YucA

My car is having a strange issue. When the engine is cold, it has a mis-fire under 3krpm under load and when idling in neutral. Anything above 3krpms is silky smooth. This issue goes away when the engine warms up to the point that its almost non-existant. Fresh 93 octane filled weekly.

No CEL, no codes, no nothing.

Car is bone stock. I adjusted the valves and did a general tune-up after picking up the car. It came with an ebay intake, and replaced it with a stocker. When i installed the stock intake box, i never had the hard metal vaccuum lines so i just have regular lines which shouldnt really cause an issue. Just something to note...

It's a pretty aggressive hesitation, and after reading about the misfiring CEL codes that can pop up, i really dont know what i should start with, because i dont get any codes thrown.

Its got fresh plugs (few weeks) and i pulled them out last weekend and they all looked kosher. I'll pull em out again this weekend and see if they can tell me anything...

What can this be? I already whacked the hell out of my MAP and reset my ecu, to no avail...

I want to know, is it a viable possibility that i have leaky/dirty injectors, or leaky o-rings?? I might toss some injector cleaner in the tank to see what else arises. Or can my ecu can be non-oem? Do Flashes or rom tunes change the threshold for sensors or...??..?

While this is not a serious issue that pratically goes away after the engine is warm, it is not normal and quite a nuisance. Any help or tips would be appreciate. I'll post any updates as they come...

YucA

Winner winner chicken dinner!

One coilpack is on its way out. Resistance is low enough to cause minor bottom end issues, but not enough to throw a code.

Now to hunt for a coilpack...

lowandsmooth

Have you found this to be the case before because I have the same symptoms just a bit of a miss fire at higher cold idle. If so how would oyu diagnose the problem I mean you could just start pulling coil packs and see what happens but this is inconvenient and expensive. anything would help thank you!!

bradskee

i had the same problem so i changed coil packs. bought all four on the formus for 50 bucks and had all four changed out in under 5 minuets. prob solved

Bernman

Interesting. I have *exactly* the same symptoms. Mine is a 2006 with only 26k (ish) miles.

To the forum junkies: Is this fairly common? What type of mileage does this problem usually show up? 26k miles is pretty low for a coil problem to show up. Are there other causes generally associated with this symptom?

RWD_RCKT

I've had it on all of my S2000's. Since I dyno'd fairly frequently, and the power never dropped off, I just figured some Honda engineer had too much sake when tuning for cold idle.

I figured it was common... I have heard it on several other forum member's cars as well.

PS. Pleasanton in the hizzy