Initial idle right after cold startup

[ChrisV 02 - Z28]

It isnt really a problem but kinda buggin me...
When I do a cold start it fires right up and idles fines AS LONG AS I DONT MOVE THE CAR. Say i just bump the car a bit in reverse to get it rolling down driveway then put it back in neutral and let clutch pedal back out, it will hunt quite a bit until the car comes to a complete stop, then learns more or less. after a few seconds it is good to go...

I have absolutley no idea what to log or look at more or less what to tweek

other then that the car runs like a beast

any help is greatly appreciated, tell me what to log and i can post it up for ya as well as my tune, I am at work right now so i will post my tunw when i get home

mods in the link of my sig

[97SilverC5]

Hard to tell without looking at your tune. I imagine its probably the RAF table though. Have you tuned that yet?

[jimmyblue]

You have a pretty heavy afterstart enrichment and
it may be more than needed (esp. after cam swaps)
making it less stable (too slow for the loop). You may
want to play with the enrichment ramp-out rate and
see if it buys you anything. Also check the P/N and
in-gear idle spark advance, this along with airflow are
the two big "modalities" to the idle condition. It may
like more idle advance (especially if over-rich).

[ChrisV 02 - Z28]

here is my current tune...

[colamotas]

bump!

[Russ K]

ChrisV 02 - Z28,

Try this idle tune, I just base lined some tables until I view the scan log. Use my idle config file to do a cold start idle scan. Don't touch the throttle or move the car until operating temp. Then stop & save the scan log.

Russ Kemp

[ChrisV 02 - Z28]

ok i will get to looking at it this weekend
what all did you tweek?

[ChrisV 02 - Z28]

Here is the warmup log i just did using your tweeks...
I used you config file to log
It idled fine, but it always did as long as i dont move the car for minute or two.

I let it warmup without touching anything and stop and saved the log, then went to move the car and it started hunting a bit, which it didnt do before the edits you made. the only time it would hunt is when i would move it without a minute of idle then you could move the car all you want and idle is fine.

I am not sure of what all you changed, because I am unsure of what all they are or do. but could you explain what all you did so i can try to figure it out

thanks

[Russ K]

ChrisV 02 - Z28,

I made a few changes based on the idle scan log. Do another cold start scan like the last one.
Use the compare file to see the changes.

Russ Kemp

[ChrisV 02 - Z28]

What is the point of adjusting the LTFT map and rpm boundaries, what should you set the ranges too, i dont actually mean what number but what are you setting the ranges too????

What does adaptive idle do?

[Russ K]

What is the point of adjusting the LTFT map and rpm boundaries, what should you set the ranges too, i dont actually mean what number but what are you setting the ranges too????

What does adaptive idle do?

In the help files > working with vcm editor > tuning how to's > advanced > volumetric efficiency, is a good explanation. On engines that have a higher idle rpm and map because of a larger than stock camshaft, I raise the low map & rpm boundaries so that the fuel cells cover the ve table.

The adaptive idle is the LTIT (long term idle trim)

Russ Kemp

[ChrisV 02 - Z28]

Also my IAC are something like 140 at idle, isnt that a bit high, could that could any issues? I slightly cracked my TB blade open wiht the set screw ever so slightly, my TPS sensor is at 0.55v i believe and I reset my TPS % to zero. I just didnt want to drill the TB blade. What is the limits on TPS voltage to be considered the IDLE??

[ChrisV 02 - Z28]

I get what the boundaries mean, but what should you aim to set them at...such as should the low map boundary be just above idle and the rpm boundaries set so FTC 4 is idle, that is what I am wanting to find out, and that isnt talked about in the help file. what is considered "mid" and "high" limits

also what is the point in changing the boundaries from stock, since each cell on the VE table has its own individual LTFT and STFT, or is it that for each FTC it has a set LTFT for the entire range of that FTC.

[Russ K]

Also my IAC are something like 140 at idle, isnt that a bit high, could that could any issues? I slightly cracked my TB blade open wiht the set screw ever so slightly, my TPS sensor is at 0.55v i believe and I reset my TPS % to zero. I just didnt want to drill the TB blade. What is the limits on TPS voltage to be considered the IDLE??

There is nothing wrong with 140 IAC, it will go to 310 if needed.
The TPS must be at 0% at idle, if not the adaptive idle won't work.

Russ Kemp

[Russ K]

I get what the boundaries mean, but what should you aim to set them at...such as should the low map boundary be just above idle and the rpm boundaries set so FTC 4 is idle, that is what I am wanting to find out, and that isnt talked about in the help file. what is considered "mid" and "high" limits

also what is the point in changing the boundaries from stock, since each cell on the VE table has its own individual LTFT and STFT, or is it that for each FTC it has a set LTFT for the entire range of that FTC.

Yes, you want the low map boundary to be ~5 kpa higher than the idle kpa, the high map at 80-85 kpa, and the mid map boundary
half way betwwen the low & high map boundary.

The low rpm boundary should be ~100 rpm higher than the idle speed, the high rpm boundary at ~2400 rpm, and the mid rpm
boundary half way between the low & high rpm boundary.
Setting the rpm & map boundaries this way, you will idle in FTC #0.

If your new cammed engine idles at say 1000 rpm & 60 kpa map, with stock LTFT map & rpm boundaries, you will be losing several
fuel trim cells. Note that the stock rpm boundaries are 2500,6502 & 6503! That is losing a lot of FTC's!

Russ Kemp

[ChrisV 02 - Z28]

ok thanks man!

[SuperC1]

Yes, you want the low map boundary to be ~5 kpa higher than the idle kpa, the high map at 80-85 kpa, and the mid map boundary
half way betwwen the low & high map boundary.

The low rpm boundary should be ~100 rpm higher than the idle speed, the high rpm boundary at ~2400 rpm, and the mid rpm
boundary half way between the low & high rpm boundary.
Setting the rpm & map boundaries this way, you will idle in FTC #0.

If your new cammed engine idles at say 1000 rpm & 60 kpa map, with stock LTFT map & rpm boundaries, you will be losing several
fuel trim cells. Note that the stock rpm boundaries are 2500,6502 & 6503! That is losing a lot of FTC's!

Russ Kemp

Hate to bring this back from the stone ages but does this apply to speed density, because currently I'm idling in ftc 22.

[Asylumwarp]

Hate to bring this back from the stone ages but does this apply to speed density, because currently I'm idling in ftc 22.

Yes this is directly related to speed density. the map sensor is for speed density. and a high 60 kpa map reading will affect your ftc. So adjust as he said to see your ftc change.