Tuning Idle

[midnite88]

Hey guys, its me again. Been awhile sice I've been on but I decided to do some tuning to the ole truck again. So to begin with, what I have. I have a 88' F-150 in the process of turning prerunner/daily driver. Goes to and from work everyday. Its got a 302 poked out to a 306, Comp XE258 Cam, 533/544 split lift, full roller FI cam, standard E7 heads, the big truck intake with standard dual TB, AOD trans that I built with 4r70w gearset, 4:10 rear gears and 33's. Also running a MS2Extra with 3.3.0 Firmware running batch fire injection, TFI for spark, PWM idle control. Pretty basic really. It runs great down the road but I cannot get it to idle for crap. Its either 12.0:1 afr or it starts surging if I lean it out. Id like it to idle in the 14's if possible but she gets cranky when I go that lean. I need to make a datalog during idle for you guys but my current tune is below. I know its a little rough, I just recently did the 3.3.0 firmware update and had to start over with alot of the tune, only to realize there is 3.3.1a now, dope

MidnightTune3-21-14.msq

[ewflyer]

just a thought here: I've noticed that a couple of people in past threads have mentioned solving idle issues like yours by changing the "number of squirts". Maybe the number of squirts is something that starts to make a difference as the engine slows down to idle speed. Like I said, just a though.

[dontz125]

Changing performance by changing number of squirts is often a sign that your injector dead time is incorrect. It's actually a rough and ready tuning technique to flip back and forth between 1 squirt simultaneous and 2 squirts alternating, all the while adjusting the dead time. When the AFR is the same for 1 and 2 squirts, the dead time is pretty close.

[BigLou240sx]

Changing performance by changing number of squirts is often a sign that your injector dead time is incorrect. It's actually a rough and ready tuning technique to flip back and forth between 1 squirt simultaneous and 2 squirts alternating, all the while adjusting the dead time. When the AFR is the same for 1 and 2 squirts, the dead time is pretty close.

Wouldn't that still be 1 squirt per bank... in other words, no difference to dead time between 1 squirt simultaneous and 2 squirts alternating? Believe that to do the dead time rough tuning technique, you'd have to go from 1 squirt simultaneous (or 2 squirts alternating) to 2 squirts simultaneous (or 4 squirts alternating) (respectively)

[dontz125]

You are correct. More / less squirts shows the problem, same number of squirts doesn't change anything.

*sigh* More coffee ...

[slow_hemi6]

Just for info I have an XE262 and my best idle an indicated 13.2. Always has been carb or efi. No good at 14.

[midnite88]

Thanks for the replies guys. XE262 is pretty close to hat I have. I think I may have slightly more duration on my cam, been awhile since I looked at the card though. I did change from 2 to 4 squirts alternating because of batch fire. I'll try going back to 2 to see if this helps. Also, is it worth my wile updating to the 3.3.1a code before fusing with it much more?

[kaeman]

from what I can tell, its always a good idea to upload the latest firmware for your ecu, they are fixing bugs or adding features or they wouldn't be making the new versions... I would update before spending to much time tuning... the bug they fixed might be something you are fighting...
don't worry about idle afr being 14.? because every engine like a little different idle afr, mine prefers to be about 13.8, since you are not worried about passing smog you just want a smooth idle, so go with whatever afr gives you the idle you want.
good luck.

[midnite88]

Well, figured out part of the problem, my fuel pressure regulator took a dump and was proving crazy fuel pressure right before the diaphragm popped and started spraying fuel all over my engine bay, made for a interesting drive home.