Holley Sniper EFI - Sneak Peak Update
After last October's cruise (a disaster for the coupe - rear end broke free on its own coming out of the German restaurant, and coming home Sunday I had to control the throttle with the clutch), I had to decide if I was done. Decided to pick at this elephant one bite at a time with the Professor's help. The problem was that A) the throttle stuck open(a lot), B) the throttle would take off(accelerate) on its own sometimes, C) the throttle would "hang" or even accelerate when shifting. Things really acted up from 2000 - 3000 rpm.
First issue, mechanical binding in accelerator cable. There was a slot in the cable sheath.
Also, the cable bracket wasn't aligned properly into the throttle body. So the Professor kindly welded a new one.(Thank You)
This is the base timing table for the Holley tune in street mode.
The Paul astutely pointed out was that the shift in timing from one rpm level to the next(250 rpm steps) was pretty large (9-11 degrees). And it was also occurring at likely shift points. So, that at 2225 rpm, if normal engine load bumped that to 2250 or 2300 rpm the timing jump occurred and forced the engine even higher. You can see from the table the large jumps occurred at a couple different places.
After multiple conversations with Holley, they replaced the Throttle Position Sensor and the Idle Air Control motor on the Throttle Body.
Then I went back and smoothed the Ignition Table to this. The idea hear is to make the transition smoother at increasing rpm.
I've done about 80 datalogs on this and we are getting closer. The engine runs a lot smoother. I can put it in 5th gear and the engine moves smoothly at 1000 rpm.(I could never do that with the Edelbrock system. It wouldn't hold 1000-1200 rpm in 1st or 2nd gear). There is also straight line acceleration up to 4200-4500 rpm now. Below is a datalog that shows the engine rpm increasing on its own. At 27 seconds, the engine rpm increases from about 2200 to 2600 all on its own. So, I'm getting closer, but it's not quite there, yet.
