tonydee64

I have a 1996 TA and I love the car...!!! But now it won't start...

It has a 383 and a weird ignition. It uses the opti for the spark signal, which is sent to a MSD, then to a coil, and then to a distributor (the intake has been modified for a dist.) for spark distribution (the ignition guts of the dist are not used). So anyway, the car has no cats, has headers, no egr, ya know... and has ran great for the past year.

I was driving the car the other day and it ran fine, then it started to slightly miss, and by the time I got it home it would barely run. Now it won't start. When I crank it, it only pops and backfires through the intake. My first instinct was to change the opti, which I did, and it didn't make any difference. The timing chain is a double roller and is definately not loose enough to slip a tooth.

To me it sounds likme the motor is horribly out of "time". So far (besides changing the opti), I have performed a compression check with all cylinders being between 190-210 psi. I have good spark going to the plugs, and the injectors all ohmed out between 14.4-14.8 when cold. The plug wires also tested out fine. The rear dist cap and rotor also look fine. I also cleaned the ignition module just in case the ground was bad. I have also unplugged the MAF but it didn't make any difference. I tested the fuel pressure by simply turing the key to the "on" position and the fuel pump showed 35psi for a second, and then quickly went back to zero. I'm stumped...any ideas?

CRAZZ28

iTrader: (13)

So it has an opti and a regular rear mount distributor?

I think the first step is to simplify the ignition system, because i cannot see any benefit of having it set up like that.

thirdgen327

iTrader: (8)

It def sounds like the opti signal. I would simplify things a bit an run one or the other...

tonydee64

Dave of Dave's High Performace in Cinci. did the conversion on the distributor, and I think Dave really knows his stuff. This car actually used to be Shane's car, a friend of Dave. He said the reason they do that is because the opti button/rotor tends to explode at high rpm. I also noticed that a couple of pins have been pulled from the ECU on purpose. I assume this is to keep the ECU from throwing certain codes, but I'm not really sure.

Also, one more fact, that last two times I've taken the car through the automatic car wash, it has stalled, but thankfully I was able to get it restarted. I know this sounds like an opti problem, but I already just replaced it and it didn't do a thing. I would think maybe a shorted wire, but I am getting good spark to the coil and to the plugs. I have no idea if the spark is timed properly, but there is defintely spark. I still wonder if I didn't hurt the motor.... although the compression checks out ok....

tonydee64

bump... anyone?

Enforcerws6

iTrader: (1)

Don't these motor like more like 42 to 45 psi on the fuel??

Does your car still have a icm module deal on it maybe it is firing the plugs out of time.

SLawson86

iTrader: (8)

yeah man, not calling anyone out nor saying somebody doesnt know anything... but i would eliminate one or the other. i hate to say it but it sounds like you have a mess of ignition... good luck, i sure hope someone who has dealt with this can give some advice because i am stumped bro...

tonydee64

Over on the Corvette forum someone told me that the opti I bought on E-bay from all_ignition is not actually a AC Delco opti, but a rebuilt cheapie. If you brought the car to me with me not knowing the history, I would say that it is the opti.. but I am getting spark to the ignition. I actually think Dave is a genius for setting all of this up...I just don't know hot to trouble shoot the Lt1 ignition, it seems to be very difficult to actually test parts like the ignition model, PCM/ECU ( I'm pretty sure it has the stock 1996 computer). I dunno, I'm thinking about going to Napa and buying another opti.....might be time to just start throwing parts at it...

tonydee64

Hey guys, I actually fixed the problem. I had removed the rotor from the new opti since I have a conventional rear dist. that actually handles the spark distribution. I didn't realize that by taking the two small screws out that hold the rotor in place that I was also in effect releasing the perforated disc that signals the opti, thereby letting it slide around within the opti case. I figured this out by taking the old opti apart. They had simply filed down the rotor into a simple button to do the hold down duty.

I've always noticed that my car ALWAYS smelled like gas, PIG rich. I noticed that the fuel regulator did not have a vacuum hose on it... not sure why, but it didn't. So, I put one on...

In the fray of all of this I also bought a Actron scanner from Autozone which allowed me to see my sensors. Sure enough, the IAT displayed -40f. I fixed the short in the wire and the car runs great now!!! No more black clouds behind me when I stand on it, no more gas smell in the passenger compartment.

One more thing, I noticed that the male plug that inserts into the opti had two of its female pins pushed back up into the plastic male portion. If they made connection to the opti connections, it wasn't a very good or consistent connection. So, before you go replacing your opti, take a look at those pins!! My opti seal between my timing chain cover and the opti was leaking oil pretty bad, so I had to remove the opti to fix the two seals, so I just figured I'd put a new opti on, besides, I think mine was toast anyway...

dhdenney

iTrader: (53)

Would like to see pics. This all sounds very interesting.

tonydee64

Well, there's really not much to see. The intake has been modified to simply accept a conventional distributor. As best I can tell, all four wires coming out of the opti are used and go into the pcm like they're supposed to. The wires that used to go to the LT1 coil go to a MSD 6a box, and then back to a coil located on the intake (instead of below the Ignition module). A coil wire simply goes from the coil back to a standard flat top (to fit underneath the cowl) hei dist. The guts of the dist. are not used, only the top portion of the cap to distribute spark. I did notice that two wires have been pulled from the ECU/PCM, I did not make notes which ones, but the car does not have EGR, rear O2 sensors, cats, air pump, etc, so perhaps those deletions have something to do with it. If you want I will go out and pull the PCM and tell you which wires were pulled from the harness, I suspect it was done to keep certain codes from being thrown.

I think the hardest part to setting this up is to phase the rear distributor at 6 degrees btdc without a timing mark on the damper. Like I said, I think Dave of Dave's Total Performance in Cinci. is a genius!!