hi again 1997 2.5dt no power, tested and showing either potentiometer or fip faulty. I changed potentiometer first and had same problem so then purchased a used fip which has been changed by local garage. He says pump timing is spot on but still blows black smoke and has diesel knock, had timing detail from auto data. thanks
What potentiometer did you change? Throttle pot? Black smoke is overfuelling or lack of air, did you play with pump? Are injectors sound? I take it your local garage know what they are doing. Diagnostics may help you out, to many things to go through on here. You need to know if any faults are logged before we can go any further.
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hi potentiometer connected to throttle changed first. diagnostic read either throttle potentiometer or fuel injection pump. No faults showing now pump changed, no4 injector changed last year. Local garage is bmw specialist so has all correct tools but will have another chat with him tomorrow. thanks
There is a fuel quantity potentiometer in the injection pump which is more likely to have failed than the throttle pot. If there are no faults it has to be a mechanical problem, you will need someone who really knows what they are doing to sort it.
Datatek
Well-Known Member
They changed the FIP Tony, could it be they got the timing wrong?
That is why i say he needs decent diag that would give me a picture to look at. But he says no fault showing, if timing was out modulation would be off scale and registering a fault. It needs a good coat of looking at by someone who knows what they are about with decent diag. Can't see how there was a diagnosis of either FIP or throttle pot. Throttle pot is easy to check for function with good diag. As long as idle switch works and it is progressive that is all you need to know. Onus then shifts to quantity servo. Think someone has miss read diag to be honest. Loss of power before that could be several other things as you know nothing involving a FIP. Neither do we know the condition of the replacement pump.
Datatek
Well-Known Member
OP originally posted in the intro section I think where I suggested FIP timing & diagnostics.
Idle rpm to low should be 750 +- 50. Cutting out when throttle is closed is usually a sign of failing fuel quantity servo feedback pot. FIP is faulty.
Raising the idle RPM with diagnostics to about 850 so wiper is sitting on a different part of track may help for a while. But problem is usually worn area of feedback track losing contact with wiper. You would usually get "Fuel quantity control fault" logged. Could also be CPS sensor but that should also log an intermittent fault. Had this on mine only thing that cured it was a new pump.
That will cure the stall on gear engagement. But stalling when coming to a halt at traffic lights etc with throttle closed is usually down to the problem described.
