Down grading pcm

awhile back I had a thread on down grading obd2 to obd1. My case was 98 pickup. 305 Vortec and 4l60e. Wanted to downgrade to 7427. Several pointed out the differences that changed the 4l60e 97-98 and I dropped getting the truck. Now the truck has been given to me. It is 16258825 with ccsd bin. Now I am thinking of piggy back using 7427 for fuel and timing and leaving the 8825 for trans. Is my thinking plausable or flawed. I would be changing fuel delivery and ignition as the failed spider is why the truck doesn’t run.

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Originally Posted by myburb

awhile back I had a thread on down grading obd2 to obd1. My case was 98 pickup. 305 Vortec and 4l60e. Wanted to downgrade to 7427. Several pointed out the differences that changed the 4l60e 97-98 and I dropped getting the truck. Now the truck has been given to me. It is 16258825 with ccsd bin. Now I am thinking of piggy back using 7427 for fuel and timing and leaving the 8825 for trans. Is my thinking plausable or flawed. I would be changing fuel delivery and ignition as the failed spider is why the truck doesn’t run.

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TBH just change the spider and go. If you want a better PCM for mods someday swap in an 0411 with a 5.0L Express van base tune.

I've never tried to use the 16258825 for Trans Only, but likely needs the following:
CKP Input for RPM.
TPS Input for shifting tables.
VSS Input for shifting tables.
TCC Input from Brake Switch
Power and Ground Wiring.
Modified Flash to eliminate engine errors.
Serial Data to figure things out.

Likely the 1998 pickup VSS output will need spliced to provide two outputs. One output spliced to a DRAC so the 16197427 will have a VSS input and the original VSS output to the 16258825.

I'm not sure going OBD1 is the best option for the 1998 pickup. I'm thinking the option of fixing the 1998 with stock parts (spider assembly) would likely be less work and less money than an OBD1 hybrid solution? I'm thinking perhaps the OBD1 hybrid option makes more $ense if the 305 was being removed and replaced with a "Performance" OBD1 engine.

dave w

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Originally Posted by dave w

I've never tried to use the 16258825 for Trans Only, but likely needs the following:
CKP Input for RPM.
TPS Input for shifting tables.
VSS Input for shifting tables.
TCC Input from Brake Switch
Power and Ground Wiring.
Modified Flash to eliminate engine errors.
Serial Data to figure things out.

Likely the 1998 pickup VSS output will need spliced to provide two outputs. One output spliced to a DRAC so the 16197427 will have a VSS input and the original VSS output to the 16258825.

I'm not sure going OBD1 is the best option for the 1998 pickup. I'm thinking the option of fixing the 1998 with stock parts (spider assembly) would likely be less work and less money than an OBD1 hybrid solution? I'm thinking perhaps the OBD1 hybrid option makes more $ense if the 305 was being removed and replaced with a "Performance" OBD1 engine.

dave w

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I have used an 0411 multiple times for transmission control but i was also using it for ignition control at the same time. I played with a Holley carbureted Vortec 350 in my Express van testing the idea for carbureted LS swaps. I have since done both a 5.3 and 6.0L with a 4L65E and 4L80E.

Thanks for the opinions. I will probably first go the repair route and if that works would probably sell it. I have no need for an old non tuneable vehicle. With the cdn dollar the way it is efi live and hp tuner are pretty pricey for a hobby. Reading the flash tool threads were looking good at one time but seemed to have died. The 0411 is something I would like to try as a project.

Update, I pulled the spider out and did the carb cleaner on the offending poppett and all working but it has possible cylinder damage from the leaking fuel but going well enough to unload it.