93 LeSabre Extreme Idle and Tranny Issue

[glaSSpax]

Thanks in advance for any help you might offer...

Custom model / 3800 TPI /235550 miles...

At startup the engine revs up something fierce. I have no way of determining what the rpms are at. It is a very high idle that can last up to 6 to 10 minutes at times. I'm reluctant to shift during this for fear of tearing out the drive shaft or even worse (blowing out the rear end).
I usually only allow it to run like that for a brief moment then I shut it down. Sometimes, after a few startup and shut-downs, the problem will correct itself.
Once the engine idles down, I shift into gear (any) with no response. In other words, the car doesn't move. Only after a (warm-up) period will the transmision kick into gear. Sometimes I have to let the car run for 15 to 20 mins before it will move.
The Check Engine Light has come on and I performed a self diag. test on it this AM. The test returned diagnostic code #21 (TPS). Does anyone have any suggestions ? I'm really concerned with the transmission issue. I appreciate what you guys do. Thanks Again...

[93buicklesabrelmtd]

Originally Posted by glaSSpax

Thanks in advance for any help you might offer...

Custom model / 3800 TPI /235550 miles...

At startup the engine revs up something fierce. I have no way of determining what the rpms are at. It is a very high idle that can last up to 6 to 10 minutes at times. I'm reluctant to shift during this for fear of tearing out the drive shaft or even worse (blowing out the rear end).
I usually only allow it to run like that for a brief moment then I shut it down. Sometimes, after a few startup and shut-downs, the problem will correct itself.
Once the engine idles down, I shift into gear (any) with no response. In other words, the car doesn't move. Only after a (warm-up) period will the transmision kick into gear. Sometimes I have to let the car run for 15 to 20 mins before it will move.
The Check Engine Light has come on and I performed a self diag. test on it this AM. The test returned diagnostic code #21 (TPS). Does anyone have any suggestions ? I'm really concerned with the transmission issue. I appreciate what you guys do. Thanks Again...

Throttle Position Sensor.
This thing can make these cars rev up to 4000 rpm some times.
I got water on mine one time. knocked it with plastic hammer.
Unplugged let it dry and it was as good as new.
Your Throttle Position Sensor is probrably DEAD. Or on its way out.

Tranny ? may be almost out or not getting enough pressure.
Check the Transmission Modulator Valve.

[LeSabre97mint]

GlaSSpax

I would check around the Throttle Position Sensor (TPS) for a loose connection. Next, take a digital OHM meter and check the TPS for resistance. This is done by unpluging it (engine off) and touching the leads of the meter to the pins of the TPS. Move the throttle and watch the meter. The meter should move evenly with the throttle.

Dan

[mcqueary]

I have almost the identical problem with my 93 LeSabre. I got codes 21, 22, and 44. The codes 21 and 22 are for the TPS, 44 is for lean mixture. My TPS measured open with an ohmmeter so I'm planning on changing it. As a temporary band-aid I disconnected the Idle Air Control connector (the 4-pin connector near the TPS) and this slowed down the idle somewhat. I also have to run the engine several minutes before the transmission will engage. I have posted a thread on this topic a few days ago. I'm wondering if the TPS and transmission problems are related. I'll post further when I get more info.

[glaSSpax]

Thanks for the response guys. Heres a question..
Where exactly is the modulator valve located ? Ive found what might be it but it doesnt look like any mv ive worked with before. whatever it is i found has a single vacuum hose leading to the top of the IM. If i remove the hose, i can turn the whole assembly freely with my hand. its located toward the front of the engine at what appears to be the base of the tranny.

[glaSSpax]

Well, turns out I was right about the Mod valve. I found some GM specs w/ an emmisions control lay-out and it shows that to be the MV. But I shoulnt be able to turn it in either direction that freely (should I) ? Let me ask this> will it be a pain to remove and replace the TPS seeing that it's sitting right above the exhaust manifold? Any other advice before i tear into this thing? Thanks.

[mcqueary]

I removed my TPS by using an offset ratcheting screwdriver (available from Sears) and a standard phillips bit. This tool accepts any standard 1/4 inch bit and came with about 4. The screwdriver is only about 4 inches long. This tool really made it easy to remove the two screws in these tight quarters. Without the offset screwdriver, you would probably have to remove the thermostat housing which could be a pain (drain coolant, etc). I haven't tried removing the vacuum modulator yet.

[93buicklesabrelmtd]

Originally Posted by glaSSpax

Well, turns out I was right about the Mod valve. I found some GM specs w/ an emmisions control lay-out and it shows that to be the MV. But I shoulnt be able to turn it in either direction that freely (should I) ? Let me ask this> will it be a pain to remove and replace the TPS seeing that it's sitting right above the exhaust manifold? Any other advice before i tear into this thing? Thanks.

I believe you should be able to turn it in either direction!!
It is not threaded into the transmission.

The nose just sits in the tranmission far enough to control the valve pressure movement. To the valve/solenoid bodies.

It is held in place by 1 bolt. I think either 13mm or 14mm
That bolt is really connected to a clamp that hold the modulator in place from poping out.

Before installing the new modulator you buy. There will be a small screw in the middle where the vaccum hose connects to it.

You will want to adjust that screw a little bit. (pressure screw)
Counter Clockwise for longer firmer shifts
Clockwise for quicker smother shifts.

I also believe you should have a restrictor valve between the modulator and the vaccume line.

The engine should have a diagram above the radiator showing the vaccum route.

[glaSSpax]

Okay. I appreciate the feedback. Yes there is a restrictor inline to the modulator valve. I may just replace it too along with the hoses. It looks like everything on this car is original (xcept the water pump, which was a royal headache to swap out.) Its one of those things where you're afraid to touch anything LOL. Okay, well Im gonna go with the mod valve swap for know. AutoZone wants $50.00 for the TPS. And I'm not completely sure if it needs to be exchanged. It has a slightly high voltage reading , but I can adjust that right ?

[mcqueary]

The TPS is best checked in the system using a voltmeter. The center terminal to ground should go from about 0.5 volts with accelerator pedal up to about 4.5 volts at full throttle. Check with ignition key in run position but engine off. This is not adjustable. One of the outer terminals of the TPS should have 5 volts coming from the computer. The other outer terminal is ground. The center terminal is the variable voltage telling the computer where the throttle is positioned.

An additional check could also be made with the TPS connector disconnected. You can use an ohmmeter on the TPS itself and see the resistance from center terminal to either of the outer terminals change as the throttle is moved. The resistance between the two outer terminals should remain the same.

If you are in no hurry, you might check ebay for a TPS. I found a used one for $15.00 including shipping. It's for a 92 but I think it will work for a 93 also. Alao a junk yard quoted me $25.00 for a used TPS.