Lean Misfires at 2700-2800 rpm

[DoctorDex]

Originally Posted by markoverclock

aem group buy.

The earliest I might be able to scrounge up enough cash for an AEM will be ~ July/August. Any chance the group buy will still be going on then?

[badass3000]

thats a huge chunk of money to replace something that we have already proven good.
I mean I took my friends ECU out of his car (that was running good) and slapped it in my car and still had the problem. My dyno tuner has already tried to 'tune' this out anyway, so I dont see how AEM could help.

I am currently in the middle of swapping out my lifters. Bigger job than I remembered. Anyway, I just have a good feeling about it. Should have a report tomorrow.

[jwetzler]

I haven't been keeping up with this thread as of recently, too much to read to catch up now.

Did anyone with the issue swap heads yet? or change cams/valve springs?

[badass3000]

Originally Posted by jwetzler

I haven't been keeping up with this thread as of recently, too much to read to catch up now.

Did anyone with the issue swap heads yet? or change cams/valve springs?

im probably the only one thinking about it.
no-one has yet, but its probably my next step (if lifter dont fix it)
I have a good set of loaded stock heads that could go on.

[badass3000]

alright, here is what happened today...

finished putting my car back together after changing the rear 12 lifters with known goods.
Fired it up and it sounded pretty good.
played with the throttle in the garage and noticed it was much smoother.
before it was very difficult to hold a steady rpm in the 2500-3500 range but now it was easy.

I was very excited.
Took it for a short drive and it seemed the problem was gone.


after about 5 miles it came back.

I havent deceided what this means yet.
Dex, didnt you say your car had to be warmed up for the problem to occur?

I should probably change all the lifters first.
but it would seem that something to do with the lifters is the problem, and not the lifters them self.
what about the oil that goes to the lifters?
if an oil passage in the head to a lifter were blocked, would the lifter just be banged until the oil was pushed out and the lifter is soft/empty?

MAN! the car was running soo good for about 5 min too!
I hope its not a fluke and that I am actualy on the right track.
damn-it!

[3000hybrid]

Originally Posted by badass3000

alright, here is what happened today...

finished putting my car back together after changing the rear 12 lifters with known goods.
Fired it up and it sounded pretty good.
played with the throttle in the garage and noticed it was much smoother.
before it was very difficult to hold a steady rpm in the 2500-3500 range but now it was easy.

I was very excited.
Took it for a short drive and it seemed the problem was gone.


after about 5 miles it came back.

I havent deceided what this means yet.
Dex, didnt you say your car had to be warmed up for the problem to occur?

I should probably change all the lifters first.
but it would seem that something to do with the lifters is the problem, and not the lifters them self.
what about the oil that goes to the lifters?
if an oil passage in the head to a lifter were blocked, would the lifter just be banged until the oil was pushed out and the lifter is soft/empty?

MAN! the car was running soo good for about 5 min too!
I hope its not a fluke and that I am actualy on the right track.
damn-it!

Is the noise exactly the same? Sometimes even with properly priming lifters they take a bit to quite down.

[badass3000]

tell you the truth, I didnt even stick my head under the hood while it was running.
I am going to retest tommorow anyway. The neighbors dont like it if I start my car after dark. Isnt that crazy? Good thing its not my DD.

[3000hybrid]

Originally Posted by badass3000

tell you the truth, I didnt even stick my head under the hood while it was running.
I am going to retest tommorow anyway. The neighbors dont like it if I start my car after dark. Isnt that crazy? Good thing its not my DD.

- I hear ya when it comes to the neighbors. My car is loud on start up too. I just let it roll down the driveway and head out in stealth mode as not to wake their baby. But when the kid gets older IT's ON LOL!

Post an update when you have time to listen to it. I have a feeling it's something to do with the lifters too.

[DoctorDex]

If it is a soft lifter/oiling issue, maybe it might be worthwhile swapping in some solid lifters? I've never heard of them being used on this platform, but I'm pretty sure our OEM lifters are identical to the DSM lifter. Here are some solids: BLE DSM Solid Upgraded Lifter Set*-*DSM Internal Engine Parts*-*Engine*-*DSMparts.com

Originally Posted by badass3000

Dex, didnt you say your car had to be warmed up for the problem to occur?

The problem doesn't occur on cold start while revving in neutral, but as soon I put it in gear and give it some load it'll miss horribly when cold. On the other hand, when the car is warm it'll miss while revving in neutral and it doesn't miss as bad under load. Go figure.

[badass3000]

yeah, Ive heard of a few that use the solid lifters on this board. Steve (3SX ouner) on his black show car and I remember Nelson and Hillbilly cursing solid lifters for some reason.
You have to adjust them periodicaly and from everything I have heard is our stock lifters are very good anyway. Matt M always uses stock lifters.

I wonder why solid lifters cost soo much?