I am lost I do not know much about engines except that you have change the oil.
I have a 94 6-Speed.
It hesitates at low RPM's only when it is very hot.
When the car tells me to do the 1-4 skip the car jerks hard.
I asked this question in the general forum and most people said it was the ECM.
What do you guys think?

Is the ECM and PCM the same object or is it 2 different things in my car.
Is the ECM/PCM the silver box just above the battery?
If I do have to change it, Where do I buy it and how much should it cost?


Thanks :confused:
Ok you guys asked for more details so let me start.

The car only hesitates when the engine is hot.

Some Examples are
When I try to do a second gear rolling start from a stop sign the car will jerk and I have clutch down and go into first gear.
When I am on the highway and the I go into 6th gear at anything lower than 60 mph it will hesitate and I have top drop back to 5th and bring it above 65 and then change gears.
When the car asks me to skip from 1st to 4th gear I have to force it into 2nd or else the car jerks real hard.

I just bought the car about a month ago and am not really sure if anything has been changed, The old owner told me that he never needed anything done to the car.

The car has only 38 000 miles on her and I think everything is original.

I did not check for any old codes and the SES light does not stay on after starting the car.

Any help is good help.
Thanks again.



[Modified by CanadaVette, 8:55 AM 6/12/2003]

 

Your 94 has a PCM, and it is the silver box with fins just above the battery. Personally I don't think its the PCM that is the cause of your problem. Even if you replace it with another, you will have to go someplace like a dealer that can reprogram the new one for you.

My suggestion is that you take your car to a decent Chevrolet dealer to have them use a diagnostic scope to check the ignition system out. It sounds to me that you have more of an ignition system problem other than a PCM problem. It could be the Opti-Spark distributor.

 

More input please

 

Your 94 has a PCM and a CCM.
The PCM is the 'Powertrian Control Module' located above the battery.
PCM controls the engine timing, fuel injection, transmission,TCC and fans

The CCM is the 'Central Command Module' located behind the dash inside the vehicle. It controls almost all of the rest of the electrical/electronic features of your car. (Courtesy lights,VATS,door ,locks, etc.)

If you get a new PCM it should come with the factory default programming and it will run 'as is'.
The CCM HAS to be programmed by a dealer before 100 miles have been driven. This is mandatory for the CCM.

 

Update
I just took the car on a 1500 mile trip and did not have one problem with the car. I got great mileage (28.2 mpg).
The car seems to be running fine.
I only get this hesitation while city driving.

 

No Check Engine light or Service Engine Soon light?

How long ago were the plugs changed? Plug wires original?
Does it do it hot? When cold? Starting off? Running 30 mph?
When does it hesitate? Every day? Every time you start from a standstill?
When you make a right turn?

Remember WE can't see or hear your car. And, we don't know its history. Only you can give enough information to get a diagnosis here. Everything can be a clue.
But I'm afraid you'll have to supply more information.
Your other option is to supply more dollars to your local mechanic.

Check the simple things and then you can eliminate them.

This is just a swag but it 'could' be your TPS (throttle position sensor).
Could be a plug wire.

Of course there's not NEARLY enough information to make a REAL diagnosis.
It "COULD" be anything at this point.

 

OK VetNutJim it is all yours


[Modified by CanadaVette, 9:00 AM 6/12/2003]

 

It "sounds" like ignition problems to me.
The following could be contributing to the problem.......


1) Opti Spark....If the owner sprayed the engine down to clean it before the sale OR had it detailed it very wwell could have gotten water in the opti-spark.
Or it could have just quit working properly for no reason...
Opti-Spark IS the distributor on your LT1

2) Bad plug wire or wires.....they are not that old and do not have a lot of miles on then but that doesn't rule thme out as suspects.

3) Bad spark(s) and easy thing to check...just change them....
2 hours in the driveway will eliminate them as part of the problem

4) Fuel Filter.....another easy/cheap item

A good thing to do is get it scanned and see what stored codes are present and you can look at all the sensor data.

Unfortunately it's likely your opti-spark