T25 1.9 TDi running problem

[Bad Dog 13]

Morning everyone, Got a T25 with 1z TDi conversion. On the way to Bustypes it ran into a problem and would not rev above 3 tho under load but revved freely in neutral. Got back and eventually found out that the MAF sensor was fooked . new sensor fitted and voila of we go again like the proverbial scalded cat. However on the motorway at about 55 mph when you floor it instead of taking of like normal, nothing it just creeps up to 80 ish. goes fine up ill 55 tho'. Any ideas ?

Cheer Euan

[big red bus]

clutch slipping?

[Bad Dog 13]

nope, clutch fine............

[ELVIS]

plugged it into vagcom yet?

[keith]

How fast did it go from 55 to 80 ish before.........and how fast now.

Can't be much wrong to get it to 80 ish......or to go uphill at 55 ish

Is it std 90hp

[Bad Dog 13]

Not done vagcom yet.

Yes standard 90, used to put foot at 50 and you got a surge up to 80 now it just crawls. but if you lift of the throttle completely then floor it, it sometimes works like it used to ?

Cheers for the input Euan

[ELVIS]

Had similar(ish) with mine during week - intermitiant gutless but also occasionally cut out at lights.

Threw up 3 fault codes. Spoke to max+caddy and he said they all related to pump and it is uncommon for it to just 'go' and more likely the connectors to pump. took em off and cleaned em with electrical cleaner (cheers dave futbus for supplies!) and they went and van ran smoothly again.

BUT.....

just after i did fuel filter and it was stinking - black/brown inside and filter element was minging so dont know if it was pump connections and by coincidence it stopped misbehaving after cleaning or that really was the problem and it was the filter done afterwards.

Maybe pump threw up codes as it had a hissy fit due to not getting proper fuel supply/interupted supply ?

Dunno, but similarish to yours and was fixed in 5 mins for £6 and a free squirt of uncle daves special spray!

maybe by lifting foot you are giving the filter a chance to refill completely as its blocked and when it refills it acts as a header tank until you floor it and drain it again as fuel demanded exceeds fuel being delivered once filter is partially emptied from extra demand. make sense?

[Bad Dog 13]

Cheers Elvis,
Sounds like a reasonable hypothesis............ haven't changed fuel filter for a while so worthwhile anyway. have also noticed that it's smoking more than usual and that the smoke is light Grey in colour and stings your eyes this is apparently neat diesel Hmmm.

The game goes on...............

[Bad Dog 13]

Have changed fuel filter, no difference ;-( more head scratching required me thinks

[ELVIS]

vagcom yet?

[Bad Dog 13]

Na don't have access to one. also during the conversion certain sensors were bypassed i think and it may therefore throw up a lot of codes. have seem vagcom leads on Fleabay for not a lot. am i right in assuming they come with a cd that you stick in a lap top hook it up and away you go or am i being a tad ignorant/optimistic lol


Cheers Euan

[ewenmaclean]

This sounds like limp mode to me - you really do need to read the codes, then start to diagnose.

It's very common to have a slight induction leak which causes the requested and actual boost to differ - have you checked your hoses - perhaps an ill-fitting connection from an intercooler? If you've got a wastegate turbo make sure the wastegate is free to move - mine was stuck on my old setup with GT15 turbo causing limp mode similar to what you describe as it would overboost over the specified value, which would make the ECU kick-in limp mode. If it is that the error will be a 00575 error. Elvis is right - it could be the pump or the accelerator potentiometer, but you can't really start checking all that until you've got the error. If I were a betting man I'd go for induction system.

Ewen

[Bad Dog 13]

Have had issues with the induction pipe since it was converted, blowing of all the time (there is no inter cooler fitted at present just a straight pipe). However when the input pipe comes off it is always followed by clouds of black smoke due to over fueling. In this case there is no black smoke, this may be due to the leak being quite small and just slowly letting the pressure out. Have pissed around long enough with the set up as is so it is now time to sort it out properly will keep you advised on progress. Thanks for all the advice.

Cheers Euan

[Bad Dog 13]

OK, Quick up date, after havin' a chat with a work colleague, i have replaced all the fuel return pipes and Bob's yer Uncle happy van once again pulls like a train all the way through the rev range Ta da