idle

[birdman]

hey guys, when it is cold out side. my truck does not like to idle, I hooked the computer to it and it said IAC and Lean left bank. I put a new IAC and did plugs and wires while i was at it.
But the truck is still stumbling, if i let it sit and idle it will smooth out, if i touch the gas to throw it off, it will idle like crap again???
also, when i put it in gear it seems to go down to 300RPM and does that when i come up to stop signs. some times it quits some times it will just idle really low.
any ideas??

 

[satan]

So, did ya give up looking for the vacuum leak ?

The "IAC" code indicates that the IAC is not controlling the idle properly, that coupled with a 'lean' code is a sure-fire pointer to 'extra air' getting into your motor after the throttle body.

The lean code being on the left bank can help a little, but sometimes a more central leak will throw the lean code on one bank and not quite throw the lean code for the other bank -- What's the mixture trim (short term) looking like on the right side?

The PCV hose (aft of the oil-filler cvapa nd under the radiator hose there) tends to wear and leak un-metered air... It'd be a good place to start looking for your leak...

Of course the intake manifolds are always suspect, hunting fo leaks with a little carb-cleaner may be in your future (listen to yor idle, spray the suspect area, listen for change to your idle) ...

 

[birdman]

will intake cleaner do the same thing? i have never had this problem with my bronco, i should have just kept driving it

 

[birdman]

i hope its not a intake gasket, the motor pulls good, and decent power for a little truck.
Hope i find the problem i got a buddy with a 6" lift for the truck and i have a set of 33s sitting here, so if the truck can prove its worth lifting i will LOL

 

[birdman]

well, i cant find a vacuum leak. But while the truck was running i noticed that the truck has a slight miss. seems sometimes its missing pretty bad and sometime very little

 

[robmedina]

I had a similar problem, I cleaned the MAF, the IAC, the throttle body, installed a new air filter and fuel filter and changed the plugs and wires and installed a new PCV (plugs, wires and PCV were last things I did) turns out the PCV valve was just sitting over the hole- put the new one in anyway and now she runs like new.

 

[birdman]

ya i put on a new IAC, new plugs & wires, and new PCV. so not sure what else, i have to wait till next weekend to see whats causing this miss

 

[birdman]

Its really weird. it can run fine sitting after start up. but if I give it a quick shot of gas, it will start to idle up and down, then figure its self out and go smooth again. driving fine but let off the gas and the rpms drop fast. if i brake but let off the gas slowly it will its not as bad.
I am kinda lost, going to see a friend this weekend hope he can help

 

[Rudie Del Rude]

check the maf. I had a similar problem, first i found a rotted vacuum hose that connects on the underside of the throttle body, swapped it out and it smoothed out a little bit but still kinda loped. Checked the readings on my maf and it was going crazy. after i swapped that out it ran perfectly.

 

[Rudie Del Rude]

will intake cleaner do the same thing? i have never had this problem with my bronco, i should have just kept driving it

As long as it has "Warning: FLAMMABLE" on the front of the can it should work. You might want to make sure the can says its safe for your cats too. Carb and choke cleaner is good for finding leaks for sure though.

 

[birdman]

ya i checked for a vacuum leak with carb cleaner and tryed propain torch and couldnt find one.
i swapped the maf a few weeks ago and it didnt make a difference either.
i will check that line on the throttle body though and see what i can find

 

[Rudie Del Rude]

its a pretty small vac hose, but its enough to throw the idle off. it runs from a nipple on the underside of the throttle body all the way over by the front of the battery i think.

 

[birdman]

the funny thing is, now that is worm out its running normal

 

[97RangerXLT]

you have a 97, there is a tsb on the lower fuel rail gasket leaking. usually you will get a bank one and two lean condition, but worth checking out if yoiu cant find a vacuum leak anywhere else.

http://www.therangerstation.com/forums/showthread.php?t=94437

there is a how to on replacing all the gaskets. if you just are doing the fuel rail gasket, you will only have to deal with the upper intake and the fuel rail o-rings and gaskets. you won't have to take the valve covers off.

Good luck,

AJ

 

[Big Jim M]

B-man if it runs normal when the temperature outside is warm and bad when it is cold outside then the first thing I'd do is instll a new temp sendor for the computer.. Many times that sendor tells the computer the engine is warm when it really isn't!
Big JIm