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Really need a expert... eng./swap/????

J

jagman454

New member
Need someone's wisdom out there please help if you can....

Overview/background
1998 Pontiac grand Prix GT, the 3.8L engine went out on me about 2 months ago. I purchased a engine/trans out of a 03 Buick Regal. I replaced both my old engine and trans with the new one out of the 03 buick regal. Engine runs perfect. I used the existing harness that was already on my pontiac, including the ECM (computer). I am having issues with the transmission. More specifically, will only sometimes shift beyond 2nd, AND ALWAYS shifts hard. Took it and got it scanned and it throws a P1810 code at me. I have the harness and ECM from the 03 buick regal. I thought that the ECM could be to blame for the shifting problems so I plugged in the ECM out of the buick regal and unplugged the battery to reset everything, car will not start. I am about to plug the old ECM in and see if it works.

Questions
1. I though that all of the 3800 series 2 engines NS cars had the same trans 4t65E, so I did not think it would matter if I mismatched... IS THIS WRONG? Should the 03 buick engine/trans work with my 98 grand prix wiring harness/ECM...
 


the transmissions have different gear ratios. your tune for the transmission is off by a considerable amount now.
 
So, can I put in a 1998 grand prix GT transmission in there with the grand prix ECM, harness, but have a regal engine?
 
So, I can keep my current grand prix ECM, and buick trans, and get a tune... is that correct? and if so where would I get something like that done? and how much can I expect to pay for this?

thanks!
 
Grand prix gt's have 3.29's. Regals have 3.05's n/a. Gtps and regal gs's have 2.93's. If you have someone local with a tuner they can help you out. They have to put in the correct gear ratio file. Other option is contact a vendor. I dont believe you can just get a regal pcm and put it in. I could be wrong thow.
 


okay, I plugged in the "brick" lol, to my existing harness and the car would not start.... any ideas? I did not unplug the battery the first time and the car would start for like one second then immediately die, I then unplugged then plugged back up the battery and the car would not start. I put the old PCM out of the grand prix back in and it started.... any ideas?
 


When you replace the BCM, the module will learn Passlock Sensor Data Code immediately. However, the existing PCM must learn the new fuel continue password.

When you replace a PCM, after programming, these modules will learn the incoming fuel continue password immediately upon receipt of a password message. Once a password message is received, and a password is learned, perform the learn procedure again if you want to change this password. A PCM which was previously installed in another vehicle will have learned the other vehicle's fuel continue password, and will require a learn procedure after programming in order to learn the current vehicle's password.



Others will chime in on what is needed. One occurance I had was my buddy had an 00 impala with an hpt flash but it was corrupt. So I got a hold of a monte carlo file and flashed his car via my dhp and it wouldnt start. I did the relearn and was good to go. ----Be sure your battery is fully charged--

If it was my car I would give it a shot. If it doesnt work dont hold me accountable.

30 Minute Re-Learn Procedure
Use this procedure after replacing lock cylinders, Passlock Module/BCM or the PCM (if necessary - see note above).

1. Turn ON the ignition, with the engine OFF.
2. Attempt to start the engine, then release the key to ON (The vehicle will not start).
3. Observe the Security telltale, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.
5. Repeat steps 1-4 two more times, for a total of 3 cycles and 30 minutes. The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

Important: The vehicle learns the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.
 
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I cant get the theft light to come up. I unplug the battery and put in the new PCM then plug in the battery again and the theft light will not come up.ny ideas?
 
yeah, I tried it and once I try and start the car I understand i'm supposed to leave the key in the "on" position, but the security sign will not come up..... any ideas?
 


So you performed the above once and the car still wont start? Does your ignition key have a black chip in it? I know some regals do. Maybe thats one issue? Differant pcm internally? Contact one of the vendors and see what they say if no one can chime in. Id like to know whats wrong. Definately a security issue thow if it starts and runs with your stock pcm.
 
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No, it does not have a black chip in the key......Do I unplug the battery before I swap PCM's? or should I just leave it?
 
I dont think it matters but you can try unplugging the battery. Maybe the BCM is recognizing the pcm is differant....Are you sure the pcm you have was from a running car? After all the pcm itself could be defective. You never know.
 
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