Fault code 17964: charge pressure control-negative deviation

meisterleipz

Veteran Member
Joined
Apr 21, 2009
Location
Richmond Hill
TDI
2000 Jetta TDI (01M)
I keep getting this code.

I have replaced all the vacuum lines to the n75 as well as the the vacuum line to the actuator. Is there only one vacuum line to the turbo?

Bad actuator maybe?....car doesn't seem to going into limp mode. It is an auto.

I have also gone through Canadian Grizzley's thread.
 

Canadian_Grizzly

Veteran Member
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Apr 7, 2005
Location
British Columbia, Canada
TDI
02 Jetta TDI
I really would suspect your actuator unless it does move when vacuum is applied. It wouldn't go into limp if it is seized in low boost position. How is the power in the car has it been a dog lately?
 

meisterleipz

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Location
Richmond Hill
TDI
2000 Jetta TDI (01M)
I don't have a vacuum pump to see if it holds vacuum. Is there another way I can see if it holds a vacuum?

I can move the lever from the actuator to the turbo but there is some resistance from the actuator side I think.

when I first start the car after it sitting over night it is quite slow...I will have the pedal to the floor and it will take its sweet time getting up to speed. After it is warmed up it is better. It is also especially slow up hills...again I will have it floored and the tranny will kick down but it will slow down. It is an auto so perhaps that has to do with it.
 

volkswheels

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Jan 9, 2009
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Long Sault, Ontario
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2006.5 Jetta TDI DSG, 2012 GolfHighline TDI DSG
Check with Canadian Tire loan a tool program for a vacuum pump, hand held style, bring the vacuum down to 18mmg's and see if actuator goes full travel:)
 

meisterleipz

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Richmond Hill
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2000 Jetta TDI (01M)
alright...I will look into it.

here is a little more description of the symptoms. sunday morning I started the car and it ran fine- went up hills no problem actually better then usual. When slowed down after about 40min of cruising and sped up again the car went sluggish. I let off the accelerator and then it seemed to get its power back. No CEL came on. On the way home no power loss and no CEL. This morning...power loss and CEL came on but then power returned after I let up on the accelerator and the CEL remained on.

this was the first long drive since doing this: http://forums.tdiclub.com/showthread.php?t=251428&highlight=17964

seemed to help.
 

meisterleipz

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2000 Jetta TDI (01M)
to remove the actuator do you just undo the 2 10mm bolts and slide it out or do you have to remove the lever retaining clip as well?
 

volkswheels

Vendor
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Location
Long Sault, Ontario
TDI
2006.5 Jetta TDI DSG, 2012 GolfHighline TDI DSG
Both 10mm nuts and retaining clip too :(
meisterleipz said:
to remove the actuator do you just undo the 2 10mm bolts and slide it out or do you have to remove the lever retaining clip as well?
 

meisterleipz

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Apr 21, 2009
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2000 Jetta TDI (01M)
I got the actuator out. the thing is so rotten...about 1/3 of the upper housing is completely rotted away. the turbo part in which the actuator lever attaches to moves completely free- when the actuator is not attached. the actuator itself very stiff and border-line seized...i am thinking that the actuator is the cause of the fault code. Is it not suppose to move without a lot of resistance?

also, the retaining clip disintegrated when I tried to remove it...any ideas on what to do now? I thinking maybe wrap wire around the location where the clip went?
 

P2B

Top Post Dawg
Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
meisterleipz said:
the splash pan that covers about half of the actuator..ya it seems to be completely intact.
Craig means the plastic splash pan that covers the whole underside of the engine - the one many people replace with a metal skid plate. If you don't have one, salt gets splashed around the engine compartment in winter and things start to rot, in particular the turbo actuator.

Simon
 

meisterleipz

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Apr 21, 2009
Location
Richmond Hill
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2000 Jetta TDI (01M)
I see. No, the splash pan is completely gone...it was gone when I bought the car. Might have to look into getting the skid plate.

I took a look at my sister's tdi actuator and it is just as stiff as mine was but she is not getting any codes. How free is the actuator suppose to move...I am starting to think that it is not the cause of my problems. What else could it be?
 

P2B

Top Post Dawg
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Jan 11, 2006
Location
Toronto & Muskoka, Canada
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2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
You need to test the actuator with a vacuum pump to see if it moves and holds vacuum - which seems unlikely as you said about 1/3 of the upper housing is completely rotted away.

Simon
 

meisterleipz

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Apr 21, 2009
Location
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2000 Jetta TDI (01M)
ya, it is rotted pretty good but isn't it the internal part that holds the vacuum? it is also pretty stiff in terms of movement...at first I didn't think the stiffness was normal but comparing it my sister's has made me second guess that.
 

craig01b

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Location
Guelph, Ontario.
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Road salt loves turbo actuators, hot and in a good spot for corrosion. All of the ones i have seen rotted, have been driven without the belly pan for at least a winter. I doesnt take much.

You are talking about a part that costs 115 bucks...that controls a very expensive piece of equipment....replace it. Mine is original, belly pan, or skid plate always intact...tells a tale.

Craig
 

meisterleipz

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Location
Richmond Hill
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2000 Jetta TDI (01M)
I understand. definitely have to look into getting a belly pan. anyone here sell them?

Just don't want to get the actuator and not fix my problem. Would a leaking inter cooler pipe cause a negative deviation?
 

craig01b

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Location
Guelph, Ontario.
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*drums fingers on desk*.....If the actuator hasn't completley failed. From your description of it, it may be sticky, intermittant, and if its rotted that badly. Complete failure is coming soon. If the actuator fails in the low/no boost position, there would be no limp mode, just underboost. No power.

Any leaks in the system downstream of the turbo, with pressurized air might do that. But, that would be consistant. What you are describing is an intermmitant thing, which a sticky, on its way out actuator might cause.

There are only 2 certain things in life....death and taxes. Everything else is a crap shoot...good luck.

C
 

meisterleipz

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Location
Richmond Hill
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2000 Jetta TDI (01M)
well said.

so, I managed to change the actuator today and... still getting the same code.

pretty frustrated right now. any other suggestions?
 

P2B

Top Post Dawg
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Location
Toronto & Muskoka, Canada
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2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
The new actuator needs to be adjusted with a vacuum pump so that it begins to move at 3 in Hg and reaches the stop at 18 in Hg.

Detailed actuator adjustment specs are posted here

Simon
 

P2B

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2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
craig01b said:
If the actuator fails in the low/no boost position, there would be no limp mode, just underboost. No power.
Actually the ECU goes into limp mode when it detects underboost too, not just overboost.

I experienced this yesterday on the 2002 TDI beater I just bought - installed a new actuator, couldn't adjust it properly because the turbo vanes are sticking from running with a bad actuator, and it kept throwing a negative deviation code and going into limp mode. I'm driving it hard and it seems to be getting better, hoping I can get it cleaned out Italian style so I don't have to pull the turbo.

meisterleipz said:
Would a leaking inter cooler pipe cause a negative deviation?
My 2002 also had a boost leak due to a crack in the pancake pipe between the intercooler and intake. The leak was clearly audible, but the car wasn't throwing any codes (because the turbo vanes were stuck at about the mid point), so you should be able to hear a boost leak bad enough to throw an underboost code.

Simon
 

craig01b

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Joined
Mar 17, 2004
Location
Guelph, Ontario.
TDI
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Starting to look like a sticky, not working n75 valve....

*cut and paste*
There is a diagnostic in VAG-COM that exercises the N75 valve. It should click. I think if you still have some vacuum in the reservoir it should also make the turbo actuator move. Have you tried cleaning it out with contact cleaner (something that won't hurt rubber or plastic)?

I once helped a guy out who had the same symptom. I have a diagnostic vacuum/pressure gauge (cheap) that I checked out the vacuum to the EGR valve. I mean, that's starting out from basics, right? It was weak! Turned out a check valve was gummed up - we cleaned it with contact cleaner and compressed air. I guess you could check the vacuum to the turbo as well if you tee'd the gauge in there; it needs vacuum to work the actuator.

They say it is possible to temporarily replace the N75 valve with the egr valve because they are mostly the same. Just be very careful with removing the valves from the nipples.

For laughs you could check to see if you can move the turbo actuator arm. I think when the vanes are sticky it usually causes over, not under pressure.*end quote*

Lots of variable here, and they all need looking at.

Craig
 

P2B

Top Post Dawg
Joined
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Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
craig01b said:
Starting to look like a sticky, not working n75 valve....
That's certainly possible, but most often a sticky N75 will cause an overboost code.

I still suspect bad actuator as the original problem, and new actuator needing adjustment as the current problem.

Simon
 

meisterleipz

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Apr 21, 2009
Location
Richmond Hill
TDI
2000 Jetta TDI (01M)
I did swap in a new used N75 and got the same code.

where can I get the actuator adjusted? I think I am out of my league here.
 

P2B

Top Post Dawg
Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
meisterleipz said:
where can I get the actuator adjusted? I think I am out of my league here.
The actuator is easy to adjust, but you do need a vacuum pump with gauge... or take it to Brandon - contact info here.

Simon
 
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