Have a odd IAC logic request

[JeepsAndGuns]

This may seem like a odd question, or request, but theres something I would like for my engine to do. I am not really sure if this is even possiable with the 7427 or not, but I figured I would ask.
This all goes back to my early days when I still had tbi and a 7747. When I would start the engine with the old 7747, the engine would rev up as soon as it fired and then dropped down to idle. I think some call this "flare up" when the engine starts. I actually loved that, as my exhaust sounds good when doing it, it caught peoples attention and helped the engine crank on up. You crank engine, VROOM, then idle.
Ever since I swapped to the 7427, it no longer does this. It just kinda starts, just goes from dead to idle, no vroom or anything. I remember reading that thread on here about the iac logic in the 7747 and it said to reduce the flare up, to lower the iac park position. I searched around on the 7427 and found that and tried to change it, raised it a little, but it made no diffrence, so I set it back. I noticed that when I turned on the key, didnt start the engine, connected tunerpro, it would hold a low number of iac counts. like it ignores the iac park position and sets itself at something diffrent. I found one parameter that was something like "iac added airflow after startup" I have raised this some and it has kinda worked, but its odd, it doesnt do it every time. Most of the time it doesnt do any diffrent, then other random times it will start then the momentairy vroom then idle. I'm just not getting the results I am looking for.
With so many more idle and iac parameters in the 7427, I am wondering if what I am wanting is even possiable. Seems I remember reading the reason the 7747 did it, was the iac parked open, and did not move untill the engine started. So basicly it would hold wide open, engine would start, then the momentairy vromm was simply the ammount of time it took the iac to close.
I am running BMHK, 454, 0E, manual trans bin. I tried (just out of curiosity) a 350, 0D, auto bin (since their are no 350 7427 man trans bins) and startup and idle was pretty much the same (I did find some interesting results with PE, but thats another thread)

So, is there any parameter, or set of parameters I can change to get the result I am looking for?

[EagleMark]

Off topic, but I meant to tell you I looked at all the knock settings in that bin and I don't think knock works? Have you ever got knock?

[1project2many]

That fast idle is often done with spark advance. Start up advance should be high then drop to match what's in the timing table. IAC is usually slower to respond.

[RobertISaar]

i've had IAC settings both cause and fix this, but spark can play a pretty big role as well.

not sure how it would be referenced in $0D though, i'm used to the $A1 nomenclature.

[EagleMark]

I get a kick out of you JeepsandGuns! You get a newer PCM that has this issue worked out and now you want it back...

Couple things I would play with are in Scalers under IAC paremeters:
1. IAC Added Air after Startup
2. Decay Period for Initial IAC Flow
3. Time until Initial Idle Speed Decay
4. Initial Idle Speed Decay Period
5.Initial Idle Speed Multiplier if in P/N

[34blazer]

increase the IAC park position counts and decrease the startup IAC decay values?

[JeepsAndGuns]

Mark, number 1 was one of the ones I have changed, with limited results. I may try the decay period. If I understand that right, thats simply the ammount of time for it to stop doing it? Mabey the decay is too short.

Wonder what parameter causes it to not hold the iac at the park position when you turn the key on, wonder if that could be disabled?

[EagleMark]

I may try the decay period. If I understand that right, thats simply the ammount of time for it to stop doing it? Mabey the decay is too short.

Yes , and it's very short, like 100msec.

Going the 1project2many route
1. Startup Spark vs. Temperature
2. Startup Spark Decay Rate vs. Temperature
3. Startup Spark Decay Multiplier vs. Temperature

[JeepsAndGuns]

I dont think the startup spark is gonna get me the result I want. Remember this thread? I had a problem with it trying to advance timing while cranking.
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?406-Startup-or-cranking-spark

Gonna try the iac added air flow decay tomorrow and see if anything changes.

[1project2many]

Increase the rpm at which spark advance is applied during cranking. In some cals it's number of ESC counts or maybe number of DRP counts before spark. Also, spark and fuel are often started separately. Increase time before fuel is delivered so IAC and advance are ready to go when fuel hits.

What makes you think IAC is changing when key is applied? Remember to test theory... let IAC have time to park after shutdown then disconnect IAC connector. If you find the rpm isn't where you want maybe problem isn't quite as you think?

I grew up with carbs. A warm engine with a slight amount of fuel in the intake would start with a tap of the key. I like that. The sunbird will start with as little as two revs sometimes when it's hot. And it doesn't flare up because there's no oil pressure to support unnecessary engine rpm. But hey, if you like the Ford route then go with it. ;)

[EagleMark]

What's with Fords trying to rev the piss out of a motor before oil pressure? My moms Ford Focus used to rev so high first thing, I cringed every time it started, but it was correct according to Furd?

People complian about 1227747 as it takes several cranks before it fires up. I like it as I usually see oil pressure gauge move before it fires up.

I've found so many things like what 1project2many describes in $0D I wouldn't know where to start. But then I wouldn't be looking for Furd Flare up of engine before oil flow...

[RobertISaar]

father in law's 03 grand marquis does the same thing.... crank it up when it's anything less than fully warmed and it will idle near 1500 after an initial flare of ~2000 or so.

i like my engines not getting above 1000 or so immediately after cranking. and they're all quite fast at firing during cranking.

[EagleMark]

Now I remember looking into the Furd Flare and it was to build heat for the cat!

I hate cats (cars should have dogs), they are contaminating the world with Platinum, rhodiumm, Cerium, iron, manganese, and nickel. Other then USA Copper is also used, but in UK Nickel is not as it casuses nickel tetracarbonyl pollution. So emmissions fixed a couple things then technoligy found it created differant pollutions?

Also, my theory on global warming as it started same time as cats were introduced...
</rant off>

[RobertISaar]

actually, it's been proven cats contribute to global warming....

it's the tradeoff of air quality is why they're still used.

[JeepsAndGuns]

Fiddled around with the decay some yesterday. Increased it 100 at a time. I am up to 400. It seems to be getting the result I am looking for. However, its not doing it every startup. Crank it up, it does like I want. Then next time I start it, it just kinda stumbles to life, no rev no nothing.
I will look for parameters like you mention, see what I can find. Just to clear something up, I am not wanting a flare up like yall are saying the fords do. I dont want it to rev up super high and hold it there for several seconds. I want a free rev to mabey 1500rpm or less, and only do it for like .5-1 second. Just like you blip the throttle. Make sense?