so my buddy has this auto 1994 z28. It had some other mystery lt1 swapped in, and for some reason it has the 110 speedo. its a true z28 though. I was missing and stalling and bogging in idle. we had already done the fuel pump and filter. it finally dies and wont start. turns out it had like a 12 oz can worth of water in the pcm. cause the case was loose. so he gets another pcm out of a buick roadmaster. runs now, but he says it has no low end power. is there a difference in performance? hes driven at least 50 miles, does it still need to re learn?

 

Iirc the pmc's are the same except for the tune. Get it flashed with the correct tune and you should be back to normal.

 

Not positive, but I think at least the cams are different. Different timing tables and fuel maps perhaps. Best thing to do is get it reflashed. Any internal engine mods done?
The 110 speedo was because for some dumb reason GM decided to make it an option to have a lower speed rated tire than the "Z rated" with a 150mph speedometer. Can't remember the exact code.

 

The Roadmaster engine had a different cam, lower compression and 87 octane tuning but by all accounts the b-body engine with b-body tuning makes more lowend power sooner. So while the tuning is not correct I would also be open to the idea there is a mechanical issue, maybe the poor running condition fouled the plugs or something.

 

ok that makes more sense. wheres the best place to have it flashed? he said the tires wont even spin anymore from a stop.

 

http://madtuner.com/

http://www.pcmforless.com/

Some say take it to a GM dealer to get it reflashed. I tried this a couple of years ago at my local dealer and no one service person knew what I was talking about. Your best bets are the two links above.

After it's reflashed and back in the car it would probably be a wise idea to change out the plugs.

 

where are you? Maybe we can recommend someone close by? madtuner is near Chicago, pcmperformance has one guy in Kansas city I believe and another in Long Island

I know a guy near Dayton OH
A guy out in CA
There are tuners all over the country

 

I'm actually in Long Island