Lt1 misfire, erratic low resolution signal
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
antfarmer2.....I just used washers. And I'm aware of why it threw codes, was still misfiring though...Not sure of any other differences between the 94 and 96 pcm except for crank sensor and trans codes coming up....
Don't want to waste money on a pcm until i have a 94 or 95 i can substitute
Don't want to waste money on a pcm until i have a 94 or 95 i can substitute
Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 17
Likes: 0
I've stuck with the msd opti mainly because it was under warranty from summit. The only problem is, ive been through three of them, and have no answer from summit on what was wrong with them, and msd wants the unit sent directly to them, which summit doesnt want me doing. I do have a used gm opti laying around, but don't have the harness for it, so not really worth the hassle of trying.
without a scope, is there any other way to watch the high res ckt for glitches?
without a scope, is there any other way to watch the high res ckt for glitches?
Drifting
Joined: Mar 2012
Posts: 1,492
Likes: 61
From: New Jersey
I would send the unit to MSD. I had a problem with the unit on mine. The prior owner put it on and when it bad I sent it to MSD. They rebuilt it and then it went bad again. I sent it back and their tech saw that it was an early unit and also diagnosed the problem with it. They gave me a new one with the changes made (better housing and bearing along with revised optical system) for no charge. It has been working fine for over a year now. Who knows what Summit has in stock and for how long.
Also make sure the MSD vacuum venting system is working properly - sending air through the opti.
Good luck.
Also make sure the MSD vacuum venting system is working properly - sending air through the opti.
Good luck.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
I would send the unit to MSD. I had a problem with the unit on mine. The prior owner put it on and when it bad I sent it to MSD. They rebuilt it and then it went bad again. I sent it back and their tech saw that it was an early unit and also diagnosed the problem with it. They gave me a new one with the changes made (better housing and bearing along with revised optical system) for no charge. It has been working fine for over a year now. Who knows what Summit has in stock and for how long.
Also make sure the MSD vacuum venting system is working properly - sending air through the opti.
Good luck.
Also make sure the MSD vacuum venting system is working properly - sending air through the opti.
Good luck.
sounds like they are useing you to get rid of old stock. No tell how long they have had them banging around.
Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 17
Likes: 0
Well after some more testing and replacing all connectors in ignition system, I'm at square on again....Today I was actually able to see spark dropping from #7 intermittently. And Ive also got dtc 36 a few times last week. So it looks like another bad msd optispark. And this one is showing problems on the high and low voltage sides....
Thanks for all the replies, Now its time to talk with msd
Thanks for all the replies, Now its time to talk with msd
Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 17
Likes: 0
New optispark bad
So this am, i was able to find an old/dirty optispark (ac delco) and the bearings sound awful. I tried it on the car, and what do you know.....no more erratic resolution and no more misfires...
Now I need to figure out best optispark to buy....any suggestions? I know this has been gone over many times....but I'm at a loss of which brand to get after msd has failed me multiple times.
Now I need to figure out best optispark to buy....any suggestions? I know this has been gone over many times....but I'm at a loss of which brand to get after msd has failed me multiple times.
Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 17
Likes: 0
no more misfires
Title says it! Went with an optispark from sac city corvette after looking at their website regarding the optical sensors. Car fired up instantly and tach is steady as well as resolution signal.
Still having an issue with pinging though. I'm suspecting either knock module or ecm...
driving down road,light throttle, light load, no spark knock heard, ecm is steadily pulling anywhere from 3-6 degrees....
If i get into the pedal, i can hear a definite spark knock that i can keep going if i stay in pedal or push harder. The ecm at this point shows its pulling a little more timing, but no big jump in numbers from when I can or cant hear knock.
Egr is operating properly, no carbon buildup on pistons, running at 180-190. I can actually make it ping when its fairly cold, which makes me think timing.....
Any suggestions? Thanks again all for input on optispark, I definitely learned some things there! ( mainly to stay away from msd opti)
Still having an issue with pinging though. I'm suspecting either knock module or ecm...
driving down road,light throttle, light load, no spark knock heard, ecm is steadily pulling anywhere from 3-6 degrees....
If i get into the pedal, i can hear a definite spark knock that i can keep going if i stay in pedal or push harder. The ecm at this point shows its pulling a little more timing, but no big jump in numbers from when I can or cant hear knock.
Egr is operating properly, no carbon buildup on pistons, running at 180-190. I can actually make it ping when its fairly cold, which makes me think timing.....
Any suggestions? Thanks again all for input on optispark, I definitely learned some things there! ( mainly to stay away from msd opti)
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Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 17
Likes: 0
Safety Car
Joined: Jun 2003
Posts: 4,250
Likes: 656
From: San Diego Ca
The information from the Tech 2 can work. We just need to look at a table of sensor values in real time. Here is a screen shot of a single screen capture of Datamaster. Note it will log continuously. This is for an EE def file which the 94 uses.
Thread Starter
Heel & Toe
Joined: Jun 2015
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Safety Car
Joined: Jun 2003
Posts: 4,250
Likes: 656
From: San Diego Ca
This might be more helpful. It is later in the same dyno run. Note the injectors are well past 100% DC and there is slight knock that has been going on since 90% Inj DC. So it could be lack of fuel due to injectors being too small. You also could try pulling a bit of timing in these cells, but this one (94 383) looks like the first fix is more fuel at wot.
Safety Car
Joined: Jun 2003
Posts: 4,250
Likes: 656
From: San Diego Ca
No you would need to actually grab a screen shot of all the data and put it together over a long run. That is why a logging program is needed. You get a continuous stream of data that you can examine. TTS Datamaster is a logging program. The Tech 2 may have a logging function as opposed to a simple reporting function. There are a number of open system free logging programs. Datamaster requires a license. I use it for EE def files 94/95s) and DA def files (92/93s). Over the years I have had enough 93/94 Corvettes and Camaros to justify the cost. I still have two 93s.