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Bad running engine

2426 Views 9 Replies 7 Participants Last post by  rangeroverklaas
Hi there,

4.6 HSE 1999 with bosch motronic with engine problem.
Faultmate ODB P0172 and P0175 say both cilinder banks lean mixture.
Also misfire at specially at nr 7, have change HT lead and plugs, no result.
Engine hesitates during acceleration.
I guess the misfire is a result of the lean mixture.
On petrol less misfire then at LPG.
It's not every day very bad, cold weather and cold engine is worse.
Something to do with an airleak after MAF sensor? , broken inlet manifold ?



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From your post it suggests you have a faultmate. It would be wise to use this to diagnose the problem, rather than guess and throw parts at it.
You can use Faultmate to test MAF to probably eliminate this as the fault.
You can also use it to read the live values from your O2 sensors to see how these are performing, together with the fuel trims.

As to the lpg on a Bosch you should really only be running a full sequential system, calibrated to ensure it doesn't throw out the petrol fuel trims.
One thing to be wary about is if your MAF is at fault and you reset the adaptive values you could make it run worse.
This link gives detailed info on what the Faultmate will do - https://blackbox-solutions.com/shop/help/SM009.html

I have the MSV2, but for normal engine OBD 11 data I use my Autotap OBD scanner which can give graphical output of values - http://www.autotap.com/autotap_for_wind ... nshots.asp
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