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| 3800SC stumble and miss after 4000rpm (Page 2/2) |
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Darth Fiero
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NOV 09, 12:36 AM
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| quote | Originally posted by Additivewalnut:
Whatre the chances I could just send you my PCM and you check and see what he screwed up? |
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Email me at sinister1880@gmail.com and we'll discuss your options.
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Additivewalnut
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NOV 14, 09:31 PM
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Updates on this. New (junkyard) MAF, ICM, put the screen back in the throttle body because it was missing for some reason, and added a ground from the ICM bracket to the engine, plugs now gapped at .035. The stumbling is way less violent and if I get my foot out of it and back in immediately and there's a 65% chance that I can get it full boost all the way to redline in 2nd gear. 3rd is still pretty stumbly. At this point I don't think it's the tune, but I'll probably still send my PCM to Darth just to be sure. Could gapping the plugs down to .030 help? I have aftermarket coils on it, maybe I go get some junkyard OEM coils?
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Spoon
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NOV 19, 11:46 AM
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| quote | Originally posted by Additivewalnut:
I have aftermarket coils on it, maybe I go get some junkyard OEM coils? |
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OMG!! I've learned a few things about 3800SC ignition coils. Choose wisely. The GM part # for those coils are specific to the SC version and has a different part # than the Non-SC. External appearance appears the same. Flip both over and check the stamping. GM also has data on the expected mileage of each type even though you may not experience or notice any ignition issues. They also did a performance evaluation of SC vs Non-SC coils. And of course it's recommended that they all be replaced as a set. So when you rush back to the boneyard popping one 3800 hood after the other and you approach that 6th and last one, you may want to ask yourself before lifting the hood, " Do I feel lucky"?
Even if they are the proper C-Packs for the SC engine, you may want to verify the mileage or get "lucky" and find a recent receipt is in the console box showing date & mileage, plus there's a good chance that only the bad one was replaced anyway.
I'll lookup that factory data and post it. I'm sure I saved it.
Spoon
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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut [This message has been edited by Spoon (edited 11-19-2023).]
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Additivewalnut
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NOV 27, 11:12 AM
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| quote | Originally posted by Spoon:
OMG!! I've learned a few things about 3800SC ignition coils. Choose wisely. The GM part # for those coils are specific to the SC version and has a different part # than the Non-SC. External appearance appears the same. Flip both over and check the stamping. GM also has data on the expected mileage of each type even though you may not experience or notice any ignition issues. They also did a performance evaluation of SC vs Non-SC coils. And of course it's recommended that they all be replaced as a set. So when you rush back to the boneyard popping one 3800 hood after the other and you approach that 6th and last one, you may want to ask yourself before lifting the hood, " Do I feel lucky"?
Even if they are the proper C-Packs for the SC engine, you may want to verify the mileage or get "lucky" and find a recent receipt is in the console box showing date & mileage, plus there's a good chance that only the bad one was replaced anyway.
I'll lookup that factory data and post it. I'm sure I saved it.
Spoon
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I went and got factory coil packs from a supercharged car, seemed to fix my cold start issue but I still have the stumble. I've gone to stock plugs at .50, stock wires, stock coils, new ICM. I wonder if it's not even spark anymore. Clogged injector? I emailed Darth asking if my tune could be the problem since I have it tuned for a 3.4 pulley while still running the stock one.
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Dukesterpro
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NOV 27, 03:39 PM
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Don't apply a tune until you get it running on base settings. Its just asking for more variables to screw with. Get a stock tune and see if it does it
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Additivewalnut
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NOV 27, 03:55 PM
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| quote | Originally posted by Dukesterpro:
Don't apply a tune until you get it running on base settings. Its just asking for more variables to screw with. Get a stock tune and see if it does it |
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In talks with Darth to do that now, hopefully that'll fix it.
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