Hey, quick question. How do you know if your TPS sensor is bad? I have a pretty inconsistant idle and a friend told me it could be the TPS so I was wondering how I can check if it's malfunctioning or anything.

Also, would it cause the car to run rich???

Thanks!

 

easiest way is to check if its fried is to unplug it, if it runs the same your tps is messed, but for the price i'd just buy a new one

 

Have your ECM scanned for codes. I believe low TPS voltage is code P220

Also, does it bog when you rev the motor while idle? Usually with a bad TPS, the motor will bog, then get going once the ECM can use engine RPMS to substitute for the TSP voltage.

 

Yes, a bad TPS can cause an erratic idle. This would happen if the inside of the TPS got corroded; for instance, if the TPS got very wet.

To check for a corroded TPS, you'd need an analog (not digital) multimeter. Disconnect the TPS connector; you'll be hooking the probes directly to the TPS sensor itself. Do NOT hook an analog meter's probes up to the engine harness, EVER- analog meters draw too much current and can blow out the computer. But for this test, we're not involving the computer at all.

So hook one probe up to the middle terminal of the TPS. Hook the second probe up to either of the end terminals; doesn't matter. Put the meter on it's resistance setting. I forget the resistance of the TPS sensor, but I think a 10K ohm setting would work. Depending on the end terminal you picked, the meter will either go to zero or stay where it is; doesn't matter.

Now, slowly move the throttle linkage SMOOTHLY as you watch the meter. The needle should swing slowly and evenly across the scale. If the needle is jerky/twitchy, then the TPS sensor should be replaced.

If you don't have an analog meter, run to the local Radio Shack; they've got a cheap one that'll work fine. Here's a link to it: http://www.radioshack.com/product.as...%5Fid=22%2D218 While you're in there, spend $5 for their alligator clip set; use this to connect the meter's probe ends to the TPS terminals. It comes with either 5 or 10 alligator clip leads; I forget which. http://www.radioshack.com/product.as...Fid=278%2D1157 If that's the meter you get, you'd put the switch on the "RX1Kohm" setting.

And like I said, you can't use the analog meter on the wiring harness, or anything to do with the computer- it'll fry the computer! But it's handy for testing most (not all!) sensors directly, such as the CTS or MAT/IAT.

You can't use a digital meter because (1) there's no needle to watch and (2) digital meters take "samples". Instead of displaying the actual results, they take a few measurements and display the average. Expensive meters have a faster sampling rate. The sampling is accurate for a constant measurement- but for a swing test like we're doing here, all you'd see is numbers jumping all over the place. You wouldn't be able to tell if you were getting a smooth swing or a jerky swing.

Hope that helps!

 

check the uppest and middle connectors of the tps harness with an ohmmeter, it should read 0.54 volts~0.56, then after this, accelerate the car and see if those numbers increase evenly, it should be smooth, like the cars rpms, should touch around 5.something volts.

 

great info tom