Cant get idle down (UPDATE)

[TYTILIDIE]

My truck idles at 900 RPM no matter what I do. I have the screw set back all the way and still wont go down. Its annoying as hell and I think its making my gas mileage less than what it should be. I checked my program in TP and it says desired RPM is 650. In gear that is. Im not sure what is going on but it sgetting old. Anyone have any ideas? I checked for leaks and dont seem to have any.

 

[sy#2921]

Re: Cant get idle down

Re: Cant get idle down

what tables have you messed with?
f13 along with f18 and 19?

 

[Tooky]

Re: Cant get idle down

Re: Cant get idle down

You sure it's not a vacuum leak? What about a sneaky like like at the rear of the lifter valley where the intake meets the block, or at an intake gasket or TB gasket?

Are your IAC counts 0 on Datamaster when the idle is revving? If so it would be further evidence to suggest a vacuum leak of some type.

 

[SBNova]

Re: Cant get idle down

Re: Cant get idle down

Are your IAC counts 0 on Datamaster when the idle is revving? If so it would be further evidence to suggest a vacuum leak of some type.

Thats what I was going to say.

Check the IAC counts when its doing this and post them. You could also have crud in the IAC passages. The IAC count is whats commanded and may not be actual if theres debris in the way.

 

[JustBeachin]

Re: Cant get idle down

Re: Cant get idle down

My truck idles at 900 RPM no matter what I do. I have the screw set back all the way and still wont go down. Its annoying as hell and I think its making my gas mileage less than what it should be. .

Are you sure it's not the RACING!?

Just a thought.

 

[turbodig]

Re: Cant get idle down

Re: Cant get idle down

I've seen worn IAC pintles do this too.

 

[TYTILIDIE]

Re: Cant get idle down

Re: Cant get idle down

Counts? I have steps. Nothing seems to be at zero though. FWIW, I set the ECM to go into closed loop and it ran like total crap. It was like I was in a diesel at full throttle there was so much smoke everywhere. The idle did come down however but I did a few autotunes in CL and and it wasnt coming up with any fixes. My AFR's were in the 8's. I went back to open loop and everything was fine. Not sure what that was all about.

 

[TYTILIDIE]

Re: Cant get idle down

Re: Cant get idle down

Counts? I have steps. Nothing seems to be at zero though. FWIW, I set the ECM to go into closed loop and it ran like total crap. It was like I was in a diesel at full throttle there was so much smoke everywhere. The idle did come down however but I did a few autotunes in CL and and it wasnt coming up with any fixes. My AFR's were in the 8's. I went back to open loop and everything was fine. Not sure what that was all about.

Any thoughts on this?

 

[gjp]

Re: Cant get idle down

Re: Cant get idle down

I had a leak in the line from the rear of the TB to the pcv valve. It was causing my idle to go up. Check the capped off line back there too.

 

[ghettosled]

Re: Cant get idle down

Re: Cant get idle down

providing you dont have a vacuum leak, or another issue and your throttle bracket is hitting either the tb casting or the torx screw, you can take a pair of pliers and bend the throttle bracket just enough to allow the tb blades to close and bring the idle down.

 

[SBNova]

Re: Cant get idle down

Re: Cant get idle down

Counts,steps, same difference. What are they when your tuck wont idle down?

 

[TYTILIDIE]

Re: Cant get idle down

Re: Cant get idle down

They fluctuate between 36 and 38. I did notice my TPS was at 3%, maybe I do need to bend the stopper back a hair. I have to dig a little more into it when my daughter goes back to her mom tomorrow. Is 36 and 38 fairly normal? I vaguely remember the steps being at those #'s on DM last time I looked and it was idleing normal.

 

[SBNova]

Re: Cant get idle down

Re: Cant get idle down

If your IAC steps are at 30, then the ecm isnt really trying to lower the idle. If it were trying, it would show lower numbers or even 0 while it attempts to close off the idle air passage. Your TPS of 3% could be whats wrong. I never looked at the TPS on myTy, but on my 85' Vette its adjustable by loosening the two torx screws that hold it on. Get a digital volt meter, of hook up using DM or TunerPro RT and adjust it. I *think* 0.54 volts is what it should be set to.

 

[TYTILIDIE]

Re: Cant get idle down

Re: Cant get idle down

OK I take it back, went out to paly with it this morning. TPS% was 0 and the IAC steps were at 126. What does that mean?

 

[TYTILIDIE]

Re: Cant get idle down (UPDATE)

I was looking at table F13 and noticed its set to run at 837RPM at 12-14 volts. IM going to play with this tomorrow nad see if it goes down. I tried another friends throttle body since i sent mine out to Blum and have the same problem. Got mine back today and did a leak test, holds air w/o a single hiss or bubble from the windex. Still deos it. Hopefully its this F13 table.