A HAPPY BUICK My Buick is finally running perfectly again, and I am thankful for the many helpful suggestions offered. Below is the original complaint I posted, and the twisted path to the solution.
Thanks again, John. ________________________________________________
92 BUICK 350 WILL NOT RUN WARM 1992 BUICK Roadmaster Limited Sedan 350 TBI Will not operate when warm. No prior problems.1.) Started while warm, died when put in gear.
2.) Restarted, died in gear, restarted, died in gear, restarted, kept rpms high to drive home while it tried to quit if rpms were allowed to drop. 3.) After parking at home would not start at all. 4.) After disconnecting battery for one minute car started (cold) and idled properly for five minutes. 5.) After shutdown warm, would not restart. 6.) After disconnecting battery for one minute car started (cold) and idled properly for four minutes until beginning to warm up, then quit. 7.) The only diagnostic code is 12.Any suggestions? Thank you. John. _____________________________________________________
Please don't laugh. My approach to auto repair is to collect knowledge from books, from friends, from internet newsgroups and from my own experience, then to list the parts possibly causing the problem. Then I start replacing the cheapest and easiest to reach parts until the problem disappears. It's a money race between me and a real mechanic with diagnostic equipment.
My first guess was a bad TCC Torque Converter Clutch solenoid, because of the stall when shifting into drive, but I put it off because I WAS able to shift in and out temporarily, and it was easier to get at stuff on top of the engine.
Some said the problem could be a bad CPS Crank Position Sensor, but I found this engine does not use one. Another possibility was a bad ECT Engine Coolant Temperature sensor, because the problem appeared when the engine warmed up. My ECT sensor measured 2.2 ohms of resistance instead of over 2000 ohms. I replaced it, the engine started, ran three minutes and quit. No help there. Later I found my ohmmeter measures in kilohms so the original ECT sensor was good. DOH !
The next temperature-affected part was the Oxygen sensor. I replaced it without trying to test it. The engine started fine, ran 30 seconds, and quit. Then I had a new flash: The problem was not temperature-related because the engine didn't run long enough to heat up for the computer to begin taking control. And each run time was shorter than the last. This erratic run-and-die action was suspiciously like the action of bad ignition modules I have replaced on other cars. Next replacement - the module.
Sure enough, it was the module. With a new module, it runs better than ever, and my total cost was $85 including parts I replaced unnecessarily. Luckily I found the problem quickly. I guess a professional diagnostic test plus parts and labor for the repair would have cost about $395.
It was not as easy as I may have indicated above. It was hell getting to the module which is fastened INSIDE the distributor cap. The intake air ducting and the ignition coil had to be removed to get to the distributor. The coil could not be removed until the distributor flange was chipped away to untrap the coil holddown bolt. I used a new cap in reassembly and I ground a recess on its flange to allow the coil to be reinstalled. And my car was down twelve days instead of the three to four days a professional shop would have taken.
Oh, and another thing: Before I began replacing parts I got it started once and something began spraying from behind the water pump pulley. It wasn't water; it was SPARKS, followed by a fusillade of bearing rollers. The water pump bearing had disintegrated with no previous leakage or other warning. Work on the stalling problem had to stop for replacement of the water pump. Luckily the water pump on a 350 is a snap to get in and out.
Good luck to all DIYers. Thanks again for the helpful ideas. John. _____________________________________________________________