Random misfire

[GA2Dr]

Hi all:

Was driving yesterday, got on it (about 80% throttle) and not long after hitting peak boost I saw the check engine light flashing. Immediately got out of the throttle. Check engine light continued to flash but never went solid and no warnings or other messages popped up. I did not notice any rough running, hesitation, etc.

When I got to the next traffic light I shut the Bronco off and immediately restarted it. No check engine light and it ran fine rest of the drive. Drove fine today and has not happened again even with going WOT a few times to test. Put Forscan on tonight and zero codes.

I have been running my current setup (mods) for at least eight months with no recent changes of any kind. In searching on the forum I understand a blinking check engine light means a misfire. Given the above should I just chalk this up to a random misfire and move on with my life?

Thanks in advance for your thoughts.

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[Bronco21Maybe]

You made mods and experienced a malfunction, but haven't told us what mods you did.

 

[GA2Dr]

Correct

 

[Bronco21Maybe]

And?

 

[SierraBronco]

We had a pretty significant misfire issue on one of our broncos. Dropped the gap down to .029 if I remember correctly. At first we still had occasional issues but now that you’re bringing it up it’s been quite some time.

 

[Desmolicious]

"A blinking check engine light in a Ford Bronco indicates a severe engine misfire. Unburned fuel is dumping into the exhaust system, which can cause extreme temperatures and quickly melt or destroy your catalytic converter. This requires immediate attention"

 

[GA2Dr]

I guess to put a finer point on this - given that I did not feel any misfire, given that there was no DTC code and given that I've now put about 60 miles on since it happened with no repeat, should I just chalk this up as kind of a random "gremlin" or is this something I should be concerned about. And if it is something to be concerned about, what, if anything, should I be looking at?

 

[BroncoChallenger]

It's something to keep an eye on, but if you got enough misfires to make the CEL flash, that tells me you're actually getting misfires while driving but not severe enough to make the CEL flash or set a code.

Usually it means your tune isn't right for the mods you've done - or at least that's what it used to mean.

Back when I had my Grand Prix GTP, I was able to tune the fuel table through a few iterations such that I could run all my mods (smaller pulley, bigger TB, clearanced manifolds, no cat, etc) and still just run premium fuel with zero misfires even at WOT. I'm not sure what capability there is to do that with these things.

 

[Hummell]

I had this happen. No codes stored but the Ford app mentioned something related to the shutters not opening/closing properly - which makes sense because I removed them completely. I went on with my life, Bronco drives fine. It happened on the interstate at about 75mph in rainy conditions.

 

[GA2Dr]

I had this happen. No codes stored but the Ford app mentioned something related to the shutters not opening/closing properly - which makes sense because I removed them completely. I went on with my life, Bronco drives fine. It happened on the interstate at about 75mph in rainy conditions.

Interesting you say rainy conditions because the only thing out of the ordinary when it happened was that it was pouring rain.

 

[Hummell]

Interesting you say rainy conditions because the only thing out of the ordinary when it happened was that it was pouring rain.

Yeah, it was pouring for me also and windy. I have an aftermarket high-mount intercooler (Wagner Tuning).

The intercooler can act like a condenser in certain wet/humid conditions from what I understand. Under heavy rain, humid air + cooling can let water collect in the charge air system (charge pipes/intercooler). Then under a pull, a slug of moisture can get carried into one cylinder and cause:

• incomplete combustion
• one or more misfires
• ECU sees active misfire → flashing CEL
• ECU cuts power / timing
• then everything clears and drives normally afterwards

 

[GA2Dr]

Well this makes a lot of sense and would explain a seemingly "random" misfire. Basically 100% humidity all day that day and heavy rain. I have a larger IC, though it's a low mount, but also have Injen CAI and aftermarket charge pipes.

 

[Hummell]

Well this makes a lot of sense and would explain a seemingly "random" misfire. Basically 100% humidity all day that day and heavy rain. I have a larger IC, though it's a low mount, but also have Injen CAI and aftermarket charge pipes.

I think it makes sense. That's what I chalked it up to and went on with my life. Recommend you do the same with a clear mind.

 

[3People1Body]

How many miles on those spark plugs? I think changing every 30-40k is recommended for boosted engines. Correct me if wrong.

 

[GA2Dr]

How many miles on those spark plugs? I think changing every 30-40k is recommended for boosted engines. Correct me if wrong.

Plugs have less than 15k miles on them. Was a thought I had if the misfire reappeared, but (knock wood) has not come back since that one instance.

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