TPS How To

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Aug 17, 2004 | 10:18 AM

Evill Ed

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TPS How To

Can someone explain to me how to measure the voltage of my TPS. Please explain how to do it such as KOEO or KOER, what leads to tap into etc..

My 93 302 has the non adjustable type. The TPS is new, but I have a surging problem when driving and the idle wont go down below 1200 rpm and surges up and down ~ 200 rpm. I cleaned and checked the AIC and EGR. The only code I get is idle not able to reach low limit 13(I Think) I think the TPS is the culprit here.

Just for refernce, the truck ran fine for 150,000 miles. Then I had a coolant leak at the TB. I fixed that, but once I reinstalled the TB, it never ran right. I thought I may have damged the TPS with the TB cleaner, so I replaced it. I used new gaskets and there are no vaccum leaks. Any Ideas?

thanks,
Ed

Aug 17, 2004 | 10:25 AM

EPNCSU2006

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From: Concord, NC

I am not sure if the wire colors are the same between my truck and yours, but here goes: Back probe the harness (tps plugged in, KOEO) to measure voltages, don't poke a hole in the insulation. Between the orange wire and the black wire, you should have a steady 5V - just verify this. Then, probe between the green wire and the black wire, and you should have less than 1V at closed throttle - .9V is ideal. Then gradually open the throttle, and watch the volt meter for spikes or dips as you open to full throttle. At full throttle, the voltmeter should read around 4.8V or so.

Aug 17, 2004 | 10:29 AM

Evill Ed

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Thanks Alot, I appreciate the quick reply.

Ed

Aug 17, 2004 | 10:37 AM

pfogle

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From: Oak Harbor, OH

The wire colors may be BLACK (ground) RED(+5V supplied by comptuer) and GREEN (return line to computer, also the center wire) Probe the green wire with the positive lead from the volt meter, and the black to the neagative lead, do not let them touch as it can cause the TPS to burn out. You should have ~0.9 volts at idle (KOEO).

Aug 17, 2004 | 11:36 AM

HardScrabble

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If you use a meter with a needle it is easier to see the spikes.

Sep 26, 2004 | 09:19 AM

blackflareside

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Need help here guys. Tetsed the TPS today, it had .48 volts at idle and 3.98 at wot. My switch has no real adjustment, just 2 round holes. I played with the ols TPS and the new one. The best I can get is .89volt at idle and 4.18 at wot. That is where it is set now.

I erased the codes. I get a code 13 in koer mode. No codes in koeo mode. The idle hangs at ~1200 rpm and will eventually drop to ~950. The engine has a surging feeling on the high way. It also feels a little rough at idle, kinda like it is missing. Under heavy acceleration my check engine light comes on and then goes off when I back off the throttle. This have been going on for months.

So far I have cleaned and checked the EGR valve and senors, the AIC, new cap and rotor, cleaned the TB. I also ran a compression check, 150 -155 psi in all 8 cylinders. All the plugs look identical, nice tan color, no oil or dark ones.

Truck has 150K mile on it. I have never changed the O2 sensor or any other emmision device.

What else sould I be looking at and checking beforre I give in and take it somewhere to be fixed?

Thanks, Ed

Sep 26, 2004 | 09:16 PM

engineguy

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From: Edmonton Canada

Well I guess this saves me from posting a topic, this is exactly what I was going to post. On my '92 nite I was cleaning my throttlebody and measured my tps voltage and found idle voltage(middle wire) to be .86v and wot to be 4.68v. I thought that wot should be 5.0v, so I modified my tps to be adjustable and set my idle to .99v and wot will only go to 4.73v and no higher. I took it for a rip and it feels stronger at wot. Can't wait to go back to the track to see if I can better my original 15.8@85mph with regular gas.