I just got my car back on the road, and got boost working correctly. Idle has been a little lumpy, but I attributed it to the custom turbo cam.
Took it for a spin yesterday and wound it out (pretty peppy) in second gear (~5800 rpm). On the way home, it started running rough. Then it died while I was decelerating. The longer I drove it, the worse it seemed to run.
I managed to get it into the garage last night, but it was clearly not well. I tried to start it this morning, and it was backfiring so bad that it took me about 5 minutes to get it started. I managed to get it sort of started, backed it into the driveway so I could check things out. The plug wires seemed to be O.K., plugged into the opti, and those I could reach were still on the plugs. None appeared burned, and I am running factory exhaust manifolds, so that should not be a problem.
When I built the engine, I put in new MSD 8.5 wires, NGK TR6 plugs (it is boosted) and a new fleabay opti with the rotor screws loctited.
I suspect what the concensus will be, but I would like to understand why, when I have already driven several hundred easier miles on the engine. What would be the reason for one high speed run to cause this, other than "because". And why would it get increasingly worse during the easy drive home?
Thanks in advance.

 

Do you have the ability to get a scanner hooked up to the diagnostic port? There's two main codes that are typically thrown when an optispark is going bad - and unfortunately one of the codes (the one that seems to be the most popular) does not trip the SES light, it's just stored in the PCM that it was tripped.

Unfortunately I don't know the main reason, but it always seem when people do a high RPM run that it suddenly dies... be it the screws back out, the rotor disintegrates, don't know.

 

Is it backfiring out of the manifold or the exhaust?

 

Yes, I have Autotap. Just checked it, no codes. Screws should not have backed out, since I loctited them. Rotor disintegrating I could accept.

StealthFormula, it seems to be the exhaust. I would really need another person to check the intake correctly, but it certainly could be since there was a considerable amount of smoke under the hood when I was starting it this morning. Note: The intake is strongly clamped b/c of the boost (running 10 pounds, so I had to make sure all clamps are secure).

 

Have somebody check for you....if the backfire is coming from the manifold then you have an ignition problem. Fuel is left there being unburndt because of the incorrect spark and ignited at the wrong time therefore backfiring up there.

I have the same problem as you currently but haven't yet diagnosed it. Pretty damn frustrating!

BTW: If you have a fuel pressure tester slap that on and see what the fuel pressure looks like. If it's too low which it may be then could be a bad pump, wiring etc. etc.

 

I have a fuel pressure gauge in the cabin, which I have verified with my Hypertech mechanical unit. Fuel pressure is good.

 

Sounds like fouled plugs. Not sure if you lowered your plug gap or not? Higher cylinder pressure fouls factory gapped plugs. Needs to be 30 to 35 with high cylinder pressure. Learned this the hard way on my 12.9 to 1 383. Just a thought.

 

Yes, gapped them at 0.035 myself prior to putting them in. I may pull a couple b/f tackling the opti just to see. Sure would be less mess. And a little easier.

 

Honestly if you have no codes being thrown, I'd try to diagnose the issue by checking elsewhere first - I'd hate to see you tear it down when there's no codes being thrown for it and then find the opti to be OK.

Have you tried the Opti diagnoses steps?
http://shbox.com/1/4th_gen_tech2.html#opti_test

 

Well, the Opti tests were of limited use, since I am alone out here in the country. I guess I should get a remote starter...
I went ahead and pulled the Opti (I was already partway there) and the Opti is fine. Plug #1, however, is black as midnight.
I'll put the Opti back together and reinstall it, replace the plugs, and report my findings. It's not a huge loss; I wanted to redo the plug wires on the passenger's side anyway, and I wanted to see what the Fleabay Opti looked like after 500 miles or so.
It's also partly my fault; everyone damns the Opti whenever there is an ignition problem, and I regrettably listened to them. Lesson learned.

 

Well, I cleaned up the Fleabay Opti, loctited the screws, sealed it, and reinstalled it. Installed new plugs. Still backfiring and won't start.
Took my original GM Opti (40k miles), cleaned it, loctited it, sealed it, installed it. Still backfiring and won't start. Had intake elbow off for easy Opti access, and it is definitely backfiring out both the exhaust and the intake. This indicates a timing issue, correct?
Since the timing chain and gears are new, I doubt the cam has jumped time. This leaves electrical. I made sure that the Opti fit into the correct slot for the cam, so that should not be an issue. The wires checked out O.K., the plugs are new, tried with 2 completely different Optis. So that seems to leave something upstream.
Coil or ICM?
I tried the Coil test from Shoebox, but the one illustrated is quite different from mine. His has a male high voltage lead, mine has a female (no big deal). His has 4 connectors to test for 8k Ohms resistance, mine has 2, which both tested 0 Ohms (short).
I'm going to try his Opti and spark test; hopefully it will be a bit closer to my 97 configuration.
Any ideas would certainly be welcome at this point.

 

Tried the Opti and spark test. Again, mine is a bit different. I have 4 wires, Pink, White, Black and Green. Using Pink as a reference for his C, I show the following voltages with key ON engine OFF:
C - 12v
A - 0.03v
D - 0.03v
B - 12v

 

when i first put my engine together it done the exact same thing.. i could spray starting fluid in the intake and it would crank up and run for a few then cut off... try cranking again and it would backfire again.. i had to spray gas in my intake get it crunk and rev the engine at 2500 rpms for 20 minutes for the computer to calibrate to the engine.. and when it finally started clearing up id let off the gas and it idled fine and didn't have another problem

 

Removed fuel rail to check for leaks - none.
Put timing light on each wire - strong spark on every one.
Put different PCM in (have no idea what tune is in it, was told fbody with minor adjustments) - would turn over, no backfiring, would not fire or start, although spark was present as well as fuel and air.
It acts like it is out of time, or the timing has jumped. Perhaps the PCM, Ignition Control Module, Coil, Crank Position Sensor?
Will probably put the OBDI PCM in next, which should bypass the Crank Position Sensor. Put a tune in it using Tunercat, see what happens. If I had a coil or ICM, I would swap those out just to test. GMPartsDirect want $79 for an ICM, $40 for a coil,$52 for a CPS and $8 for a reluctor ring. Does anyone have an ICM or coil they are willing to loan for a few days? That wold be optimal. I install yours, it works or it does not, and I send yours back to you. If it works, I get a replacement for mine. If it does not fix the problem, then I try the next possible source of the problem. That would eliminate the coil and the ICM. The CPS or CKS and reluctor ring are not used by the OBDI PCM. So moving to an OBDI PCM would be a natural progression and remove he CKS from the equation.

VENTING STARTS NOW
this is just so frustrating right now. I have all my ducks in a row to make the conversion to OBDI, I have modded the PCM to work with an OBDII knock sensor, I have purchased Tunercat to write the new download files, I have obtained files that I should be able to put in my mods, save them, and write them to the PCM. I have Datamaster to monitor and log to check the paramenters of interest. Once it runs right again on relatively stock OBDI files, I can start on the 2-BAR tune using the 2 bar map sitting in front of me. I have Dm_156_OpenLoop.bin which he is running. I could change if for my differences, smaler injectors, a bit less boost, and see what happens.
VENTING STOPS NOW
When I get it running right, I have an excellent solution for going dual pumps without breaking the bank, taking the best, most cost effective parts and methods from several ideas and implementations and putting it all together in one. I'll probably make it a full blown project, part numbers, prices, sources, pictures, assembly from start to finish. Specific th the LT1, of course.