Startup Misfire

So recently my truck has developed a small stumble when i start it for the first time in a few days. It lasts 1 maybe 2-3 seconds tops, the problem is that its not all that cold...maybe 65 degrees in the evenings now, and even when i start it for the first time in a few days in 90 degree heat i get the same thing. If i start it for 2 min or even 1 min...then restart it again...no stumble.

Things that have changed......

1. I have recently started driving the truck a lot less...no longer dailying it.
2. BC of number 1 i started using 93 octane (10K miles currently).
3. MBRP exhaust went on a few weeks ago.

Possible causes....

Hard rain the other night after a visit to the comedy club with the GF....maybe 1 foot of water in a parking lot...drove though it pretty fast...maybe a bit of water ingestion???? I checked the filter seemed dry. Checked the MAF also, and it seem clean...sprayed it with electrical cleaner anyway. I also pulled the wires on the reward lower spark plugs on the motor, and put dielectric grease on them

93 octane not as volatile therefore the truck isn't producing strong enough spark or too much fuel on startup causes a small stumble???

I hate bringing my stuff to the dealer...i have a bad rattle in the door with the stereo up and of course they couldn't hear it... so I'm gonna dig into that myself. I would rather just not waste my time unless its something serious, which i doubt. My Terminator always stumbles at idle, but like the raptor...when I floor it she loves it and never misses a beat!!!!


Anyone else having these issues? Maybe I will change the plugs (all 16 of the damn things, and test the resistance in the coils at the same time)? I may go buy an K&N filter tomorrow just to make sure its not the stocker causing issues if it got wet.

I'm still gonna go beat on it this weekend, but I figured that i would put the subject out there, because the info is limited after some searching.

What year, engine, build date?

every so often my truck stumbles on start up as well but its not very frequent i have a stock 2011 6.2L running 87 octane with 6000 miles on it

so you have burned threw a tank or 2 of 93 if not it will calibrate automatically to the new fuel but you have to let it. put a few tanks threw if it still is doing it take to the dealer

Lots of guys here experiencing rough idle. As for me when I start my truck it idles at 1-1.2k rpm for about 15 seconds sometimes sounding like its back firing but after 10-15 sec sounds normal and falls to triple digit rpm. I fill up 91 or 94 depending on my mood hahah


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I use e-30 and it purrrrs like a kitten. is rpm fluctuation rough idle? I think not. unless your talking vuuu vuuuv vuuu. but a vuuuuuuuuuuuuuuuu vuuuuuuu is not.

Netix said:

Lots of guys here experiencing rough idle. As for me when I start my truck it idles at 1-1.2k rpm for about 15 seconds sometimes sounding like its back firing but after 10-15 sec sounds normal and falls to triple digit rpm. I fill up 91 or 94 depending on my mood hahah


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I don't think it's rough idle. It actually does stumble when started. I experienced it one time when it was really bad. I turned the key... The truck cranked. Then I heard the first sound of the engine starting but then kinda broke down (can't really describe it well). Then bursted into life. I would say it started up about 2 seconds later than it usually would. Sorry about my horrible description.. Haven't had much sleep lately...

Wilson said:

I use e-30 and it purrrrs like a kitten. is rpm fluctuation rough idle? I think not. unless your talking vuuu vuuuv vuuu. but a vuuuuuuuuuuuuuuuu vuuuuuuu is not.

Click to expand...

ummm can we get a youtube of this noise you talk about!!! ha ha ha... go wilison!!!

no idea what wilson is describing............

Mine just started doing this within the last week too... It is a 2012 with just over 10,000 miles. It's not rough enough to make me think it's gonna die - just rough enough to get my attention...