My 90 SSE has recently started throwing a code for a throttle position sensor. This is the first codes it has thrown in over a year and after a new timing chain, cam pos. snsr, top end clean out with new intake gaskets and complete tune-up with coil pack. What I'm getting at is the car runs like its new. For the past month I start the car up and it idles way to high at initial startup. It also creeps higher. It starts out around 1500 rpm's and creeps to about 2200-2500 rpm's dependent where it holds steady. When I put it in drive the obviously come down and stopped in traffic after warm up it's at about 1200 rpm's. Not to mention it has the TPS code. I changed out the TPS and it did nothing to make the code go away afterwards and unhooking the battery and what not. I thought the excessive idle might be a vacuum matter so I checked all my vacuum lines coming and going from the intake and around, nothing. All hoses are good and the one I found a bit dry rotted I replaced. I also went around with a can of carb cleaner spraying around all the hoses, throttle body and along the seams of the intake and could find nowhere that apparently was affected. I'm pushing 200k on this car and since the a/c is still ice cold, I'd really like to hold on to it. Any thoughts what I should be looking at next?

Thanks for any an all help.

Mike

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68 Chrysler 300 Convertible
68 Ford Mustang
90 Pontiac Bonneville SSE
98 GMC Yukon SLT
08 Mercury Milan Premier

Sounds like a Idle Air Control valve. It's on the throttle body. Try unplugging it, to see if the RPM still creeps up. If it fixes the creeping issue, then find one at a junkyard and see if that fixes it. Also, while you're at it, now is a good time to clean out the IAC air passages and the mass airflow sensor (only use the mass airflow sensor cleaner, everything else will likely ruin the sensor)

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Boost addict


The Fleet:
'93 SSEi - Twincharged + manual Build thread
'97 Camaro - Top swap
'05 STS - V8, AWD, her DD
'92 Trofeo - Fair weather DD
'99 Montana - top swap 3800
'04 Sierra 2500HD - LLY Duramax

Current project:
Something cool, trust me.

Upcoming projects:
'92 Bonneville SSE
'87 LeSabre T-type
'67 LeSabre

Gone to greener pastures:
'84 Sierra Classic - Twin turbo 3800
'97 LeSabre - Top swap

RIP:
'86 LeSabre - pictures
'93 SE - L67

Did you actually set the TPS? When installed and closed throttle, you should see around .4 volts and around 5 at wot. There are 3 wires, with the key on, one is ground, one is 5 volts supp;y and the 3rd is the signal to the ECM. Measure between the signal and ground. Loosen the screws and move the sensor until .4 is seen. Tighten the screws and then open the throttle all the way and see if it reads close to 5 volts.

Disconnect the battery for atleast 15 minutes and then reconnect and see how it does.

Just re-read your post; replacing the sensor did not clear the code? That means you might have a problem with wiring or ecm. Best way to tell is to get a DMM and check the readings at the connector for the TPS and check each wire for a short to ground and continuity.

_________________
Boost addict


The Fleet:
'93 SSEi - Twincharged + manual Build thread
'97 Camaro - Top swap
'05 STS - V8, AWD, her DD
'92 Trofeo - Fair weather DD
'99 Montana - top swap 3800
'04 Sierra 2500HD - LLY Duramax

Current project:
Something cool, trust me.

Upcoming projects:
'92 Bonneville SSE
'87 LeSabre T-type
'67 LeSabre

Gone to greener pastures:
'84 Sierra Classic - Twin turbo 3800
'97 LeSabre - Top swap

RIP:
'86 LeSabre - pictures
'93 SE - L67

Here is a good Techinfo article to follow:

http://www.pontiacbonnevilleclub.com/forum/viewtopic.php?f=48&t=9098

That link was great. I never did the final adjustments with it as I didn't realize it needed to be adjusted. I have a MM and will use those to set it and hopefully that fix it. I'll keep you posted. As a side note, when I had the intake off I cleaned out everything and there was no carbon build up when reinstalled 1.5 years ago. Ran like a top until recent with the high idle.

Mike

_________________
68 Chrysler 300 Convertible
68 Ford Mustang
90 Pontiac Bonneville SSE
98 GMC Yukon SLT
08 Mercury Milan Premier

Just wanted to thank everyone. The TPS steps helped a ton and the code i clear.

Mike

_________________
68 Chrysler 300 Convertible
68 Ford Mustang
90 Pontiac Bonneville SSE
98 GMC Yukon SLT
08 Mercury Milan Premier

Congrats, glad we could help.