I am running out of suggestions to fix a problem I have been having with my vehicle.

Here are the ignition/other important specs:

MSD6AL ignition
HVC coil
MSD 8.5mm plug wires
NGK 8 Vpower plugs &/or NGKR ZFR7F11 plugs - gap adjusted between 27 & 32
Hondata 4B using p75ecu
720cc/min RC injectors
AEM fuel rail/ FPR - base pressure @ ~45
Inline & intank Holley fuel pumps
Full tank of C-16 VP racing fuel

Here is the problem:
The vehicle patters, or flutters past ~5500 rpm. This occurs under non-boosted, and boosted condition. Under boosted conditions, the maximum boost reached is ~1.17 kg/cm2 (even when the boost controller is set anywhere between 1.35-1.75 kg/cm2).

This first occured on the dyno. The vehicle was working fine @ ~ 1.65kg/cm2 and made 486whp (on a mustang dyno). The next run was @ 1.7 kg/cm2, where the vehicle ran smooth and made 491whp. After that, the only change that was made was ~2% fuel added after 7000rpm. The next run, the fluttering occurred, and no increase in power was seen after 5500rpm (ie. max power occurred @ 5400rpm - 355whp, power curve was flat after that point). Also lambda readings were around 11.8-12.2:1 for the duration of the run. No ignition timing changes were made from the good run to the poor run.

To try to fix the problem, the following things were tryed:

-plug gap was changed from 32 to 27
-NGK 8 Vpower plugs were replaced with new NGKR 7F11 plugs
-another set of MSD plug wires were tryed
-Blaster3 coil was tryed instead of HVC coil
-6AL was replaced with Mallory Digital ignition
-p75 rom was replaced with a p28 rom using a non-vtec map
-distributor was swapped with a distributor from a different functional vehicle
-O2 sensor was replaced with a different O2 sensor

If you have any suggestions about the problem, I would like to hear them.
For more info on my setup visit:
www.cadvision.com/unrynhen/prelude.html

Thanks in advance,

XES
H23A turbo prelude
491whp & 401ft-lbs on mustang dyno
traction limited run = 12.3 @ 118mph with terrible 2.2sec 60ft time

 

What exactly happens above 5500 RPM's? Fluttering, like it's misfiring and/or missing somewhat but will still pull through it but it just sucks?

How high do you rev the engine? Cause I overrevved my engine and I screwed up my Crankshaft Position Sensor and it kinda did what your describing. But mine was worse.

It's worth checking out. Good luck.

 

It just stops producing power completely. When the plugs were failing in the past it would really stutter on and off all the way up the rpm range. The rpm was not consistent. New plugs fixed that problem. That is not happening this time. It is a subtle problem, and the car isn't smooth at all. I wish I could show you guys 'cause it just isn't driving right.

As for overreving it, no i never go past 8000 rpm, there is not much need to (the cams don't make the same amount of power real high in the rpm range).