High Idle--Please Help

[romeroom]

1994 Lesabre

Suddenly when I start the car it goes into very high idle mode...almost as if you had the car floored.

I checked (electrically and by temporarily replacing with new ones) the Idle Air Control valve, Throttle Position sensor, Mass Airflow sensor. All are good.

There is a "Check Engine" light on, but I'm avoiding going to a service garage because they all charge a bunch of money just fo have it checked. Autozone does not do Buicks younger than 1996.

Any ideas?

[maxwedge]

welcome to AF. Get it scanned and post back, there is no short cut here, look what you have done already! BTW does it ever come down to a normal idle?

[Richard S]

I recommend getting a scanner if you can afford it and read the code. I had a TPS problem the other day and I posted on TPS problem. Hotz28 gave a good link to a place you can purchase one reasonable. I think this car has OBDI. Check the underhood decal, most are at the front by the hood latch. If it is OBDI there is a way to get the codes but it not the best way.
You can bend a paper clip and stick it in the A and B terminal of the ALDL connector. ALDL is the assembly line diagnostic link under the steering wheel. Do not start the car. Turn key to on position, Motor not running. Watch the check engine light. It will flash the code three times. It will have a code 12 in it this is normal. Then it will flash the other code or codes. Example (Diagnostic mode) will flash 1 pause then flash 2 times and do this three times, TPS voltage high will put in a code 21. It will flash 2 times pause flash 1 time, it will also flash 3 times. Be careful if you decide to do this that you don't touch any other pins in the ALDL or start the car. When you get through be sure you pull the paper clip out before you start the car.

[HotZ28]

Sorry, but the 94 is also an OBD 1.5 bastard and the "paper clip" method will not work on this one!

[romeroom]

Thanks for all your suggestions. (By the way it is a OBD1.5 bastard)

After checking for vacuum leaks all around the hoses and intake manifold, I bit the bullet and took it to Belle Tire where they scanned it (for $70) and determined it was the PCM. [According to them the dealer would have to put in a new computer and they would need to program it]....OK.... Well, I just had Advance Auto overnight a new PCM to a local store, and all I have to do is take the old EPROM chip from the old computer and put it on the new one. I will switch the PCM's and post results.

Question: CAN SOMEBODY TELL ME WHY IT COSTS BELLE TIRE AND SIMILAR OUTFITS $70 TO CONNECT A CAR TO THEY'RE COMPUTER AND READ THE RESULTS???!!! If it's the $70/per service charge, does it take an hour to check a code or two?

[HotZ28]

Originally Posted by ROMEROOM

Question: CAN SOMEBODY TELL ME WHY IT COSTS BELLE TIRE AND SIMILAR OUTFITS $70 TO CONNECT A CAR TO THEY'RE COMPUTER AND READ THE RESULTS???!!! If it's the $70/per service charge, does it take an hour to check a code or two?

It takes less than two minutes to hook up a scanner and check DTC's. What you are paying for is overhead. (They have to pay the lease on the shop and keep the lights and water turned on)!

[Richard S]

You probably already know this but just as a reminder, ground yourself while working with the computer to get rid of static electricity. I haven't experienced it personally.

Just FYI. Not saying the place you took it is not reputable but I ran into the same thing with Pep Boys. I don't know what kind of scanner was used on yours but they said mine would not link and I had a computer problem. It wasn't the computer.

[maxwedge]

A highline scanner can cost $5k!!

[Blue Bowtie]

Look for substantial vacuum leaks, such as the PCV hose, EGR valve, power brake booster, and especially the rubber grommet on top of the throttle body where the vacuum lines "T" in two directions (under the metal offset bracket). That grommet is prone to failure and leakage.