Engine swap issue

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Engine swap issue

Post by jhainer »

Ok I have a 93 suburban 4x4 came with a 5.7 with a 4l60E my son killed the 5.7 towing a enclosed car trailer with a full size chevy truck inside the suburban also had 35's at the time it wasn't pretty to say the least. anyways I was able to pick up a 454 cheap out of a 91 3500 it dropped right in everything hooked up correctly I did have to get a different flywheel as the torque convertor holes didn't line up so at the same time I figured I would replace the convertor with a stall it's either a 2000 or 2500 stall can't remember but anyways truck has a hesitation issue motor sputters well during the swap I noticed the 454 manifolds do not have an o2 sensor like the 5.7 does so I bought a new y pipe with the o2 sensor bung and put an o2 in truck ran much better but still not great. now it is still running on the 5.7 computer so my thinking is that could be the problem so I have been looking for a prom for it but problem is gm didn't put the 4l60e behind a 454 only the 4l80e now some would say swap it out and move on and then I can get a factory prom before he poped the motor my daughter poped the trans she drove to pick up my granddaughter 50 mile in 4x4 high at about 70 miles and hr she pulled the truck in the drive shut it off when I started it a hr later it wouldn't move so I had the trans rebuilt by a local hot rod trans builder Sid Neal if any one knows him so replacing the trans wasn't a dig concern when doing the swap. truck runs and drives now just not great heard keep using the 5.7 computer and just adjust tehhe timing until it runs right is one thing I was told a custom burnt chip was a second third was that will never work it can't be done well it has been so here I am trying to get advice will the 7.4 4l80e computer control the 454 4l60e trans correctly? also any other suggestions. here is the truck I did remove the 35's and the 3 inch lift and went back to a 2 inch lift in the photo the truck is stock. and this is the main reason I own the truck just to pull my boat. Image

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Post by playtoy_18 »

That was hard to read without paragraphs or many periods lol.
As I can tell it’s a 454 TBI™ swap but using the stock ecm/prom.
They might use the same ecm but you should most definately put a 454 prom in it.
I can burn a stock or deleted prom for it,I would suggest at minimum verifying correct ECM/prom before even starting to diag the issue.

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Post by s10mods »

I would highly suggest dumping the 60 for an 80. Theres a reason the 4l60E never came behind a big block. they cant handle it. If you dont fix the problem it will continue to be a problem. The 4L60E was a 1/2 ton transmission never designed for big block power.
I would upgrade to a 454 pcm and a 4L80E trans then everything will work correctly.

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