- I have no codes being thrown
- O2 sensors seem to be ok
- everything seems fine until I do a quick tap of the accelerator (the car is parked) and then the fuel mixture stays rich. The o2 sensor reads around 0.78 volts.

Where should I start?

 

 

Thanks. 99 XJ8 is generally on my signature, but I posted from my phone. If you look at my other posts which are in the x308 forum you'll see that. I intentionally posted this question here for the wider audience for my non-model-specific question.

I appreciate the information that you provided.

 

The problem with posting here is that some of the cars have hi-tech PCMs, some mid-tech and some quite lo-tech. They have 6 or 4 (possibly only 2) sensors AND in addition those sensors vary - some wideband and some not.

Your question means we need to ignore many of the above but if it's meant to be a General question that is going to need a quite messy detailed set of replies.

At a guess no-one will feel inclined to provide a reply that covers all this.

I'm afraid I fit in that category but good luck....

(I have, however, often posted about fuel trims and about how OBDII cars are structured so feel free to read those posts and figure out your situation.)