Cranks, but no spark ( checked two cylinders with a plug). Tested ICM/coil and tried different ones, load tested batt twice, checked every wire related to the coil/cps that I could think of, replaced cps, cleaned/checked grounds, checked for 5v refs, No codes thrown, MSD opti, wires, and plugs are a week old and it ran great on the way to work, but it just wouldn't start after. Coil,ICM, and CPS are getting voltage. I spent 5 hours testing and am stumped. Ideas??

 

first off whats the year and engine type? What have u done/ or repaired on the car?

 

96' LT1, no emissions or VATS, Current performance wiring tune, Mid length headers, true duals & 50 series flows, New CPS, CTS, coil (tested good), ICM ( has been tested as well), MSD opti, MSD wires, TR-55 plugs @ .048, Battery has been load tested twice, all fuses checked twice, power to coil/CPS/ICM in run, no codes, cleaned MAF, new O2s, checked IAT sensor,

 

How do you test the ICM and Coil?

 

I had Napa test both of my ICMs. They can test the coil as well, but you can do it yourself if you have a multimeter ( the coil not the ICM).

 

just an idea, but it could very well be the coil still, sometimes they test good, but are still bad. just my $0.02

 

By any chance, have you replaced the 18" harness going to the opti? It separates on the pass side of the engine and are known to go bad.

 

Must read 5v from the opti to clip, then clip to PCM.. test both

 

MSD opti replaces that section of harness. I checked continuity in all of those circuits on both sides of the plug. Checked all ignition circuits and power to the PCM, sensors, etc. Everything is A ok. It isn't the coil I have tried 2 that both test good. I have checked all the wiring now and it is either the computer or opti and I am leaning on the PCM since it isn't throwing codes for things that are not working, the opti is new, and I can't find so much as a bad ground related to ignition or PCM power ( did find a bad ground for the ECT and IAT which explains my other hot start issue). Has any body ordered a rebuilt from Schuck's with good results? Will I have to have it flashed with my tune or can I just transfer the part that unbolts from the top with two little screws? Can the dealership test one for the high and low resolution circuits with it out of the vehicle?

 

Not familar with the MSD, but is there any chance you forgot to put the little Opti drive shaft in? Maybe the MSD is built in? You would have continuity, but the opti wouldn't be spinning. Check this out:
http://shbox.com/1/4th_gen_tech2.html#opti_test

When I was having problems with my '93, GM said they could only test it on the vehicle. I sent mine to one of the mail order PCM tuners guys happened to have the same car as me, he put my PCM in his car and ran it a couple days....tested fine. You might try to find someone with the same year and tranny and test it that way.

BTW, www.camaroz28.com/forums is an EXCELLENT site for LT1s. When I had my LT1, this site was a godsend. It's a lot like this site, but more tailored for LT1 cars. Check it out!

 

spm4520: Thanks for the link, I knew abot the one , but not the camaroz28.com. I will check it out. Everything was installed in the MSD opti as per the instructions and it ran fine for a couple of days, even ran great to where it woudn't start so I am pretty sure the drive is installed correctly.

Apparently the only way to test the PCM is with it in the car at a dealership. I called Current Performance wiring and Jared is setting me up with a re-manned Delphi PCM with my tune loaded, shipped to my door tomorrow for $235 (pretty good service if you ask me...from Florida to Oregon -coast to coast overnight). If that isn't the problem MSD is going to have some explaining to do!

 

Oh boy, the new PCM didn't do a thing. Now I really need help. The only other thing I can think to shake a stick at is the one week old MSD opti.

Since my last post I have:Replaced the PCM, charged the battery, tested grounds and pins to the ECT, MAF, MAP, CPS, voltage to the injectors ..12+( they are not pulsing properly on the noid light though...opti signal?), battery ground, coil & ICM ground, continuity on the opti plug-but not from the opti up (MSD doesn't use the harness), checked coil wire...33ohms, plug boots are snug, and the opti shows no signs of a possible water invasion, checked fuel pressure. Cranks over just fine but won't fire and the injectors aren't pulsing right. Keep in mind this thing ran great when I drove it 10 miles as well as the 3 days prior to work before it developed a no start condition. I blue locktited the rotor screws and made sure they were good and snug when I installed the opti. I feel like all that leaves is the opti though, just hard to believe. Please throw your suggestions in and I will investigate them.

 

I was affaid you were going to come back and say that. This stuff is like cancer, I fought these EXACT same issues for nearly a year before I finally broke down and spent the money on a coil conversion kit. The sad part is that I spent over $1200 replacing parts as you are doing BEFORE buying the conversion. Then I spent another $600 on the conversion!

One thing that you could try is going to your local auto parts store and ebuying an off the shelf opti and swapping it in. At least then you would know. Take it back within a couple hours and they aren't going to care.

 

-----One thing that you could try is going to your local auto parts store and ebuying an off the shelf opti and swapping it in. At least then you would know. Take it back within a couple hours and they aren't going to care.-----

Unfortunately no "off the shelfer's" around here otherwise I would take you up on that idea.

-----The sad part is that I spent over $1200 replacing parts as you are doing BEFORE buying the conversion. Then I spent another $600 on the conversion!-----

Yep, I'm there. The Delteq still requires a functioning opti sensor though it just doesn't bring the secondary voltage ( coil to rotor to cap to wires to plugs) back into the opti for distribution. I believe the opti sensor is the problem ( and not the cap and rotor) as the opti is getting 12+ volts of Switched IGN power and I can't get a spark, or an injector pulse ( although I have fuel pressure and 12+ volts to the injectors) except spiratically one in a while (injector pulse, not spark).

The way I understand it and please correct me if I am wrong is that if the PCM doesn't receive a signal from the optical sensor it will not send a signal to the ICM to fire the coil back into the opti for distribution to the cylinders and also would not allow the PCM to fire the injectors, because it believes the motor is sitting still with no signal from the opti.

I just don't want to blame the opti, waste a bunch of time pulling and returning the opti, get upset with MSD ( I am trying to rule out the MSD opti, but I can't seem to. I mean damn it is a week old and $530. I EXPECT it to last a hell of a lot longer than that. I still have hope that a top of the line manufacturer can offer better than just a beautiful looking product.), put it all back together and realize it isn't the problem. Please keep the ideas and thoughts coming I have tried everything I can think of short of pulling the opti.

 

Are you getting the voltage switching signal to the ICM? If so, it either a bad connection there, or the coil, the wire, or the cap/rotor.

 

Followed this procedure off of shbox.com:

------Disconnect the ICM connector. Leave coil connected.
Turn key to ON.
Check for dc voltage with a digital meter at harness terminal "A" to ground and and also "D" to ground.Result should be 10v dc or more on both terminals.

If you get no voltage, use the diagram and chase back toward the coil and the ignition fuse. Power for the ICM comes from the ignition fuse and through the coil, so any of that could be bad.-----Good

If you have good voltage, switch the meter to ac scale and connect test leads to terminal "B" and to ground. Observe meter while cranking the engine. You should see between 1 and 4 volts ac (those are the pulses that trigger the coil to fire).----Bad

If you don't see the proper ac voltage the problem could be the optispark, the harness to the optispark, the PCM or any of the wiring in between. Visually inspect all the connections you can get to for poor contact or corrosion.-----

The problem is not the harness to the optispark..all checks out with good continuity and 12 volt power (At least up to and on the other side of the MSD weather pack harness) , The problem is not the PCM as I have a brand new Delphi one in and also has the same problem with the old one. I am getting almost full battery DC voltage at terminals A&D on the ICM plug, but am not getting the 1-4 v AC switching signal. I tested the wire from terminal B back to the PCM pin (black 5) and it is A OK ( I believe the PCM needs the opti signal to calculate when to throw the switching signal to the ICM, as well as injector pulse to the injectors). Ground from ICM terminal C has been checked and rechecked...perfect. I think this rules out the coil as it is not being told to fire with no signal from the ICM. Injectors have 12+volts.

So to recap there is no injector pulse, no spark at the coil, no switching AC voltage, all the wiring checks out good, both ICMs passed multiple bench tests, both coils passed static tests, PCM has been replaced, ALL grounds check out perfect, 12volt power is where it is supposed to be. Can anyone think of anything else or does this pretty much mean that Brand new MSD opti isn't as good as the money that bought it.

 

IF you aren't getting the switching voltage to the ICM, then don't worry about the coil or the ICM... they can't be at fault.

Are you getting the switching voltage coming from the opti? I checked mine beside the intake at that harness.

If I missed it, I'm sorry... don't have time to read the entire thread again.

 

I am not sure which wire to check for that. Do I check the high res (purple/white) , low res (red/black), or dis ref low sig ( pink/black), The other wire, red, is getting full 12+ volts with the key on. I am guessing I need to check the pink/black one on AC v and watch for switching 1-4 AC v or should it be a constant 5v DC signal? Can I just probe the weather pack or do I need to disconnect the plug to keep from frying the PCM?

 

Well, I e-mailed MSD on Saturday explaining my situation and asking for advice....no response yet

I tried to register on their forum to post up. It registered me and I went into my email to finish registration only to find I have to wait for a moderator to approve me...not much help there and ....no response yet.


So, I decided to go ahead and call them up during a non peak time of the day, towards the end to give them a chance to respond to y other contact attempts....on hold for 45 minutes with no sign of life...gave up

Pretty darn disappointed with MSD at the moment. I would have at least liked to get it shipped back before I leave for So Cal tomorrow (without my rig), but I guess I will have to wait until the 5th and then however long shipping to and from MSD takes, I may just take it back to the point of purchase order a Delphi and say F!!! MSD (although I love their wires) if I can't get any support.

 

Responded to your PM.