Lean Misfires at 2700-2800 rpm

[TurboBob]

Originally Posted by DoctorDex

I have an HKS and I have no idea how it works. All I know is it doesn't do anything for this problem.

does it help spark blow-out?

[DoctorDex]

Originally Posted by TurboBob

does it help spark blow-out?

Edited:I think it probably does as I don't even have a hint of spark blow out up to 26 psi with AFRs of ~ 11.5. I've also noticed I'm able to burn through much richer AFRs (~10.5) while trying to get my WOT tune safely dialed in.

The thing I believe has helped the most with spark blow out is iridium plugs (gapped to .028). Prior to switching to iridiums, I was running coppers and I'd have bad blow out (even with a tiny gap of .026).

[DoctorDex]

Does anybody with this problem still have a working EGR system?

I've tried disconnecting/reconnecting the EGR in the past and it didn't seem to do anything. However, I recently noticed the throttle body nipples where I had connected the EGR solenoid is plugged, so it didn't matter whether the EGR system was hooked up or not, it still wasn't working.

[badass3000]

not me.
Ive been driving my car a little more, and noticed a few things...
1)like I said, I no longer notice a bad spot at 2800, its just low on power untill after that rpm.
2)at idle, I swear I can hear the miss.
3)I have seen a few counts of knock in this area while under vac (<0psi)
4)an abnormaly noisy valvetrain

[DoctorDex]

Originally Posted by badass3000

not me.
Ive been driving my car a little more, and noticed a few things...
1)like I said, I no longer notice a bad spot at 2800, its just low on power untill after that rpm.
2)at idle, I swear I can hear the miss.
3)I have seen a few counts of knock in this area while under vac (<0psi)
4)an abnormaly noisy valvetrain

I think I'd have to agree with most of the above.

1) I still have a lean spot, which starts at 2500+rpm and goes to 3000+rpm. I notice less power in this range, it misses and then it takes off after 3000rpm.

2) My idle will be rock solid on cold start (when it is warming up in the morning). However, once I drive the car for awhile and then I let it idle, I can definitely hear a miss and the idle tends to fluctuate more than at cold start as a result.

3) I see a few counts of knock through 2500 - 3000rpm multiple times per day.

4) Valvetrain noise Rear > Front.

[badass3000]

Originally Posted by DoctorDex

I think I'd have to agree with most of the above.

1) I still have a lean spot, which starts at 2500+rpm and goes to 3000+rpm. I notice less power in this range, it misses and then it takes off after 3000rpm.

2) My idle will be rock solid on cold start (when it is warming up in the morning). However, once I drive the car for awhile and then I let it idle, I can definitely hear a miss and the idle tends to fluctuate more than at cold start as a result.

3) I see a few counts of knock through 2500 - 3000rpm multiple times per day.

4) Valvetrain noise Rear > Front.
I sti

1)it does seem to be worse between 2500-3000rpm for me too.
2)cold start, haha. its too warm here to confirm
3)same here
4)I cant pinpoint the location of my noise, maby both VC's

[TurboBob]

My car does this, somewhat.

2500 - 3000 seems to be the range.

It looks lean sometimes when watching the O2 trim, but I think there is a misfire happening that is fooling the O2 sensor. I think the leanness is false.
(the methanol spray test not-withstanding)

It clears up abruptly at 3000 RPM.

My car is stock fuel, MAFT Pro, closed loop, 13G's.

Bob

[ProwlerGT]

You guys may want to check this out. This dude may have inadvertently solved this problem. Would be good if so.

His original problem stated (hesitation sputtering, but clears after 3000rpm):
Hesitation, sputtering, peice of Crap.

Here's the fix just posted tonight:
Hesitation, sputtering, peice of Crap.

So I'm gonna ask him which piston. Have ya'll inspected your pistons thoroughly already? I haven't checked your list in a while.

[markoverclock]

Originally Posted by ProwlerGT

You guys may want to check this out. This dude may have inadvertently solved this problem. Would be good if so.

His original problem stated (hesitation sputtering, but clears after 3000rpm):
Hesitation, sputtering, peice of Crap.

Here's the fix just posted tonight:
Hesitation, sputtering, peice of Crap.

So I'm gonna ask him which piston. Have ya'll inspected your pistons thoroughly already? I haven't checked your list in a while.

new motor with forged pistons.

[ProwlerGT]

Originally Posted by markoverclock

new motor with forged pistons.

Are you saying thats what fixed yours?

Just for an FYI for me.... whats the difference in forged pistons vs stock ones? What does it mean when people say "forged" ahead of something regarding engines etc... mechanical stuff.. Yes, I know thats a newbie kinda question, but I don't have forged pistons so I don't know. lol