Throttle Actuator Control Valve - Source of busted boost?

Nitrowolf

Veteran Member
Joined
Sep 22, 2005
Location
Kansas City
TDI
White 2003 Jetta TDI
So... what does the Throttle Actuator Control Valve actually do? I've searched, but can't come up with anyone mentioning it.

I am wondering if mine might be on the fritz.

Symptoms: Car will boost up to about 10 psi, and feels a little laggy, like there is a boost leake. Then it will creep up to 18 - 20 psi (PSI max is set to 23 psi), if I keep it above 15 - 18 PSI, it will throw a Negative pressure deviation code and car cut boost completely. I have checked N75, vacuum lines, ECU, turbo actuator, MAF, etc... all appear to be working fine.

There doesn't appear to be anything wrong mechanically that I can find, and I've tried two different ECUs thinking maybe I screwed one up, but symptoms remain.

So, the only thing I haven't been able to check is the Throttle Actuator Conrol Valve. The strange thing is, if it were a vacuum or turbo actuator issue or something like that, I should be smoking like a train when I floor it to bring up boost... I'm not smoking a bit. This leads me to believe fuel is being limited somehow, which leads me to the throttle valve.

ECU is requesting 23 psi, but it's not getting it, or so says VAG-COM, which is what's throwing the code and cutting boost out.

Can anyone shed some light on this and/or how to diagnose or solve the problem?

Thanks!
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
I wish I knew what a TACV was. I'd be looking for air obstruction. New air filter, perhaps clean intake manifold. That type of thing.
 

Nitrowolf

Veteran Member
Joined
Sep 22, 2005
Location
Kansas City
TDI
White 2003 Jetta TDI
Air filter is new, and the intake doesn't have a CCV or EGR, so no obstruction there.

Maybe I'll take off the OMI and see if something is stuck in there... dead bird, lizards, that sort of thing. :)
 
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