Time for a new opti?
08-25-2009, 11:38 AM
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Time for a new opti? So my car (signature) will run fine for about 5 minutes and then die, just like that. 
I'm getting frustrated because i've been trying to fix it before i had to drive to college, but now i'm in college and my car is stuck in my garage at home. I believe it's the sensor in the opti but i just want to be sure before i shell out $250+ dollars. I tested the fuel pressure and injectors and they are fine. Getting spark is the problem because it will stop getting spark just before it dies. I threw in a new ignition coil because i thought the old one could be overheating and it made no difference. At first the idle surged a little but that could have been because that was the first time starting after putting in new mid-length headers and spark plugs. The longer i let it sit and cool down, the longer it will run the next time i start it, and it has been getting progressively worse (runs for less time). Sometimes after it dies i'll hear a strange winding sound from the front of the engine, like the tone of and electric motor starting and stopping, for a few seconds and then it will stop. When that happens, my tach will jump randomly between 0-3,000 rpm. I think the optical sensor in the opti is giving false readings causing the PCM to stop making spark at some point and thinking it is still running after it dies, which makes the tach jump around. I don't have many chance to try to fix it so i'd appreciate some good advice!
I'm getting frustrated because i've been trying to fix it before i had to drive to college, but now i'm in college and my car is stuck in my garage at home. I believe it's the sensor in the opti but i just want to be sure before i shell out $250+ dollars. I tested the fuel pressure and injectors and they are fine. Getting spark is the problem because it will stop getting spark just before it dies. I threw in a new ignition coil because i thought the old one could be overheating and it made no difference. At first the idle surged a little but that could have been because that was the first time starting after putting in new mid-length headers and spark plugs. The longer i let it sit and cool down, the longer it will run the next time i start it, and it has been getting progressively worse (runs for less time). Sometimes after it dies i'll hear a strange winding sound from the front of the engine, like the tone of and electric motor starting and stopping, for a few seconds and then it will stop. When that happens, my tach will jump randomly between 0-3,000 rpm. I think the optical sensor in the opti is giving false readings causing the PCM to stop making spark at some point and thinking it is still running after it dies, which makes the tach jump around. I don't have many chance to try to fix it so i'd appreciate some good advice! 
08-25-2009, 11:40 AM
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sounds like the sensor in the opti mine did that before i changed the sensor and worked fine for a couple months. now today mine did it again gotta love advanced auto parts shitty electrical parts
08-25-2009, 12:04 PM
#5
Yeah, the sensor is inside the opti. You have to remove cap and rotor, remove the intermediate plate, remove the optical wheel, then unbolt the sensor and put it all back together. But then you have to be sure that your optical wheel is still completely flat and free of debris. You also would question the condition of the cap and rotor. If you are going that far, might as well just throw on a new OEM unit...
08-25-2009, 12:08 PM
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I didn't even know you could buy the optical sensor separately. Seems like that installation would provide lots of opportunities to eff something up, so I would probably just replace the entire unit.
08-25-2009, 03:17 PM
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Yeah, the sensor is inside the opti. You have to remove cap and rotor, remove the intermediate plate, remove the optical wheel, then unbolt the sensor and put it all back together. But then you have to be sure that your optical wheel is still completely flat and free of debris. You also would question the condition of the cap and rotor. If you are going that far, might as well just throw on a new OEM unit...
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08-25-2009, 03:55 PM
#8
hmmm.. it's tempting to just replace the sensor. Misubishi makes the sensor and i guess they are known to fail. My car has 110,xxx miles on the clock and as far as i know it has the original opti so i should just replace the whole stupid thing. My car seems to miss under WOT and hard acceleration so maybe a new opti would clear that up too, because it's not a fuel problem. My mechanic said the problem could be my crank position sensor, but '95 and older cars don't have a CPS. I think they rely on the optical sensor in the opti to detect engine speed and misfires and stuff and send signals to the PCM. Hopefully someone knows more about this stuff than i do!
08-25-2009, 08:05 PM
#9
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ok thanks. Is the OEM opti made by AC Delco? If i replace it than all i have to do is remove the water pump and the harmonic balance with a puller, then line up the new opti and plug her in, right?
08-25-2009, 08:14 PM
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