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TDIBrandon February 26th, 2012 16:25

Low Power, no limp mode
Hey guys, Long time reader here with a problem.

Car is a 1999.5 Jetta. only thing it has is a straight pipe.

Background. I have been experiencing a "limp mode" situation for a while. I would have no top end and it would go into limp mode whenever I got high in rpm.

I read through the numerous threads on diagnosing a limp mode. I replaced all the 3mm vacuum lines (couldnt get the larger 5mm until tomorrow, so will do them) cleaned intake manifold and put a newer clean egr on. put a newer actuator on and have full movement in both the actuator and the turbo vnt.
That seemed to have fixed my limp mode.

But, now I'm experiencing a no power situation that can't be corrected by cycling the car off and on.

It's hard to describe but I have no bottom end or top end. I have no CEL. The exhaust sounds throatier, and my turbo is no longer loud through my exhaust (straight pipe).

I tried the maf with a couple spares I had.. no difference
I replaced the fuel filter with no difference either.

It sure seems like limp mode, but it doesn't go away.

Any help would be appreciated.

Seatman February 26th, 2012 17:09

Any chance the vac pipes got mixed up? There's vac diagrams in this link

Also worth testing the maf

TDIBrandon February 26th, 2012 18:17

I'm fairly certain I got the vacuum lines correct, but I'll check again to be safe.

I changed out a maf I had in there and now the car has low power until roughly 2800rpm, then it seems to have full power until redline

Seatman February 26th, 2012 18:20

If you have the egr still in place, pull the vac line to it and plug the line with a small bolt, see if that hepls at all. You'll get a light for it but it'll help rule it in or out. Mine's been acting up and giving me a wierd sort of hesitation thing but I had it disconnected and the car ran smooth all the way. I've reconnected it for now to help with heat but it'll be off when the weather perks up.

TDIBrandon February 27th, 2012 04:56

It's a weird change. It just runs different now right from idle. Best way i can describe the low power is its like a big turbo car. Sugglish until about 3000 but then what feels like full boost.

csstevej February 27th, 2012 05:17

Did you adjust the actuator after replacement? It should start to move by 5hg of vacuum and be fully opened by 18hg, if not adjust the linkage on the actuator. It can be done on the car.Mt .02.

Laserface February 27th, 2012 05:44

Sounds like an actuator problem. If the VNT vanes aren't moving properly ("stuck" in the open position), the car will not build low end boost and act like it has a big turbo on it. The exhaust is throatier because the vanes are wide open and the turbo is not doing as much muffling of the exhaust. You cant hear the turbo because its not building boost. The engine probably sounds normal above 3000 RPM, right?

My vote is for vacuum hose routing, but actuator adjustment or a bad N75 valve could be to blame.

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