I've been chasing down some (what I feel 'missing horsepower'). Only managed 300rwhp & 317rwtq. Car rapidly drops in power after 5300rpm, runs fairly rich throughout rpm range (11.9-12.7afr), and seems even richer at idle. No DTC's stored. Can someone view my files and see if any red flags pop up. Mods in signature. I haven't done the false knock test, but the knock seems random and usually occurs throughout the mid rpm ranges.

http://www.mediafire.com/file/1zemokxy1nm/run1.xls

http://www.mediafire.com/file/zlnzzwzkz2y/run2.xls

 

I only had a chance to look at run 1, but noticed some weird things happening at idle: 1) there's a considerable split between the average O2 values, with the left bank at 616 and the right bank at 372. 2) a large range in spark advance, jumping around from 23 to 32 for no obvious reason (and there's a clear downward trend in advance as rpm is increasing within idle range). 3) in addition to the variable spark timing, knock retard is present, sometimes considerable amounts (up to 5 degrees); could be valvetrain noise from the rockers or dual springs? I'd make sure your rockers are adjusted, valve float would also explain power loss at upper rpm. 4) MAP readings oscillating, not correlated to RPM; intake valves not fully closing?

Any other mods not listed in your sig? Different injectors or descreened maf?

 

Javelin, thanks for the reply. I believe my crane double springs are sufficient to prevent valve float. I originally had the rockers at 5/8 turn, then readjusted to 3/8 turn and gained about 4rwhp, but still the considerable drop off around 5300 rpm. the tune supposedly desensitized the knock sensor, and I do have an lt4 knock module as well. cat is gutted, and have stock 24# injectors. I requested the mail order tune have timing advanced to solve the bogging I experienced during take off after the cam/valvetrain upgrade. Could this be too much advance? See the link to my related thread and dyno sheet if you have a chance.

https://www.camaroz28.com/forums/sho...d.php?t=735376

 

Looked ar run1.xls... man you got something rattling or a bad knock sensor. You have retard from the get go after starting it up, I have a feeling the PCM has put you into the low octane retard tables due to all that knock. To see actual knock counts incrementing look specifically at row 2358 in the spreadsheet, you are idling around 800, map is stable around 50 +/-2, TPS% and TPS volts indicate closed TB. And then knock count jumps and it throws 5* retard out of the blue, a couple of rows later you goose the throttle again speed is 0 at a stop and you bump the knock count and throw 7* retard at it . ST BLMs are a good at row 2358. At row 2403 you shift, the KC is NOT incrementing, but as you pick up RPM the retard increases again to 6.2* again an indication of the low octane tables or the PCM is remembering all that knock and pulling timing. You have a combination of retard w/o kc incrementing and retard with KC incrementing, but they most probably are caused by the same thing. If the knock is real then it's happening at idle and no load conditions where it could only be caused by something wrong, hopefully it's just a mechanical rattle. Will look at other trace later on..

 

Looked at run2.xls ..your retard is still there w/o the knock count incrementing row 5113 start of wot run looks like 2nd gear up to 5160 RPM / 65 MPH all looked good timing was retarded 3.5* but the KC never incremented. I did notice on the run starting at 9389 you did pick up some knock at 9339 and 4* of retard but it cleared up fast, could be a fluke. The 8802 run (1st gear) looked good no knock no retard. I did notice in the 2nd gear runs 5113 and 9339 you never got above 77% tps however your injector Duty Cycles were 72-L and 76-R with AFGS at 213 with 23% more TPS to go that's near the top for leaning out. Would like to see how they looked at a full 100% TPS dyno load pull in 3rd. Have you verified your fueling under load.

 

my fueling under wot load is around 40psi...a little low, but not too worried at the moment...especially since my dyno was showing a rich mixture. I guess I can replace the knock sensor and see if that changes anything with regards to the knock retard & counts.