The Engineer

Background: I’ve had a MSD Opti installed in my LT bracket car for about two months. In that time, I’ve had the rotor screws get loose two times. The last time I reinstalled it, I used slightly longer #6-32 Allen socket-head screws w/ a lot of thread-locker. The symptoms of the loose screws and rotor were always the same; a random high-RPM miss that would continually get worse.

Now I’ve got a "new problem" which I think is due to the MSD Opti. Last night at the track during a run it was somewhat like the ignition “shut-off” at the 1/8 mile and I aborted the run, but I was able to drive it off the track and back to the pits Also, the car had been "running perfect" up to that point after the last time I installed the MSD (new screws & thread-locker).

Now the car won’t hardly start and it’s constantly displaying DTC P0372 (high-resolution pulse count low) which is generated in the Opti. This problem happened “instantaneously” during the run, so I don’t think it is related to loose screws and rotor this time.

From all indications it is the Opti again, but I’m not sure exactly what failed within the MSD this time??? Again it was an instantaneous problem this time with the P0372 code (completely different symptoms from the loose rotor).

So, what does everyone think about this problem with the symptoms (doesn't want to start) and DTC P0372? I guess I’ll start removing the MSD tomorrow after work.

WD

speed_demon24

Damn I'm glad I just got the cap/rotor kit instead of wasting $500 on the opti. Is it still under warranty? If its displaying opti codes chances are its the opti.

OneFlyn95z28

We had the same thing happen last night with a STOCK opti.

We are working with MSD on there small problems. One of them is the loctite breaks down the plastic. Does not mater if you have a stock opti or an MSD.

The more you put on the worse you make the problem

I will be calling the Engineering Dept tomorrow I will point out this thread for them

The Engineer

Are you talking about the Loctite breaking-down the plastic rotor, or other plastic distributor components?

I had thought about some of the Loctite resin possibly getting into optical sender/receptor module (being centrifuged by the rotation). However, this last MSD failure was instantaneous! You would think the Loctite would be a slow process causing a problem. As I understand it, Loctite is an anaerobic resin, basically cures in the absence of oxygen.

Do you have an engineering point-of-contact at MSD (name and extension)?

WD

jimbob65

Had the problem with the MSD cap and rotor screws backing out. Changed from Permatex "Blue" (medium strength) to Loctite "Green" (high strength) and the screws still backed out. Put the "Stock" cap and rotor back on, ran great. Then me and Ellis talked with the engineer for MSD (gave him my MSD rotor for analysis) and he mentioned about not using stuff that contains methacrylate ester or acrylic acid (can't remember which one) as it breaks down the plastic of the rotor. Then the screws will just back out. Sure enough, the last run of the night (stock cap and rotor)...bammm lost all power just past the 1/8 mile. Ellis trailered me home (thanks)....Tomorrow, I will take apart and see if plastic is soft around the "Stock" rotor screw holes. If the plastic is not melted then the problem is more than likely heat related (e.g. breaking down the thread locker). Ellis mentioned about a dry (like factory) thread locker might be the answer to holding the screws in. I know when I had a stock (not touched opti) I never had this problem...

The Engineer

I talked with the MSD tech department today, and they are sending me a new optical sender/receptor module and strobe disc. That is about all it could be in the Opti, one or both of those items causing the high-resolution pulse problem.

Again, completely different symptoms this time, then when the rotor got loose.

Additionally, for what it's worth, the tech support person at MSD insisted the thread-locker resin will not damage the plastic rotor. We'll see tonight when I get the MSD Opti apart again and give it a good visual inspection.

WD

Injuneer

One question would be why did the ignition "shut off", if the only code was for the high resolution pulse pattern? The PCM is fully capable of running the engine with only the low resolution pulse. It just loses a tiny bit of timing accuracy, and results in a small increase in spark scatter. The GM sheets I have show the code description to be "high res pulse loss".

OneFlyn95z28

Just got off the phone and they will be calling you again today warren

The Engineer

I was at WOT near the 2-3 shift point in the run, then it was "like" the ignition was turned off. The car completely fell flat (like the engine shut off) and I let off the gas, then I was surprised to learn the engine was still running as I coasted down the track. I thought it had died completely during the run.

Now it takes a lot of cranking for it to finally start and the P0372 code (high resolution pulse count missing/low) is always on. Therefore, something has to be wrong with the optical sender/receptor module, or strobe wheel in the distributor.

So, can optical sender/receptor modules fail instantaneously as this one appears to have? From the P0372 code displayed, I’m confident the problem is in the distributor. And if not the module, or strobe wheel within the Opti, what would cause this problem? I’m removing the distributor after work today and hopefully I’ll be able to determine exactly what went wrong.

Also, I appreciate everyone’s thoughts and input on this problem.

WD

mdacton

permatex makes all lock tight.

Try the paste stuff, comes in a tube like chap stick.....blue should work fine.

When you take it apart see what sensor msd is using. Is it still the mitsu one? Those are pretty good.......so I would say its trash in the wheel or something, but you won't know til you take it apart.

dangalla

+1 i figured id wait around to see how it worked for others while i was waiting for mine to quit working

bump for more responses

The Engineer

The last time a reassembled the MSD everything was perfectly cleaned in great detail. And, the failure this time was completely instantaneous, so I don’t know where any debris would have come from to cause the sudden failure. Other that some thread-locker resin, but the distributor has been in for about three weeks now following the last reinstall.

Again, has anyone experienced the optical sender/receptor modules to fail instantaneously?

WD

OutKast

Be sure to check the opti harness, on the 93's the connector/plug is on the passenger side of the intake. I was lucky to find mine in bad shape before I starting taking everything apart for a new opti. Just another place to look....

mdacton

I'm pretty sure that same sensor is used in a ton of other cars like chrystlers and they seem to work and hold up fine......but then again your opti gets alot hotter and is in a worse enviroment.

Rolnaz

I am awaiting your find, as I only bought the MSD Cap and Rotor setup, but Know I am experinces my ingition failure only once the car warms up and I press more than 1/2 the pedal.

I don't want to rip the waterpump and opti out if it could possibly be something else. I have my OTC wires on order and am awaiting there arrival, so if I have to pull it I will do those at the same time.