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Downunder11

New Member
My 2.5 DSE 1996 will start okay and idle OK. It will rev until redline when stationary. As soon as it goes into drive it won't rev past 1,000rpm 90% of the time. Occasionally it will drive normally, but not often. Specialist says no fault codes are coming up on Nanocom however is suggesting either faulty potentiometer or Map sensor. Does anyone have any ideas??
 
Have you tried different diagnostics and the following handy book
71PquRsxZTL.jpg

Addit: @Saint.V8 , @Grrrrrr , @Henry_b and the other P38 owners, is the potentiometer the same as the TPS*? Or is the idle control thingy?

*Nooooo, not tyre pressure sensor :p
 
Last edited:
Think they mean the throttle position sensor but if that was shot then I don't think it would rev at all.

MAP is worth checking. The pipe runs from fuel filter to under the inlet manifold. Need to make sure the inlet manifold end is clear and pipe is good. Diagnostics should show change in pressure as turbo spools up.
 
Downunder11 said:
My 2.5 DSE 1996 will start okay and idle OK. It will rev until redline when stationary. As soon as it goes into drive it won't rev past 1,000rpm 90% of the time. Occasionally it will drive normally, but not often. Specialist says no fault codes are coming up on Nanocom however is suggesting either faulty potentiometer or Map sensor. Does anyone have any ideas??
Click to expand...
Faulty potentiometer? More details needed, do you mean the fuel quantity servo potentiometer?
 
Any smoke out the back when revving? Easy to check the lift pump is working properly so I'd be tempted to rule that out. There's a how to by @wammers in the Technical Section.
 
Downunder11 said:
No smoke really, revs fine in park too.
Click to expand...
It's pre EGR so I'd look at the MAP sensor on live data for starters, a duff sensor will put it into limp mode. If the guy has a Nanocom looking at live data from the CPS, needle lift sensor, modulation etc should give some clue as to what is happening.
 
Nanocom can record a trace of what is going on. Then you can zip the CSV file and upload it here. One of the gurus might spot something. Think there are 2 or maybe 3 sections in the EDC module.
 
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