Thread: Idle = AFR problems

Hi,

if i let my engine run at idle it runs first time with 14.7 afr but if i let them run longer at idle it runs every leaner up to 19 afr!!! where could be the problem? If it is cold i hear a mid loud knock which comes from the head! rod bearings are ok. When the engine is warm the knock is gone. Can made the problems the injectors, maf or what?

Thanks for your help!

Sascha

at what rpms do you have your idle set? stock ecu?

it´s approx 1250 rpm and i use the power fc. first i had mean the Z32 maf makes troubble but now i had order an aftermarket one and than it was the same issue..

If you're using a K&N or any other oil-type air filter it could have coated the mass air flow sensor with oil. When the sensor is coated it won't see airflow and will assume there's less air going into the engine. The ecm responds by leaning out the mixture and causing all sorts of problems.

Check for vac leaks too

yes i will check the vac lines again. ok but from where comes the knock which i can hear at the head??

a ''knocking'' could come from the timing tensioner, how old is yours?

i think that is the first timing tensioner but the chain is very strong. the knock is to hear directly on the head between cam and block!

well its not just the chain that would be weak you can get noises from the chain rattling again the tensioner or the top timing chin guide. its hard to pinpoint knock sometimeswhere it sounds like its coming from one place but its realy another. not saying it is or isnt. trying pulling the valve cover and checking the top timing chain guide for any wear marks or grooves. that there.

Chain tensioner and/or hydraulic lifters