I had my bugeye WRX on a rolling road today and they had to stop the run as it was running dangerously lean.
The car has been modded and remapped. It seems to be running fine.

Any advice on what could be causing this would be appreciated.

 

how lean? do you have an afr plot?

 

Over 12.8 lean.
Will try to post the graph later.

 

Here's the graphs if you can make them out.

 

suggest you get it checked by who ever tuned it

 

Thanks. I will do.

The way I was thinking was that something mechanical must have gone wrong with the car, as surely the original map is OK and cannot change?
Could you tell me what the possibilities are? Fuel leak, MAF, lambda?

 

inlet pipe leak, fuel pressure regulator faulty, fuel pump faulty, maf faulty..

or it was mapped with a fault that is no longer there like an intercooler pipe leak etc..

Simon

 

Is mapped with a passing VTA dump valve a possibility?

I had some other problems with my VTA passing giving a surging effect and changed it back to standard re-circ.

 

yes very possibly

 

Thanks for your help Simon.

That gives me a good starting point when I take it to the mapper.

 

no probs

 

vacuum hose off the fuel pressure regulator?