Chad Million

ok so i have a 94 trans am lt1 6 spd

it runs terrible

so far replaced the opti twice this week . cts , mass , map , computer , msd wires , ngk plugs , etc....

have checked for continuity between opti and computer checks out

data at idle : mass 10-11 gps , map 2.0-2.5 v , injectors 5-, 10 ms . all high i know.... all sensors are good

have checked all ground found a few repaired them and nope

oh and i get a code 16 with koeo only if cleared while running it will not return

computer at koeo will see 54 rpm ???? which i believe is the code 16

i have ran through all the pinouts i am lost here .

this has all been confirmed with a modis and a otc genesis

i have a reman pcm i have not had it flashed is this a base line tune they put on it ?

but it ran just as bad if not worse with the old tuned pcm

i got the car like this i am almost out of options here

i have exercised all options here

please help me

Chad Million

not saying im lost on the wiring but lost on this car

pillarpod

why did you change the opti twice and the computer?

AdsoYo

iTrader: (1)

so even though it throws a dtc 16 the engine still runs? The PCM should shut off fuel to the engine with a dtc 16. Hows the opti harness look? Maybe the pigtails aren't making good contact?

What do you mean by runs terrible? Can you elaborate?

Chad Million

runs extremely rich no throttle response no power horrible stumble etc...... not good.

new opti harness directly wired to the computer . the opti was changed twice just because i can do it quickly and it was just another thing to rule out plus it was a cheapy and still suspect . it is a richporter . the computer was replaced when i had to pour it out to start the car and it lost comm with a few parameters . yes pour it out .......water from who knows what has not done it again .

i have cut and exposed the whole harness no burnt pinched or bare wires . all have continuity . i have even risked the damaged and back probed the computer .

seriously i have worked on many more advanced cars than this one why is it so damn confusing

Chad Million

fuel pressure is 41 psi at idle , no cats , etc i have checked more than i would like to admit . injectors are clean . and like i said it throws the 16 code as soon as you hit the key . yes it always starts . i have also replaced the icm , coil , and repaired any wiring that even looked suspect , i have watched all wave forms with my labscope , i am a mechanic . just cant seem to figure this turd out i am just hoping to get some insight from someone that has gone through the same thing or close to it .

additional when watching the low res pulse what should i see at idle cant find much info as most repair guides have not been updated on these cars for a while .

englundjd

you should get a good opti, AC-Delco or msd

Chad Million

ha pulled off a msd opti in the first round im guessing its still good after all of this it will be going back on tomorrow . i am getting my money back for the richporter . but it did run the same before so ......

englundjd

was it throwing the dtc 16 with the msd on there?

Chad Million

yes it was . and it has all been changed . i am going to the junkyard and getting some harness ends for the computer tomorrow thats the last thing i can think of i have ruled everything else out . unless i am missing something obvious

Chad Million

but it is the craziest thing only throws dtc 16 when the key is on engine off . if i clear it out without staring it its a hard fault . but if i start it and clear it , it goes away ????? also replaced the battery i know low voltage can cause this.

englundjd

i think you should try a good opti, spend the cash and get a AC-Delco or new MSD

Chad Million

ok so like i said i got the car in this condition when i got it , it was drivable . somewhat ....
i did an oil change with mobile 1 and a day after is when it was none drivable . so it clicked today maybe just maybe the good fresh oil loosened some sticky lifters ......sure enough loosened all of the valves up and bam it runs much better with better throttle response and less backfires . but not all the way fixed . but much better , not chasing my tail actually moved forward a little woo hoo

Big Al

iTrader: (1)

Start at the distributor connector and check for proper voltages and correct pulses. You'll need an oscilloscope to check but it's worth it. I use a cheap used scope I picked up for $35. Lots less than what you're spending throwing parts at it. If you need help finding a scope PM me. Don't buy something complicated, any working POS scope will work.

Al 73 Z28, 86 IROC and 95 Z28

Chad Million

i do have a old scope but none of that turned out to be the issue it was my 12v b12 wire [orange] as i said i checked continuity between every wire and replaced most connectors with solder and heat shrink . the pin in the ecm connector was corroded in half here is were it got tricky every time i checked for voltage i had to press the probe into it therefor reconnecting the circuit and the same goes for back probing . so lesson is take all connections apart and visually inspect ...........so woo hoo .......but in my crazed state of mind i fear i may have cracked a head from lack of a cooling system hooked up , and lack of f&%$s . random start ups and rich runs ,misfires, high revs , etc..... i know dumb move but we have all been there when your pulling your hair out

so if anyone has a cheap set of heads pm me

Chad Million

ok so new issue the computer is pulling 250+ degrees of timing advance under slight load normal at free rev ????

any one

redc4ia

Try a new non-MSD Opti-Spark distributor. MSD has issues with the optical part of the distributor on 94 and 95 LT1s. I have a 94 corvette and have been working with them since May 2 to get my distributor fixed. Same symptoms, as soon as you try to start it the computer throws a code. It will start and run, but not well. Sounds like they are getting close to a solution, but probably not until next month.