Throttle stopping injection

[Hustler1098]

Nemo,

What do you run off the stop in the 1/4?

[art leong]

I was just going through this thread. This is for a totally different application. I have a electronicly controled 4 cylinder using LS1 coil over plug setup. I tried using a 2 step that was setup for the LS1 coils. It did what it was supossed to it held the motor at 4200 on the starting line, but the car was off 2 tenths in the short times (compared to just putting it on the floor and using the transbrake, same rpms).
I also developed a lot of blowby when using the 2 step and damaged one of the plugs (broke the porcelain).
I was wondering if the ecu was giving the motor full fuel while the spark was being knocked off a cylinder at a time.
When I read about your fuel problems with the throttle stop. I wonder if the problems aren't related?

[Rich Biebel]

Art...mechanical fuel injection and electronic fuel injection don't have much in common. I've run both so I know quite a bit about them. I did win in S/C using the same Terminator Dave Steltz has now....and I went quite a few rounds over the course of 1-2 seasons of running S/C at Div 1 events. I also built an EFI LT-1 Firebird and tuned it myself and got it running decent. The EFI gets various inputs from sensors to adjust the amount of fuel going in the engine. The mechanical injection is dumb.....it dumps fuel simply by rpm and barrel valve position. The biggest issue with a Ron's type unit is that the barrel valve is at wide open fuel flow very early in it's travel...so at part throttle you will likely be way fat on alcohol.....that is not a bad thing sometimes...but other times it will be and that is the problem.....inconsistancy tracked back to part throttle fuel mixture. I had it mostly under control using the electronic leanout. On my Firebird.....I added a 2 step and a finger button intending to try it as I saw so many people using that setup. I tried it once in the pits and really hated the way the engine was loaded as well as trying to hold the finger button and the brake pedal....I never used it and the next year NHRA banned finger buttons anyway. I foot braked that Firebird every run I ever made with it. I have zero experience with coil pack stuff.....and don't want any!!! EFI is great but it sure takes a lot of experience to get them running real nice. My old car has been tuned recently by a racer with a lot of EFI experience.....I'm glad to learn I had it running pretty well down the track....he was able to clean it up some around the pits/staging/burnout and on the launch.....picked up maybe 1/2 tenth