car won't start sometimes on 1992 Toyota Celica

I have a strange problem with my car. The problem is that is doesn't happen all the time. It will run fine for a while then all of a sudden it starts to heistate the rpms drops and it starts to shake. Then it cuts off. I have taken it to my mechanic twice and when I take it to my mechanic he checks it out test drives it and it runs fine. Idrove it about two or three weeks and the same thing happens. Sometimes when I leave work it won't start right away. After 20 minutes it starts but it shakes and the heistation starts. Please let me know what could be causing this problem? drop it of my mechanic drives it checks it out and can;t find anything wrong. I pick it up drive it about two or three weeks and it happens again. The last time I went to that store, when I came out of the store and went to start it all the lights and everthing came on but it would'nt start. after about 20 minutes it started up but then the shaking a heistating started. Would could be causing this problem? My mechanic says he can't trce the problem

by in Philadelphia, PA on April 14, 2009
3 answers 1 comment
ANSWER by on April 14, 2009
It is hard to diagnose intermittent problems. An engine needs three things to run, mechanical integrity, fuel and spark. The engine has to have mechanical integrity develop compression ect... because it starts runs and , restarts once it has failed. So you are left with looking at fuel problems and ignition. either of which could also have computer control problems. I bought a BMW that had a similar intermittent problem. To determine first if it was a fuel or ignition problem, I attached a fuel pressure gauge and left it under the hood of the car with it tied out of the way of harm, secondly I had a timing light in my car and when the car finally stopped running I was able to tape the fuel pressure gauge to the windscreen and bring the timing light into the car and crank the car over to see whether it had lost fuel or spark and then I was able to start diagnosing things related to the loss of spark in my case. The is a diagnostic socket under the hood of your car with about 20 pins in it. Two pins are marked (B+) the other is marked (FP) bridging B+ and FP by passes the main relay and supplies the fuel pump with power if it doesn't work when jumpered directly the fuel pump is most likely bad. I have seen distributor sensors fail causing your type of problem as well.
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ANSWER by on March 23, 2010
Replace your oxygen sensors.
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ANSWER by on September 01, 2010
Did you find out what was wrong with the car? I have a 95 Celica and am having the exact same issue. Mechanic can't figure it out because the car doesn't do it while he is driving it etc.
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COMMENT by on January 29, 2011
I have the same problem with my Celica 1996 Noone can help :(
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