REDLT4

Hi everyone. My first post here.
I am thinking I will need one pretty soon, but is the msd unit really worth twice what you pay for an oem replacement? I've searched and seen some threads with people who were not pleased with the msd, and others where people raved about it. Maybe I'm just having sticker shock, but is the oem gen II opti that far off from the msd? It's for a 96 lt4, basiclly stock. I know the rotor is of a better design, but I'm thinking about the 6500 rpm limit on mine is as far as I will ever spin it to, so maybe that isn't of great concern. Should I shell out the extra $ ? Discuss

BTC

Most people would recommend an AC/Delco. I considered an MSD. I'm glad I didn't buy one.

2000GTP

One of the advantages of the MSD is if you buy the one for your application, you get the benefit of being able to convert to a vented opti by runnning the appropriate vacuum lines. Other then that, there is no real advantage. Converting from a non vented to vented application with a Delco opti is a more involved process.

96capricemgr

The MSD cap and rotor for the "unvented opti" also convert it to vented so the complete unit does not get credit for that benefit.

I used an MSD cap and rotor on a 70K mile stock base, now has about 85K total on the base 15-16 on the cap and rotor, all seems well.

Green96Z

I use a stock opti with an MSD cap and rotor. I've also read a lot of the pros and cons of the MSD opti hype, and I think that if it ever came down to it, I would probably install the same as I have now and wait to see if MSD comes out with a better one. The MSD cap and rotor are definitely leaps and bounds above the stocker, and I am very impressed with its construction. I have about 10K miles on my cap and rotor, and have had zero problems so far.

my96z

I just installed a unit I bought off of a member of this board. It looks like a nice piece and well built. No problems thus far.

I also did a search on the MSD opti but never seen much anything about it.

Jeff

REDLT4

Thanks for the feedback guys. I haven't been able to confirm this, but I think I'm losing the low res signal from my opti intermittently, which is causing the engine to die, and then just as suddenly, come back. It's not setting any opti codes, but my tach is going haywire which narrows it down to the opti, pcm, or wiring. This means the optical portion is my problem, so just replacing the cap and rotor probably won't make this intermittent problem go away.

ak95ta

Ive had nothing but problems with mine. The first on failed within 300 miles. Sent it to them. Got it back. Installed it. Lasted 10 miles and failed again. Then them *******s tried to stick me with the repair bill since repairs only have a 30 day garantee (putting it back on the car wasn't a concern at the time). Fought with them and they made it good. It's still not back on the car (same as before, not a concern since I legally can't drive it till April 1st). Such a pain in the *** to change on my car due to the SFI balancer/hub, E.W.P, and blower stuff.

REDLT4

Was this one of the early ones? Also what failed?

ak95ta

I don't know if it was one of the early ones. Im not sure af any of the changes that were made. The optical sensor failed both times. There was an unknown cause of failure.(nothing rubbed or came apart) But none the less, I am dredding putting it back on and having it fail 10 miles down the road, as it has been sitting on the shelf for the past 3 months, and I know they wont warantee it again. Sad thing is that there was nothing wrong with the stock unit, just 100k miles on the clock.

The Engineer

Do a search on "MSD Opti", there is a ton of MSD Opti information already here on the forum (good points as-well-as problems and solutions). With many of my previous posts and personal experiences with the MSD.

WD

Injuneer

If you lose the Opti pulse patterns, you will get codes. If you aren't getting codes, I'd look very carefully at other parts of the ignition and fuel injection.

REDLT4

I've seen and read about optical opti problems that generated no codes. I could see a code generated if you lose the high res only, but per my fsm to set a dtc 1371 requires the loss of the low res signal, the problem is the engine has to run for the pcm to compare it to the high res signal, and the engine has to have the low res signal to run, so it's a catch 22, how can a trouble code for just the low res signal loss ever be set? If you lose both, I would expect to see a dtc 0323 which means the signals are intermittent, but I've heard of the opt failing without setting this code. I've eliminated everything else as the culprit, with the exception of the PCM and it seems to run the engine normally, except when this cutout happens.
I wish it would just outright fail, so I could be sure, but intermittent behavior is a pain to try to track down. I've eliminated fuel as a problem by watching a pressure guage when it acted up, and no drop in pressure happened. I've ohmed out most of the ignition wires without finding any faults. I've checked my grounds with no luck. The reason I suspected the opti in the first place was the erratic behavior of my tach when the malfunction happens. The tach gets it's feed from the PCM, the PCM creates this signal off of the low res portion of the opti, and since the low res signal is needed for tach function and to make the engine run(both of which I am losing) I suspect the optical portion of my opti.

Injuneer

I'm not sure I follow your logic, and I assure you, its entirely possible to set P1371.

The PCM continuously counts high res pulses. If it doesn't see the low res pulse after 720 counts on the high res pulse, it sets P1371 and shuts down the fuel system. The engine does not shut down until the PCM has counted more than 720 high res pulses after the last low res rising edge pulse... so, the engine continues to run for 4 crank revolutions, even after the loss of the low res pulse. The PCM is able to time the ignition and injection for this period by counting the high res pulses.

REDLT4

Thanks you for the expalnation, but I was wondering how you know the high res pulse count the PCM watches after it loses the low res. I maybe just missed it in my manual, and I'll have to confirm that after I get home, but I don't remember it telling me this under DTC 1371. This info does cause me to question the diagnosis I've made, but do you have any suggestions about what circuit I could setup to watch while driving, and when the malfunction happens, confirm where my problem lies. I'm quite sure it's the ignition I'm losing, based on the fuel pressure test. Could I watch the power to the coil or ignition module?