I have a LS376/515 crate engine in a 78 TA with T56 and the Holley Terminator EFI system. I am new to tuning EFI systems and have been reading and watching as many "how to's" as I can find online. I have this system very driveable now but, it still goes very rich when accelerating- in carb terms the "tip in" seems too much and the AF will drop to the 9-10 range for 1 sec or so and then start to clean up.
I am using a tune that comes with the system named 480HP LS2 as the base tune and have been "learning" from there after I input the correct displacement. I haven't changed that timing table at all but, the base fuel and AF target table have been changed slightly in the idle and cruise area. In high load and WOT areas the AF is 12.7. I have also reduced the ramp in the fuel modifier AE vs TPS% so that it's not adding anything until 70% and that seemed to help.
Cam specs for this engine: 226/236, .525"/.525", 2.165in /1.590 ex. Engine is rated at 533hp/477tq and I figure I'm getting around 300hp/320/tq - it runs slightly behind my 2002 Firehawk in 4th from 70 - 110mph and my Firehawk put down 310rwhp a couple years ago on a chassis dyno.
So- long background. Any tips to finding why it goes rich when rolling into the throttle? I am planning on getting the car to a chassis dyno to have it tuned, in the meantime are there any tips from people here?
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Greg
'78 Trans Am - Y88-R LS3/T56,
Holley EFI, UMI Performance
I talked to Andrew and we went over several set up related items, one of the checks he had me perform was to see if the my TBI body was progressive or synchronized. Holley says this system is synchronized but the linkage from the main barrels to the secondaries has a slot allowing an estimated 30% movement on the primary side before the secondary side starts to open. I check the "progressive" box in the engine config and then input 35% and that cleared a lot of issue up. Now when I hit the throttle the engine just revs up, in 1st gear it starts spinning the tires at 3k rpm from a roll and the power just keeps coming hard through 6k.
Andrew hasn't touched my tune yet so this is a basic tune from Holley with a little touch up from me and what I have read and learned.
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Greg
'78 Trans Am - Y88-R LS3/T56,
Holley EFI, UMI Performance
The Following User Says Thank You to Gscherer78ta For This Useful Post:
I Wanted to add an update to this thread. I've had a couple of tunes now from Andrew and Lance was correct, it's just getting better and better. The skinny pedal produces a lot of results now and we are still working on only the base fuel table and driveability. Haven't even gotten into trying to tune for more power.
Andrew is professional and easy to work with and very responsive.
Greg
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Greg
'78 Trans Am - Y88-R LS3/T56,
Holley EFI, UMI Performance
The Following User Says Thank You to Gscherer78ta For This Useful Post:
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