Try something for me

[paddlenbike]

3.4 V6 owners, from a speed of 45+ mph, push in the clutch (or shift into neutral if you have an auto) and note what the RPMs do as your speed declines to 0. (Engine should already be warm when you do this.)

When moving at 30+ MPH my RPMs will consistently stay at 1500, then below 25 mph or so the idle slowly comes down until stopped when the idle returns to the normal 700 RPM range. I never noticed this before and I'm wondering if it's simply because the engine is being force-fed air when moving or if something went wrong during my TB cleaning. Idle is perfectly normal at all other times.

Oh, and please don't crash when trying this. :tongueout: Thanks!

[20005spd]

FTR mine is a 5spd, ive already noticed my truck doing exactly this. im pretty sure its done it since ive had it 96kmiles. i just kinda assumed its normal, if it did it at idle id be a lil worried.

[4x4mike]

You know how mine works. I assume it always does this.


Oh, and please don't crash when trying this. tongueout Thanks!
Have to put the disclaimer to cover your ass :gay:

[YotaFun]

Mine started to dothis a couple of months ago.
It use to but now dosen't

I cleaned the IACV, and made sure my TPS was good,
And still no go, a little better but still not like it use to be...

[paddlenbike]

I thought it might be normal. I would think the engine is ingesting a little more air when moving (especially with the deckplate mod), so the EFI will add fuel to keep the A/F ratio the same, which would have the effect of increasing the idle with no load. I did notice though that Mike's 4Runner (also a 5-speed like mine) does not do this--his will maintain 700 RPMs at 70 mph. Both of our trucks have recently cleaned throttle bodies and IAC valves and otherwise run/idle great and are getting excellent gas mileage, so I guess I shouldn't worry. Just curious who's junk is messed up. :)

[MTL_4runner]

I thought it might be normal. I would think the engine is ingesting a little more air when moving (especially with the deckplate mod), so the EFI will add fuel to keep the A/F ratio the same, which would have the effect of increasing the idle with no load. I did notice though that Mike's 4Runner (also a 5-speed like mine) does not do this--his will maintain 700 RPMs at 70 mph. Both of our trucks have recently cleaned throttle bodies and IAC valves and otherwise run/idle great and are getting excellent gas mileage, so I guess I shouldn't worry. Just curious who's junk is messed up. :)




The IAC should not matter what speed the truck is at, so in neutral with your foot off the accelerator, the engine should be idling around 700RPM. If your IAC was not working right, the idle would also be higher with the truck at 0MPH which doesn't seem to be the case. It may be that the engine control is set higher at above certain speed for standard vehicles since letting out the clutch quickly could spin the wheels but I'm only speculating.

[4x4mike]

his will maintain 700 RPMs at 70 mph.

Downhill no less.

When you were looking at my gagues the tranny was in N and we were just ghost riding. I didn't put the transmission into gear until we were at about 60 and I pop it into 5th with the clutch. I think we were getting up to 75 and 80 and it was at normal idle rpms. Calculated mpg: 99.9 :angel:

[Nuthuts96]

pretty sure when i was coasting down hills (while moving cross-country, with trailer), the rpm's would drop to idle speed at 60mph+ .
if you're not opening the throttle more (accelerator down), you're not letting more fuel in the intake, thus no [more] air in the intake than what would be flowing in at idle. so i'm thinking, it should be idle rpm's at any speed if in N or clutch disengaged (pedal down).

right guys? or have i just started too early :drink: :D

[20005spd]

my truck doesnt do this all the time, its just spotty. it has got me wondering many times though so your post was very interesting to me. i kinda figured it might be something to do with the tranny spinning at vehicle speed sort of forcing the engine to rev up a lil bit... just something to ponder

[MTL_4runner]

pretty sure when i was coasting down hills (while moving cross-country, with trailer), the rpm's would drop to idle speed at 60mph+ .
if you're not opening the throttle more (accelerator down), you're not letting more fuel in the intake, thus no [more] air in the intake than what would be flowing in at idle. so i'm thinking, it should be idle rpm's at any speed if in N or clutch disengaged (pedal down).

right guys? or have i just started too early :drink: :D


Correct.

Throttle plate limits air and IAC does the fine tune air adjustment to hold the idle at 700 RPM. If the throttle doesn't move and the vehicle is in neutral, the idle should stay rock steady regardless of vehicle speed.

[20005spd]

so whats the mystery behind this anyone got any real ideas?

[paddlenbike]

I don't know either, which is why I posted the question. I wouldn't know what to do about it anyway since the IAC is clean and functioning properly. The only odd thing I see is a high idle when moving. If I were to never push the clutch in and coast to a stop, I would never know the difference.

[RunnerUp]

maybe its like the toyota tick... no one knows why, but mosts trucks do it...

[CJM]

maybe its like the toyota tick... no one knows why, but mosts trucks do it...


I still cant figure it out on mine. When running it does that tick sound and no one has a clue other than maybe an exhaust leak..

[20005spd]

you could be hearing the evap purge valve clicking. mine does it and its normal. and i also have a very small exhaust leak in the engine area

[YotaFun]

We'll I tried this again last night and wouldn't you know it, idle fell back down to 700rpm.

The things I have done recently are:
Valve cover gaskets
Cleaned entire intake plenum
Cleaned throttle body
Cleaned IAC
Replaced PCV

Made sure everything was torqued to spec and hoses were good.