The issue I am having is the the trottle seems slow to respond when coming off an idle. When I just try the rev the engine when in neutral it seems to lag or take a while to come up on RPM...it is NOT crisp.
I am not sure if this is a trottle cracker issue, but I assume it is not getting enough fuel dumped in when the throttle is opening quickly. Need a squirt, like a carb give a squirt of fuel when the trottle is opened!
Any help appreciated.
are you saying you have a hesitation?
'02 Corvette
LS6, MN6, LT's/X pipe and TI's, Honker CAI, AI 243 heads, PatG Custom Cam, FAST 102, LS2 TB, Red Top inj, HPTuners & NGK/AFX
Originally Posted by printmanjackson
Not so much hesitation, the rpm climbs relatively slow, kind of like if I were opening the throttle slowly vs a quick rev.
Responds like a carburetor with no squirter!
HP tuners/stock ecu are on my street car. I also have two super stock cars that run LT1's with a Big stuff and Holley fuel injection systems. Both the Big Stuff and the Holley have Accerleration Enrichment vs TPS and MAP tables to adjust for this sort of thing. What does HP tunes have as an equivilant?
Last edited by fjb2069; 09-07-2011 at 08:50 PM.
BUMP
I wanna hear about this one, as I have the same problem too in my 4.8 powered 69 C10!
Post your tune and a log file.
2000 Camaro SS M6
11:1 Stock bottom end
76mm Altitude compensator
Tune attached!
Can you post a log of the issue, it would help explain a few things. Do you mean light throttle transition or when you mash it in neutral to do a quick 5-6000 rpm rev? The way your tune is setup your VE table is referenced during quick throttle transitions. This is the "air shot", looks like your VE in the 1200-2800 rpm range looks a little low in the high map regions (85-105 kpa).
2000 Camaro SS M6
11:1 Stock bottom end
76mm Altitude compensator
Probably needs more "fuel" in those areas of the VE.
PS, I've seen timing issues cause this as well.
Post a log.........
EFI specialist
Advanced diagnostics, tuning, emissions
HPtuners dealer and tech support
email=[email protected]
Mash it in neutral.
Suggestion for VE in the 1200-1800 range?
I will try your sugggestion long with taking a log.
Throttle Follower AirFlow vs TPS set it back to stock. Also zero out the some tables on the Torque Managment,so you can feel the power of the car.
PLease explain torque managment suggestion?
I attached a log file. I set the Airflow vs rpm to stock.
What I noticed is that when I first start the engine cold the throttle response is very good, but as the car warms up the trottle response becomes slower. Looking closer I see the change in throttle response occurs as soon as the commanded AFR goes from 13.6 to 14.6. I assume this is when closed loop gets enabled. Even if car is hot and I restart it ther response is good until the commanded AFr goest to 14.6.
I believe there is a closed loop delay after startup, but I can not find the table?
I would thinkg the motor should be able to respond even when idling at 14.6AFR.
Check out log and let me know what you think.
Last edited by fjb2069; 09-15-2011 at 06:03 PM.
your tune needs lots of work,if im you i would put MAF back to stock and retune the timing high & low,In drive,in park timing back to stock and add 27 or 28 in the 0 RPM to 1200 RPM up to 0.28 Cylinder Airmass,(same in the high & low) and VE also back to stock then retune. And start ( Russ Idle-Airfow.cfg ) in order to get the correct Base Running Airflow.Torque Managment zero out ( Traction Control spark retard vs RPM, Aggressive Retard vs RPM and Torque loss % vs Spark Retard ).
I appreciate your advise and will consider. But the car runs well aside from this one issue and the tune you are viewing was dyno tuned by SPEED INC and paid $$$ for it. I hate to think it was no good. I will Bring up your comments with them.
Tune looked like whoever did what they did knew what they were doing to get it to drive well. The torque management stuff mentioned only has to do with traction control, not an issues at all. The tune needs a little VE work and I'm sure that is the main issue as sudden throttle changes (transient airmass) reference the ve table.
2000 Camaro SS M6
11:1 Stock bottom end
76mm Altitude compensator
Here is a log with my wideband hooked up. As soon as the system goes to closed loop the AFR goes from ~13.8 to ~15-16!
THe commanded AFR is 14.6, but running a lot leaner at idle. What might this be caused by?
What are the specs on your setup?
2000 Camaro SS M6
11:1 Stock bottom end
76mm Altitude compensator
Engine:
346 ci LS6 Chevy
AFR 205 Heads
Comp Cams xr281
SLP Oil Pump and chain
Canton Pan
Canton Remote Filter
Harland Rockers
Katech Coil Mounts
Hooker Headers
Fast 90mm Intake Ported
Nick Williams 90mm TB
Afco Aluminum Radiator
Magna Flow 3� Custom Stainless Exhaust
MSD Wires
2002 GM engine wiring harness
S&P LS1 engine plates with Energy Suspension poly motor mounts.
Rick's Hot Rod Shop stainless EFI gas tank
Aeromotive in tank A1000 pump
Aeromotive Filter
Aeromotive Regular
#10 and #8 Braided lines and Fittings
Drivetrain:
T56 6 speed w/ ATS hydraulic clutch
Mcleod Shifter
LS7 clutch
3� Aluminum Drive shaft
Detroit Speed 9� Ford
Strange Aluminum 3 rd member 4:11 Truetrac
That cam has a decent amount of overlap. At an idle overlap causes the o2 sensors to not read properly. I imagine the difference only exsist at idle?
2000 Camaro SS M6
11:1 Stock bottom end
76mm Altitude compensator
Reply With Quote