1992 Buick Century 3300 -- Posession Report

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Pushed Buick everytime it was up to temp. Replaced crank trigger sensor, and ignition module, drove for a couple weeks. Next the car would not seem to downshift when needed, torque converter clutch failed, transmission was rebuilt. In the mean time the battery died and was replaced.

Now when the car is started it revs high, too high to get into gear, was intermitent and could run for an hour or more with no problem. Problem is now permanent. Computer gives codes for coolant sensor low temp, replaced sensor, will check wiring next. Does not seem like this one sensor should make it rev so high, this is beyond fast idle. Tested the IAC, electrically it was good but would not mechanically move when hit directly so it was replaced. Did not trust TPS so it was replaced. The computer gives two long busts followed by one long burst repleatedly at the end of the coolant sensor error code.

Any suggestions taken seriously and followed up. Please help. Car runs smoothly. Fuel injectors have good impediance, new plugs and wires, runs smooth just fast. Oxygen sensor has about 25K miles on it. Am I stupid or does this car not have an EGR valve or IAT?

Thank you in advance.

posted by  electrodes

look for a vacume leak

posted by  windman

Agreed, it just had to be a vacuum leak. Vacuum reading would start out low and then come up as the engine came up to speed, doubted advanced timing. Just could not find the leak. I sprayed carb cleaner around things to look for increased idle speed, no luck...

The Haynes manual is good for removing hair from the butt (for '92 Buick). Nothing more.

Emissions tag revealed PCV valve which could not be found using a Haynes manual. Turned the PCV upside down and the car ran just right, no problems. Replaced the valve for $3.99, cleared the computer and went for a drive.

Idle is good. Highway is smooth as silk. However, the check engine light came on twice, both times when coming to a stop at a stop light and the engine stumbled just a little each time. Made it home and checked the error codes, Result: 12,12,12,15,15,15,16,16,16,2-long, 1-long, 2-long, 1-long, 2-long, 1-long and then started over. If the Haynes manual has any value at all it would be telling me the coolant temp sensor has a low temp reading and bad system voltage. The TPS tested fine with multi-meter. The wire between the TPS and coolant temp sensor was also fine. I am on my third coolant temp sensor and second TPS, the wire between them is just fine.

Question: Assume I need to trace ground wires from the ECM around where the temp sensor plugs in...? Any suggestions? The car also seemed like it had too low of a shift point and kind of lugged, that would seem completely seperate and the tranny has a warranty. Please help...?

posted by  electrodes

With the big problem fixed I started the car to drive it to work fully expecting no problems. As soon as possible, the check engine light came on again, it stumbled, and then revved higher and higher back up to the original 2,500 rpm.

Why...why...why....?

It seemed to cut out at idle a little bit until it really got up to speed
and a little warmer. Any suggestings?

posted by  electrodes

Rarely the car would start and run perfectly and I finally used the opportunity to get the car to a garage to be fixed. It had a bad ground inside the computer which was telling the car that is was not charging correctly although it really was.

Use of a paperclip for diagnosis left too much to be desired as did the Haynes manual. New computer fixed the seemingly endless and mostly intermittent fast idle problem. $318.00 total to have diagnosed and repaired, no complaints.

posted by  electrodes

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