Lean Misfires at 2700-2800 rpm

[DoctorDex]

Don't I feel stupid, it turns out my relay is still in place. When I hotwired my pump, I bypassed the relay, but I left it relay in place. I'm going to pull it this evening and jumper the socket and hopefully this will help.

[DoctorDex]

Pulled the relay this evening and it made no difference to the misfires. That would've been too easy. Oh well, maybe it'll help with the garbage data I see from time to time.

Edit: Garbage data = occasional knock spikes @ idle or cruise of 30 - 40 counts that has no effect on timing. I usually get maybe 1 or 2 instances every few days. From what I can tell there has been no change.

[DoctorDex]

Do you guys also get the misfires while in neutral at this rpm range?

[davidm5287]

I don't get it in neutral.

[DoctorDex]

I think I do, but the miss is less noticeable (ie. the car doesn't lurch). If I have my exhaust in sport mode, it sounds like it bogs for a split second and then the rpms jump and I hear a loud pop from my exhaust (I have no cats). Of course, I don't feel the miss as much (ie. the car doens't lurch to the same degree), because the car isn't under load.

[badass3000]

...or in gear.
I havent noticed it in N

[DoctorDex]

If it is the CAS itself, you'd think it would be directly related to rpm or timing. My car misses at slightly different rpm points when in neutral vs. while in gear.

Maybe I have 2 unrelated problems?

Anyways, here's what happens to me in neutral:

When I rev it up slowly, it wants to studder at various points and it refuses to get past the points unless I give it significantly more throttle. For example, when I gradually rev it higher it goes smoothly until I hit 2600 rpm. There it studders, quickly drops down to 2500 rpm and starts to gradually rise to 2600 rpm. It continues to studder @ 2600 rpm and it refuses to go past 2600 rpm until I give it significantly more throttle. Once past the studder point, I'm able to let off the throttle (just a bit) and it will continue to gradually rev higher until I get to 3000 rpm. At 3000 rpm I hit another studder point and I go through the same thing again. Once I get to 4000rpm+ the engine revs smoothly all the way to redline.

I think I remember reading a while back that someone had this studdering in neutral problem and they attributed it to some sort of strange incompatability of the Apexi SAFC-2. I don't know if they had any proof and I don't quite understand how it could do this.

At the moment I'm having a hard timing relating these two issues. The studdering/missing happens within roughly the same rpm range, but at slightly different rpm points. Tomorrow I'll check my logs and see if it has any relation to degree of timing advance.

While at cruise, my misses occcur predominantly in the 2650-2850 range between 24-26 degrees of timing advance.

Badass/David: Have either of you tried a known good ECU?

Edit Nevermind Badass, just finished reading all 11 pages and I noticed you have tried a good ECU. However, I'm a little confused by your old post. When you tried the new ECU it fixed your problem, but your old one worked good that day too?

I'm going to do my best to find a known good ECU and to see if it fixes this problem.

[badass3000]

yeah, I am confused about the ECU I tried also. That was going to be my next step, to retry a known good ECU.
You have payed AvPro already, correct.
So if we find out our ECU's are bad then we will need to get together and call them up.

[DoctorDex]

Actually, in the end I never ended up going through AvPro because they told me they probably couldn't fix my problem. Instead, I changed the caps (again), checked pretty much every trace that I could and had a humiseal coating reapplied. Hasn't seemed to do much good though.

[davidm5287]

I don't know if it helps the either of you, but my ECU is rebuilt and while my car was at ESP the guys up there tried 3 good known ECUs from their cars and there was still no change.