Friday night I went to our local test and tune and made a couple passes. The first one it ran slower than usual 8.42 at 81.35 so I hot lapped it and it ran an 8.36 at 82.23. It has been doing this for a while but this is not the problem. On my 3rd pass it started cutting out in the burnout box but I thought I will run it to see what will happen. I launched and got out about about 50' and it started cutting out and I worked the throttle trying to see if it made any difference. The only time it stopped cutting out was when I was off the throttle, but one thing that is strange is I ran an 8.66 at 83.01 mph cutting out all the way down the track. After I let it cool off and put the street tires back on I was about to leave and the car was running fine. So I took it down the track again just to see what would happen and it cut out down the track so I let off and took it home (1 hour drive). The car was running good on the way home so I put it to the floor and it cut out a few times and then it back fired hard. The SES light came on and the car started running great. I shut it off and start it up again drive about a mile and it would back fire again SES light would come back on and it would run great. So I took it to my buddy who has a scanner and Code 36 and Code 42 came up. Code 36 shows it to be the high resolution in the opti and Code 42 shows up to be the IC ground for the high resolution to the opti. What I don't understand is if it is the opti going bad then why would it back fire then throw the SES light and run like a raped ape. Any help would be great. Thanks again.

 

The high res pulse is used to fine tune the ignition timing. If the module starts putting out faulty high res pulses, the timing will become erratic and the engine will start to run poorly. The PCM will detect the incorrect data (less than 60 high res pulses between pairs of low res pulses). After 5 consecutive occurances of the problem, PCM sets DTC 36 and defaults to only the low resolution pulse pattern for ignition timing. Engine runs better, with a minor loss of ignition timing accuracy and a slight increase in spark scatter, compared to what it can do by using a combination of the high res and low res patterns.

Sounds like the optical module may be heat soaking. Also check the Opti harness connector for corrosion or damaged pins.

DTC 42 is for a grounded ICM circuit. It is not specific to the high resolution pulse, although a faulty Opti is one of the possible reasons for the code. There is a fairly detailed diagnostic chart for DTC 42 in the shop manual. Get a copy of that and work your way through it.

 

Is it possible that the ICM is the problem or is the opti creating the Code 42 problem and what I need to do is replace the opti?

 

You have to work your way through the diagnostic chart. Either is possible.

 

Where is the ICM located?

 

the icm is the little black rectangular part directly above your ignition coil. it has one plug (3 prong if i remember correctly) on it and 2 8mm bolts holding it on good luck