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my 91 buick lesabre 3800 v6 is hard to start hesitates and idols at 3-5 thousand rpms at times other times it runs fine it only has 59000 miles and just put a new computer in it and cam senser plaese help
Answer -
What mechanical work or ANY kind of work has been performed on the vehicle recently ?. As most problems that occur after a recent repair was made can be traced back to the area of where the repair was made as a vacuum line may have been knocked loose or a wire connection came loose, Look around in the area where work was performed..
WHY was the computer and cam sensor replaced ?. It is possible that whoever replaced these 2 components may have inadvertently knocked something loose such as an electrical wire connector or vacuum line during the replacement procedures.
And or it is possible that while trying to diagnose the original problem something was adjusted incorrectly during the diagnostic procedures.
It is also possible that you have a faulty or have developed a problem with the new computer and or have a faulty electrical connection at the computers electrical connectors.
There are so many possible items that can cause HIGH IDLE that it would be impossible to list all the possibilities.
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the cam sensor was replaced as a possible soultion to our problem but with no luck then we had the computer replaced also to try and fix it even befor we had work done it was hard starting hesitating and over reving i have checked all vaccume hoses clasps and fittings and all are in good conditon all wires are in order and sensors in place and connected with there wires ....... do you think the throttle could be getting stuck internally because the gas pedal is not getting stuck so its not that part but just maybe the throttle is not closing all the way ?
AnswerAs you have discovered GUESSING does not always work and it is very expensive.
Here are a few of the more common problems:
1. There tends to be a re-ocurring problem with a BLACKISH RESIDUE BUILDUP that develops around the throttle plate area and it also gets into the IDLE AIR BY-PASS HOLE right next to the throttle plate.
Most any parts store will carry a spray desolving compound that you simply spray onto this residue buildup and into the idle air by-pass hole to clean out the residue. It may take several cleanings to get it all cleaned out.
2. There may be a fault in the IDLE AIR CONTROL MOTOR (IAC).
3. There could be a problem with a carbon buildup within the EGR valve and or the EGR controller has a fault.
4. You may have a weak PRESSURE and or VOLUME output from the fuel pump.
5. An intermittent crankshaft sensor can also cause this problem.
6. An intermittent fault in the TPS (Throttle Positioning sensor) can also cause this problem.
7. I do recall some GM engines that have a fault in the FUEL RAIL and FUEL PRESSURE REGULATOR.
Have you tried any DRY GAS in the fuel tank just in case you got a heavy buildup of water in the fuel system ?. Try a couple of applications over a 2 week period.
All these things need to be tested for proper oreration and examined for faults.
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