KevsfastZ

iTrader: (8)

Hey guys,

Well I just recently raised my rev limiter from stock to 6600. Problem is that 3/4 of the time when I shift past stock rev limit it will start misfiring in the next gear. Ex, WOT in first shifting at 6300, when I ****** 2nd it will miss for 1 second. It also does not throw a SES light, any ideas?

Thanks in advance,

Kevin D

1999Transamman

iTrader: (18)

The stock tachs are slow, so you might actually be hitting the new rev limit but the guage wont read what the actual RPMs are.

KevsfastZ

iTrader: (8)

I'm on a shift light.

1999Transamman

iTrader: (18)

That throws out that theory. Let me do some homework on this one. How many miles on the car?

KevsfastZ

iTrader: (8)

Car just rolled 69k tonight. I appreciate the help.

Kevin D

1999Transamman

iTrader: (18)

I was going to say the coils but they wouldnt do that with 69K on them. Have you looked at all the connections for them, if there is moisture or corrosion you could have eratic problems like this. Im not a pro on tuning but just a thought, was any kind of tuning done to compensate for the new rev limit, fuel, ect...?

KevsfastZ

iTrader: (8)

Plugs and wires are in great condition, no further tuning was done beside the raise in rev limit. This used to happen once in awhile with the stock limit when power shifting.

Kevin D

1999Transamman

iTrader: (18)

If the plugs and wires are good, I would definitly look at the tune, I would think it would have to be adjusted for the rev increase.

KevsfastZ

iTrader: (8)

hmm the tune I have on the car is pretty solid, as I stated before, when I was power shifting it would sometimes throw an SES light (random multiple cylinder misfire)

1999Transamman

iTrader: (18)

Well then the tune is solid, and this happens sometimes. Only when power shifting right? This has me stumped. Anyone else have any thoughts on this? Come on guys chime in.

03 BUSA

iTrader: (25)

I would check the plug/wires and make sure it is not the rev limiter. You might be just touching it and seems like a misfire. Also, factory tachs are off, so unless you are going off of a second tach I would not go totally off of that.

KMStevens

iTrader: (4)

are you on stock valvesprings? maybe the valves are floating at the higher rpm's, causing the missfires?

blackcat

This same exact thing happens to my car. Has anyone else seen this?

I have changed from stock plugs/wires to NGK TR55's and MSD wires

I then changed from those plugs to AC Delco Iridiums and the same MSD Wires.

Mods are: LID, Cutout, and ASP Underdrive pully and alternator pulley.

Car has 51K on it.

Tim

TCW

iTrader: (3)

Off topic, Kevin did you use to drive a probe by any chance?

blackcat

The testing that i have done is:

Reving it up to redline and the car will just putter at idle and seem to gasp for air until it finds idle, then it will idle out just fine.

Run it on a scanner and every cylinder has misfired around 80 to 150 times.

Running it WOT on the scanner shows a 1st to 2nd shift purpously hitting the rev limiter then switching to 2nd the car just hesitates for about 5-10 seconds while holding down the gas. The 5th cylinder most of the time will have the problem, So I am going to systematically check the coil first, then the injector, and then the wire, and then the plug. Even thought I just changed the plugs twice, and the wires once.

I will let you know how it turns out.

Tim