I am getting a random misfire code on my 09 GT. I checked the plugs no issue there. The misfire first happened at the track (quarter mile). I reset the code and it did not come back for two days. I disconnected a connector on #6 injector to see if the SCT was giving me all the info available, it then gave me the cylinder failing. I reconnected and cleared the code. I gave it a romp and nothing happened then later in the day the check engine light came back on, same code. I have FRPP hot rod cams, under drive pulley's, C&L CAI, delete plugs, 4:10 gears, Blow By Racing tune. My initial thought was a fouled plug but they look fine. If anyone has experienced this code under similar circumstance or know what is going on here I appreciate your information in advance.

 

Bad gas. I was getting the random misfire code a while back. Put some new gas in it from a different station and get some fuel additive (NOT octane booster) that is for this problem.

 

How long have you had the tune?


What was the last thing worked on or changed?

Gas can definately make a a difference. Under WOT you should be able to feel it misfiring.

 

I got delete plugs last. I have had no issue with the tune for about a month and I beat it up on a regular basis. I will change gas and add some additive and see what happens. Thanks for the reply.

 

An alternator going bad will cause random misfire codes. Insufficient voltage.
Very common. Should still be under warranty.

 

I was thinking the same thing.

Also, check the plumbing for the intake for any loose parts that may let in unmetered air. Follow each vacuum line for leaks or being loose.

If I were to guess, it would be tune related.

I just loaded my tune I got dyno tuned with in march. It ran 12.5-13.0. It was 11.5 on the dyno. Things change. Keep it in mind.

 

got some additive in a fresh tank of gas earlier no code yet... fingers are crossed. I went to the Ford Dealerships and got flack for mods. They seem to think that as soon as you mod anything that the entire warranty is void... I have Hotrod cams which are a Ford product, not sure what gives there but will see if I can find someone in my local club that has a contact. I do want to get it done under warranty for obvious reasons if the problem persists.

 

sorry to bump old thread. i had hotrod cams installed for a week with bama tune with no drivability issues although i thought it shook more than it should. a week later i installed steeda cmdp after 2 days random misfire code. i was thinking possibly e10 gas here in bc so switched to chevron as they do not have a notice about ethanol on their pumps. did switching gas fix the problem or should i be looking at other areas such as tune or tensioner?

373 gears, bbk cai, bbk tb, mds cop, hotrod cams, steeda cmdp and udp, bbk shorty headers, pypes xpipe, stock cats, pypes pipe boms axle back, 91 bama performance tune, automatic transmission.

 

I've been getting misfires ever since the frpp cams. It's very rare, once a month or longer but I'm curious about it.

 

What do you mean by misfires?