Does your boost gauge move when you turn the ignition?
 

I am new to Turbos and am trouble shooting a potential problem with my car. In looking at the factory gauge it rises just under the .2 bar hash mark when you open the ignition. Turn the ignition off and it goes back down under zero. The car aslo idles at this same .1 bar mark. Is this normal?

http://forums.pelicanparts.com/uploa...1303009660.jpg


Here is my dilemma on full boost it overshoots the 1bar hash by the same amount showing 1.1bar. The needle touches the top of the 1. Could I have a wastegate issue or is the gauge off the .1 bar it starts off with?? My car has a K27-7200 turbo, GHL exhaust and a 1 bar spring. All of this was done by the previous owner. I have less than 500 miles on it since I bought it.

Anyone else's gauge move with the ignition?

Summer project includes, bigger intercooler, AFM gauge, .8 bar spring and real boost gauge.

Thanks

The boost gauge is not precise, so the needle may be off. With your needle a little past the 0 bar, I would say you are off by that much.

Boost gauge movement.
 

The boost gauge on my 87 930 moves when I start the vehicle and it's not even connected to the sending unit located at the intercooler.

:D

Mine doesn't move, and believe it or not it's fairly accurate when compaired against the aftermarket gauage I have installed. Dumb luck, I guess.

If you're feeling industrious, you might want to pull off the sending unit (the large orange rubber capped thingy beneath the IC) and test it's range of resistance under differing pressures. Provided you have an ohm meter, a source of controllable compressed air and a known accurate pressure guage, you can test resistance values to see if maybe that's your culprit. At the very least, make sure the power and ground connections back there are tight and clean.
Here's where you can find the resistance data:
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/468501-boost-sensor-resistance-data.html

Sounds like the electrical zero of the guage is off this happens on some of the instruments I calibrate but I have a pot in the circuit that allows me to zero the electronics I doubt that you have a pot on the inside of the guage but I could be mistaken.

Thanks for the tips guys. Last time I saw the orange boost sensor I noticed two wires, one connected and one off to the side. The sensor itself had two tabs for wires. That could be the problem right there, maybe it needs the other wire. I am going to pull off the intercooler and make sure everything is tight, clean and hooked up right.

Anyone have a picture of one hooked up properly, 2 or 1 wires?

Come to think of it, you're right. There is only on wire connected to it. Ground is provided by the mount itself. At least that's how mine's been since day 1.

Probably the issue is as gsmith has described...and probably not much you can do about it other than put a pot (of ? variable resistance) in-line and zero accordingly. But who knows, there may be an adjustment on the back or internally in the gauge. Easy enough to pull out the entire tach from the dash and take a look.

Update....

Fixed gauge issue. It appears that the terminals on the sender were a little dirtier than they loOKed. They were not corroded or gunk-ed up so I assumed they were OK. I ended up taking them off, cleaning them with sandpaper and re installing with some battery terminal protector. I also cleaned and coated with di electric grease engine wire harness where this wire ends up.

No more issues, perfect zero every time.

Thank you to everyone that chimed in, its appreciated.