Need some advice on idle of T-rex
Need some advice on idle of T-rex ok after a few days of messing with my tune, i logged my iac counts they were stuck around 110-150 on hot idle at 950rpm. well i drilled another hole in the throttle blade starting small and working my way up in size to get my iac counts to 65 on hot idle. well i got the car to stop surging by doing this. once this was dailed in i could crank the car on cold start and hot start without touching the gas and the car wouldn't search for idle. drivibility was almost perfect with the exception of a slight off idle bog when taking off from a stop. well today i changed the idle to 1050 as i like the way its sounds better at 1050 so again my iac counts went back up, so i drilled the hole one size bigger to bring the iacs back in line. so now here lies the problem, on a cold start i have to floor the gas pedal to get the car cranked and it surges to find idle for a second then levels out. it also does this on the hot start. now when driving the car i can get the car over 3000 rpm in any gear and the rpm hangs in the 1300rpm range until i come to a complete stop. when logging the iacs are around 121 to 110 when coming to a stop and will not go any lower. now if i command the iac to 70 using the scanner function from a high rpm accel and let off the gas the rpm drops to the 1050 rpm and doesn't hang at 1300rpm. so basically my question is why won't the computer lower the iac on decel to correct for the high iac making the car stick in the 1300 rpm range. if i command it the car drops back to 1050 as i have programed in the idle table. i can lower the iac counts in the scanner to (0) and the car will almost go dead so i know that the holes in the throttle blade aren't to large for the iac to correct for. any and all advice would be great as i am stuck right now and badly need some help on this issue. i have a log and the current tune if someone could help. 
You need to dial in your desired airflow (base running airflow) based on your short term and long term idle trims. Check the stickies.
The sticking idle at cruise is in your throttle cracker table. You need to tailor that table to suit your car's setup. It might also help if you take 50% out of the throttle follower as well.
Either way, use the search or read the stickies. There are tons of idle threads full of info to help you out.
The sticking idle at cruise is in your throttle cracker table. You need to tailor that table to suit your car's setup. It might also help if you take 50% out of the throttle follower as well.
Either way, use the search or read the stickies. There are tons of idle threads full of info to help you out.
The hanging you describe sounds a lot like the throttle cracker. TC is based on vehicle speed and RPM. There are also two parameters that define when the TC is to be come active and deactive based on vehicles speed. Try raising these two parameters by 2-3 MPH as well as reducing the TC airflow in the lower RPM/VSS areas.
ok got my raf dailed in after doing a cold start to hot start this morning my stft and ltft and almost perfect. i am still having the cruise effect over 40mph when i push the clutch in, but once the speed is below 25-30 the idle doesn't hang and goes to the command idle point. i have tried lowering my throttle cracker table in these cells and with no luck the idle still hangs, i even tried to zero out the throttle cracker table with no luck. any more suggestions?
Check your spark table parameters. You may be only getting base spark timing from 69kph and below. Above 69 kph, 0% TSP might be going to your main spark tables and it will bring your idle way up. If you change it to where your base spark table runs any time you're at 0% TPS, then this should cure this problem. Turn the limit up to 410 khp.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Originally Posted by Patrick G
Check your spark table parameters. You may be only getting base spark timing from 69kph and below. Above 69 kph, 0% TSP might be going to your main spark tables and it will bring your idle way up. If you change it to where your base spark table runs any time you're at 0% TPS, then this should cure this problem. Turn the limit up to 410 khp.
