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Running rich

Z

zcacogp

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What are the exhaust gas readings like, and do you have a later car (with a cat and - presumably - lambda), or an earlier one without? Oli.
 
The car is a late '91, Oli. It has a bridge spoiler (if that helps) and all I can tell you about the exhaust gasses is that they smell rich. I have considered the lambda sensor but it is running sooo rich that I don't think it would be that. I have a feeling it could be some problem with the injectors but I am hoping it could be something less complicated.
 
I've has a problem with the car running rich since I bought it last October but the extent of the problem has been masked by a very optimistic speedo reading and infrequent running during the winter. The problem is worse than I anticipated to the extent that the oil now smells of petrol. The car has been running smoothly and without any starting problems.

I have removed the temperature sensor, tested it and found it to be ok and I can't detect any obvious air leaks but don't know what to do next "" apart from booking it in for a diagnostic test.

Does anyone know of any simple diagnostic test procedures which would eliminate any of the possible culprits?
 
My car started running rich a couple of years ago and it turned out to be the air flow meter but I don't know how to test it. They do go when they get old. Promax diagnosed the problem replaced the AFM and it's been fine ever since.
 
ORIGINAL: bluedexter The car is a late '91, Oli. It has a bridge spoiler (if that helps) and all I can tell you about the exhaust gasses is that they smell rich. I have considered the lambda sensor but it is running sooo rich that I don't think it would be that. I have a feeling it could be some problem with the injectors but I am hoping it could be something less complicated.
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If it is that rich and lambda is working as it should then lambda will be constantly telling the ECU to go lean. I'd suspect a lambda fault - are the wires going to it all as they should be? Is the sensor working as it should? (If Lambda is signalling wrongly then it will force the ECU into running rich, which the lambda then won't be able to sort out ... ) You need proper diagnostics (i.e. someone who can probe lambda), NOT a general garage bodge-artist who will just replace bits. (The latter approach will solve the problem by trial and error, but it may be later rather than sooner - to your financial detriment.) Oli.
 
ORIGINAL: marty My car started running rich a couple of years ago and it turned out to be the air flow meter but I don't know how to test it. They do go when they get old. Promax diagnosed the problem replaced the AFM and it's been fine ever since.
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They do, and I have a theory about them. (Come with me on this one.) 1. AFM's work by having a flap, which is blown out of position by incoming air. 2. It is held in place by a spring. This spring is what determines how much it moves in the air flow. 3. Springs become weaker with time. (We know this from suspension, speedometers and lots of other things.) 4. Spring weaker = more flap movement = ECU signalled that more air is coming in = more fuel goes in = engine runs rich. Solution? Tighten the spring up. Simple - huh? Oli.
 
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