. If I can manage not to dip the clutch after driving off from cold it keeps going but the first junction see's it stalling no matter what I do with the Go pedal! If I just let the car sit (for over 5 mins sometimes) until the temp gauge starts to move then all is well.
The (authorised) dealer has had it in twice and can't find any faults and have replaced coils, throttle sensors etc. It's going back in this week but I'm less than hopefull.
It sounds like a running too rich problem to me as when it's warming up, blipping the throttle causes the revs to die rather than rise.
Can anyone suggest a proper cure as just waiting for it to warm up is both annoying and causing more wear on the engine than preferable?
The (authorised) dealer has had it in twice and can't find any faults and have replaced coils, throttle sensors etc. It's going back in this week but I'm less than hopefull.
It sounds like a running too rich problem to me as when it's warming up, blipping the throttle causes the revs to die rather than rise.
Can anyone suggest a proper cure as just waiting for it to warm up is both annoying and causing more wear on the engine than preferable?
quote:
Help! My V8S always starts perfectly no matter how cold it is but after about 1 minute it frequently stalls and cannot be restarted for half an hour at least. If I can manage not to dip the clutch after driving off from cold it keeps going but the first junction see's it stalling no matter what I do with the Go pedal! If I just let the car sit (for over 5 mins sometimes) until the temp gauge starts to move then all is well.
The (authorised) dealer has had it in twice and can't find any faults and have replaced coils, throttle sensors etc. It's going back in this week but I'm less than hopefull.
It sounds like a running too rich problem to me as when it's warming up, blipping the throttle causes the revs to die rather than rise.
Can anyone suggest a proper cure as just waiting for it to warm up is both annoying and causing more wear on the engine than preferable?
Basically if you're after loads of power and want to keep the compbustion temperature down (like I do) richer is better, but if you take it too far the engine can foul the plugs or even flood when it's really cold.
Might be some other problem making the plugs susceptable to fouling - like running the wrong grade plugs, weak spark or something. But could also be just a smidge too rich and the cold start enrichment pushes it over the edge. When I had mine set well rich during the summer it was a pig for the first few minutes on winter days because it would splutter and die every time I touched the throttle - dropping the fuel pressure leaned it out slightly and it was back to normal. If you have an adjustable fuel regulator a professional can do this in a couple of minutes - it is not a DIY job unless you really know what you're doing. If you have a fixed pressure regulator this is less likely to be the cause, but worth considering the possibility the regaultor is up the creek or you jave a sticking injector or something.
Cheers,
Peter Humphries (and a green V8S)
You can get similar problems with duff temp sensors so that the ECU thinks it is colder than it is and still maintains enrichment or if the injectors are out or spec/leaking.
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
Chances are very likely, that it is a problem of too rich mixture. If it should not be the case or the only problem, here is my recent story...
Had a similar problem with my wife's 18 year old saab turbo16v (Bosch LH Jetronic & Bosch electronic ignition). Warm engine stalls without warning and won't start for some time (1 hour at the end)
Assuming, that the principle should be comparable to the Lucas V8 system I recommend the following road map.
1)Try to source wether it is an ignition or a fuel injection problem: If the rev'meter drops immediately, when the engine stalls, it is likely, that it is an ignition problem, as it should be fed by the same sensor in the distributor (normally Hall Sensor). If the needle comes slowly down with the engine speed (don't push the clutch, when you feel the engine will stall), then it's most probably a fuel problem.
2) When the engine stalls, take out the spark plug(s) immediately. Are they wet? If so, too much fuel--> see Pete & green V8's advice.
3) If spark plug(s) are not wet. Is there a reasonable el. arc, when you turn the starter an when s.b. holds the spark plug 5mm to the engine block. (use isolated item to hold the spark)
4) If no arc --> then ignition problem, secondary side
5) Assuming,that you have checked already according to Peter, whether sparks correspond to the specification recommended by TVR.If sparks are dry and you have an arc, what is the colour of elctrodes & ceramics & bottom, after you tried to start the engine for some time, and it won't start? If they're almost white, then you have no fuel injected.
6)Does the fuelpump work? Do you (or other person) hear it, when you try to start the engine?
7) If the fuelpump runs, the injectors won't open!
Now it is good to take out the electronic schematics (diagrams) of the V8S EFi system.
8) Before you start to check or change any sensors, check first the mass of the EFi ECU and the fuel pump. It sounds stupid, but most people, so did I with the saab, start to look into the most expensive items (sensors, fuel pump, ECU...) and forget about the most simple.
The lead to mass, may be far away from the ECU! (e.g. for the saab: ECU in footwell, according mass point on cylinder head)
Even if mass points do not look corroded, they may cause problems. Untighten the fixing screw or bolt and spray with WD40, prior tightening.
9)Also unplug and plug the EFi ECU main plug.
10) If the problem goes on, only then you need to go deeper into the fuel system, and that's where you have to interprete the electrical wiring of the V8 Lucas system. I don't know that one but the Bosch L system of the V6 should go into a limp mode if a sensor strikes (air flow, throttle potentiometer, temp and pressure sensors). This should not stall the engine, unless delivers wrong signals (like what Steve explains) . Only sensor, that will stall the engine, if kaput is the hall sensor of the ignition or the ECU of the ignition. But then we're at the beginning again: go to 1)
Hope you'll find the demon
Cheers Patrick
Had a similar problem with my wife's 18 year old saab turbo16v (Bosch LH Jetronic & Bosch electronic ignition). Warm engine stalls without warning and won't start for some time (1 hour at the end)
Assuming, that the principle should be comparable to the Lucas V8 system I recommend the following road map.
1)Try to source wether it is an ignition or a fuel injection problem: If the rev'meter drops immediately, when the engine stalls, it is likely, that it is an ignition problem, as it should be fed by the same sensor in the distributor (normally Hall Sensor). If the needle comes slowly down with the engine speed (don't push the clutch, when you feel the engine will stall), then it's most probably a fuel problem.
2) When the engine stalls, take out the spark plug(s) immediately. Are they wet? If so, too much fuel--> see Pete & green V8's advice.
3) If spark plug(s) are not wet. Is there a reasonable el. arc, when you turn the starter an when s.b. holds the spark plug 5mm to the engine block. (use isolated item to hold the spark)
4) If no arc --> then ignition problem, secondary side
5) Assuming,that you have checked already according to Peter, whether sparks correspond to the specification recommended by TVR.If sparks are dry and you have an arc, what is the colour of elctrodes & ceramics & bottom, after you tried to start the engine for some time, and it won't start? If they're almost white, then you have no fuel injected.
6)Does the fuelpump work? Do you (or other person) hear it, when you try to start the engine?
7) If the fuelpump runs, the injectors won't open!
Now it is good to take out the electronic schematics (diagrams) of the V8S EFi system.
8) Before you start to check or change any sensors, check first the mass of the EFi ECU and the fuel pump. It sounds stupid, but most people, so did I with the saab, start to look into the most expensive items (sensors, fuel pump, ECU...) and forget about the most simple.
The lead to mass, may be far away from the ECU! (e.g. for the saab: ECU in footwell, according mass point on cylinder head)
Even if mass points do not look corroded, they may cause problems. Untighten the fixing screw or bolt and spray with WD40, prior tightening.
9)Also unplug and plug the EFi ECU main plug.
10) If the problem goes on, only then you need to go deeper into the fuel system, and that's where you have to interprete the electrical wiring of the V8 Lucas system. I don't know that one but the Bosch L system of the V6 should go into a limp mode if a sensor strikes (air flow, throttle potentiometer, temp and pressure sensors). This should not stall the engine, unless delivers wrong signals (like what Steve explains) . Only sensor, that will stall the engine, if kaput is the hall sensor of the ignition or the ECU of the ignition. But then we're at the beginning again: go to 1)
Hope you'll find the demon
Cheers Patrick
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