Loss of power TDI

[Ninjabob81]

Hi all,
Over the last few weeks my 96 850tdi has developed a bit of what was an intermittent fault, now it appears to be permanent.

When driving, rolling off the throttle and then getting back on it every now and then it was as if there was zero boost, if you came off the throttle and back on again it’d suddenly pick up and off you go. Did it maybe a few times every 20 mile drive.

Nipped out this morning and its now permanent. Flat as a pancake. No boost leaks, starts and drives fine other than the fact it now feels like a DI and less of a TDI.

No vacuum hoses off or split, map sensor pipe is clear as well as the nipple on the inlet manifold for it. Anyone got any values that I should be getting at the MAP sensor pins just to rule out a duff sensor?

Wondering whether its MAF related?

Cheers for any help,

Rob.

[rudi dudi]

Tcv or maf

[Ninjabob81]

Originally Posted by rudi dudi

Tcv or maf

Is there any way to test the tcv or MAF on the bench with a multimeter?

[rudi dudi]

No idea sorry.As I have a vast selection of these tdi's at my disposal I have tge luxury of swapping parts over to see

[Baffler]

Could be either but most likely the TCV.

Firstly, you could try a shot of spray lubricant, e.g. 3in1 not WD40, through the TCV and take it for a drive. If it improves try removing it and cleaning thoroughly with carb cleaner, let it dry out then get some dry PTFE spray through it before reassembly. For total piece of mind buy a new one.

The MAF (no longer available) is a bit trickier as you'll need to carefully remove the sealed black plastic cover to inspect the rheostat track for wear and or adjust the wiper arm. There are a few YouTube vids so take the Bosch part number off the cover and do a Google search for same.

[Ninjabob81]

Originally Posted by Baffler

Could be either but most likely the TCV.

Firstly, you could try a shot of spray lubricant, e.g. 3in1 not WD40, through the TCV and take it for a drive. If it improves try removing it and cleaning thoroughly with carb cleaner, let it dry out then get some dry PTFE spray through it before reassembly. For total piece of mind buy a new one.

The MAF (no longer available) is a bit trickier as you'll need to carefully remove the sealed black plastic cover to inspect the rheostat track for wear and or adjust the wiper arm. There are a few YouTube vids so take the Bosch part number off the cover and do a Google search for same.

Awesome, massive thanks for the help, I’ll give it a look today.

Thanks again,

Rob

[V70Zig]

Originally Posted by Ninjabob81

Awesome, massive thanks for the help, I’ll give it a look today.

Thanks again,

Rob

If you think it's the MAF, post up the number on it also the TCV number. I'm a hoarder and might have them both in garage.....swapped mine out and it didn't solve my particular problem.

Moved on to P3 so no use to me.

[Ninjabob81]

Originally Posted by V70Zig

If you think it's the MAF, post up the number on it also the TCV number. I'm a hoarder and might have them both in garage.....swapped mine out and it didn't solve my particular problem.

Moved on to P3 so no use to me.

Ah mate...😂 I’ve just this minute hit buy it now on a MAF sensor from a breakers... In loughborough!!

Thanks for the offer though. 👍🏻

[Ninjabob81]

Well.. Spent the last hour cleaning the tcv, double checking vac lines, finally made it to the MAF...

On close inspection I found a lovely crack in the top cover. On even closer inspection I found complete carnage inside...😂

New (second hand) MAF being picked up in the morning...

[Ninjabob81]

Maybe I ought to change this thread into a “how the hell do I upload a photo off my Iphone” thread...😂

I’m no Bill Gates but I can’t figure it out for the life of me..