MERGED-(Fresh opti pull pics) & (Ignition stutter-Code crackers needed)
Thread Starter
Instructor
Joined: Jun 2004
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From: OH/FL
My car was back to it's old tricks again...stumbling with no codes at 205degrees, kicking codes at 210...running like kaka for the afternoon...it was miserable. Clearing codes, pulling the fuse...nothing worked. 
Safety Car
Joined: Oct 2007
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From: :45 minutes from everywhere / E-I-E-I-O
I don't know what else it can be besides PCM.
I found my post where I noted the H41 right away after 3 days unplugged.
If it did not come up until the fans came on, and ONLY after the fans came on, then we could say a fan part might be bad, and causing a load that the PCM couldn't handle. But it seems to come up on a cold hook-up sometimes. It came up once on a cold hook-up for me today.
I swapped relays, kept both unplugged, kept primary unplugged, kept secondary unplugged, and tried both. Even the same test twice gave different results.
A 'cold' history code can only be the computer. I thought we had it limited to the fan circuit, or the PCM. I can't find any fault in the fan - I had a question about the primary fan kick-in temp, but that question is now answered.
Since it can't be the fan, what's left?
I found my post where I noted the H41 right away after 3 days unplugged.
If it did not come up until the fans came on, and ONLY after the fans came on, then we could say a fan part might be bad, and causing a load that the PCM couldn't handle. But it seems to come up on a cold hook-up sometimes. It came up once on a cold hook-up for me today.
I swapped relays, kept both unplugged, kept primary unplugged, kept secondary unplugged, and tried both. Even the same test twice gave different results.
A 'cold' history code can only be the computer. I thought we had it limited to the fan circuit, or the PCM. I can't find any fault in the fan - I had a question about the primary fan kick-in temp, but that question is now answered.
Since it can't be the fan, what's left?
Last edited by schrade; Jul 18, 2008 at 08:24 PM.
Thread Starter
Instructor
Joined: Jun 2004
Posts: 174
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From: OH/FL
I tried a guy locally with a 1995 Vette 6spd...I wanted to swap PCM's but his was modified for a supercharged LT1. Might not work in my car.
Know of a good source for a PCM? Also, don't they need to be programmed to our cars specifically, or at least the year and tranny?
Know of a good source for a PCM? Also, don't they need to be programmed to our cars specifically, or at least the year and tranny?
Safety Car
Joined: Oct 2007
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From: :45 minutes from everywhere / E-I-E-I-O
FWIW...The engine started bucking on me (as per the usual now) and the CEL came on. Upon quickly pulling over and checking the DelTeq "brain" box, the LED was solid and not blinking. This is good, as a blinking light indicates that the DelTeq system is not getting a solid signal from the OptiSpark.
.
.
This is interesting "not getting a solid signal from the opti...".
Safety Car
Joined: Oct 2007
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From: :45 minutes from everywhere / E-I-E-I-O
Message from Car Quest...
"Blue Streak called; your PCM has so many problems, that they won't be able to warranty a repair."
I did the by-pass on the PCM backprobin' it, and the PCM feed was good. I shoulda' stopped there. No problem - I learned a few more thing (like how to cook your fingertips usin' a paperclip to jump a 30 amp fan relay circuit
)
Which probably means they WILL work on it after they ship a reman that they do now have, and Zeits will get my old one in a couple of weeks!!!
Zeits - empty your mailbox............
"Blue Streak called; your PCM has so many problems, that they won't be able to warranty a repair."
I did the by-pass on the PCM backprobin' it, and the PCM feed was good. I shoulda' stopped there. No problem - I learned a few more thing (like how to cook your fingertips usin' a paperclip to jump a 30 amp fan relay circuit
)Which probably means they WILL work on it after they ship a reman that they do now have, and Zeits will get my old one in a couple of weeks!!!
Zeits - empty your mailbox............
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Le Mans Master
Joined: Dec 2004
Posts: 5,789
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Message from Car Quest...
"Blue Streak called; your PCM has so many problems, that they won't be able to warranty a repair."
I did the by-pass on the PCM backprobin' it, and the PCM feed was good. I shoulda' stopped there. No problem - I learned a few more thing (like how to cook your fingertips usin' a paperclip to jump a 30 amp fan relay circuit )
Which probably means they WILL work on it after they ship a reman that they do now have, and Zeits will get my old one in a couple of weeks!!!
Zeits - empty your mailbox............
"Blue Streak called; your PCM has so many problems, that they won't be able to warranty a repair."
I did the by-pass on the PCM backprobin' it, and the PCM feed was good. I shoulda' stopped there. No problem - I learned a few more thing (like how to cook your fingertips usin' a paperclip to jump a 30 amp fan relay circuit
)Which probably means they WILL work on it after they ship a reman that they do now have, and Zeits will get my old one in a couple of weeks!!!
Zeits - empty your mailbox............
Pro
Joined: Jun 2003
Posts: 618
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From: Kingston Springs Tn
I have been watching this post for sometime and my 93 lt1 is doing exactly the same thing as yours. I keep trying everything you are trying and nothing has fixed mine either. I guess I am going to check the fan relays as that is the only thing I have not done yet. Maybe we can all get this worked out soon!!!
Pro
Joined: Jun 2003
Posts: 618
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From: Kingston Springs Tn
Ok guys....I have been searching and searching for my problem as you have and I think I have found it......http://forums.corvetteforum.com/show....php?t=1795666
Look at this post, I pulled my ecu apart and the back of my circuit board looks as bad if not worse than this one. The solder mask and sealing material is really bubbling bad and I am sure this is my problem. Because as the car heats up so does the ecu and when it gets hot thats when the problems start. I am ordering a new computer in the morning and will let you know what happens....Good Luck!!!
Look at this post, I pulled my ecu apart and the back of my circuit board looks as bad if not worse than this one. The solder mask and sealing material is really bubbling bad and I am sure this is my problem. Because as the car heats up so does the ecu and when it gets hot thats when the problems start. I am ordering a new computer in the morning and will let you know what happens....Good Luck!!!
Thread Starter
Instructor
Joined: Jun 2004
Posts: 174
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From: OH/FL
Thanks, new dude! 
I've been putting off the PCM for some strange reason, waiting for Schrade to give me the
. However, if you find a good source for a decent PCM, please share.
I still DD my Corvette, so no breaking the PCM apart yet.
I've been putting off the PCM for some strange reason, waiting for Schrade to give me the
. However, if you find a good source for a decent PCM, please share.I still DD my Corvette, so no breaking the PCM apart yet.
Pro
Joined: Jun 2003
Posts: 618
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From: Kingston Springs Tn
Apparently what happens is the coating GM used is defective. When the board gets hot it causes the coating to bubble or something allowing enough room for the chips to raise just enough to loose the current shutting down the system. The new remanu boards are supposed to use a better nore heat resistant coating. Most of the time the components are goods just the heat causes the seperation of the chips long enough for failure. As far as a replacement look at Advance autoparts. They have remanu units from Cardone with 1 year warr. for for $135 after core. Hey its better than nothing!!
Last edited by blankmantn; Aug 4, 2008 at 12:50 AM.
Safety Car
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From: :45 minutes from everywhere / E-I-E-I-O
I have been watching this post for sometime and my 93 lt1 is doing exactly the same thing as yours. I keep trying everything you are trying and nothing has fixed mine either. I guess I am going to check the fan relays as that is the only thing I have not done yet. Maybe we can all get this worked out soon!!!
Voltage spikes (like the fan kickin' in) definitely affect a bad PCM; I saw that in mine '94, and Clay in his '95, but, but of course, they will not affect a GOOD PCM.
Thread Starter
Instructor
Joined: Jun 2004
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From: OH/FL
Schrade...didn't you get screwed over by Advance? I thought they had a code in their system and then came back saying it wasn't available...
Thread Starter
Instructor
Joined: Jun 2004
Posts: 174
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From: OH/FL
Actually, I've noticed two pretty good spikes: A/C turning on, and those electric fans turning on...
I'm not surprised that it is probably the PCM...Florida was pretty ri-donk-ulously hot. My dash is a little warped up by the center defrost vent panel from the sun.
Apparently it may have helped bake the electronics also...
Safety Car
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From: :45 minutes from everywhere / E-I-E-I-O
He's right there blankmantn... Advance got bad info on the PCM, from the PCM supplier. Although you're workin' on a '93, stay at the store till the Advance guy gets a Cardon [supplier guy] ON THE PHONE. I PROMISE - you need to do that.
Believe it or not, the dealer's price for PCM doesn't seem to be too high... DO your homework on it.
Pro
Joined: Jun 2003
Posts: 618
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From: Kingston Springs Tn
Hey I just checked Rockauto.com....where did you see $95 for one???
ACDELCO Part # PT418 {4-WAY FEMALE BLACK #12116930}
CONNECTOR,DIODE NETWORK
* Non-stock item--shipping delayed up to 3 business days
$27.79 $0.00 $27.79
A-1 CARDONE Part # 779278 {Remanufactured.{Return and Rebuild Only - please contact customer service for more info}}
w/OEM #16159278
* Non-stock item--shipping delayed up to 2 business days
$180.79 $175.00 $355.79
A-1 CARDONE Part # 773993 {Remanufactured. {Return and Rebuild Only - Please Contact Customer Service for More Info}}
w/OEM #16163993; Part Available Thru Rebuild & Return Only.
* Non-stock item--shipping delayed up to 2 business days
ACDELCO Part # PT418 {4-WAY FEMALE BLACK #12116930}
CONNECTOR,DIODE NETWORK
* Non-stock item--shipping delayed up to 3 business days
$27.79 $0.00 $27.79
A-1 CARDONE Part # 779278 {Remanufactured.{Return and Rebuild Only - please contact customer service for more info}}
w/OEM #16159278
* Non-stock item--shipping delayed up to 2 business days
$180.79 $175.00 $355.79
A-1 CARDONE Part # 773993 {Remanufactured. {Return and Rebuild Only - Please Contact Customer Service for More Info}}
w/OEM #16163993; Part Available Thru Rebuild & Return Only.
* Non-stock item--shipping delayed up to 2 business days