will not rev past 2500rpm, tried everything!! Help

Problem : no power, will not rev past 2500rpm, won't go over 20mph!

What I've tried: new MAF, MAP has normal output (0- 14psi), new turbo and vnt actuator, tested N75 valve, cleaned out intake manifold, pump and injectors work (spray into open air), fuel supply appears to be unrestricted (vacum gauge, inline between filter and pump, reads 8).

Comment: took it for a ride, timing advance stays at 1. My friends TDI goes all the way up to 15 while under boost. Could be a problem with the pump???, computer??? Sorry, I do not have VCDS, I have a code reader that does live data (hey, it's something!)

Any suggestions???

So there are or are not codes? Your generic ready should be able to read the codes and then post the results.

timing is adjusted from no.3 injector , should be a sensor on it

Generally it'll code for a bad injector, but a possibility. Pump sounds like it could be suspect as well.

Did it ever fail a turbo? CAT could be plugged, but if it was it would likely trail a ton of blue smoke.

Good call, clogged cat. I was wrong about the timing advance, it does/did actually advance to 15 TDC under boost, I was looking at the wrong measurement. About the cat. I disconected the down pipe, what a difference. Now I am in the process of gutting the cat. For now I will leave the muffler in place. If the car runs a lot better without the muffler, I will run a straight pipe. I did mention a new turbo, I guess that was the big clue. The old turbo clogged the cat, before I had a chance to change it out. Thanks again, good call.

Never used to be a problem, never used to be considered in the "troubleshooting tree" but, I'm seeing more and more of this sort of issue with these 15 year old cats.

A good way to check if yours is clogging: do a WOT run to include going past 3000 rpm. say 2500-3500 rpm. Duty cycle in Group 11 is normally in the 30-35% range at WOT and 3000 rpm. As a general rule of thumb, if it's requiring more than 40-50% duty cycle in group 11 wot 3000 rpm then chances are you are on your way to getting plugged up.

When it's remedied, there's a profound change in the way the turbo responds - for the better

Lots of good aftermarket cats nowadays, and a good opportunity to upgrade the exhaust to something better

Yep, if they sit for a few weeks or longer they are finished. I bought a car way back, like 05' or so that had been sitting since 01'. The cat was like a brick.

OK, I have gutted the cat, replaced the turbo, cleaned eveything, N-75 seems to work properly, so does the VNT actuator. I have VCDS (Ross Tech). What test should I run? Is there anyone on this forum willing to look at my VCDS log?

Eddie
772-979-6515

So you have effectively removed the catalytic converter? Isn't this designed to remove pollutants from the exhaust?

Perhaps but it is a 15 year old car. The rules have changed over the years cats were not really needed on ALH cars.

I can guarantee that a 15 year old cat on an ALH was not doing anything.

Is it revving up yet? If not, take the boost pipe off the intake and if that doesn't work try taking the intake manifold off.
Does anyone else remember that thread the end of last year? The guy had this tiny blockage in the intake manifold and it wouldn't rev properly? It's usually caused by a blockage in the intake anyway, whether it's because the turbo has broken it's shaft, someone has left a rag or there's just a bit of whatever stuck in there it's definitely up there as one of the main causes.

Read it all: http://forums.tdiclub.com/showthread.php?t=348987

Cheers,

PH

That's the one, well found!

I just went through troubleshooting a problem with nearly the same symptoms. I'm assuming that your gutted cat mod didn't fix the super low power issue?
Were you getting limp mode under load previously? If you back the downpipe away from the exhaust manifold so there's a half inch gap, does it run like it's new? (if you run like this for long the gasket in there will disintegrate)
The group 11 logs on a WOT run from <2K to 4K rpm or as high as it'll get is what you want. Get a plot of a couple of these logs and post them somewhere and post the link. If you can figure out how to insert one in this thread that would work too.

If it runs great and revs to 4K in 2nd or 3rd gear with the downpipe disconnected or backed off, yet wont rev up with the downpipe snugged up, your exhaust is still clogged up.
Do you get any codes?

John