LA sequential fuel and spark EFI conversion

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I've been trying to dial in the cold start on my setup. The one thing that has been driving me nuts in how high the engine revs once it starts. It would rev to about 2000 RPM then drop back down. The way the software works (as I understand it), is it opens the IAC wide open during cranking then ramps back down to whatever the setpoint is for the given engine temperature. I ultimately ended up taking the IAC off, running the plunger all the way until it came out of the motor, and put a small piece of 5/16" fuel line on the shaft to act as a travel limiter. This seem to do the trick since it only ramps to about 1600 now after the start. I'll have to see how this works out when it gets cold outside. I'm thinking the air passage hole in the top of the throttle body may be too big. It's .550", I don't know how big the hole is on the higher end throttle bodies, but I'd be interested to learn.

Messing with the fuel table I also learned under normal driving, the engine ends up operating in the same RPM and MAP as the engine idles. I assume this is under deceleration because it ends up being rich. I took some fuel out, then it idles super lean. Good thing is there is an easy fix for that. I enabled the idle VE table, which is simply a small table the computer uses when certain engine idle criteria are met. This fixed the problem immediately. Now it can idle at a nice AFR and I don't see a rich condition under decel.

Learning every time I take it out.....
 
I've been trying to dial in the cold start on my setup. The one thing that has been driving me nuts in how high the engine revs once it starts. It would rev to about 2000 RPM then drop back down. The way the software works (as I understand it), is it opens the IAC wide open during cranking then ramps back down to whatever the setpoint is for the given engine temperature. I ultimately ended up taking the IAC off, running the plunger all the way until it came out of the motor, and put a small piece of 5/16" fuel line on the shaft to act as a travel limiter. This seem to do the trick since it only ramps to about 1600 now after the start. I'll have to see how this works out when it gets cold outside. I'm thinking the air passage hole in the top of the throttle body may be too big. It's .550", I don't know how big the hole is on the higher end throttle bodies, but I'd be interested to learn.

Messing with the fuel table I also learned under normal driving, the engine ends up operating in the same RPM and MAP as the engine idles. I assume this is under deceleration because it ends up being rich. I took some fuel out, then it idles super lean. Good thing is there is an easy fix for that. I enabled the idle VE table, which is simply a small table the computer uses when certain engine idle criteria are met. This fixed the problem immediately. Now it can idle at a nice AFR and I don't see a rich condition under decel.

Learning every time I take it out.....
Yes the iacs are typically run with more air on start up and ramp down as it warms up. It’s kind of counter intuitive to a choke on a carb being closed at cold and slowly opening.
Are you running the iac in open loop or closed loop? The two settings work differently but I haven’t gotten my rig running yet with tuner studio to try it out.

Does tuner studio have a decel enrichment cutoff? The Holley sniper has one but I’ve left it off.
 
Took my dart out for a spin today after messing with the tune, ended up pulling some timing out at idle to around 24 and upped the afr just a tad, but the biggest plus was upping the idle rpm by 100 to 1100 seemed to help with my in gear vacuum.
I've read a good way to determine idle timing is to find the amount of advance with the highest MAP. I didn't do this but seems like a good idea. My idle timing bounces between 18-20 degrees based on MAP. I mentioned 13" of vacuum above, my Kpa to inHg calculation in my head was wrong. I idle between 58-60Kpa, that's 15-17". I'd imagine the best way to handle your low engine vacuum may be to adjust the tables to your real working area.
 
Yes the iacs are typically run with more air on start up and ramp down as it warms up. It’s kind of counter intuitive to a choke on a carb being closed at cold and slowly opening.
Are you running the iac in open loop or closed loop? The two settings work differently but I haven’t gotten my rig running yet with tuner studio to try it out.

Does tuner studio have a decel enrichment cutoff? The Holley sniper has one but I’ve left it off.
I've run it in both open loop and closed loop. I honestly think it works better in open loop. The stepper position is based on temperature in open loop. In closed loop it tries to reach a target RPM. I find adjusting the timing at idle vs. opening and closing the IAC has better results. The engine reacts much faster to timing changes than it does to waiting on the stepper motor to move. I had to set the closed loop IAC control fairly aggressive to keep up with the idle, which in turn caused the start up to to be undesirable. I'm happy with the open loop control for now.
I'll have to look into decel enrichment cutoff. I'm sure there's something for it, but not spelled out that clearly.
 
I've run it in both open loop and closed loop. I honestly think it works better in open loop. The stepper position is based on temperature in open loop. In closed loop it tries to reach a target RPM. I find adjusting the timing at idle vs. opening and closing the IAC has better results. The engine reacts much faster to timing changes than it does to waiting on the stepper motor to move. I had to set the closed loop IAC control fairly aggressive to keep up with the idle, which in turn caused the start up to to be undesirable. I'm happy with the open loop control for now.
I'll have to look into decel enrichment cutoff. I'm sure there's something for it, but not spelled out that clearly.

Good idea, I'll try messing with the idle in open loop I always thought the IAC was probably quick enough to compensate but if you've had good results I'll give it a shot. On my last outing I activated the decel enrichment cutoff and noticed that it worked really transitioning from low/high loads at different rpms.
 
Any chance you have a better picture of your coil pack brackets? They are laid out very nicely!
 
Any chance you have a better picture of your coil pack brackets? They are laid out very nicely!

I don’t have any of when I was making them. I just took this one last night for you. The lower portion is a flat bar that back 2 intake bolts go through. Then a perpendicular flat bar welded to that with some tubing perpendicular to that. The tubing goes through the flat bar. I set it all up to get spacing correct, then tacked the tubing in place. It took a lot of time and it is really tight back there.
D4B85353-05BB-46CC-B3F8-794E3FCF90A5.jpeg
 
I don’t have any of when I was making them. I just took this one last night for you. The lower portion is a flat bar that back 2 intake bolts go through. Then a perpendicular flat bar welded to that with some tubing perpendicular to that. The tubing goes through the flat bar. I set it all up to get spacing correct, then tacked the tubing in place. It took a lot of time and it is really tight back there.
View attachment 1715790877

Nice!

I missed that you packed LS coils in there. I guess I didn't look close and assumed they were the two ended block coils like the Viper runs.

And yes, I know it is in the text. Been a long time since I read it. :lol:
 
I don’t have any of when I was making them. I just took this one last night for you. The lower portion is a flat bar that back 2 intake bolts go through. Then a perpendicular flat bar welded to that with some tubing perpendicular to that. The tubing goes through the flat bar. I set it all up to get spacing correct, then tacked the tubing in place. It took a lot of time and it is really tight back there.

Thank you! It really is tight back there, and the coils are a bit bigger than I had realized. I’m going to attempt similar positioning, but am curious to see how my distributor sensor will impact space in the area.
 
Thank you! It really is tight back there, and the coils are a bit bigger than I had realized. I’m going to attempt similar positioning, but am curious to see how my distributor sensor will impact space in the area.

mug you’re using a distributor base as a cam sensor, they won’t fit in this arrangement. It’s really tight and it took a while for me to make it work. I made this bracket with the engine on a stand and it was a pain. It would be much worse if it’s in the car
 
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