Long term fuel trim upper limit CEL solved

S60UT · Post by **S60UT** » 31 Aug 2021, 17:05

Anyone who has followed my thread for the 00 V70R knows I've been fighting this CEL for 11 months now. Just moved to TN from Utah and my niece works at a Euro Indy shop. Owner is a certified master BMW mechanic and had a P80 VR, S70 T5 and currently has a V NA (he's also got a beautiful E30 M3). He did some diags and deduced it as a weak fuel pump. I was surprised as I tested the pressure at idle before and it was within spec's. He said he taped the fuel gauge to the windshield and under boost the pressure dropped to 30 psi. He loves P80's and understood that I wanted to source and replace the pump myself. It's been 310 miles since the swap and no CEL or pending codes. All green lights in Vida. Fuel economy has increased from 15 mpg average to 21. While trouble shooting this I thoroughly checked for Vac leaks, replaced MAF, both O2's, purge valve and turbo intake pipe. Funny thing was the car was still starting, running great and building boost with the CEL. I'm sure you folks can understand the satisfaction/relief of FINALLY finding the root cause of a problem.

Post by **scot850** » 31 Aug 2021, 23:13

Well no wonder it was so hard to find. Being able to run the diagnostics while running makes a huge help finding this issue.

Glad it is all well now so you can just go and enjoy it! Thanks for sharing.

Neil.

Post by **kallekula** » 01 Sep 2021, 10:29

I usually tape the gauge on the windshield for easy viewing when driving. Good pressure on idle can be misleading like you figured out