S2 1989 2.9 efi
Discussion
Hi can anyone help, I have a 2.9 efi that start perfect, after about 30 seconds is sounds like it over fuelling and runs rich and lumpy and has a slight backfire . I have replaced the following , full set of injectors,set of leads, spark plugs, distributor cap, temperature switch, the only thing that l am unsure about is the fuel injector power supply , I may have them on the wrong way as all my numbers are missing off the conection plugs that go to the injectors. I purchased a second hand one with the firing order on it but the main plug is a oval type ,mine is a round type??
Gerry
Disappointing that you've had no response.
Does anybody wlse have a round multi-plug on the engine wiring loom (the big connector beside the rocker cover under the coil) instead of the black oval one? We want to check that it's been replaced correctly when the injectors were changed.
Disappointing that you've had no response.
Does anybody wlse have a round multi-plug on the engine wiring loom (the big connector beside the rocker cover under the coil) instead of the black oval one? We want to check that it's been replaced correctly when the injectors were changed.
Graham, that's brilliant, that's exactly the connector.
Gerry's problem is that he has the same type of engine loom, but doesn't know which wire goes to which fuel injector. Would it be too much to ask if you could do a diagram of the order of the injector connectors from the main loom?
(I'm not sure if the injectors have a "firing order" or not - but best to be right!)
Gerry's problem is that he has the same type of engine loom, but doesn't know which wire goes to which fuel injector. Would it be too much to ask if you could do a diagram of the order of the injector connectors from the main loom?
(I'm not sure if the injectors have a "firing order" or not - but best to be right!)
tvrgit said:
(I'm not sure if the injectors have a "firing order" or not - but best to be right!)
The injectors "fire" in two sets of three (each bank I believe)not individually like spark plugs so may be possible to meter out wires and determine the two sets then its just a 50 - 50 to get them right ?Hi Gerry, really need a little more info to try and help.
You have listed a number of parts you have changed, my first question is, were these parts changed to try and rectify this fault or for some other reason and you now have this fault after carrying out that work? Sorry but it's not clear in you 1st post.
If the car is backfiring, that to me indicates an ignition timing issue as it suggests the plugs are firing whilst the valves are open.
Does the problem worsten as the engine heats up?
Does the problem worsten if you try to raise the engine revs?
Cheers,
Ceejay73
You have listed a number of parts you have changed, my first question is, were these parts changed to try and rectify this fault or for some other reason and you now have this fault after carrying out that work? Sorry but it's not clear in you 1st post.
If the car is backfiring, that to me indicates an ignition timing issue as it suggests the plugs are firing whilst the valves are open.
Does the problem worsten as the engine heats up?
Does the problem worsten if you try to raise the engine revs?
Cheers,
Ceejay73
phillpot said:
The injectors "fire" in two sets of three (each bank I believe)not individually like spark plugs so may be possible to meter out wires and determine the two sets then its just a 50 - 50 to get them right ?
That was my understanding as well, but even then, it's not easy to tell from the loom which side goes where.Ceejay73 said:
Hi Gerry, really need a little more info to try and help.
You have listed a number of parts you have changed, my first question is, were these parts changed to try and rectify this fault or for some other reason and you now have this fault after carrying out that work? Sorry but it's not clear in you 1st post.
If the car is backfiring, that to me indicates an ignition timing issue as it suggests the plugs are firing whilst the valves are open.
Does the problem worsten as the engine heats up?
Does the problem worsten if you try to raise the engine revs?
Cheers,
Ceejay73
Hi Ceejay,You have listed a number of parts you have changed, my first question is, were these parts changed to try and rectify this fault or for some other reason and you now have this fault after carrying out that work? Sorry but it's not clear in you 1st post.
If the car is backfiring, that to me indicates an ignition timing issue as it suggests the plugs are firing whilst the valves are open.
Does the problem worsten as the engine heats up?
Does the problem worsten if you try to raise the engine revs?
Cheers,
Ceejay73
Thanks for your information, yes l had similar problems before l started to change the parts listed .
I had another multi plug for the injectors of a oval type not the round like mine and l opened it up to find all the wires are joined and they are just a the same power supply so l don't think its the injector conection as they don't seem to be in any order.
as l said and it still runs very rick, but l noticed that when l took the plugs out they were all sooted up but one was wet (petrol) so not firing so it could now be ignition fault? but why does it start so easy and why misfire when hot/warm.
l don't want to play about with the distributor as l have been told it has to go back onto a machine to get it right.Is it possible to change the elecronic ignition module without moving or removing the distributor.
tvrgit said:
Gerry
Disappointing that you've had no response.
Does anybody wlse have a round multi-plug on the engine wiring loom (the big connector beside the rocker cover under the coil) instead of the black oval one? We want to check that it's been replaced correctly when the injectors were changed.
Hi Andrew,Disappointing that you've had no response.
Does anybody wlse have a round multi-plug on the engine wiring loom (the big connector beside the rocker cover under the coil) instead of the black oval one? We want to check that it's been replaced correctly when the injectors were changed.
Stripped the oval plug today and found that they are all connected to one power supply so it looks like they have no firing order, l took the spark plugs out to find them all sooted up as expected but one was wet with fuel so l am now thinking ignition module ,what do you think.
Gerry
Gerry Mc said:
Hi Andrew,
Stripped the oval plug today and found that they are all connected to one power supply so it looks like they have no firing order, l took the spark plugs out to find them all sooted up as expected but one was wet with fuel so l am now thinking ignition module ,what do you think.
Gerry
I'd be tempted to go for the ignition module as well - but I don't understand why it's fine for 30 seconds or so, and THEN going all lumpy, unless it's breaking down under heat. But once it's already hot, why does it fo the same thing when you start it a second time?Stripped the oval plug today and found that they are all connected to one power supply so it looks like they have no firing order, l took the spark plugs out to find them all sooted up as expected but one was wet with fuel so l am now thinking ignition module ,what do you think.
Gerry
Despite what you read, you CAN set up the distributor without the factory tool - I did one where the owner had removed the distributor without setting up TDC etc first, so we had to do it from scratch, and it's still running fine.
I've had another thought - see on the passenger side, just in front of the bulkhead above the exhaust, is there a wee tiny solenoid (about the size of an aspirin bottle) with two wires, connected into a vacuum line? Yours might not have it, it's a fuel canister purge valve that was fitted I think to the S3 onwards. If you do have one, and it's leaking, then it could be opening and introducing air into the inlet at random. Just a check.
Been out and checked my wiring as far as I could....its not easy as the wires are wrapped really close to the plugs. As far as I can see the front 3 seem to be brown with a black tracer but the rears (appear) to be just brown... mine all have the numbers on. I am reluctant to either strip the wrapping back or remove the plugs to have a better look at the mo as I dont want to introduce any issues. But, if you need more info let me know !
Regards and Good Luck
Graham
Regards and Good Luck
Graham
Ignition amps can give heat related problems, in fact that is often how they start to fail. Amp can be changed without removing the distributor. If I remember correctly you need a small (1/4" drive) 8mm socket and there are 2 screws on the bulkhead side of the distributor. It's fiddly but I managed to do mine without too much trouble.
However.
Is it always the same plug that is wet?
If so, I would swap out that plug with another and see if the fault moves with it. If not swap out the plug lead with another and see if the fault moves.
Ceejay73
However.
Is it always the same plug that is wet?
If so, I would swap out that plug with another and see if the fault moves with it. If not swap out the plug lead with another and see if the fault moves.
Ceejay73
Ceejay73 said:
Ignition amps can give heat related problems, in fact that is often how they start to fail. Amp can be changed without removing the distributor. If I remember correctly you need a small (1/4" drive) 8mm socket and there are 2 screws on the bulkhead side of the distributor. It's fiddly but I managed to do mine without too much trouble.
However.
Is it always the same plug that is wet?
If so, I would swap out that plug with another and see if the fault moves with it. If not swap out the plug lead with another and see if the fault moves.
Ceejay73
Hi Ceejay,However.
Is it always the same plug that is wet?
If so, I would swap out that plug with another and see if the fault moves with it. If not swap out the plug lead with another and see if the fault moves.
Ceejay73
I will try the plug lead and a new plug to eliminate, thanks
for your help and interest.
Gerry
[quote=Gerry Mcg Hi can anyone help, I have a 2.9 efi that start perfect, after about 30 seconds is sounds like it over fuelling and runs rich and lumpy and has a backfire on tickover . I have replaced the following , full set of injectors,set of leads, spark plugs, distributor cap, temperature switch, Coil,ignition pack.
I think its over fueling but don't know what can cause this ,it also runs rich.
Any help would be appreciated.
Gerry
I think its over fueling but don't know what can cause this ,it also runs rich.
Any help would be appreciated.
Gerry
this may not help much bit despite skills and experience I find there are occassions when its worth just paying a bloke who's really good at stuff.
i had a 525d which caused me lots of confusion at start up........1 hour at £90 / hour diagnosed the very thing i needed to do.
Not local to you but this was clive atthowe in norfolk - a very special man with engines that dont behave.
i had a 525d which caused me lots of confusion at start up........1 hour at £90 / hour diagnosed the very thing i needed to do.
Not local to you but this was clive atthowe in norfolk - a very special man with engines that dont behave.
I would be checking the fuel pressure now. It could possibly be a regulator fault or even just the vacuum hose from the reg to the throttle body has come off.
Also, do the new injectors match the old ones? The V6 engine used can come from many sources and the injectors have to match the fuel pressure used. My spare engine has 2.5 bar reg/injectors but my S3 was running 3 bar. Worth checking the fuel pressure and Stan Wiess does a chart of flow rates for Bosch injectors.
Also, do the new injectors match the old ones? The V6 engine used can come from many sources and the injectors have to match the fuel pressure used. My spare engine has 2.5 bar reg/injectors but my S3 was running 3 bar. Worth checking the fuel pressure and Stan Wiess does a chart of flow rates for Bosch injectors.
Jed-S said:
It could possibly be a regulator fault or even just the vacuum hose from the reg to the throttle body has come off.
That was a problem I once saw with mine... the end of the hose at the regulator had split and become detached and the effect was very similar to what you describe. at the time I thought it felt catastrophic but was glad that the cure was so simple at the end of the day... definitely worth checking the whole hose.K
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