hey guys. i've used this forum exclusively to do the complete GM tbi upgrade to my friend's 4.2 wrangler. it had the usual motorcraft carb swap already due to the crap carter carb that it came with smoked the old motor.
heres a brief rundown of what i've done til this point:
he had a rebuilt engine shipped to a shop that did his motor swap. drove it 200 miles or less with the motocraft carb. and burned up a piston in cyl 6. wasnt happy. called me cuz he was sick of the bs with the shop, and nobody would honor any warranty. I overnighted another engine kit, it has .060 over pistons in it, new rings, bearings, etc. then got it fired up, only to find the head musta been warped too. basically he got a junk rebuilt motor. so i swapped the head with a freshly machined head.
then he decided that since we could NOT get that damn ford carb to run worth a crap so he wanted to go FI. i researched options vs costs, again, from this wonderful site and opted for the GM 4.3 tbi swap. i took the computer, MAP sensor, TPS, IAC, TBI unit, and temp sensor from a 92 chevy blazer 4.3. had a machine shop custom make me an adapter plate for the TBI.... but it wouldnt fire. found i had no injector spray. so i goosed it with some starting fluid, it fired, and like magic i suddenly had injectors! ran like a champ after some minor distributor adjustments. after we ran it around town we discovered it would lurch and pop and sputter at lower rpms, such as when driving 25-30mph in town in 3rd gear. but it ran perfect anything above 2500 rpms. never had a problem starting it again.
THEN, a few months later he decided he wanted to upgrade the distributor. i read about the HEI upgrade, and tried to do that. but could not obtain the proper distributor gear to run that set up within the time frame i had to work on his jeep. so we bought a brand new stock distributor, but got the ford distributor adapter and the ford 300 c.i. inline 6 distributor cap (because of it being bigger and farther spacing between posts). also ran with the TFI coil for better spark. went to fire it up, and no go. again, no injectors. so once again i goosed it with some spray, and it fired right up, and had great injectors as soon as it fired! kinda confused me, but figured it happened the first time, so no biggie. got the distributor timed properly, let it run a bit, then shut it off. i fired it up a few times, it was GREAT. i literally put a glass of water on the valve cover and it didnt move. went inside, drank some beers, and 4 hrs later came back to start it, no injectors. no matter how long it cranked. so i sprayed it AGAIN, and fired up and drove fine. shut it off, and it fired right back up. after lots of playing with it, i've discovered it will give injector signal every time to start it as long as its at least remotely warm. as soon as this winter weather cools it down, it loses its initial pulse signal to get it started. i dont understand. at all. ive changed the temp sensor with a new one, no change. the old distributor was JUNK i found out as it had many floppy parts and the magnetic deal that reads the star wheel under the rotor was constantly touching. but now that its got a good distributor it does this ****. HELP. im only here in town to help him out for a few days. im going the yard tomorrow to get a different computer in hopes maybe it was a freak coincidence that it went bad the same time i swapped the distributor, but i doubt it. please help me!
thanks, mike
heres a brief rundown of what i've done til this point:
he had a rebuilt engine shipped to a shop that did his motor swap. drove it 200 miles or less with the motocraft carb. and burned up a piston in cyl 6. wasnt happy. called me cuz he was sick of the bs with the shop, and nobody would honor any warranty. I overnighted another engine kit, it has .060 over pistons in it, new rings, bearings, etc. then got it fired up, only to find the head musta been warped too. basically he got a junk rebuilt motor. so i swapped the head with a freshly machined head.
then he decided that since we could NOT get that damn ford carb to run worth a crap so he wanted to go FI. i researched options vs costs, again, from this wonderful site and opted for the GM 4.3 tbi swap. i took the computer, MAP sensor, TPS, IAC, TBI unit, and temp sensor from a 92 chevy blazer 4.3. had a machine shop custom make me an adapter plate for the TBI.... but it wouldnt fire. found i had no injector spray. so i goosed it with some starting fluid, it fired, and like magic i suddenly had injectors! ran like a champ after some minor distributor adjustments. after we ran it around town we discovered it would lurch and pop and sputter at lower rpms, such as when driving 25-30mph in town in 3rd gear. but it ran perfect anything above 2500 rpms. never had a problem starting it again.
THEN, a few months later he decided he wanted to upgrade the distributor. i read about the HEI upgrade, and tried to do that. but could not obtain the proper distributor gear to run that set up within the time frame i had to work on his jeep. so we bought a brand new stock distributor, but got the ford distributor adapter and the ford 300 c.i. inline 6 distributor cap (because of it being bigger and farther spacing between posts). also ran with the TFI coil for better spark. went to fire it up, and no go. again, no injectors. so once again i goosed it with some spray, and it fired right up, and had great injectors as soon as it fired! kinda confused me, but figured it happened the first time, so no biggie. got the distributor timed properly, let it run a bit, then shut it off. i fired it up a few times, it was GREAT. i literally put a glass of water on the valve cover and it didnt move. went inside, drank some beers, and 4 hrs later came back to start it, no injectors. no matter how long it cranked. so i sprayed it AGAIN, and fired up and drove fine. shut it off, and it fired right back up. after lots of playing with it, i've discovered it will give injector signal every time to start it as long as its at least remotely warm. as soon as this winter weather cools it down, it loses its initial pulse signal to get it started. i dont understand. at all. ive changed the temp sensor with a new one, no change. the old distributor was JUNK i found out as it had many floppy parts and the magnetic deal that reads the star wheel under the rotor was constantly touching. but now that its got a good distributor it does this ****. HELP. im only here in town to help him out for a few days. im going the yard tomorrow to get a different computer in hopes maybe it was a freak coincidence that it went bad the same time i swapped the distributor, but i doubt it. please help me!
thanks, mike