Cause of parked eratic idle ??

[CarbonFiber AWD]

I've searched and did not quite find an answer to this.....being it that it could be a varied batch of things. (Stock everything..82K)
When in PARK, and warm....the idle will surge from 700 to 8 or 900 RPM continuously.
When first started ...it idles fine and even.
Vacuum leak ? Sticky injector ? Bad plug or wire ? EGR ? :squint:

Has anyone fixed this same problem without having to do ALL of these steps and more ?

Another note which might hint as to what this may be.......I've noticed that while cruising at very low throttle inputs (almost off the gas) the engine seems to be confused as what to do...hold speed,drop speed ??
TPS switch perhaps or the same BS from the earlier idle prob ??
SIgned....want a smoother truck ! :tup:

Thanks................Vinny

 

[wantingasy]

Re: Cause of parked eratic idle ??

I have that exact problem too!!!!!!! I hate it. When I start it, it idles fine, then when it starts to warm up and the idle drops, sometimes the TY want to like cut out, but then will jump up to 900rpm. It does a kind of bobber action.lol. Easing on the gas pedal I have the same problem as you described also. But then like above 1500 rpm, everything is fine. You'll learn to just hit the gas kind of hard.hah

 

[CarbonFiber AWD]

Re: Cause of parked eratic idle ??

I have that exact problem too!!!!!!! I hate it. When I start it, it idles fine, then when it starts to warm up and the idle drops, sometimes the TY want to like cut out, but then will jump up to 900rpm. It does a kind of bobber action.lol. Easing on the gas pedal I have the same problem as you described also. But then like above 1500 rpm, everything is fine. You'll learn to just hit the gas kind of hard.hah

I won't ever get used to a badly tuned ride. I'd rather diagnose this before it causes OTHER concerns.
My best guess was the TPS .....but I think I can hear ( behind the dash) a slight fart frrrrrrrrp sound when I gently decelerate , indicating a vac leak perhaps. Its VERY sutble sounding and you have to have the windows up and stereo off to catch it.I don't know. :squint:
One of these SY/TY veterans knows what this is I'm sure. :tup:
I hope I don't just hear...."your shits out of tune,fix it" !! :roll:
Lol..............V'

 

[attackdog]

Re: Cause of parked eratic idle ??

My SY does the same thing. Let us know what you find so we can fix our trucks too. Thanks.
-Deano

 

[jjorgensen52]

Re: Cause of parked eratic idle ??

I won't ever get used to a badly tuned ride. I'd rather diagnose this before it causes OTHER concerns.
My best guess was the TPS .....but I think I can hear ( behind the dash) a slight fart frrrrrrrrp sound when I gently decelerate , indicating a vac leak perhaps. Its VERY sutble sounding and you have to have the windows up and stereo off to catch it.I don't know. :squint:
One of these SY/TY veterans knows what this is I'm sure. :tup:
I hope I don't just hear...."your shits out of tune,fix it" !! :roll:
Lol..............V'

I have the same problem, except more severe... mine hunts 300 or 400 rpm and stalls when warm... repeatedly. Which sucks. I did have a vac leak but I fixed that. It didn't make it any better, so i think there must be more... time will tell, I wont get to work on it until thanksgiving :tdown:

 

[gjp]

Re: Cause of parked eratic idle ??

Fart sound sounds like the brake booster valve. Next time it idles bad try disconecting and cap off the hose to the brake booster. A leaking valve could cause a bad idle.

 

[CarbonFiber AWD]

Re: Cause of parked eratic idle ??

Well, if your vac leak affected nothing once repaired....perhaps the TPS is a good first replacent ??
I am perhaps due again for rotor,cap and plugs as well as its first change of wires at 82K !
Maybe this will be found once I do all of these things. I hope. :rant:
Any chance there is something else in the hardware I'm not thinking about here ??
..............V'

 

[jbone]

Re: Cause of parked eratic idle ??

the thing I never understood was mine would almost stall out and have crappy idle when cold but it would go away as it got warmer

 

[QUICK STORM]

Re: Cause of parked eratic idle ??

make sure the ignition module gets changed out along with the basic maintenance items

 

[CarbonFiber AWD]

Re: Cause of parked eratic idle ??

Brake booster valve ?? Really ? I've never messed with the boosters on my past cars. Whats involved in changing one out ??Much ?

I also hadn't heard to swap out the Ig. Module for basics either ! All good pointers guys, thanks ! :tup:

More ??
...............V'

 

[gjp]

Re: Cause of parked eratic idle ??

My booster valve started making a sound. (like a fart or sick duck quack when I would let of the gas) I replaced with the nice RPM setup. With my truck I had a high idle at times and turned out to be the valve. Thats why I said to block it off. A leaky egr would cause a stall as well as the ig. module. I would recomend pulling the cap and rotor and looking in there. Module is easy to change. Just remove the 2 connectors and the 2 6mm screws. Clean it up good and put the supplied silicone on and replace.

 

[ZavzTy547]

Re: Cause of parked eratic idle ??

My booster valve started making a sound. (like a fart or sick duck quack when I would let of the gas) I replaced with the nice RPM setup. With my truck I had a high idle at times and turned out to be the valve. Thats why I said to block it off. A leaky egr would cause a stall as well as the ig. module. I would recomend pulling the cap and rotor and looking in there. Module is easy to change. Just remove the 2 connectors and the 2 6mm screws. Clean it up good and put the supplied silicone on and replace.

My truck stalls out at warm-up, then it idles fine after that. I'm not sure if it's affiliated with a vac leak but I know I have a vac leak in my dash, cause my cruise control does not work and I get a hiss after boost, I want to weed out a possible stall do to a vac leak by fixing the leak. On that note, does anyone have scamatics on replacing a vac leak in the dash? Also, how do you reset or adjust the TPS valve?
Thanks
G

 

[SY2932]

Re: Cause of parked eratic idle ??

Brake booster valve ?? Really ? I've never messed with the boosters on my past cars. Whats involved in changing one out ??Much ?

I also hadn't heard to swap out the Ig. Module for basics either ! All good pointers guys, thanks ! :tup:

More ??
...............V'

Piece of cake (unlike most things with these trucks), simply pull the barbed fitting on the check valve that goes into the power brake booster out. There many be considerable force required to pull it out since it is barbed and has vacuum trying to suck it in. You can see it in the upper right of this pic:

It is connected on the end of that zig zag shaped rubber hose that connects to the intake. Part number for it is #18022219. It can be had from the "stealership" for about $6 or $7.

I don't consider the ignition module to be a "routine maintenance" item like the plugs, wires cap & rotor are. It has been my experience that when these go bad, your truck won't run, period. There is "no middle road" so to speak with them and it either works or it doesn't.

On the IAC valve, the pintle should not extend more than 28 MM or 1 1/8" beyond the motor housing. This distance is measured from the base of the IAC where the threads stop to the tip on the pintle. Driving the truck above 35 MPH after it has reached operation temperature will make the ECM reset the IAC valve.

 

[QUICK STORM]

Re: Cause of parked eratic idle ??

in saying basic/routine maintenace it was meant as change it now along with the basic maintenace as most people over look this module for a driveability problem. heat kills the module.

 

[wantingasy]

Re: Cause of parked eratic idle ??

I was thinking that my idle was because I needed cap/rotor/plugs/wires. So I changed those out thinking it would be better, but it's not. I have an MSD coil and it looks fine. Hmm...Brake booster line. Maybe I'll order the stainless one from RPM ( or whoever has it ). I bought a fuel pressure gauge from detroit turbo, but don't know how to work it. Maybe I'll order a different one and ensure my FP is at 42.

 

[jjorgensen52]

Re: Cause of parked eratic idle ??

My truck has brand new plugs, wires, cap, rotor, module, and coil :lol: ... I did not replace the brake booster valve... my truck has almost always made that sort of sick duck quacking noise, I thought it was the ABS system because it seemed to go along with that... hrrrm

 

[CarbonFiber AWD]

Re: Cause of parked eratic idle ??

Piece of cake (unlike most things with these trucks), simply pull the barbed fitting on the check valve that goes into the power brake booster out. There many be considerable force required to pull it out since it is barbed and has vacuum trying to suck it in. You can see it in the upper right of this pic:

It is connected on the end of that zig zag shaped rubber hose that connects to the intake. Part number for it is #18022219. It can be had from the "stealership" for about $6 or $7.

I don't consider the ignition module to be a "routine maintenance" item like the plugs, wires cap & rotor are. It has been my experience that when these go bad, your truck won't run, period. There is "no middle road" so to speak with them and it either works or it doesn't.

On the IAC valve, the pintle should not extend more than 28 MM or 1 1/8" beyond the motor housing. This distance is measured from the base of the IAC where the threads stop to the tip on the pintle. Driving the truck above 35 MPH after it has reached operation temperature will make the ECM reset the IAC valve.

Actually Mike, I couldn't SEE the Brake valve in that picture because I couldn't stop looking at how "WOW" that bay is !
Is the valve not available through parts stores ie: O'reilly ?
Also....not sure what the IAC stands for ??
V'

 

[SY2932]

Re: Cause of parked eratic idle ??

Thanks, I have over 100 hours invested in that endeavor

.

I can't speak for O'reilly's but I tried to purchase one from Autozone when I had to replace mine several years ago. I ended up returning it because the barbed end that went into the brake booster was too small...

IAC=Idle Air Control valve. I am still at work working on my bud's upper intake for my write up. When I get home this evening, I will scan the page outlining how it is adjusted:

 

[Black Knight]

Re: Cause of parked eratic idle ??

Don't buy it from a parts house, got my first one Napa and it didn't fit either, had to get it from the dealer.

 

[CarbonFiber AWD]

Re: Cause of parked eratic idle ??

Don't buy it from a parts house, got my first one Napa and it didn't fit either, had to get it from the dealer.

Stealership it IS then. :squint: Oh well......could be worse. I find it unusual for a check valve to go bad though. At least its a cheap and easy part to do.lol

Thanks for all the help guys and SY2932 !! :tup:
.......V'