Question about Fuel: Steady State: Target Injector Timing. My intake valve closing angle is 44 deg ABDC. According to the ACCEL instructions I should enter 584 deg in the table. My calibration came out of the box with 360 deg for all table entries. Will this make a difference? Thanks in advance for any help.

Scooter

Might of sounded like a doofus in that last post. I bought into the sales pitch about getting a cal that would be close after submitting my engine specs plus all the warnings in the literature about inexperienced tuners making changes causing catrastophic engine failure. Anyway, I changed the target injector timing (TIT) and it made no difference. Found the data logging function and concentrated on my idle RPM's and MAP's in the VE table, adjusted slightly numerous times and brought Actual A:F pretty close to Target A:F. Running better. This stuff's pretty cool.

Scooter

Glad you got it figured out. It should make a difference at higher power levels when the injector needs all of the time necessary and at the right point in the stroke to inject fuel.

I bought my unit from a dealer who swore I was going to get a cal that was near close. I knew right away he was full of BS when he said he didn't need to know my cam specs or other basic info about my engine.

I've heard that I should be able to tune this thing for a smooth idle, no matter what cam. wondering if that's true. I've been playing with it all morning. In the Idle Config screen I set the min TPS% values where I can disable idle IAC control and idle timing correction. Also closed loop enable/disable switch. Played with various combinations. Disabling closed loop had the biggest impact as far as smoothing out the idle. Forgot to play with ignition system delay. Right now, at idle, timing shows at 20 deg. Finally got it where timing doesn't jump around until I force it to 10 deg. Still jumps between 9 - 11 deg, won't stay solid 10. Also can't the IAC setting to stay at a solid number, 5 I believe is what I'm looking for. Cam @ .050 is only 236/242 .521/.540. Should I be able to get a better idle, currently bouncing between 850-950 RPM.

Scooter

It's hard to say without more specs on your motor but I would guess the answer to be "yes." I don't know what the timing should be on an SBC at idle, but you need to remember that you can't go by specs for vacuum advance type systems. You need to set the idle timing to be the equivalent of base idle plus vacuum advance. I would guess you need more than 20. Also make sure that you've got your VE map smooth at idle conditions. You can do this by taking a look at the 3D plot. Big disparities between adjacent cells can also cause a rough idle.

first, I highlight all the fuel cells it's hitting at idle and make them all the same number. Not sure what a/f you're shooting for but some motors like to be a bit richer than 14.7:1 at idle with a lumpy cam. Give it what it wants, don't get hung up on the numbers. If you richen it to 14:1 for example and it picks up rpms and smooths out then it's happier there.

I also don't lock the timing at idle, I make use of the idle timing compensation to smooth the idle. Even a bone stock new car will jump around at idle, and the computers help with moving the timing around to stabilize the idle speed is welcome. I also run at least 20 degrees at idle also. That doesn't mean it will stay at 20 though, it may jump 5+ degrees either way to keep the idle even.

Make sure the tps is properly set and that the config number for idle tps is correct; the computer needs to know when it's idling vs off-idle.

I also like to properly set the minimum idle screw properly to allow full use of the IAC. Once the engine is fully warmed up I shut off all idle timing compensation and then command a very low idle rpm number, like say 300 rpm. This will close the iac all the way down trying to get the rpms that low, and the only thing keeping the idle speed is the throttle body blade setting. Set this to get your minimum idle speed of say 850 rpm (or whatever speed you want). Lock the throttle body screw down and then reset your desired rpm in the computer, double-check your tps to see if it changed (which is likely if you moved the throttle blade screw), and turn the idle timing compensation back on.

When set as above the iac will be pretty much closed off and not need to maintain your normal warmed up idle speed, so it will have full range to work as it should for higher cold idle, or any different loads on the engine that try to pull the idle speed lower than you request. If the throttle body blade is too far closed you'll use up the iac to try to get the idle speed up; too high and it'll close the iac down and will be pulling timing to try to lower the rpms.

Jody

Thanks guys, good info. With the holidays over it's back to real world and I'm out of town on a job. Maybe back on it this weekend and put that info to work. I will keep you posted.

Scooter

Ya'll probably gave up on this one but it's not dead. I wasn't quite happy with the idle and didn't want to run it for fear of running it too lean and losing too much. I'm an over-cautious perfectionist. I scheduled chassis dyno time with somebody that knows EFI. Working 6 weeks on, 2 weeks off and the guy with the dyno booked 3 weeks in advance guess what happened. After 3 hours on the dyno, the truck is a REAL BLAST. The stocker 60's on the rear ain't gonna last long which is a good thing. Their sole purpose was to get thru the dyno tune and see how long they'd last.

My reason for resurrecting this thread is because I'm a SS nut with a SS pickup that's been in work for years, lusting for a Chevelle SS and visiting that site for years, posted my deal on there and was referred to this site. You guys responded with suggestions and encouragement and wanted tokeep the fire burning. Camaro people rock. 18436572 forever! Thanks guys.

Scooter