Hello all, I have a majore problem with my 94z my top end power is none exsistent, and my accelleration sucks now. I had recently just ripped the whole top of the engine apart to retap the header bolts since 2 were stripped, While the engine was ripped apart i decided to port match the heads an intake just smoothed out the lip on the runners i did leave a rough surfes on the intake runners but polished the hell outta the exhaust ports an ported out the throttlebody as well ( didnt kno if that could cause this problem)???? when i re assembled i had to hook all my emissions junk back up to pass emissions an as stated befor acceleration an high rpm power is gone! also when i get on it you can hear this really loud air suckin sound it almost sounds like my carburated 85 K5 when i floor it it never made a sound like that till now. Im at a loss with this problem i fixed all exhaust leaks, lifter adjustment, switched out my egr an smog pump, O2s, anythin an everythin an still no luck. I was also thinkin it maybe could be a clogged CAT, it is an old one an the car never had one on till my emmissions came around? Can someone please help! the car has pacesetter LT's 4" exhaust all the way back 503 comp cam custome intake LS7 lifters T56 6 speed an a bunch of suspention mods. The car starts, idles an runs fine its just lack of top end power an ****ty acceleration, please any help would be greatly appreciated.

 

First, you should have this in the LT1 engine section and should get way more responce than in this section. From the sounds of it you have had so much apart and done so much to it, that figuring it out might be tricky. Have you scanned it for codes? Intake and exhaust leaks can cause problems and you had so much removed that I would check all that very carefully. Do you have anyway to scan it to see whats happening, like DataMaster? You have 4" exhaust and a cat on there now? I would check that to be sure its not plugged and personally remove it until until the next test. Mine was every other year and would put a spraight pipe in between tests. Thats a long time between testing for me and worth having that thing off the car. Porting out your heads is a tricky thing and can really screw things up if done wrong. Sounds like you didn't take it to any extremes like other who screwed up the heads, but it hards to say. Last thing, do you have it tuned?

 

Yes the 4" exhaust an cat are on the car now the cat is a 3" with reducers i had taken it off my 85 blazer for emmissions other whys i do rip it off an run straight pipes but i had the cat on the car for a few weeks without problems just started after i got the car back together. You see i was failing emmissions cuz i had a exhaust leak at the header cuz the stripped bolts in the head it was screwing up my O2's, so upon assembly i made sure everythin was sealed up good an tight. I have scanned for codes an nothin that would cause this only codes im gettin are for the a/c system since i removed all that as well. Like i had sad you didt do anythin extreme with port matching the heads didnt touch the bowls or the valves just smoothed out the lip on the runners left the intake ports rough an exhaust ports smooth. The ecm is NOT tuned as well but again that was never a problem till now. I dont kno what i did wrong but i went through everythin countless times now an the cars still kicking my ***.