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Help ! As far as I can tell she's all original unmolested 5.7 LT1 automatic transmission. RPO codes state 2.73 rear with limited slip. I've had her for two weeks. Car is amazing I'm an old timer never owned anything other than a carbed motor so please bear with me. She seemed to be a little sluggish off the line. But once got up to around 30mph she got to 70mph really quick at least to me. I believe from what I've read here it's possible she was starting in second due to possibly being in limp mode. She didn't go into OD from what I could tell. The tranny oil was brownish so I changed filter and topped her off with approximately 4 quarts of Dex 6 synthetic. She shifted way better but again still seemed to only be going from 2nd to 3rd. I'm NYC not alot of room to really role. Drove for about 40 miles over 3 days. Then IT happened. On the 4th day after doing tranny filter it wouldn't shift at all. But then it got worse. Not only didn't it shift but everytime it felt like it should be shifting when feathering the gas it would screech to a halt. I thought the rear brakes locked up at first. But it lets go and will repeat over and over. A few times it almost felt when going real slow that it instead of uplifting from second downshifted to first which I know she's never been in. I checked the tps with a volt meter. Have a ground a 5v constant and the last wire fluctuates gradual with depression of accelerator. If car is def in limp mode (fyi I've learned of this after the locking up of wheels) I've learned from this forum to check the fuse that controls certain sensors and also controls the transmission fuse. Assuming I've comprehended that info correctly where is that fuse located. This is a 1994 Pontiac Formula. It's very clear on the LS1 later gens I see there are two fuse boxes under the hood. So where is mine or where is that fuse. I'm on a wing and a prayer I assume. I've disconnected battery I've pulled fuses 4,5 pcm battery and ign to try to reset the pcm. The oil is perfectly on full. Topped it off after was warm. Again it's not just shifting when it should shift its locking up. I did notice when underneath it the front right abs wires were cut. The abs light has been on since bought it. Can the transmission actually jam up like that ? Or are the brakes coming on when it should shift? There's a grinding noise then skids then stops momentarily then lets go I'm pretty much alone here. I don't have a garage many tools or much money. Like I said on a wing and a prayer. Thank you all
 

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Welcome to the forum.

1st thing you need to do is get an obd 1 scanner that also does real time sensor data. 94 codes can't be read by shorting pins on aldl. So first read the codes. There are a bunch that don't light the check engine light (CEL) To help you understand & diagnose any codes you have, get the 94 service manual @ following link. Code info starts on page 6E3-A-40 of manual. My Files

After reading codes do a running sensor scan. Scanner should read engine and transmission data. See what transmission data says. See if the shift solenoids are being commanded on & off by pcm. Also see if logic switches are working correctly. Auto trans section of manual will have logic switch table showing which switches should be on and which switches should be off for all gears.

If logic switches are not working correctly, or if a shift solenoid is malfunctioning, then it is possible for pcm to command 2 gears on at once and lock up trans. Also be prepared to have mechanical problems with trans causing the lock up. A valve in valve body could be sticking open, even if pcm is not commanding a solenoid to open it. Or torque converter problems.

After reading the last couple of sentences of your post, with your money situation, I come to this conclusion. Since you can't work on it, and mechanics in N.Y. city probably charge around $100 an hour, your best bet is to get rid of car. NYC has an excellent public transportation system.

I'm sorry there are no easy fixes for your problem.
 
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