LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

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Old 01-06-2005, 10:56 AM
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Unhappy Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

Hey guys,

I have a big time miss at low rpm under heavy load (4th gear at <2500 rpm for example). I currently have a MSD 6a, and I tried taking it off and running stock ignition setup, but it misses even worse under those circumstances; this is what leads me to believe that its the opti. I checked all plugs, wires etc. and they're all fine, all tight and no burns or drive belt-severed wires. I was wondering if its just time to go ahead and get a Delteq at this point? I was planning on getting one anyway, I guess now is the time to get it. I was also wondering if anyone has any less expensive routes to getting the Delteq unit (i heard you can get coils off of summit or ebay inexpensively). I have OTVC plug wires so i can re-make those with no problem... suggestions?

also, i've used seafoam through my intake (brake booster/throttle body) and in my fuel tank already so i dont *think* injectors are the issue.

edit: Should i also get a set of NGK TR55 spark plugs while i'm at it? Thinking of Valve cover-mounted wire looms....

Thanks!

Last edited by pillagenburn; 01-06-2005 at 11:01 AM.
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Old 01-06-2005, 11:23 AM
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Re: Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

It sounds like your having a opti problem. Especially if its doing this at higher RPMS at WOT as well. I guess you wont know for sure unless you are able to get it on a dyno, or hook up some kind of scaning tool or somthing.

I my self went with the delteq, and love it. I am not 100% sure if my opti was going bad. But I noticed that sucker pulls much harder up top, so I dont know if the opti was going out on the upper rpms's. I do know that after my delteq, and madz28.com tune, I went from a 13.8 @101 to 13.3 @ 104! I cant say the Delteq was the full reason I dropped that much time out of my et. I think it was the combo of the tune and delteq. But regardless I ordered mine from Elitesparkplugs.com . I went with the full radiator shroud kit.

But if you want to order the bare bones and get things seperate, you can order the jegs or msd coild from jegs, or I also found the coils on this site https://ssl.perfora.net/aphindustrie...dex.shopscript

Hope this helps,
Mike
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Old 01-06-2005, 12:23 PM
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Re: Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

Definately the Opti!! I had the same problem and went with Delteq, trust me it's worth every penny!!
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Old 01-06-2005, 05:51 PM
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Re: Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

Sounds like the same problems I had when my opti started going south.

And Aintno6 I got you beat. Went from 13.03 to 12.05 just changing the opti and going from a 3" cut out to single 3" dump before the rear end.
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Old 01-06-2005, 08:52 PM
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Re: Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

I had the same problem over the last 3-4 weeks. It would miss at WOT up until about 3k rpm or so, then all of a sudden clear up and run as usual to redline. Tinkering around, i found one of my wires was arcing over to the header, even though the wire was almost an inch away from it. You could see the spark jump across. One zip-tie and 5 minutes, and the miss is gone.

I was about to buy another opti because of this... glad i didn't. Check your wires over real thoroughly.
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Old 01-06-2005, 09:50 PM
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Re: Missing at low RPM under load ... opticrap? ign. coil? plugs/wires are OK

Originally Posted by ScreamnChicken
Sounds like the same problems I had when my opti started going south.

And Aintno6 I got you beat. Went from 13.03 to 12.05 just changing the opti and going from a 3" cut out to single 3" dump before the rear end.

Dam dude that is awsome. I bet you were really happy to get that worked out. I plan on running a setup very similar to yours. Hopefully I can achieve the same results.

Mike
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