Okay so a few weeks ago my engine bay caught fire due to a minor leak in one of the o-rings on the fuel rail. Some of my wires on the engine wiring harness were damaged so i have replaced all of them. After the fire happened and i restored the car back to working condition, it can only run for about 15 minutes, or until it gets to about 200 degrees f. I checked the codes and the only one i am getting is code 36- high res failure. I checked the connection and i have continuity from the PCM to the opti. When i pulled out the oscilloscope, the high res wire kept changing from a square wave to an odd wave with a much lower voltage. Im thinking its either the opti has gone, but i doubt it since it runs fine until it heats up, or the PCM could have been damaged by the fire.

 

Its possible that heat soak is causing the optical module in the Opti to corrupt the high res output.

 

Look for poor connections/wires on the opti 'harness'. My buddy just had issues with his for second time lol.

 

all of the wiring is good, the connectors to the ICM, Coil, and Test connector have all been replaced. The Coil is brand new. Ive narrowed it down to either the ICM, the Opti, or the PCM.

 

Does it have a good engine ground?
The squarewave is generated by the optical module and goes to the PCM; I doubt has anything to do with the ICM or even PCM. A continuity check won't likely uncover intermittent problems. Pull the opti harness off of the distributor and check the pins and make sure aren't corroded and haven't lost their 'spring'.

 

My 95 z28 starts to backfire, change rpms erratically and finally dies after about 10 minutes or less of running the engine. When accelerating, the engine dies for a second and then jumps back to normal. The only code i get is 36, high res failure. Ive replaced the ICM, the Coil, the PCM, and i have checked and rechecked all of the wires and connectors. is there anything else besides the opti that could be causing this problem?

 

Read it and weep.

https://www.camaroz28.com/forums/sho...highlight=opti

 

replace opti my friend. I just went through this with my motor swap, I accidentally put the bad one in and it gave me the same symptoms, ran erratically after a minute and chugged like crap before dying and not starting. and impressive millage there:214k

 

I had a Jeep Cherokee that would stall out only when sitting in rush hour traffic or still for ~15 mins. Driving was fine. Narrowed it down to a bad crank position sensor, which is similar to the opti sensor, I used water from a hose to cool the sensor and it would run forever.

My bet is on the Opti sensor.

 

The code is based on the PCM counting the pulse signals from the optical sensor in the Opti. Why would you replace all those other parts, when the problem is clearly with the Opti. Have you inspected (among the connectots you describe) the Opti harness connectors for damage and/or corrosion?

 

You've put a 'scope on it and determined that the output signal from the Opti is intermittently corrupt. The PCM sets code 36 when it doesn't get the correct pulse count from the high resolution side, compared to the counts from the low resolution side. Not sure how much clearer it could get.

 

eeennggggg(the sound of a foul buzzer) The first problem... A 36 will NOT shut the engine down.

(foul buzzer again) The ICM can have NO effect on the opti feedback signal. NONE. Your problem with the hi res signal is either between the opti or the PCM. BUT, the PCM is an input and it's not likely the problem. The other thing regarding the PCM is this. I have yet to see or hear from anyone else that has actually seen a defective OBDI PCM. Period.

Last point is this. If you suspect something is heating up and malfunctioning then heat it up while ever thing else is dead cold and see if it has a problem right from the first attempt to start it. Use a blow dryer on the item in question only to the point that it just gets too hot to touch. Then you can isolate the opti as the cause of the problem and see for yourself that the 36 won't shut the engine down.

Unless that is you are also getting a low res failure at the same time. In which case you will have found the cause of both the 36 and why the engine is shutting down.

 

I got a better question.

Why did you start this post in the middle of another post that you started the day before and apparently didn't pay attention to the other post?

https://www.camaroz28.com/forums/sho...02#post6268702

In which post I told you that a 36 will NOT shut the engine down. Granted a 36 is a problem. But there is something else going on.

Finish the post you start.

STOP THROWING PARTS AT THIS. Use the peeps brains for the solution. Why did you ask the question in the first place?

 

Merging related threads. What a mess.

 

Well ..... the great thing about this board is that we all get to share our experiences! Don't want to start a flame war, but I beg to differ with the above qoute. An intermittent DTC code 36 (high resolution failure) WILL shut the engine down.

I just went through this with my car (see sig.). Car would start just fine, run for anywhere from one(1) to two(2) minutes max, and then backfire and die. Scanning revealed a hard set DTC code 36, which I could then erase with the scanner, and the car would restart, run again for one (1) minute or so, backfire, stall and re-set DTC code 36 again! Trust me, if the optical portion of the Opti starts sending the PCM an intermittent high resolution pulse, the PCM will shut down the engine. Replace the Opti and all will be good again.