I have a none thirdgen question but, will also help with my future map swap on my tpi.


well to start off with I have a 89 pont. grand am quad 4. now when I bought the car it had the LO QUAD 4 and it was blown so I found a HO 91 GTZ QUAD 4 put it in and the car starts and runs but, has a rough idle like a over camed car or a lean miss fire.

now I checked every thing twice all looks good inj. , map, tps ect.
I was not sure but, on the old blocks there was like a 4 deg. timming differance from the newer ones so I took a VIN A chip(H.O.) and put it in and it idles at 2000 rpms but, smooth.

if I put the LO chip in and bring it up to 2000 rpms the miss is still felt but, not as bad.

The H.O. has more comprestion and a lot bigger cams than the L.O but, thats about all.

do the map tpi cars run like crap with really big cams? the mass air flows kinda do but, not like they are missing.