OK...I have an update. I guess it does turn off at exactly 85.3 degrees C every time. It has power to pink connector on coil, it has readings at the connector to MAF, ICM, and opti wiring harness. Coil is good and ICM is new, PCM is new.I have literally gutted the car looking for and removing electrical stuff and yet it does the exact same thing every time. Now the plugs are pretty much fouled out b/c of it loading up when it cuts out. I am goin to go out and get a halogen light and heat the opti to see if that can cause this.... Please help me out if you know of anything I should try.

 

Why should we help you when you don't listen to us in the first place.

I told you it wasn't the PCM but you apparently got one anyway.

I told you if you don't have any DTC's related to the opti, it wasn't that either. And then it still won't shut down the spark anyway. It only shuts off the fuel.

You still haven't told us what code you get when it cuts out.

If you are actually loosing spark than this next part is critical.
I said to look at the IC signal going to the ICM. Have you clarified it's signal yet and confirmed it is dropping out when the engine shuts down?

I quote "Here is where you need a good meter to check the IC signal on the white wire to the B terminal of the coil. If the coil has no spark then you would expect the AC signal to the white wire to have dropped out."

and last
If you think it's at, near or even remotely connected to a closed loop issue. Have you tried disconnecting an O2 to force it into open loop yet?

If you are just going to ignore what we give you, let us know. We have better things to do.

 

perhaps there was a break down in communication.

There are no DTC's that come up when it cuts out, no codes, nothing.

I replaced the PCM because it has a lifetime warranty and my buddy works at the store so he ordered me a new one just in case.

I have disconnected the o2's with almost every other sensor I can possibly think of, as well as disconnected are peripheral electronics not essential to the vitals.

I have checked for continuity at the ICM to PCM just after it cuts out, when there is no spark; it checks out fine. I can't seem to get a reading at the precise moment it cuts out due to accessibility. To get accurate AC readings I will have to go out and purchase a better meter, this is a viable option. This is further complicated as I am unclear the exact mechanics of optispark, it seems the pcm is receiving the signals from the optical sensor then sending information to the ICM-->Coil; I am not great at reading schematics, so forgive my ignorance.

I have all voltage readings from the aforementioned; I however felt it would be a bit cumbersome to list all of the values I recorded from all the tested locations. I have also reprogrammed it so that all temp switch/constants are offset to the maximal value in hopes that might show something. To be clear I no longer believe it is closed loop dependent, however I can't seem to change the name of the thread.

I apologize if you or anyone believed I was not taking their information to heart, I honestly am about fed up

 

I know you said you disconnected the O2 sensors but are you disconnecting the o2s after it dies or before?

When it dies, if it's loading up with fuel that it's fouling the plugs up, it's probably flooding the cylinders and doesn't want to restart because it's flooded. A way to tell if it's not starting because it's flooded is to hold the gas pedal all the way to the floor and try to start the car - the PCM goes into a "clear flood" mode which turns the injectors off but continues giving it spark and cranking until it will finally clear the flood out and fire up.

If it fires up doing it that way - you might want to change the oil asap... if it's been doing this a lot and it really is flooding the cylinders, it's not firing up until some of the gas seeps past the piston rings and gets in your oil and that will spell disaster.

That said - if the reason the car is dying is because it's flooding the engine, there's only so many reasons why it would do that and should narrow it down quite a bit. O2s, map, MAF, tune... maybe someone can add a few other things that'd cause it to load up.

 

Thanks for the input. I have checked the spark at the coil during these periods and there is none. I have both disconnected the o2's before and after it has died without any difference. Thanks for reminding me to check my oil, I will do that ASAP

 

well I got a good AC meter and have checked the AC signal to the B terminal of the ICM, which I think is what speedyg was refering to. Yes it does drop out. I went ahead and replaced the spark plugs b/c the others were done for. So now knowing for sure that the signal drops out, I ohmed out the wire to the pin 5 on the black connector and it is .5 at hot and cold. ???


sorry for the slow turn around I'm in grad school have 2 part time jobs and an internship

 

Seems to me that you have a solution. I know you said your ICM was new but not sure if you meant before or after this problem started.

I would not trust your hot/cold. Right after you turn off the engine and you ohm, it could be just enough to get a good connection. Even moving the wire will give you a good connection again. I know this from first hand experience.

My thinking is the ICM or the wire. I looked back and I mentioned the ICM 16 days ago...

 

Thanks for the reply. I did ohm out the ICM wiring to the PCM and all looked about the same. I would think that one would have a higher reading. you could be right however, electrical bugs are sensitive things. I did replace the ICM after the problem began, and I still have the old one; both ICMs seem to perform the same. I am starting to look elsewhere, I am wondering about the security module relay. I pulled it out once and switched it with the relay close to it (under the passenger dash) and it started right up; of course it went back to its old habit soon. I did finely get a code today, MALF 41; its an open ignition circuit code. I can tell there is something that is going out as it just started priming intermittently with the key in the on position.

I am tempted to simply yank the wiring inside and out on a car in a junk yard, may actually not be that simple....but at this point...

 

My apologies for being rough on you. I had no idea you where that busy. I have a new found respect.

All right that being said, the fact that the signal is dropping out makes little sense even though I told you to expect it. There is nothing that will cause the PCM to shut off the IC signal. Even the VATS only shuts off the fuel enable signal to the PCM but has no effect on the ignition.

BUT you did witness a code for the IC open circuit. My suggestion is always to remove one end of the wire and put a meter on each end and wiggle the crap out of it. However your problem could be at the connections themselves. That would never see the problem. So while it's running good while cold, wiggle the crap out of the white wire and especially at the connection ends to see if the engine acts up.

Instead of replacing the entire wire harness, why not simply run another wire to go in tandem with the white wire already there? Shove the ends of the second wire into the connector right next to the pins from the back of the connector.

If all that doesn't produce any results, put the meter (set to AC) on the IC line at the ICM. Monitor it for change particularly when the engine starts to act up. Then simply unplug the end at the ICM and see if the signal returns. Remember when you have 2 devices connected. One is an output (PCM) and the other is an input (ICM). You don't really know which one is bad. The output could disappear or the input device could be pulling the signal near ground. The fact that you got a code for it indicates you still have a wiring issue. Remembering that you have a new ICM. You still have to go with what the testing shows.

 

thanks again for your info, you really seem to know quite a bit about electronics. I'm hoping this weekend I will have some time to test a few things out. The problem is I have little time to work on it, however, its something that sticks in the back of my head and am always about.

 

Ok...I ran it again today. Same as usual except high and low resolution codes were on. Obviously opti was the next suspect. So I decided to remove it and inspect it. I got it out and took it apart, everything looks brand new. The wiring harness I checked once before, but I will double check its resistance. The opti looks great but its an aftermarket one and I can tell the optical sensor is not the stock one. I have another opti that I dismanteled with the stock sensor, from what it looks like there is no way to remove that. Is that correct? So as of right now I have the two resolution codes and also the ignition open circuit.

 

Ok...I've taken my time and thought I had it but apparently not. I went ahead and checked all wiring again ohming each to the pcm and moving the wires to check for any increase. I found one that increased 3x, it was the low resolution wire from the opti. I made a new wiring harness and tried to start it again, nothing. I tested the harness and ohmed it. I replaced the opti with a new one. went to start it...nothing. I then tested the Ignition control wire on the ICM and got no A/c signal. I ran all the way back to the pcm and there is no signal coming from the B5 pin. ?

 

check the #11 U/H 10 amp fuse. Then check the pink/black wire(A) and the white/black wire(D) at the ICM with KOEO(key on engine off) for battery power. Use the black wire going to the C pin of the ICM as your meter ground not the engine or the negative battery terminal. Should be at least 12 volts.
Inform us of the measurements.

Now you have to check what is going to the opti. Back probe the harness to the opti with KOEO and confirm you have at least 12 volts between the pink/black wire and the red wire.

If that is good, confirm you have 4 to 6 volts from the pink/black (reference) and the purple/white and then from the pink/black to the red/black wires.

SUMMARY: KOEO
Check number 11 fuse

Voltage at the ICM using the black wire as ground=pin A_______Pin D_______

Voltage to the opti pink/black to Red=____________

Voltage from the opti pink/black to purple/white=______ pink/black to red/black=______

 

Ok great now I think we're getting somewhere:



SUMMARY: KOEO
Check number 11 fuse=GOOD

Voltage at the ICM using the black wire as ground=pin A__12.25__Pin D_12.25__

Voltage to the opti pink/black to Red=___12+_____

When opti is uplugged
Voltage from the opti pink/black to purple/white=___5___ pink/black to red/black=___5___

When opti is plugged in
Voltage from the opti pink/black to purple/white=__1.65___ pink/black to red/black=__2.12____

 

Unfortunately the book has 3 scenarios. Under 0.5, 4 to 6, and above 6 volts.

I would like to see if they ever get above 4 volts. However if the hi and low res signals were not being recognized, we would expect either a DTC16 or a DTC36.

My suggestion is probe the low res and hi res again with koeo and the wire connected. Then rotate the engine over by hand and watch the 2 signals to see if they ever go over 4 volts.

Then reset all codes and try it again. Scan for codes. If there are any go for them.

If there aren't any codes, let's look at your measurements. Then decide if it's an output problem with the opti/wiring/PCM or focus attention on the IC signal/wiring.