Td5 power loss...kind of?

[2 rocks]

Hey people's
Having a bit of an issue with one of our Td5s that I've not encountered in 10 years with our other.

Disclosure: this is a daily driver I bought cheap and am slowly working through. At the moment it has a filthy air filter and needs an oil change. It has a Chinese MAF and I've been told the fuel pump is ailing. Silicon turbo hoses are fitted. D2a.

However, I thought I was going mad, but I'm finding sometimes a dramatic loss of power. This morning for instance the trip to work consisted of two legs. First leg it was very reluctant to gain road speed, changing through the gears so not in limp-mode, but I was burying the pedal to get acceleration. It's almost like the throttle is in low-range mode and very long travel.

Stopped, re-started for the second part of the journey and throttle response very different, accelerating normally (I think...as our other one is chipped).

Could it be the TPS or are there other sensors that may affect response and rev ability?

I assume if it was air filter or MAF it would always be rubbish and not change from start to start? Any other ideas - waste gate, modulator, buggered ECU? I presume he fuel pump shouldn't be an issue really as long as it's delivering, as the fuel is pressurised in the injectors.
Perplexed...
Cheers
Mike

[sierrafery]

Hi, unplug that chinese MAF and drive it so to see .... if it goes better get VDO unit or better drive without it...do you still have EGR? and what about oil in the ECU red plug or head plug?

[Brenton.T]

+1 for the maf.
Could also be the boost modulator, which is cheap to bypass. Either join the hose runing from the inlet intercooler pipe to hose on the wastegate or run a longer hose. Doesn't adversely affect anything and is quite common.

I had power loss recently, and the thing that made the most difference was the map sensor. If the maf doesn't make a difference, pull the map sensor out and give a clean. If you've had a discovery for so long I'm guessing you're no stranger to these things.

[2 rocks]

Thanks guys, I had forgotten about the MAP so will give it a clean...I'll try the MAF too, but it actually ran better with the Chinese one than the one that was in there :)
Yes the red plug is good and was one of the first things I checked when I picked it up.
I can't shake the feeling it could be the TPS, might get it plugged in and see what the reading is across the pedal range.
Cheers
Mike

[jasonharrison]

+1 for the maf.
Could also be the boost modulator, which is cheap to bypass. Either join the hose runing from the inlet intercooler pipe to hose on the wastegate or run a longer hose. Doesn't adversely affect anything and is quite common.


Funnily enough I found an increase in fuel economy reconnecting my boost modulator. Bypassed I made about 15psi and modulated I make a hair over 19psi.

[Brenton.T]

Funnily enough I found an increase in fuel economy reconnecting my boost modulator. Bypassed I made about 15psi and modulated I make a hair over 19psi.

Makes sense, the modulator just restricts flow to the wastegate actuator so it stays shut longer.

My car lost power yesterday. It's not as hopeless as it has been, but I can't accelerate up hills at the minute. Pretty sure my intercooler carked it yesterday, and I've got a 3 hour drive today. Fingers crossed the bearings in the turbo hopd themselves together...

[Mr Simon.]

Similar symptoms to my d2 fuel pump failure. Could still drive it but was sluggish one day good the next then just a slug all time rough idle no noise when ignition on when previously it would whirl away. Replaced it with a Lucas pump from UK. Should have used a VDO. Lucas is working fine but oh my is it noisy when cold.

[Carnut1100]

Had a thing today where it felt like no boost.
Fine on the flat but hills and overtaking were painful.
After work on the way home it was normal.
..