1997 4.0 loss of power above 3000rpm

I did a nice drive with my new acquisition P38 4.0 1997 it ran great for about 1500 miles to italy. then at some stage it in the alps it started to loose power above 3000 rpms as if there was not enough air or petrol.

symptoms (Dr House style)
- started great
- Idle is good
- Accelation normal up to 3000 rpms
- No noise in the engine
- No smoke
- No Bubbles in the coolant

Suspects
- MAF I have a SAGEM (connector OK)
- Hot leads ( no sparks in the dark
- coils (if it was Coil I would have expected troubles below 3000 too, it just perfect in low rev)
- Petrol pump pressure (I have no device to mesure petrol pressure in injection pipe)
- throttle position potentiometre
-O2 sensor
....
Does anyone have an idea
thanks
Ivan

You're on the right track.

Crankshaft sensor

Thanks you for confirming all my resolution option of possible.
did anyone actually resolve a problem like mine ?
so that I don't have to check/replace all the potential suspects.
Thanks
Ivan

greenslade,
thank you for,the additional lead on the crankshaft sensor.
since I have an oil leak around the oil pump might be affectes I check this one too.
Ivan

Iaranicki said:

greenslade,
thank you for,the additional lead on the crankshaft sensor.
since I have an oil leak around the oil pump might be affectes I check this one too.
Ivan

Click to expand...

IIRC - Oil pump is at the front of the engine and the Crank Sensor is at the back...

OK My statement was stupid just checked the position of the crank sensor on the top rear no oil on it.
Is it a common problem crank sensor fault?
Ivan

Dirt in Fuel filter

Crank sensors often go weird when they get hot. A way to test it is give it a shot with one of those spray coolant thingys when it's acting up. If the cooling improves the situation, then it's the sensor.

Its the Maf..... Clue is in the post Alps is high Maf is the sensor for that.

Thank you for the different suggestions.
I think that lowfat is likely to be the closest.
I unplugges the MAF succeed to keep it running at very low idle and went for a drive amazing the engine was back with full paower and revs climbing to 5000rpms...
So I guess that unplugging the MAF makes the ECM adopt the default value for the MAF that obviously is much better thanthe signal my MAF was send to the ECM!
So I norrowing down my suspicion to the MAF now my options are
1- Cleaning
2- Changing for a low cost replacement (not LR)
3- Changing for Original SAGEM from LR ££££
4- Buying a second hand from Ebay (bet)
5- or finding athe same original SAGEM MAF for other car apparently it is a very comon part mounted on many cars. I read somewhere vW have the same Sagem MAF for much cheaper is this true?

I gues I will clean it first but would not think this will make a big difference.

any suggestion on what is the best and cheapest option?

thanks again it great to be able to get such expert guidance.
ivan

Thank you for the different suggestions.
I think that lowfat is likely to be the closest.
I unplugges the MAF succeed to keep it running at very low idle and went for a drive amazing the engine was back with full paower and revs climbing to 5000rpms...
So I guess that unplugging the MAF makes the ECM adopt the default value for the MAF that obviously is much better thanthe signal my MAF was send to the ECM!
So I norrowing down my suspicion to the MAF now my options are
1- Cleaning
2- Changing for a low cost replacement (not LR)
3- Changing for Original SAGEM from LR ££££
4- Buying a second hand from Ebay (bet)
5- or finding athe same original SAGEM MAF for other car apparently it is a very comon part mounted on many cars. I read somewhere vW have the same Sagem MAF for much cheaper is this true?

I gues I will clean it first but would not think this will make a big difference.

any suggestion on what is the best and cheapest option?

thanks again it great to be able to get such expert guidance.
ivan

The cheepo ones are no good. Bite the bullet and buy a new OEM one if you plan to keep the car. A secondhand one if you can run it before you pay.