help with spark blow out.

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Sep 12, 2004 | 08:45 PM

parish8

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single digit dreamer

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From: omaha ne

help with spark blow out.

i really dont know if i am blowing out my spark or i have some other problem. i have a miss up top, especialy when i push it(nitrous or cut out open with lots of boost). i have tried several diferent plugs and they all seem to make a diference.

i have new msd wires, no help

older tr6 plugs gaped at .035 or so missed 6000, then 5800, then 5600, missed worse as i put miles on them.

new tr6 plugs helped but it still missed above 6000rpm

gaped tr6's to .030 and no change

tried some autolite 104's(i think) helped a little but not much

then some ngk br7ef at .025, completely fixed the problem, i was shifting at 6500rpm no problem. 600miles later starting to miss again. i pulled a plug and the gap didn't open at all. here is a pic of the plug.

i am running leaded fuel. i monitor my tune almost constantly, no knock retard, fueling is in the mid 11's at wot and 13-14.5 the rest of the time. truck runs great other than that top end miss. on the dyno i stoped the pull at 6000rpm and wasn't at my peak hp yet so i think i am missing out short shifting it.

any ideas?

Sep 13, 2004 | 05:31 AM

SS00Blue

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Joined: Mar 2002

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I'm sorry to hi-jack, but how are you keeping your O2s alive on leaded. SD tune? I know it won't affect WOT. I was just wondering. I used the denso "lead resistant" and I already burned through one with only 10 gallons of Torco.

Thanks.

SC-

BTW - With the truck coil packs, you should have plenty of spark. If you're missing, perhaps one of them is burnt up. Are you logging? If so, one cylinder should misfire, or all of them. Which are you seeing.

Sep 13, 2004 | 04:31 PM

parish8

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single digit dreamer

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From: omaha ne

i am in open loop with all the o2's pulled. it is still on the maf though. runs great. the only problem i have right now is i max the maf so my fueling up top is guessing but so far it hasn't varried much. at 12 psi i see 11.2-1 and at 17psi i see 11.9 or so. no matter what i do i seem to be in the 11's somewhere for my a/f ratio at WOT.

the key for running in open looped seemed to be geting my VE table filled in corectly. once i did that it runs great with consistant fueling.

Sep 13, 2004 | 04:59 PM

1dirtyZ

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From: the not so stock tribe

i thought torco doesn't effect your o2's?

Sep 13, 2004 | 05:10 PM

Orian

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Generally speaking more boost equates into more spark blow out. I used to have this problem with my Supra. Anything over 27psi of boost would blow out the spark. I recommend you try a smaller gap. I used to run .27 in that car. Hope this helps.

Sep 13, 2004 | 05:38 PM

2001WS6Vert

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From: Cincinnati, Ohio

Does a data log show a particular problem cylinder? I had a 4500+ miss that took quite awhile to figure out. After new plugs it was better for awhile. It ended up being a bad coil (after the cylinder pressure got too high it would breakdown). The EFIlive also showed the wrong cylinder that was mis-firing, it was one further down in the firing order.

Sep 13, 2004 | 06:13 PM

Pro Stock John

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From: Chicago, IL

I"ve been running AC Delcos gapped at like .027 and they have lasted longer for me than TR8's.

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Sep 13, 2004 | 06:42 PM

parish8

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single digit dreamer

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From: omaha ne

i have the miss fire test shut off. my cam is prety big and shows missfires and these br8 plugs are prety cold and seem to have a slight miss fire down low. if i leave the test on it sets a code and wont lock up my converter.

there are clues to the problem here but i dont know what it means. for one thing new plugs help or fixes it. but the problem comes back and gets noticable worse every few hundred miles. another thing is it will miss so bad the motor wont even pull to the next gear if i let it develop. it will completly stop accelerating(more than one cylinder missing). seems to me that would indicate it isn't a coil. could my leaded fuel be effecting the spark some how. i did have some crazy deposites in my exhaust ports last time i had the header off.