just changed sparkplugs. theyre gapped right. installed aem tru boost on saturday. today i went out to test it and its misfiring around 5000rpm and will barely go higher. why?!?!

 

???

 

Boost level? Last time you did a boost leak? When you say they are gapped right, what is the current gap?

 

what are they gapped to? What plugs are they?

 

ngk iridiums. theyre gaped at .032. its holding boost just fine at 20-21psi.

 

It can either be the ignition timing too low from programming or knocksums driving it down, it can be from a rich AFR or a combination of them both, or it can be your gaps being too large.

Gap them down to .018 and see if that fixes your issue. Be careful not to break the iridium electrode.

 

.018?! thats really on the cold side....for a evo 8?
i will gap them down a tad.

 

Our 14 years experience with the 4g63 tells us that you will be just fine.


On our quest to 602whp on the stock 4g63 motor, closing the plug gap helped to improve ignition and prevent misfires due to spark blowout.

 

im not questioning your knowledge haha. i just hope its safe...im only pushing around 320hp.

 

Like TTP said, it is most likely the gap.

.032 is way too large.

 

holy .032, i had mine at .026 while i was stockish, then drove across the country and back and added some power, had ur same problem so put new plugs in gapped at.022, been perfect ever since

 

what are the ngk bpr9es plugs set at from the box?
mike

 

You should not be using bpr9es. The plug is too cold for the car and will misfire due to the wrong heat range.

Unless you plan on nitromethane use, then get an 8 or 7 range plug.

 

ok. ...i have a 2.3 stroker and ets 61mm kit. aem ems, etc....still use the 8s? thanks
mike

 

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