basically this is what i have, stock 97 lt1 bottom end freshly rebuilt with about 5k on it. hotcam kit, lt4 ED TC, pcm4less tuning all the free mods, lt4 km, bbk 58mmtb, stage 2 P&P heads with 600lift springs flow 276@.600 in and 195@.600ex and a P&P lt1 intake that is thermal coated and svo 30# inj. and a LPE CAI. 1LE elbow. and jethot LTs with ORY and 3"exhaust.

anyways, i just swapped heads b/c i had a few stripped out plug holes and it was runnining descent b4 aside from the rockers needing to be readjusted an exleak from the header and the lose plugs from being in stripped out holes.

now i have added the injectors, the new tune the new heads(old ones were stage 2 also) and the 58mm tb.

and now when you snap the throttle at any rpm really i get a back fire. if i rev it smootly it doesnt do it.

has anyone had this prob and know what it could possibly be. are the rockers set wrong or something i have comp pro mag full roller SA 1.6 rockers and i set them with it running 1/4 turn past no clicking and then set the locks. is that wrong ....what could it be, is it the TB what do you guys think i dont wanna drive it like this please help

 

i dont know if this is gonna help but i ad a similar problem but the car was also hesitating and felling reall ****ty when i drove it found out the spark plug wires were wrong on the Opti..changed the wires got them in the right place and everythign was koo...hope that jelps a lil....??just my thopught

 

Is the tune for the new set up? It's possible that the valve adj is wrong causing this but 1/4 turn is OK.Did ya set them running? Plug wires crossed,plug gap to much(.035 is good) tip in fuel to lean on tune,wires cross firing under load(all wires aren't the same quality don't care who made them)fuel pressure(pump or reg),fuel filter,etc,etc.

 

check fuel pressure. thats what mine was doing and i had a lean backfire everytime when you give it the gas hard.

 

if the plug wires were crossed wouldnt it backfire all the time not just when you goose it???

i just got home from work and im about to go out and start tinkering with it and triple check all the plugwires. all i know is i had some crap autozone lifetime wires on there and now i have the taylor OVC kit and it seems like more of a pain to me.

ill check the fuel pressure and the wires tonight though, any other ideas, im open to anything, i just want the thing to run right dang it, im tired of messin with it.

 

found it, 5 and 7 were swapped, i feel like an idiot thanks everyone

 

It happens

Good luck and glad ya found it.