Fault code 17964: charge pressure control-negative deviation

meisterleipz

Veteran Member
Joined
Apr 21, 2009
Location
Richmond Hill
TDI
2000 Jetta TDI (01M)
Car has finally been fixed!!! Took the car to Windex.

I replaced the actuator since it was not holding vacuum. As it turns out my used replacement was bad as well. Luckily Windex was able to hook me up with a good working used actuator.

Even after the actuator replacement and adjustment the car still had the negative boost deviation.

Windex checked over all the vac lines again and all were ok. Took off the egr boot and egr itself and it was clogged pretty bad. Windex cleaned er out (thanks Adam for the late night on wed!) put it all back together and car ran a lot better but still somewhat sluggish.

Re-checked the vac lines- removed the small check valve from the N75 and determined that it was completely clogged. Windex used a drill bit to clean it out and put it back in and then took the car for test drive....wow...a new car. Thing has so much power!!! I can see why the auto tranny's go bad.

Thanks again Adam for all the help and knowledge you shared.

Next, I will be installing the new skid plate from THETDIWAGONGUY, changing oil, fuel filter, slight actuator adjustment and...o ya...my annoying 'not working cruise' issue.
 

Windex

Top Post Dawg
Joined
Apr 1, 2006
Location
Cambridge
TDI
05 B5V 01E FRF
Glad to help!:D

In the end you had:

A bad Turbo Actuator X2 -
A clogged intake and EGR/AntiShudderValve - Causing the Negative pressure code
and a plugged vacuum check valve. causing low boost

Go easy on that 01M...:cool:
 

meisterleipz

Veteran Member
Joined
Apr 21, 2009
Location
Richmond Hill
TDI
2000 Jetta TDI (01M)
car is overboosting now. getting 17965 CEL. :confused:

This car has been nothing but problems- probably the worst TDI I have ever had in terms of small annoying problems.:mad:
 

VTjoe

Active member
Joined
Sep 10, 2003
Location
Burlington, VT, USA
TDI
Jetta 2001 (A4)
I diagnosed the negative deviation code on my 2001 TDI earlier today.

It ended up being due to a minor leak plus low vacuum flow due to a clog at the first check valve. Apparently some of my lines have begun to dry-rot and a piece had lodged in that connection. After cleaning that connection, turbo is back!

The minor vacuum leak was in the N75, between vacuum and air-filter. I will be replacing that valve along with several hoses.
 

NewTDIGuy29

New member
Joined
Nov 21, 2012
Location
Western Mass
TDI
2000 Jetta TDI
I also just dealt with this. After some investigation I found a 1" long slit in the large rubber hose that connects to the EGR valve to the hard plastic intercooler pipe. A few wraps of black Duct tape later and no more intermittent CEL or limp mode under high load.
 

gpooleii

Member
Joined
Jan 28, 2014
Location
Colorado Springs, CO USA
TDI
2000 VW Beetle
Thanks for posting threads all the way to "fixed". I've had the same long line of repairs and efforts with no change in low power / no limp mode, fault 17964.

The low power was intermittent a bit at first (on "jammin the gas" there were several times early on when I could feel a very sudden surge of power) This is no longer happening. Just low power all the time now.

So far I have:
* replaced ALL engine vacuum lines (one of the EGR/anti-shudder lines had a hole in it. That restored power for a week or so. Then lost it again and has not returned).
* replaced air filter
* replaced the MAF sensor (and made sure the screen was clean)
* examined the N75 in-line check valve
* cleaned the EGR valve
* cleaned the intake manifold
* observed the actuator moving under full unregulated vacuum (I disconnected the turbo actuator vacuum line from the N75 and connected it directly to unregulated vacuum straight off the vacuum pump, then observed it while I had someone start the car)

Here's the lack of boost I measured tonight:
At full throttle/3rd gear @ 3000 rpm I'm getting the following readings from Measuring Block 011:
> Specified MAP: 1693 (this seems a little low- I've read it should run 1850-1950)
> Actual MAP: 837 (compare with barometric pressure at the time of 775)
> MAP valve DC: 93%

From what I read here I will:
* diagnose the operation of the N75 (though I don't think this is the problem)
* re-evaluate the turbo vane actuator. Check it with an accurate vacuum pump and gauge. Remove it, examine it for full travel, probably replace it.
* get a splash guard...(sheepishly) ha.
 
Last edited:

gpooleii

Member
Joined
Jan 28, 2014
Location
Colorado Springs, CO USA
TDI
2000 VW Beetle
I temporarily replaced the N75 turbo control valve with the nearly identical valve for the EGR control. The sluggishness was gone. So I bought a new N75 and replace it. No problems since then.
 
Top