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mustanghunter7
09-28-2008, 09:13 AM
i have an vdo boost gauge mounted in an a pillar gauge holder and am haveing a problem the factor boost gauge will be at 15 psi and the vdo gauge will be at 10 psi they use to be both the same now they are different also note that these are not the redings at full throttle then i cant really tell but the factory one is maxed out and the vdo one is at apx 16 psi:dunno:

turbojd
09-28-2008, 11:03 AM
All the GN factory tachs and boost guages are known to do this, after all we are talking about a 21-22 tr, old dash cluster. The contacts oxidize and after time cause this problem. If it bothers you that much call John at Caspers electronics, he can fix it.

Keller
09-28-2008, 01:44 PM
Agreed. As long as you are picking up the VDO boost level from the same general area (i.e. not behind an inline restriction) then chalk it up to a withering stock boost gauge. That, or check for leaking lines.

I have seen a car with the external gauge plugged in behind a restriction. The car knocked all the time and the guy never knew why. Threw a scan tool on it for him and started screaming when it shot up over 22 PSI...on pump gas. He was already on his third set of head gaskets after doing some head porting and other mods, and had no idea why he kept blowing gaskets.

mustanghunter7
09-29-2008, 12:08 PM
yeah i am not sure its a bad factory gauge because before i changed out the wast gate accuator with a kirban unit and the boost controller with a rjc unit the stock gauge and vdo gauge were pretty close in there readings any thoughts?

Keller
09-29-2008, 12:54 PM
So...you diddled with everything and now its messed up, right? Is that what you are saying, or did I misunderstand you somehow?

If you have the RJC controller in there, it does change things. Where the boost gauges are in relation to the controllers is going to be important. Now you have two items controlling boost.

Where is your VDO picking up boost from? Is the stock wastegate controller still hooked up? Do you really want it to be and why?

mustanghunter7
10-16-2008, 06:12 PM
ok i checked where the vdo boost gauge was hooked up to and it is taped of of the 2nd port from the rear on the vacume block

Keller
10-16-2008, 11:29 PM
That is a good place to tap it. I assume the stock gauge is still tapped off this same location?