C4 tpi engine revs up in neutral, starts miss firing at 1500rpm in drive.
09-20-2016, 11:32 AM
#1
Instructor
Thread Starter
C4 tpi engine revs up in neutral, starts miss firing at 1500rpm in drive.
Got a L98 tpi motor will not accelerate past 1500 rpm while driving and starts miss firing like maybe timing. Triple checked timing base at 6 and mark goes way above marker with brown wire plugged back in. New plugs, new wires, new cap, new rotor, new O2, new tps, and several other sensors.
Could a new spark plug foul out ? Egr blocked and vacuum line plugged. air pump still on. will ecm still keep memory if i have been disconnecting positive post only? got a code 41 and 42 with performance chip. factory chip still give code 41 sometimes. been reading a lot of threads but running out of answers.
Really could use some help here, two weeks of trial and error.
Could a new spark plug foul out ? Egr blocked and vacuum line plugged. air pump still on. will ecm still keep memory if i have been disconnecting positive post only? got a code 41 and 42 with performance chip. factory chip still give code 41 sometimes. been reading a lot of threads but running out of answers.
Really could use some help here, two weeks of trial and error.
Last edited by Street89vette; 09-20-2016 at 02:20 PM.
09-20-2016, 01:51 PM
#2
Melting Slicks
Is it a maf car, if so try cleaning it.
Here are some other things I can think of to try. Bend the metal tong up some in the center of the rotor to make sure it contacts the bushing in the center of the cap. Make sure your dist is grounded good, I always add a dedicated grd from the dist base to the block and some aftermarket HEI like MSD come with one. You can make an alligator clamp jumper wire to test that, just make sure the surface you clamp is sanded/wired clean. Maybe even it's just a poor main engine/batt ground?
Here are some other things I can think of to try. Bend the metal tong up some in the center of the rotor to make sure it contacts the bushing in the center of the cap. Make sure your dist is grounded good, I always add a dedicated grd from the dist base to the block and some aftermarket HEI like MSD come with one. You can make an alligator clamp jumper wire to test that, just make sure the surface you clamp is sanded/wired clean. Maybe even it's just a poor main engine/batt ground?
09-20-2016, 03:19 PM
#3
Is it a maf car, if so try cleaning it.
Here are some other things I can think of to try. Bend the metal tong up some in the center of the rotor to make sure it contacts the bushing in the center of the cap. Make sure your dist is grounded good, I always add a dedicated grd from the dist base to the block and some aftermarket HEI like MSD come with one. You can make an alligator clamp jumper wire to test that, just make sure the surface you clamp is sanded/wired clean. Maybe even it's just a poor main engine/batt ground?
Here are some other things I can think of to try. Bend the metal tong up some in the center of the rotor to make sure it contacts the bushing in the center of the cap. Make sure your dist is grounded good, I always add a dedicated grd from the dist base to the block and some aftermarket HEI like MSD come with one. You can make an alligator clamp jumper wire to test that, just make sure the surface you clamp is sanded/wired clean. Maybe even it's just a poor main engine/batt ground?
sounds like timing to me. i'd say you have distributor issues.
as far as i know, the only time you get backfiring is when the timing is off, or, your valves are really mal adjusted. you have a spark going off when the intake valve is still open. that can either be from the distributor timing being off, or, from the valves being too loose and never closing, or, maybe you have a hole burned the base of the valve.
i'd start with checking timing for sure. you will need a timing light which you should be able to get off kijiji or craigslist for reach cheap, even new i think they are about 30$. you don't need anything fancy.