rev limiter?

ok you taco gurus, here's one for ya'll. I was on my way home late last night and on my last stretch of the drive is a long lonely road so I jumped on it to feel the torque of the supercharger kick in. Then as it was winding out, I wasn't looking at the tach or nutin but it felt like the rev limiter kicked in. So I backed off and the check engine light on the dash was flashing and the truck was running really rough. My heart sunk. All the rest of the way home it felt like it was running on 5, it would idle but super rough. Like I said, it was late and dark so I turned off thinking I would get after it in the morning. I found it a bit hard to sleep, did a plug wire come off? did an injector malfunction? did it suck a valve? What ever it was, I was surely going to have to open up my wallet nice and wide! So, this morning when it got light outside I opened up the hood and nothing seemed amiss but of course that dont mean nutin if the problem is internal. So I got out my OBD Link and my Torque App and fired up the truck.... confused the hell out of me it ran fine and smooth as ever, no check engine light flashing, all seemed well. I took her into town and did some shopping and I was afraid to tach it out but she is just as insanely fast and torquey as ever. Did the rev limiter get stuck or something? Glad as hell its back to normal but what the hell caused it???

 

If the check engine light was flashing it should have set a code. That should be where you look first.

 

well yes, of course, thats why I headed out with my OBD Link and my Torque App intending to do just that but by the time I got out there the check engine light had stopped flashing... thus, the mystery... what the hell happened?

 

It still should have set a code even if it stopped flashing. The code might be pending or stored. From what you describe it sounds like a misfire on one cylinder. The code should tell you which one.

 

Oh, shoot, didnt know that... I went out and did the scan and it says:
P0302-Powertrain
Cylinder 2 Misfire Detected

 

Check your plug gap on that cylinder.

 

I dont really have a place to work on it, I have to take into the shop tomorrow anyway, I'll talk to the guys down there about it... Thanks!!

 

Just be sure not to drive too far with the cel flashing. When it flashes it is letting you know that damage might be done to the engine or cats.

 

I actually put about 30 miles on it today and there was no flashing check engine light at all. Almost like it never happened.

 

my old 3 series had a cylinder misfire twice, both times i turned it off and started it again with no issues. never did anything to it and the car ran without issue for another 60k before getting rid of it?

 

thats good info for sure but I'm going to be discussing my issue at length tomorrow when I take it in. I think I'll have them replace the plugs and wires.

 

Were you driving it normally? Hard to compare driving recklessly at night to driving normally during the day.

 

True!

 

A misfire at high RPM with forced induction is usually caused by improperly gapped spark plugs. Check and re-gap the plugs, replace if they are worn or fouled. Assuming you have a 4.0 V6 you don't have spark plug wires to replace. You could swap the #2 coil pack with a different cylinder and see if the misfire moves to the other cylinder, that would indicate a bad coil pack.

 

good grief, coil packs? never heard of such a thing... are they expensive?