Base Idle Speed

GTS · #1 Mon, January 3rd, 2011, 02:43 AM

So I was messing around and found the Base Idle Speed table. I see it's idle speed vs EOT. So I thought well I'll just keep the rpm up when the EOT is lower. Kind of a self adjusting high idle. So I left the first two pointers at 1200 @ -40°, moved the 3rd to 1000 @ 130°, Moved the 4th to 703 @ 135°, 5 to 703 @ 160° and left 6 at 703 @ 8191.75°.

I stuck the chip in on a cold engine and wam it idled up to about 1000rpm. I got all excited! Then after the engine was warmed up (confirmed temps with AE) it never idled down. Is there something I need to do somewhere else for this table to work the way I set it up?

***907DAVE*** · #2 Mon, January 3rd, 2011, 05:24 AM

There is some funny stuff going on with the idle control with these trucks, and I really dont think many have figured much of it out.

If they have, they are staying tight lipped about it..........

Only thing I can suggest is to make minor adjustment and creep up on what you are looking for it to do. This means you may need to make 6 files that are each a little bit different, and see which one works best.

Also, there is a safety concern when setting your idle this way. I can see an accidental "side step" of the brake pedal resulting in an accident. But for you OBS guys I dont think there is any other option when trying to duplicate an "automatic idle".

Just out of curiosity, did you remember to convert to Fahrenheit?

GTS · #3 Mon, January 3rd, 2011, 12:59 PM

You know I didn't even notice it was in Celsius! Thanks for that pointer! I'll have to go back and change that and see what happens! :-)

I do know what you are saying about it being a possible hazard. I did notice when I first tried this in my parking lot where it is icy right now when I'd apply the brakes the front tires would want to lock while the rears were still wanting to push me. So I swapped programs. In all theory if I can get it to work properly it would only be that way for a few minutes so it shouldn't be to big of a deal, mainly just get out of my driveway and by the time I get to the first like a couple miles away it should be nearly getting up to temp where it'll be idling down. I may have to leave one program on the chip that doesn't have the high idle so that I can switch out of it if I need to when it's icy out.

GTS · #4 Mon, January 3rd, 2011, 07:29 PM

Well that worked like a champ! Now that you pointed that out a couple other tables based of temps seem to make a bit more sense that they are Celsius not Fahrenheit.

***cleatus12r*** · #5 Tue, January 4th, 2011, 02:43 PM

Dang the metric system!!

I have given Bill a hard time about metric units in the programming for a long time. Maybe one day I'll convince him to make my definitions all NORMAL.

Dave is also on the right track about the auto-high idle on the OBS trucks.....it doesn't exist. You simply get to set your base idle speed; that's it.

GTS · #6 Tue, January 4th, 2011, 03:47 PM

That's a real bummer!