Attached is a picture of what my Denso IK22 plugs looked like after 10k miles of daily driving.

The story behind this is: I took the car in to the dealer due to various little nuances, one of which was the dreaded stumble at start-up and some rough idling. After looking at the condition of the plugs (as attached in the picture below), the dealer techs were convinced that the plugs were the problem and started pointing at my mods as the culprit. They were then replaced with the OEM plugs and I was on my way. Not one full day of driving has passed and the stumble and rough idle are still there, (after a dealer reflash, with and without the Unichip, btw). Regardless of dealer service issues and the stumble at startup, I am worried about the carbon buildup on the plugs, which I don't consider to be normal.

Since I only possess what I consider to be minimal mechanical knowledge, I would like your opinions on what could possibly be causing my plugs to look like this after 10k miles of use. Is this a tuning issue? Should i dump the Unichip? I don't have anyone locally to do a custom tune.

Thanks in advance!

Mark

 

They look fouled, which is a known hazard of running colder than stock plugs for daily driving. The MCS runs really rich even when stock, which normally coats the plugs with carbon except for the very tips, and aftermarket software may exacerbate the situation.

If they're fouled all the way to the iridium tips I'd check the coil pack especially considering the stumble, but note that one bad coil would only result in two fouled plugs, while something like a bad primary 02 sensor would foul all of them. Did the dealer read any codes?

I got rid of my stumble a couple years ago with a GIAC flash, but have heard that things improved with the later factory software...

 

Thanks for the info!

The dealer did not read any codes. In fact, they had originally told me that their most recent fix for the stumble has been the redesign and replacement of a fuel valve of some sort that trapped to many gasses in its orignal design, whose eventual release caused the stumble. (don't know if there is any truth in that statement)

Afterwards I asked them if they had replaced that valve and they told me that they hadn't because they only do if the car throws any codes, which mine didn't.

 

Hello
Sorry the little offtopic, my plugs are NGK JCW kit. Who many miles I have to change them?

Best Regards

 

"In fact, they had originally told me that their most recent fix for the stumble has been the redesign and replacement of a fuel valve of some sort that trapped to many gasses in its orignal design, whose eventual release caused the stumble."

Re-Rah... "trapped too many gasses" is the best part, especialy the "trapped" part. After being trapped where do they put them? Can you take them home for the kids? In a jar? With some decorative rocks?

 

Looks like your running very rich. Have you tried removing the Unichip and drive for a few hunderd miles? I'm running the same plugs with a very early MTH flash and my plugs look great after 15K miles.

 

I got the car back from service on Friday; the Unichip has been removed since then and I am running the stock plugs right now. I'll probably keep it like this for a couple of weeks and check the plugs afterwards.

The curious thing about this is the car has been running strong as usual through all this. The only issues i've had are the stumble at morning start-up, which has been getting progressively worse for the past couple of months, and a bit of a rough idle, which is really minimal.

BTW, both symptoms are still unchanged after almost a week since changing plugs and removing Unichip.

I'm also looking into the GIAC flash right now since, in addition to the post by BFG9000, I've heard of several others getting rid of the stumble with it. But I'll probably wait on that until I get this sorted out.

Maybe I can eventually get a couple of Dyno's done comparing w & w/o Unichip and w/ GIAC...