Turbo gauge inop

[j930]

just bought my first porsche. the turbo gauge does not move? how do I know if its the gauge or the turbo? What should I be looking for?

[spuggy]

Originally Posted by j930

just bought my first porsche. the turbo gauge does not move? how do I know if its the gauge or the turbo? What should I be looking for?

The stock gauge reads relative boost. It does nothing until the turbo builds boost over atmospheric pressure. Have you had the car in boost?

If yes and the gauge still does nothing, take the spade off the boost terminal at the back of the instrument, boost gauge should peg with power applied. Connect to ground the boost sensor terminal to ground, it should read nothing. If not, it's the instrument.

Now you get to check the boost sensor - which the resistance of which should vary according to pressure.

If that all checks out, look for the sensor wire to be shorted out to ground somewhere/somehow.

[jwasbury]

First of all, welcome to the forum...and congrats on your new car.

Originally Posted by j930

how do I know if its the gauge or the turbo? What should I be looking for?

Let's start with the assumption that its the gauge because if your turbo wasn't making boost you'd know it. If your car can't out-accelerate a late model Toyota Corolla, then I'd be suspicious of the turbo itself. Boost is like porn...you know it when you see it. If it feels like warp-drive kicked in at 3k RPM when your foot is heavy on the go-pedal, you've got boost...and you're probably giggling like a school girl.

This is why you were asked:

Originally Posted by spuggy

Have you had the car in boost?

Spuggy has given you great info about troubleshooting your gauge. Assuming your engine is in stock configuration, the sending unit for the gauge can be found under the intercooler and is item#14 in this diagram:


Enjoy the ride sir.

[j930]

we checked the sending unit and there are two posts, one upper and one lower there is nothing attached to the upper post and I made sure the lower was tight. When the key is off the gauge is below 0, when I start it up it rises to 0? I believe the turbo is working because its the fastest car I have ever driven but I dont like seeing the gauge at 0.