Cold Idle Questions

My setup:

1227747 $42 ARPC 5.0L manual bin on a CJ5 with 304 V8 and manual tranny with no EGR or smog equipment. Also has headers and performer intake.

I have the system running very well except for a few issues:

My first question is how do I increase the cold idle RPM while the motor waits for the closed loop conditions to kick in? The motor runs well at 800 RPM or so in very cold temps until the system goes closed loop, then it runs at 1100-1200 RPM and slows down as it warms up. I have the motor running in constant closed loop (don't go open loop idle) if that helps to know.

Another question I have is can I decrease the minimum coolant temp for closed loop and the cold engine closed loop timer with a heated O2 sensor? Its an NGK sensor post header if that helps.

Last question. My hard/fast takeoffs suck especially when compared to my carb setup. when I try a hard takeoff from a stop (warm or cold), the motor seems like it cant keep up for just a moment then goes like crazy once it gets going. What are some tips/tricks for dialing in a proper takeoff (I can barely spin my tires in the dirt and that just ain't right!).

Thanks!

It would be all too handy if there was a desired rpm table for a cold motor during the choke phase, but all I can find is the "IAC position vs coolant temp". Is this the table I want to change to get a little more idle for my cold motor? If I increase the steps, will also have to bump up my fueling to compensate?

i know the heated NGK sensors heat up in under 60 seconds, so I can possibly decrease the closed loop timer to 60, but what about the minimum coolant temp? It is somewhere around 70* minimum temp, but with a heated o2, couldn't I drop this to its minimum and rely solely on the timer? This would help on those nasty cold mornings.

and nobody has any tips or tricks to get the perfect launch? I've toyed with my AE per delta TPS table, but it seems to not affect the split second where the motor doesn't get the clue that I'm trying to giddy up. And, of course, it being a split second, it's hard to capture in a data log, and it takes a serious edge off of any power I try to put down during a launch.

cold engines have less efficient combustion and require more fuel to run, and o2 sensors only hit stoich. the heater helps the o2 get to operating temperature faster for sure, but there still are temperature requirements for running stoich. you can reduce the coolant temp and timer values quite a bit, especially with a calibration designed for a non-heated o2, but if you go too far you'll end up with a band of rough running somewhere in between cold and warm. it'll want more fuel, and the o2 will forbid it.

you dont want closed loop on a cold nasty morning, you want open loop so it can run a bit richer until it's hot enough in those combustion chambers and in your intake where it doesn't matter. in your tbi, intake temperature is the big one - that big hunk of cast iron is a primary element in fuel vaporization. before the coolant gets it roasting hot, it's just a river of pooling inefficient fuel, and since your fuel ends up just running all over the place instead of atomizing, you need more fuel that you'd expect. if it runs substantially better in closed loop than open loop, it's probably because the fueling in your tune is way, way off.

one way to get a bit of a baseline on closed loop enable temps/timers that i've used, is to set the values really low, and just let it run like crap, for testing purposes. drive gently till the trims level out and it stops running like crap, and record the time and coolant temperature when that happens. go like 15-20% above that for safety and variance in operating conditions, and you should be ok.

take-off power? ae helps, but mostly just for small transitions so it doesn't bog during normal driving. ae is 'lots of gas, because it's going to go lean for a sec, and we have catching up to do.', not 'we need tons of gas cause we're trying to burn rubber'.

heavy acceleration power is all power enrichment fuel, and proper timing advance. remember, everything you do when you first smack the pedal to the ground is in that 100+kpa map column of your tables. is the missing 'giddy up' somewhere around 1500rpm? 1200rpm? are you by chance at like 6 degrees of timing advance in those regions?

try a bit more timing advance in the low map low rpm areas. stock maps are really slack in that area, perhaps since bad drivers might horribly lug the engine or try towing a boat up a hill at 1200rpm. your PE fuel might be a bit off in that area too; most people don't have their high MAP ve columns tuned very well; since they're a bit scary to gather data for with narrowband sensors, and the fact your engine seems to want closed loop so badly also leads me to believe your fueling could use a bit more work in general.

there is a cool compensation timming table in the 7747 also you might adjust, and afr vs temp.

Thanks for the reply gentlemen. As for the timing, I should've mentions that I'm currently fuel only, and my timing is handled by a DUI dizzy at 12* base timing and I'm at 5,000' elevation. I suppose that means my base timing is like 7* at sea level (elevation compensation of 1* per 1000'). I'll kick the base timing up to 14-15* and work on my VE table and see if that helps my launches.

i did adjust the Afr vs temp table, and that helped a bit. The idle speed hasn't changed any though. Now it runs cold at 850 rpm, goes to 975, when in closed loop, the. 800 for warm idle. I'll work on the things suggested and report back. Thanks

if you can set it up to have computer controlled timming it will help both problems you are having.cold engine open loop some bin files advance the timming 15 degrezz then on a hot restart they may retard timming up to 5 degrezz till operating temp is met.

I was afraid someone would say that. Haha. I don't like the idea of hacking up my DUI dizzy to run on the computer, but I'm not opposed to it. Is it hard to convert these DUI units to ESC?

you must already have timing reference for the ecm if injection is working, so it should be trivial, just install an ICM to fire the coil instead of having the distributor do it?