1990 S4 Stalling problem, please help!!!!
 

Hi there

I recently removed the cats on my 1990 928 S4 and replaced then with bypass pipes.
The cats on my Porsche had just about had it, but I can not afford an x pipe replacement at the moment. Since then when the car gets up to operating temperature it suddenly cuts out. I changed the O2 sensor when I removed the exhaust so I assume it is not that. I have cleaned every connection I could find around the engine, MAF sensor connector, TPS etc.

Could anyone please tell me what else I should be checking. I don't know if it is simply coincidence that this problem is occuring since I did the exhaust. What would cause the car to cut out / stall when at idle? It only does it when the engine temperature starts to rise. Any help would be most appreciated.

Regards
Simon

I assume that the O2 sensor light is not coming on...

Unplug O2 sensor & run. It will run rich, but see if it continues to cut out. If it does not, faulty o2 sensor.

Thanks for the replies guys.

The O2 sensor light is on. I will try unplugging the sensor connector to see if the car still stalls and let you know how I get on. If this does not cure the problem is there anything else I should be looking at?

Thanks once more for your help.

Unplugged the O2 sensor and the car did not stall even when up to temperature! The new O2 sensor I installed was the correct Bosch sensor for the car. Has anyone else ever had a new O2 sensor that was faulty from new? How could I check this?

If the new sensor is ok would this mean that the LH ECU is not working correctly? I would be grateful for any help as I am at a loss of what to do next! Many thanks for the help so far.

Simon

I had a faulty brand-new Bosche O2 sensor, that is why I suggested you try this - glad it was that simple

Thanks for the quick reply

I suppose all I can do is get another O2 sensor any try again. I am hoping this will sort it out as I know the LH ecu's can be quite costly to repair / replace if that was the problem!