# P0404 engine misfire Hardbody



## vince_ka24e (Aug 23, 2015)

hey guys im having a bit of a dilemma. my truck is having a misfire and im trying to figure out what is causing it. its had a recent tune up like plugs, wires, cap, rotor. The code came back immediately and i pulled 2 plugs the number four plug had gunk build up not wet but gunky and burned and im trying to figure out if it may be a leaking fuel injector, or valve seal or what now im hoping maybe someone has had a similar problem. i used a bore scope to look into the cylinder and it was pretty hard to make everything out but im trying to look for input. thank you in advance.


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## vince_ka24e (Aug 23, 2015)

as a side note i do tend to make alot of short trips these past few months and since it's winter i do let it idle a bit too if that helps.


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## vince_ka24e (Aug 23, 2015)

i also believe it only happens at idle. on cold start up the tach doesn't move a bit but at idle it slightly bounces around if that makes any sense.


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## vince_ka24e (Aug 23, 2015)

so i have a scan tool on my laptop and found that with the code present my ignition timing advance says it's at 10 btdc but after clearing it, it says 15 btdc so maybe some sort of safety/limp mode to avoid pre detonation. it also says at idle the timing advance is 6 btdc.


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## jp2code (Jun 2, 2011)

Did you see this?

http://www.obd-codes.com/p0404

Here's a video on how to clean it:

https://www.youtube.com/watch?v=bt5lRTt6BsU


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## vince_ka24e (Aug 23, 2015)

whoops i ment P0304....my mistake but that is too helpful i might just do that to do that. this week im gunna do a compression test and drain down test. also run some fuel trim tests.


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## jp2code (Jun 2, 2011)

vince_ka24e said:


> whoops i ment P0304....


I suppose you figured this one out, then: http://www.obd-codes.com/p0304


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## vince_ka24e (Aug 23, 2015)

well i ran a cylinder pressure test to see if any valves were sticking open everything tested good there. I ohm tested my injectors and all were consistent at 8.6 ohms which is a little lower then what it should be at 10-14 ohms so idk what issues that would cause but it was consistent so i wasn't too worried and none of the injectors are leaking. So in all i determined it must just be carbon build up so i put some chevron techron in my gas tank and took a long hard drive down the free way and now it seems to idle better but we'll see if the code comes back.


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