4.2 BFM system too lean only on bank 1

[josepe306]

Cheers guys and thank you for your responds. Yes, car runs lean on both LPG and gasoline which makes me think it's not the injectors. Both arms on the intake manifold seem to be working fine, I opened it two months to take a look at the 4 little bolts that unwind in time and I cleaned and lubricated it as well as I took a look at the flaps - were looking goof. I don't have back lambda sensors, they were deleted from the ECU but are still there. I'm going to measure the vacuum in the intake manifold on Sunday and I will definitely get new vacuum lines everywhere just in case. Something very interesting - today I went for a 700 kms trip and deleted/reset the trims on departure. After half an hour of driving with average 90 miles per hour long term fuel trim adaptation was 3,4% and then suddenly without me doing nothing it started raisin reaching 13%? Makes no sense to me!? Another idea is the fuel pressure under load- some guys say both fuel pump work simultaneously whose ssp says there is a "main" one - the one on the right that runs all the time and the one on the left runs at cold start and at high engine load. Any ideas?

[ainarssems]

If it's one bank it would suggest that it either gets more than fair share of air which means restricted airflow on the other bank so 2 main issues would be valve timing or blocked exhaust/catalytic converter. Or it does not get enough fuel so could be blocked or sticky injector but ECU should be able to detect that and throw a fault code for single cylinder. Couple of things to check are misfire count per cylinder and knock sensor voltage to see if 1 or couple cylinders differ from the rest, then maybe swap injectors between banks. Fuel pressure/flow could affect as well so testing fuel pressure under load would be beneficial.

Also do a compression test on all cylinders both cold and warm and see if it is the same for all cylinders / both banks

[josepe306]

well, the cat has no catalytic converters and the rear lambda sensor are deleted from the ECU as well
Next thing i`ll do is check the petrol injector but i thin if i had a leaking/bad petrol injector running on LPG bank 1 would`n run lean, am I right?
Another thing that might have happened is that i have done something wrong assembling the intake manifold after cleaning and lubricating it - i will definitely check it out opening the manifold once again and this time i will renew all vacuum hoses
ECU detects no single misfire no matter running on petrol/LPG.
ainarssems - that`s a good point, i have tested the fuel pressure only at idle. it should be 4 bars without the fuel regulator connected and 3,5 with put under vacuum as far as i know.

[Mechcanico Lee]

Your smoke test should of shown any inlet manifold leaks ....or have you had the manifold off again since the first smoke test ?

I would of thought if fuel pressure is low under load it would show on both banks , and you also said that under heavy load your fuel corrections where only 3/ 4 % ......fuel pressure is most critical under heavy load so the corrections should of shown this .....but still worth doing to rule out .

Same question as in my first post .... was this fault present before the timing chains were replaced ?

Do a vaccum test on engine before you remove the inlet manifold ...... get the diagnostic results before you strip things then if you find faults when it goes back together you can see before and after results .


You say there are no catalytic converters .....has the petrol ecm had a programme change to stop cat converter in efficient codes from showing ?