042719 black gto road test torque converter.hplblack gto 042619 ve stock dfco etc disable 8.hpt
hello all,
so I've been fighting this one for about 6 months now and just really getting my but kicked! was hoping somebody on here might have some experience with a similar situation. its an 05 gto automatic. under heavy load, tps above 50%, the engine cuts out, doesn't die, just wont accelerate any further. acts like its hitting a rev limiter. watching the log file, all airflow values gradually drop, and injector pulse drops with it when it hits about 4000rpm. I am even holding the throttle open at 90% but it will not move any air. however, this is where it gets tricky, it will run the rpm up if I keep throttle position below 50%, all the way to 6000. engine runs great, pulls good, doesn't skip a beat. even if I get above 4000 rpm and open up the throttle past 50%, it just stops revving drops back to 4000.
I have been calibrating the a/f ratio, and got it within a reasonable range, but still no effect to my problem. it was extremely rich reaching 9-1
I have talked to a few tuners and I am really leaning towards a mechanical problem. I have eliminated possibilities with restricted intake duct, or exhaust system. I have checked my lifter preload, and measured .030 on intake, .060 on exhaust. right now I am leaning towards the possibility of either lifters collapsing down at high rpm, or throttle blade closing without the sensor reading it (highly unlikely)
also, this all started when I swapped the heads, valve springs, and intake. the car originally had this cam installed along with headers and never had a problem. everything else is stock and original to the car. I am in the process of installing a procharger, haven't installed it yet though.
my mods are:
comp GRIND # LS1 3727R /3731R HR114 +4
DURATION @ .050 INTAKE 234 ROCKER
ARM RATIO
VALVE ADJ INTAKE .000 DURATION @ .050 EXHAUST 242
INTAKE 1.70
VALVE ADJ EXHAUST .000 LOBE LIFT INTAKE .3530
EXHAUST 1.70
VALVE LIFT INTAKE .601 LOBE LIFT EXHAUST .3590
VALVE LIFT EXHAUST .609 LOBE SEPARATION 114.0
DURATION .006 INTAKE C/L 110.0
headers
comp 7.4 pushrods intake, 7.350 exhaust
unknown stall converter
installed 12/10/18
ls3 intake
ls3 heads, hand ported, with ls9 exhaust valves installed
patriot dual gold springs,
btr ls9 dual spring retainers (to compensate for installed height)
gm 2 bar map