1991 gm went to the 480le how did they do that?

[pholliday1]

Interested in the computer/harness differences to upgrade a tbi turbo 400 to 480le.Not sure if gm used a standalone computer for this or upgraded there existing ecm....anyone?

[Captkaos]

The ECM controlled the 4L80E.  It was a one year only in our trucks and was only available on the 1Ton Crew Cabs.

[zieg85]

Wasn't the 91 C2500 Suburban one, the one I parted out sure looked factory

[Captkaos]

OOPS! forgot about the Burb's.  Yes it would have been.

[ehjorten]

I can confirm what Captkaos states! 

Newer trucks now have separate controllers for the transmission and engine.  One major issue with the '91 is there is no support in the tuner world for the 454-4L80e PROM.  MegaShift could be your new friend!

[pholliday1]

Seems like a little of a stretch you'd almost need a 91 burb donor because chances of finding donor crewcab are really slim.

[bluecrew]

I have a 91 crew cab.  For the right price, it could be a donor...$$$!

[pholliday1]

Ha ha !thank you for your offer , I would dare say 91 crewcabs are few and far between especially as nice as ehorten.

[ehjorten]

Searched for 3 years for mine...across the country and in the end this one ended up within 1 hour of my home town!   Needless to say...I never moved so fast!  Thanks for the compliments.  It isn't without it's flaws...but I enjoy working on it and driving it!

[bluecrew]

Ha ha !thank you for your offer , I would dare say 91 crewcabs are few and far between especially as nice as ehorten.

Agreed, his IS one heII of a crew.  Kind of a pipe dream for the rest of us, but sure is nice to look at, no matter how jealous it makes me.

[Captkaos]

They used the same standalone computer up to about 1993, so you aren't limited on your sources.