Totally confused; need help

4Cornered

Member
Joined
Mar 20, 2006
Location
Southwest Montana
TDI
2002 Golf
I have a 2002 Golf TDI with 108,000 miles. It has progressively started to lose power and make noise in the last week. Yesterday, while returning from a test drive, I noticed that it was producing black smoke while going uphill. The idle seems much the same as usual, perhaps a bit louder, but I have both the upper and lower covers off. I have VCDS and the only DTC codes being produced are intermittent glow plug failure. I ran the basic settings tests and the solenoid for the turbocharger is moving freely. I checked to see if the car would rev to 5100 rpm in neutral after being warmed up, it does. There is a clattering noise which started occuring during acceleration in 2nd through 4th gear in the 2000+ rpm range. I've cleaned the snow screen, checked the air filter, run it with and without the MAF plugged in (no discernable difference), run it up hill in 3rd, 4th and 5th gear with Wide Open Throttle. I am hoping someone might have suggestions and have a couple of questions.

1) If the car is going into limp mode, will it always (or commonly) produce some DTC that the VCDS will find?
2) Could the power loss, noise increase and smoke production be the result of an injector (or injectors) getting progressively plugged? If so, how can I tell if it is an injector problem, or something else.
3) Could the problems be from a sticking (failing) valve? Seems unlikely, but how could it be ruled out? The car has been lubed with synthetic oil since break-in and has virtually no consumption between changes.

Any help would be appreciated; its a 90 mile round trip to the nearest town with a dealership.
 

dieseldorf

Top Post Dawg
Joined
Oct 11, 2000
Location
MA
TDI
ex- 1996 wagon, ex-2000 Jetta
Limp mode certainly does NOT always set DTCs.

has the intake manifold ever been cleaned? Is the MAF sensor original?
 

Joester

Vendor
Joined
Aug 17, 2009
Location
St. Louis
TDI
2002 Golf TDI
i would think MAF if there was no noticable difference. if you unplug a good MAF you will definitely definitely notice the difference. its like half as fast as it was.
 

Tom W.

Veteran Member
Joined
Dec 9, 2005
Location
Raleigh, NC
TDI
mash-up GettaTDI150, 1986 Jetta Delux D, 2005 Passat TDI sedan
Loosing power, make noise- could be you have a leak somewhere between the turbo and the intake manifold. Not unusual . You have to put the car up on ramps, climb under while the car is running, and listen/look/feel all along the pipes from the turbo to the intercooler, the intercooler itself, and all the way up to the intake manifold. could be a split pipe, or a loose clamp- I've seen both.
 

4Cornered

Member
Joined
Mar 20, 2006
Location
Southwest Montana
TDI
2002 Golf
Responding to comments

Thanks for the suggestions:

1) The MAF is orginal.
2) Have had the car up on ramps while checking the turbo soleniod. I did not notice any leaks. Would the graphing Manifold pressure in VCDS indicate low pressure in the intake between the compressor side of the turbocharger and the intake valves?
3) The intake manifold has not been cleaned.

By the way, my wife drives the car to work, her commute is 14 miles one way over a 7000+ foot pass. So the car does get warm, and it has been doing this climb twice a day at 70 mph in 5th gear until recently.
 

dieseldorf

Top Post Dawg
Joined
Oct 11, 2000
Location
MA
TDI
ex- 1996 wagon, ex-2000 Jetta
These are both immediate conceners, IME.

Thanks for the suggestions:

1) The MAF is orginal.

3) The intake manifold has not been cleaned.

The intake will need to be cleaned.

The VCDS test for a failing/failed MAF sensor isn't quite as good as it should be. I'd give strong consideration to getting a fresh one in there. The part is inexpensive. It can do amazing things for restoring driveability as the failure is often gradual.
 

4Cornered

Member
Joined
Mar 20, 2006
Location
Southwest Montana
TDI
2002 Golf
Will try these

I have a replacement MAF ordered, while waiting for it to get here, I'll clean the intake manifold. Hope that clears things up. As is my wife is using my 1984 Subaru to commute and making comments regarding time to go over pass.

Thanks for the suggestions.
 

dieseldorf

Top Post Dawg
Joined
Oct 11, 2000
Location
MA
TDI
ex- 1996 wagon, ex-2000 Jetta
My pleasure. Let us know how else we might help.

I hope doing these fairly minor tasks returns your 2002 to better than new operating condition. A weak/failing MAF sensor can turn these cars into total pooches.
 

75r90rider

Veteran Member
Joined
Sep 6, 2010
Location
Midwest
TDI
quite a few diesels over the years
These are both immediate conceners, IME.




The intake will need to be cleaned.

The VCDS test for a failing/failed MAF sensor isn't quite as good as it should be. I'd give strong consideration to getting a fresh one in there. The part is inexpensive. It can do amazing things for restoring driveability as the failure is often gradual.
In my experience, dieseldorf is 100% on the money.
 
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