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Chipping + Cutout


USMC850T

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First of all let me describe the situation. When boosting just north of 15 PSI, I experience a very very fast stutter, where my loud jerk exhaust goes completely silent for an instant (really a very short period of time). This can happen repeatedly very rapid succession if I continue to push the pedal down.

I don't think it's a missfire, as I have no codes. Sombody who I ran into at autozone said it could be a vacumn hose collapsing (it would have to be a vac hose from the boost controller assembly).

What I thought is that Speedtuning may have monkeyed up my order (17psi chip is what I wanted) and installed at 15 PSI chip. What happens when you boost past the ECU's boost map. Again this is occuring around 16 psi, regarless of RPM.

Thanks in advance

Jeff

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Well, just to post whore a bit more... get some Champion RC7YCs (your local discount auto parts/auto zone should be able to order them) and gap them to .023ish

They may have it as Champion 340 or Champion RC7YC.

man, Autozone doesnt have em and can't order them according to the three I went to. Napa may be able to get em, but I just ordered mine from www.rockauto.com

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man, Autozone doesnt have em and can't order them according to the three I went to. Napa may be able to get em, but I just ordered mine from www.rockauto.com

hmm, I haven't gone to auto zone, but I know for a fact Ben and I ordered ours from Advance Auto Parts (Discount Auto Parts).

rockauto looks solid man. :)

Thanks for the tip on the site.

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So what you're telling me is that since the mixture of charge fuel and air entering the cylinders is under such high pressure that the spark isn't able to travel the gap? Sounds like an easy fix.

I've heard I should go a heat range lower too. If I do that, exactly which plugs should I get?

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RICA recommended NGK Iridium IX with my ECU...but really OEM plugs or any copper plug will work just fine...just make sure check the gap before putting them in.

problem with irdium lugs - very easy to break the tip when trying to change the gap

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I put an Iridium race plug in my 2 stroke yamaha 250 over the summer and they made a huge difference. My bike was a monster after I put them in. I've not experienced them in my car yet though (big difference between an 11:1 CR 250cc thumper and a turboed 2.3L I5. I'm gonna go to the local autoparts store and pick up some RC7YC's tomorrow and regap them.

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Guest 300+_T5R_855

So what you're telling me is that since the mixture of charge fuel and air entering the cylinders is under such high pressure that the spark isn't able to travel the gap? Sounds like an easy fix.

I've heard I should go a heat range lower too. If I do that, exactly which plugs should I get?

Not exactly. It is likely detonation. By closing the gap you in essence cool down the combustion temps by using a smaller spark. What's happening is the plugs are getting so hot it's firing before it sparks trying to push the piston back down before it crests. What you are feeling is the ECU backing out timing flattening out the power band.

Colder plugs, tighter gap, better fuel...hang on.

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