Thread: TD5 Fluctuating boost under load

Although the driver demand fault would send you elsewhere, it may be an idea to clean your MAP sensor and maybe the EGR valve if you still have one. A slowly reacting MAP sensor may give the computer out of range input vs the accelerator position.

My car had a slight hesitation when I first got it much the same as you report , and it disappeared after I did those things.

It's a common problem with TPS's in petrol cars also as a gap can form in the potentiometer at the point most used ie cruise, and when you have no accelerator on downhill, then apply accelerator , you go through the gap and the computer gets an out of range signal.
It shouldn't happen with the twin or 3 track duplication of a D2 , but just an idea.
Regards Philip A

Egr is removed.

Was also thinking along the lines of fuel supply problems, as this seems to be a commonly recommended check to perform.

Hints at MAF going out of range...

Driver demand could be throttle pot or oil in loom

boost drop could be slight overboost, check the wastegate is moving freely

A live data log would reveal things IMO, the driver demand fault code + the fact that the symptom is not present with cruise control makes the TPS very suspect but could be many reasons...
just to rule these out:
- did you check/clean the small strainer under the FPR when you replaced it?
- what about oil in the red plug thing? ...even though the inputs from the TPS are in the black plug

anyway, on live data record the drop in boost must be visible on the MAP reading too i'm sure and all the values must be watched on that "line" then, strangely this boost thing can be the other way around too i mean there will be a drop in MAP reading when the boost drops on the gauge if the boost drops for some 'physical' reason(e'g sticking wastegate) but there can be a MAP/IAT missbehaviour which can cause a boost drop as well(though this should leave a specific fault code) so the live reading log is very important, save a fueling inputs session with nanocom from a journey and attach it here if you can.

won't hurt to unplug the TPS and give it some contact spray untill then, eventually if you check the ECM red plug anyway give some contact spray in the black plug too

FPR was replaced before I bought the vehicle.

Have had oil in harness, but have cut and put a secondary plug just after the head to stop ingress into the ECM.
Have cleaned the red plug numerous times.

If I could find the SD card for the Nanocom I'd do a live data stream.

Have cleaned the Sensor in the inlet manifold and cleaned the MAP (bit if dust and a few Mosquitos jammed in the mesh)

Originally Posted by Phat-Customs

Have had oil in harness, but have cut and put a secondary plug just after the head to stop ingress into the ECM.

but did you replace the injector loom too? cos otherwise the whole thing is useless, i mean you've fixed only half of the issue then

No mate, I havnt replaced the internal harness, it's on my list of things to do though.

then do it ASAP cos it can give you all kind of missfire symptoms, except the driver demand fault code