Xu9jaz Overfueling - Need Help

[Guest ajsik]

What things could cause overfueling on XU9JAZ ?

 

cold engine is starting/running fine.

 

- warm engine is starting very bad, only with throtle pedal help

- warm engine is misfiring when revving form idle revs hard, when reving slow no misfire.

- Runnnig in low revs bellow 2000rpms is difficult (you have to press throtle pedal very smooth when accelarating to prevent kangoo effect ...)

- the exhaust smells by fuel ...

 

I have to open the throtlebody a little on idle by the small screw (for pre-adjusting closed position), to keep warm engine idleing ... but it idle at ~1500rpm

 

It was hapening with old engine, then with other engine with Gutmann camshaft and now after removing GM camshaft and fitting stock one, it still remains ...

 

 

I have checked these:

 

sparks color is after a 150miles drive, something between gray and brick red ... no white or black .... so it seems that when car is driven in mid revs it runs on good mixture ...

 

fuel pressure is 2,9 - OK

O2 sensor is new - OK

idle and full throtle switch is OK

AFM gives good values - OK (AFM screw is untouched)

Temperature sensor is OK

SAD - OK

Edited February 22, 2007 by ajsik

[Richie-Van-GTi 71 2 Cars]

check throttle position switch is switching off at idle, if not it will over fuel at idle and will be more noticeable when warm as SAD is closed so less air

[Guest ajsik]

check throttle position switch is switching off at idle, if not it will over fuel at idle and will be more noticeable when warm as SAD is closed so less air

 

The switch is closed (i measured it), but the the flap is particulary open by the small closed position adjustable screw, to let some more air flow in idle to the intake. If I close the flap, the engine starts to dies ... :-(

[Richie-Van-GTi 71 2 Cars]

try adjusting the afm screw, you state its untouched but as the afm wears it often needs tweaking.

[Guest ajsik]

try adjusting the afm screw, you state its untouched but as the afm wears it often needs tweaking.

 

so if the engine won't idle warm , caused by overfueling the AFM setup could help ? How to setup AFM, how many turns and how to do this properly without CO analyser ... for me is important stable idle not CO level :-) MOT is far away and I drive the car once a week for fun ...

[Richie-Van-GTi 71 2 Cars]

IIRC turning clockwise reduces the fuel, but either way just try turning it with engine running when warm and try to stabilise the idle.

[Guest ajsik]

IIRC turning clockwise reduces the fuel, but either way just try turning it with engine running when warm and try to stabilise the idle.

 

I have just found some other symptom, engine starts erratic idling after the oil temp raise, water is 90° fan is running but still no problems, after oil temp raise to ~70°C it starts to problem with idle and misfire in low revs.

 

engine is idling at 1400-1500 without any major problems but when i try to rev engine it misfires ... than it comes back to 1500 and idles... of course idling at 1000rpms is a big problem.

 

I hope that AFM screw will help reduce amout of fuel that goes to the engine on idle. Can it affect amout of fuel when is engine in mid revs or high revs (afraid of lean mixture :-) )? Or the ECU will it correct with O2 sensor data ?