Overboosting problems

Nugget3816

Member
Joined
Feb 6, 2018
Location
Indiana
TDI
02 Beetle 1.9
I've got a 2002 VW beetle with a 1.9, I'm having issues diagnosing a problem. I've changed MAF sensor and VNT actuator, but it still doesn't go passed 4000 RPM. If I disconnect the vacuum to the actuator it'll rev up to over 5000 RPM, it runs fine up until it hits third gear and then it just has no giddy up and go. It takes about 3/4 of a mile to hit 60 mph. I'm pretty much baffled at this point. Any suggestions would be appreciated.
 

PB_NB

Veteran Member
Joined
Nov 20, 2007
Location
Vancouver, B.C.
TDI
1999 New Beetle
Hi Nugget, you should really scan the car with VCDS if you have one. Throwing parts at the problem just empties your wallet! If it is overboosting, you will be able to log that and work towards correcting it.

Your other/previous posting on this same topic should be linked to this so you can benefit from the knowledge from the experts on this forum.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
Perhaps track down Canadian Grizzlie's "diagnosing limp mode" HOW-TO that's listed in his signature... a clear methodical scientific way to track down causes of over/underboosting.
 

Nugget3816

Member
Joined
Feb 6, 2018
Location
Indiana
TDI
02 Beetle 1.9
Ok, so turbo has been cleaned. Took it out for a test drive, engine light came on after about 2 miles. Put it on the scanner and still having an overboosting problem.
 

Nugget3816

Member
Joined
Feb 6, 2018
Location
Indiana
TDI
02 Beetle 1.9
Ok, so now I have no engine light coming on. But I did find out my N75 is junk, I was pulling it up on to car ramps and it wouldn't do it. Just alot of black smoke, switched it with the egr solenoid and it climbed right up. Still seems a little sluggish though.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
what is the code?
bad n75 vlave and bad vacuum lines or a bad actuator, this is the only few things that really can cause this issue save for some rarer things but we will cross that bridge when we get to it.
 

Nugget3816

Member
Joined
Feb 6, 2018
Location
Indiana
TDI
02 Beetle 1.9
It's definitely a bad N75. Now I'm just trying to fine tune the actuator, I can't get it to "open" all the way. It won't quite touch the stop set screw. If it does then it'll only move maybe an 1/8 of an inch.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
replace actuator, and all your lines, then the n75 last as its the most $$$
 

Nugget3816

Member
Joined
Feb 6, 2018
Location
Indiana
TDI
02 Beetle 1.9
Took the beetle to a shop, they ran diagnostic on and come to find out the intake is almost completely sooted up and plugged.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Interesting!

I'm trying to figure out how disconnecting the actuator can allow the engine to rev to over 5k rpm (I'd not want to go that high, but).

Curious as to what the Big Guns around here have to say about this.
 
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