i have 24 hours to fix it. LT1 experts please read!!!

[383TA]

ok i have a 94 TA, and the car has started to pop and back fire at low rpm's but only when the motor was warmed up, and it got worse the high the temp went. so we hooked it up to a hand held and it didnt put out any codes, so we decided to replace the pcm, went to do that, and found that my old pcm's knock module was gone, so i figured that was the problem well i got the new knock module back in and the new pcm, and now the thing run's like total [****] it will idle but the second you put any load on it, it just pop's and pings and jurks, at full throttle it took the car 15 sec, to move about 30 feet. so we hooked it to the hand held again and still no codes?!?!?!?!?!?!?!? WTF? we are having the closing crusie this sat. it is the biggest event of the year for the UFBA and i have never missed it. but this might cause me too, any help would be great! thanks!

[Joe 1320]

Optispark has most likely bit the dust.

[383TA]

doesnt optispark put out a code?

[Joe 1320]

Only if the optical section fries, which is not as common as the cap and rotor portion..... that won't set a code.

[BAS]

Re: i have 24 hours to fix it. LT1 experts please read!!!

Have the dealership look at it with a Tech 1 scanner.

Or get Diacom and a laptop.

What was your handheld?

Did you buy the car off someone else?

Who swapped your motor?

Who built your motor?

When did this start happening?

Originally posted by 383TA
ok i have a 94 TA, and the car has started to pop and back fire at low rpm's but only when the motor was warmed up, and it got worse the high the temp went. so we hooked it up to a hand held and it didnt put out any codes, so we decided to replace the pcm, went to do that, and found that my old pcm's knock module was gone, so i figured that was the problem well i got the new knock module back in and the new pcm, and now the thing run's like total shit! it will idle but the second you put any load on it, it just pop's and pings and jurks, at full throttle it took the car 15 sec, to move about 30 feet. so we hooked it to the hand held again and still no codes?!?!?!?!?!?!?!? WTF? we are having the closing crusie this sat. it is the biggest event of the year for the UFBA and i have never missed it. but this might cause me too, any help would be great! thanks!

[Injuneer]

If you have a "383TA", what's in it and who did the programming? When you swapped PCM's did you put your "383" program into the new PCM?

When you put the original scanner on it, what did the long term fuel corrections look like? If they were getting way out of whack, the new PCM isn't going to respond very quickly to resolving the problems. If your BLM's were "off", but not by enough to set a code, its not going to set any codes with the new PCM. It'll just sit there trying to "learn"... and if you had something other than 24# injectors programmed into the original PCM, it isn't going to be able to handle it.

Why did you suspect the PCM? From my experience that is seldom the cause for problems like this. You need to look at components that are susceptible to breakdown under high temperature loads:

-IC Module
-plug and coil wire insulation
-coil
-optical sensor in Opti (might not set a code, if the pulse patterns are still there, but "distorted"... it can only sense the "absence" of pulses).

[383TA]

the guy that has been doing alot of this stuff, told me that the new PCM doesnt need any special programing. so does it? what does it need?

[Injuneer]

What size injectors are you running? How big is the cam? What do the heads flow? What are MAP readings at idle? Have you checked the coolant temp sensor (the one in the water pump housing)? TPS sensor? MAF sensor?