Weird Boost gauge reading and engine cut-out
 

My 82's OEM boost gauge is reading wacky and the engine cuts out as soon as I hit 3500 RPM. So far, per the manual, i've run a few tests.

Unplug the wire from the charge pressure sending unit, turn on ignition and it pegs the gauge. Ground the wire and the gauge drops to zero. If I plug it into the sending unit w/ignition on it goes to .25Bar (engine off).

Wastegate - Pulled the air line and at idle your supposed to feel vacuum, I can't feel anything. Hose is new, maybe its just me. Didn't have anyone to hit the gas so cant say if pressure turned positive at higher revs. I put 20 PSI into the wastegate with the engine idleing and it opened up just fine so I assume all is well there.

I removed the OB switch wire and grounded it, took the car for a ride. 3500 RPM seems to be when i'm at REALLY good boost. If she had wings I swear she would have went airborne! No hesitation, ran smooth as silk to redline in 2nd.

My assumption is the boost sending unit is crap at this point, would like to hear of other tests or opinions.

Thanks for any input..

One other thing, what air line goes on the stock air cleaner over on the left side (about a 3/4" nipple there)?

:)

Earth your IC.

Would that be the vent from the turbo drip tank ?

Maybe, as I have a different headers/tank that's why it's empty. I have it plugged off for now..

Appreciate the input either way Nathan! I spoke with my shop today and HE said to try grounding the IC!! So I went home and ran a wire from the horizontal front mount stud to a bare spot in the body.. same thing. Turn the key on, get a reading just under .3 bar on the gauge. He also suggested getting a manual boost gauge to see what is really going on. The OB cutoff switch is a totally separate entity so I'm a bit worried on having that bypassed. I thought it may have somehow been tied into the boost reading but it isn't. I'm sure it's electrical at this point (as the odd reading is with the engine not running!) but just don't see where it can be. It's a single wire from the boost switch and from the OB cutout sw., guess i'll try and see where they go....

Could be the gauge, wiring or the sender.

Maybe someone knows the resistance of the sender when it is not under boost and you could check it with a meter.