NefMoto

Hi,

I have a strange problem with a audi tt, hope you guys can think with me  :)   

Im getting lambda 1.99 with a short term fuel trim off +27% at idle and across the rev range just free reving.
Engine is shaking at idle but runs on 4 cilinders, spark plugs are really black.
I tougth i had a bad lambda sensor but when unplugging it fuel control should go in open loop but engine still runs te same.
When free reving and letting go high in RPM the lambda changes to 1.7 ???

Fault codes: Cilinder row 1 too lean

List of what i already did/tested:

Smoke test on inlet side = no leaks
Smoke test on exhaust sidee = no leaks
Compression test = all 4 cilinders have 150PSI
Injectors are tested and cleaned
Switched out the EVAP system with a working one
Measured vacuum at inlet manifold and airrmass flow. Compared to a car with the same engine, both are the same values.
Switched out spark plugs and coils
Flashed a original map to the ecu
Lambda signal voltage with engine not running is the same as the good car
Fuel pressure requested 50bar, actual 50bar, follow's requested pressure good when reving.

A bit of a strange one that lambda 1 cannot be met at idle ???

Hope you guys have some tips!
Sorry English is not my first language!

It looks like wiring issues or massive exhaust leak before sensor

Found the problem, Lambda sensor was giving false measurements.

Changed the lambda sensor and now get -27% fuel trim(lambda 0.8 ) on idle with no vacuum leaks and a good pcv valve. ???