are there any tests i can run on these 2 sensors to make sure they are running correctly?
thanks

-Phil

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Pontiac Firefly 87 1.0L
Pontiac Fiero 86 SE 2.8L
Buick Skyhawk 76 3.8L
GMC Jimmy 85 305
"It's not how fast you go, but how good you look goin"

quote Originally posted by Phil86SE: are there any tests i can run on these 2 sensors to make sure they are running correctly?

The TPS is fairly easy - it's just a variable pot. Two contacts are the outter ring of the pot, center is the swiper. So if you go from inner to either outter leg (use an analog meter, it's easier to see dropouts) and swing the arm slowly through it's range, you'll see it either go from high to low, or vice versa depending on which outter you probe.

IAC is a bit harder - but all it is, is a stepper motor. Start probing contacts - you'll find two pairs that conduct. That'll at least tell you the coils in it are good.

Click on my site below, and follow through the links to find my number if you get in a bind. You didn't put a city... but hey, BC's not THAT big... hehehehe....

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87/88 V6 5spd Notchback Hybrid

My page: http://www.fieroclub.com

IAC can be tested for resistance easy enough. That will at least tell you if a coil is open or badly shorted. (If only a few turns have shorted you can't alsways tell.)

Also, Test resistance from each coil to the shell. It should not show any thing on the meter. If it does a coil is shorting to the shell and the IAC needs replaced.

The rub is that coil resistance tests almost always pass on the IAC. The most common problems are dirt and wear inside the thing. Those will keep it from moving properly when the ECM needs it to.

You can try cleaning it out with some electronics parts cleaner. Harsh chemicals like carb cleaner can ruin it. (Eats the plastic parts and insulation.)

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RIP Crew of Columbia. 01-Feb-03

is it supposed to go from hi to low or is it supposed to stay constant?

and im not sure if i have an analog meter out in the garage so would anything else work in place of it?
thanks again for all the help
-Phil

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Pontiac Firefly 87 1.0L
Pontiac Fiero 86 SE 2.8L
Buick Skyhawk 76 3.8L
GMC Jimmy 85 305
"It's not how fast you go, but how good you look goin"

NONONO you don't want the car running.

Pull the connector off the IAC. (DO NOT probe the harness connector!)

There are two terminals on the IAC for each coil. touch one terminal the try each of the others. Only one will give you a reading. If they all do then the IAC has a short.

then try the other pair of terminals together. They should read the same ohms or very close to it.

If the meter moves at all when you touch the shell and one of the terminals for each coil then that coil is shorted to the shell.

Again... IACs usually fail mechanically. It is pretty rare to have one die electrically.

On the TPS....

Again unplug the sensor and DO NOT probe the harness connector.

Use the center and either of the others. Doesn't matter which.

Move the TPS and watch the needle. You want to see the ohm change in a smooth movement over the whole range of throttle rotation. Depending which terminal you are on the number will start high and drop or low and go up. Test it both ways. you don't care so much what the numbers are. you want them to change smoothly.

thanks for the help and the lesson
after i eat some grub i will head out and see what i can figure out...
i need to see if i can find something to measure resistance with first though

thanks though

-Phil

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Pontiac Firefly 87 1.0L
Pontiac Fiero 86 SE 2.8L
Buick Skyhawk 76 3.8L
GMC Jimmy 85 305
"It's not how fast you go, but how good you look goin"