Thread: D2a Td5 power issue

Originally Posted by johnp38

Steve I really think you may have a wiring issue, check the loom carefully starting from the maf, water temp, airbox, wastegate modulator and so on back towards the ecu.

Unwrap if sections look worn and use a bright light too as it helps spot the wire peeking through the insulation.

I concur John, the MAF is spiking all over... As are the injector balances as pointed out by PhillipA.

Originally Posted by steveG

Been running with the MAF disconnected for a while now, and runs pretty nicely.
Finally got around to fitting the new VDO one. Seemed to be working normally for about the first 1km after I fitted it, then felt like the power dropped back to what it was with the original MAF plugged in - and it became a slug again.
Unplugged the new MAF - goes OK again.

I've attached a couple of logs. 20230415.csv is with the MAF connected, and 230515NR is with it unplugged.
The only differences I can see when its unplugged are:

• boost is higher
• there are values in EGR Inlet and Wastegate graphs ( compared to zero with MAF plugged in)

Any ideas where to go from here?

PS - Just a random thought - but I haven't actually checked the inlet duct pre-air filter. Would a restriction there (eg rats nest) perhaps give the behaviour I'm getting?

Attachment 184867Attachment 184868

Steve

The boost is lower with the MAF connected, that's why you aren't seeing the wastegate do anything.

The EGR is incorrectly labelled, it's just the wastegate again, nano bug.

It's the first time i see such thing so i dont know what can be the effect of it but the fuel temp reading is higher than the coolant temp which is not normal, the FT should be with around 10*C lower than the ECT after the engine ran for a while, they can be very close after cold start but the FT never higher. As the FT is quite important for the management this oddity might mix up the fuelling. The question is why is this happenning? one of the sensors is misreading or if the fuel cooler is the cylindrical type it has a thermostat in it which if it's stuck closed the fuel is not cooled enough hence it gets hotter

Originally Posted by sierrafery

It's the first time i see such thing so i dont know what can be the effect of it but the fuel temp reading is higher than the coolant temp which is not normal, the FT should be with around 10*C lower than the ECT after the engine ran for a while, they can be very close after cold start but the FT never higher. As the FT is quite important for the management this oddity might mix up the fuelling. The question is why is this happenning? one of the sensors is misreading or if the fuel cooler is the cylindrical type it has a thermostat in it which if it's stuck closed the fuel is not cooled enough hence it gets hotter

I removed the fuel cooler 2 summers ago, closest fuel temp has ever got to coolant temp was 5 celsius, usually bouncing between 5-10 celsius below coolant temp. This includes towing 600 odd km on a hot day.

In these logs is 5 to 12 degrees higher which might be odd for the management

Thanks for the feedback everyone.
I’ll have a look over the wiring for any damage etc.
Physically where is the fuel temp sensor located?

Steve

The FT sensor is in the FPR, you can swap the ECT and FT sensors between them cos they are the same and see what happens then cos if one of them is not good the readings will be reverted but you'll still not know which one is bad, you can put it in water, measure the temperature of it and check the resistance of the sensor, it should be like this