PROM to run later 4l80e in 91-93?

**Casey** · 11-04-2021

Hi all! I have a question I desperately need help with. The 4l80e in my 1991 V2500 Suburban just blew, and normally I would just get the trans rebuilt and call it a day, but I've been gathering parts for an 8.1 swap. I have read that you can get a PROM for my ECU (7060) that will allow me to run the later solenoid but it's only mentioned with no further information. Is such a PROM available?

If not I suppose my options are getting my unit rebuilt and then changing out the vavlebody and whatever else down the road or swap in a later unit and swap the valve body, etc. now, or swapping in a later unit now and changing my ecu to a 94-95 and repinning my harness?

Any help or insight would be appreciated. It's my daily so I can't afford for it to be down long. Thanks!

**Padgett** · 11-04-2021

Suggest contacting on of the tuners (e.g. GMtuners or HPtuners ) and ask them.

**dave w** · 11-04-2021

16156930 PCM Information $31: http://gearhead-efi.com/Fuel-Injecti...Information-31

16196395 PCM Information $OE: http://gearhead-efi.com/Fuel-Injecti...Information-OE

16147060 PCM Information $85: http://gearhead-efi.com/Fuel-Injecti...Information-85

16197427 will also operate a 4L80E

I'm unaware of a simple PROM swap allowing the 16147060 to use the newer 4L80E.

Any of the PCM's listed above can be setup to Run 4L80E Transmission Only: https://sites.google.com/site/astros...h-16197427-ecm

dave w

**Casey** · 11-04-2021

Darn, I had a feeling it wasn't going to be that easy haha. Well, I will look in to the info provided. Thanks again!

**Daveo91** · 11-04-2021

I also have a '91 V2500 Suburban and have gone through similar issues as you, although kind of in reverse. I wanted to upgrade from the 7060 to the 7427 but wanted to use my '91 trans unmodified. I looked at all the angles and was going to have a shop modify the trans so I could use the later PCM, but it turns out I didn't need to. At some point my trans was replaced with a later model that had the upgraded valve body and force motor. Got lucky!

I agree with Dave W - in all my searching and research there's no easy fix to the '91-'93 4L80e force motor cleaning cycle.

I've now completed the 7427 conversion and going through the tuning process. It's been challenging but I think the upgrade was worth it. I built a stroker 383 with vortec heads - the 7060 just did not like the new engine. I was getting a horrible surge on decel that I could not tune out. From day 1, that surge was gone with the 7427. But still lots of other challenges to deal with. I'm getting there.

**Casey** · 11-04-2021

Originally Posted by Daveo91

I also have a '91 V2500 Suburban and have gone through similar issues as you, although kind of in reverse. I wanted to upgrade from the 7060 to the 7427 but wanted to use my '91 trans unmodified. I looked at all the angles and was going to have a shop modify the trans so I could use the later PCM, but it turns out I didn't need to. At some point my trans was replaced with a later model that had the upgraded valve body and force motor. Got lucky!

I agree with Dave W - in all my searching and research there's no easy fix to the '91-'93 4L80e force motor cleaning cycle.

I've now completed the 7427 conversion and going through the tuning process. It's been challenging but I think the upgrade was worth it. I built a stroker 383 with vortec heads - the 7060 just did not like the new engine. I was getting a horrible surge on decel that I could not tune out. From day 1, that surge was gone with the 7427. But still lots of other challenges to deal with. I'm getting there.

Interesting. So help me understand; you ran the later force motor with your 7060 instructing it to run the cleaning cycle and didn't have any issues? I came across a post where a guy claimed he did that trouble free for 25k miles. I'm going today to pull a '94 with 140k on it with plans of just swapping in my force motor and valve body but if I can just throw it in that might be nice.

**tayto** · 11-04-2021

upgrade to the newer style 7427 TBI PCM and I can walk you through how to "update" your pre-1993 4L80E. If not you can install any 94+ 4L80E with the PCM upgrade...

EDIT: i recently updated a '92 4L80E with new PCS motor and 7427 swap. you will need to mod the valve body (easy) and run a 94+ separator plate (transgo makes)

**Daveo91** · 11-05-2021

Originally Posted by Casey

Interesting. So help me understand; you ran the later force motor with your 7060 instructing it to run the cleaning cycle and didn't have any issues? I came across a post where a guy claimed he did that trouble free for 25k miles. I'm going today to pull a '94 with 140k on it with plans of just swapping in my force motor and valve body but if I can just throw it in that might be nice.

Yes. It's pretty crazy. I've owned the truck since 2014 and who knows how many years and miles it's been that way. When I had the engine out for rebuild I found the ID tag on the tranny: it was a 1993 replacement. Perhaps the replacement transmissions had the upgrades made in '93 even though the production ones weren't changed till '94. Or maybe someone else upgraded it along the way. Don't know, but it doesn't seem to have any issues at all even though it was run that way for many years and thousands of miles. There is a caveat, however: it's possible that the decel surge I mentioned was caused or exacerbated by the wrong PCM for the newer trans. The reason I say this is I remember it being there before I did anything at all to the engine. The 383 made it much more pronounced (and annoying) but it was there before too. I spent a long time in TP trying to tune it out, but nothing I did ever affected it. Fuel was being cyclically shut off and restarted in about 2 second cycles. I finally gave up and converted to '7427. I agree with others - that's the way to go if you're going for long term. But with the planned 8.1 swap maybe you'll be OK with 7060. I'll be interested to see how it turns out, either way. Love the idea of an 8.1 swap into a burb, I've considered both that and a Vortec 454. Good luck.

**dave w** · 11-05-2021

The GM 8.1 Liter has Coil-on-Plug Ignition . . . or maybe the engine swap is a Crate 496 / 8.1?

dave w

GM 8.1 Liter.jpg

**Casey** · 11-06-2021

Yep, coil on plug. I will be using the 8.1 ECU.

Daveo91, I will need to PM you once I have had the '94 I pulled today inspected.

20211105_094010.jpg

**Daveo91** · 11-06-2021

Originally Posted by Casey

Yep, coil on plug. I will be using the 8.1 ECU.

Daveo91, I will need to PM you once I have had the '94 I pulled today inspected.

20211105_094010.jpg