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Discussion Starter · #21 ·
FINALLY FIXED!!!

Ok for anyone else having a similar problem, here is the answer:

It was a faulty Engine Coolant Temperature Sensor. It wasn't reading correctly, throwing off the ECU for cold starts, thus misfiring and fowling plugs and going away once warmed up!!!

Something as simple as this has cost me 3 sets of spark plugs and countless time spent trying to figure this out!

It was still reading according to my HONDATA, but it was reading wrong... as the voltages were off...

Hope this can help others who are experiencing the same problems!!
 

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FINALLY FIXED!!!

Ok for anyone else having a similar problem, here is the answer:

It was a faulty Engine Coolant Temperature Sensor. It wasn't reading correctly, throwing off the ECU for cold starts, thus misfiring and fowling plugs and going away once warmed up!!!

Something as simple as this has cost me 3 sets of spark plugs and countless time spent trying to figure this out!

It was still reading according to my HONDATA, but it was reading wrong... as the voltages were off...

Hope this can help others who are experiencing the same problems!!

wow man im glad its fixed. thanks for the information.
 

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Long shot, but hows your engine block electrical ground? Ground issues will makes sensors, injectors, and all kinds of stuff go haywire, and can be temperature sensitive.
 

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Discussion Starter · #29 ·
sounds like you do have a fouling issue. I'm assuming your tailpipe is black as well?
Yes it is. Running very rich. I am assuming the tune needs to be leaned out before this problem stops. Currently being tuned by Vit with a e-tune.

I am now constantly, after every pull/log, taking out my plugs, reporting the condition and cleaning them for the next pull/log.

Hard to lean a vehicle out if there is no wideband o2 sensor to look at, wouldn't you think? hmmm....:corona:
 

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lol just use your spark plugs as your O2 :dance:

just curious how many times have you removed and cleaned the plugs?
 

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i know some plugs have "gone bad" after repeated cleanings. happens a lot in the small engines we service at work. Especially the honda GX120's....
 

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Discussion Starter · #34 ·
purchased a new o2 sensor today... waiting for shipping to come in now.. (1 week est.)

Hope that may be my issue.

Hondata on their forums suggested I may need to take this into a Dyno-Shop to correct the issue...
 

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Discussion Starter · #35 ·
Long shot, but hows your engine block electrical ground? Ground issues will makes sensors, injectors, and all kinds of stuff go haywire, and can be temperature sensitive.
Sorry, I didn't see this earlier. Good points.

I have checked all my electrical ground and added some extras just in case. I replaced my coolant temperature sensor thinking that could be the cause. I also just ordered in a new primary o2 sensor to see if that may fix it as well.
 

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I have the same issue, misfire at cold start, mine is a 8th gen k20z3, ones the car warm up the misfire disapear.... no solutions yet?
 
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