Hesitation

[bigd]

I've searched EvoM and am having a hard time finding a consistent answer through all the muck.. I've noticed recently that my 06 will hesitate somewhere around 3k rpm. It's a quick stutter/hiccup then it will continue to accelerate normally. It happens around 3k rpm in at least 6th gear. I've heard everything... faulty plugs, boost cut, MAF glitches, faulty tune, fuel cut, faulty boost controller, vacuum leaks, etc. I'll mess with it later tonight to find out which gears/throttle load/boost level/etc it specifically happens.


The car has less than 8k miles and the power mods include catless 3" exhaust, Hallman MBC, custom tune by Al, catch can, basically the Warr package.

Al said his equipment registered a controlled and levelled AFR, but the dyno equipment registered a leaner AFR as the boost was peaking. If it's knocking from peak boost and a lean condition, would the computer just pull timing for a split second or could it be palpably knocking? I thought knock couldn't be felt by the driver...

I guess I can avoid WOT pulls from low RPM, but that's a crappy band-aid. I want to find the root of the problem.

[Warrtalon]

I can't imagine the tune being lean enough to cause that sort of reaction at peak boost. Rolling into boost from low rpm in 6th is an awful lot of load, especially if your boost is turned up a bit. It's not fuel cut, because the flash removes that, and sputtering at peak boost is usually caused by blowing out spark. Have you tried a fresh set of NGK BPR7ES gapped to .026 just to check? They're only $7-8 for the set, and if it doesn't change, then put your stock Iridiums back in.

Anyway, the tunes on Evos are meant to be lean on spoolup, because that aids in spoolup. It does not knock like being lean at high boost in higher rpms. The AFRs should go from the 12.0-12.5 range during spoolup down to the mid-to-low 11s after spoolup. If you are knocking, the ECU would pull timing. You can sometimes feel that loss of power, but it's not a sputter or stutter.

[bigd]

Ok that's what I thought. From what I understood the tune is doing what it should and this is unrelated.

A couple people having this problem changed plugs (as you said- blown spark) and it solved it. I'll try that tonight, there's an NAPA and an AZ nearby. Thanks.

[turbolarry]

Originally Posted by bigd

I want to find the root of the problem.

Yea, start with the simple stuff and work your way up. Consider getting some type of logging capabilities so you can check the tune in the future. It's a very good investment and will bring you on step closer to be tuning yourself.

[bigd]

Originally Posted by turbolarry

Yea, start with the simple stuff and work your way up. Consider getting some type of logging capabilities so you can check the tune in the future. It's a very good investment and will bring you on step closer to be tuning yourself.

That's my exact thoughts. As for data logging, it's already in the plans.

The more I know for myself the less I need rely on people who want money to do the same thing. (:

[bigd]

BPR7ES don't fit the IX.
and the problem happens closer to 4k rpm...

Here's my thread on EvoM.
http://forums.evolutionm.net/showthread.php?t=214171

[Warrtalon]

Damn, I forgot that the IXs have the weird plugs that protrude further into the head. I do not yet know what aftermarket plugs work on the IX.

[SicLanEvo]

I had that problem on my Eclipse GST and my evo and the 7ES both times. From my understanding like warr said the plugs are different and i don't know which ones they are using for the IX's. But that would be my starting point.

[bigd]

Well as of last night and this morning I couldn't reproduce the problem.

I guess uninstalling and reinstalling them fixed it, or running leaded and oxygenated gas at PMI is what caused it... I dunno. I'm going to order some new plugs anyways incase the problem shows again.