RUNNING RICH
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Peter Empson
PCGB Member
Hi Ryan,
Which screw are you referring to? Do you mean the idle screw adjustment?
You might want to look here before doing anything.
As such the fuelling is controlled by the chip in the ECU so it's not easily user adjustable. However 944's will seem very rich compared to most modern cars and that is nothing to be worried about, but if in any doubt I'd get it to a garage and get them to give it the once over.
Which screw are you referring to? Do you mean the idle screw adjustment?
You might want to look here before doing anything.
As such the fuelling is controlled by the chip in the ECU so it's not easily user adjustable. However 944's will seem very rich compared to most modern cars and that is nothing to be worried about, but if in any doubt I'd get it to a garage and get them to give it the once over.
Could be that the MAF is reading high when at high air flows. If by load they mean under heavy acceleration, this is where the most air is flowing through the engine. If the MAF is telling the DME that there is more air flowing into the engine than there actually is then the injection system would inject too much fuel. Although if the S2's injection system is anything like the lux's then it actuall ignores the AFM above 4000rpm and when at wide open throttle. Under those conditions it injects based upon RPM's so the AFM/MAF has no influence. My guess would be that its not the MAF but then I don't really know how the s2's injection system works or quite how load could influence AFR.
Temp sensor could cause it as any error would be more apparent as the air flow rate increased as the air mass calculation would give more and more innacuracy. Could also be overpressure in the fuel rail as this would cause the fuel flow through the injectors to increase. This should show itself under all conditions, again though it might become more apparent as more fuel is being injected into the engine.
Temp sensor could cause it as any error would be more apparent as the air flow rate increased as the air mass calculation would give more and more innacuracy. Could also be overpressure in the fuel rail as this would cause the fuel flow through the injectors to increase. This should show itself under all conditions, again though it might become more apparent as more fuel is being injected into the engine.
its a SciVision unit, it directly replaces the AFM. It has a little box of magic which converts the signal into the something the DME recognises. I don't think it has a 12V supply, although it does connect to a wire in a small box in front of the fuse box, I think it was mentioned as a voltage signal cable in the instructions IIRC. So that could be a 12v line.... I have no idea 
Acceleration is fine, not seen any black smoke. I hammered it round an airfield over the weekend, no smoke that I could see.
Acceleration is fine, not seen any black smoke. I hammered it round an airfield over the weekend, no smoke that I could see.
Neil Haughey
New member
So Hartech are saying specifically that the engine is running too much fuel enrichment only under heavy load? not rpm related? Do you have a performance chip? as these tend to not lean out in the midrange as the motor should do with a standard setup (promax chip seems to stay rich). Still though sounds like the MAF output.
Engine temp sensor will cause rich or lean running all the time the engine is at a particular temperature, I suspected this on my 968 as it was running rough at idle and especially so when cold, much better once warmed up.
Fuel pressure regulator can cause all sorts of problems my S2 did run very rich sometimes because the injectors struggled with too much fuel pressure, but in both cases I would suspect an outfit like Hartech would spot a problem with either straight away. Hartech and Jon Mitchell are probably the 2 most respected expert indies for the 944/968 series cars.
Engine temp sensor will cause rich or lean running all the time the engine is at a particular temperature, I suspected this on my 968 as it was running rough at idle and especially so when cold, much better once warmed up.
Fuel pressure regulator can cause all sorts of problems my S2 did run very rich sometimes because the injectors struggled with too much fuel pressure, but in both cases I would suspect an outfit like Hartech would spot a problem with either straight away. Hartech and Jon Mitchell are probably the 2 most respected expert indies for the 944/968 series cars.
bluedexter
New member
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 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.
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.
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.
As above or fuel pressure regulator.
Pull the vac line off it and see if there is any fuel in it.
Pull the vac line off it and see if there is any fuel in it.
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