Engine won't idle until warm

[duffbeer911]

Hi,
I've got this issue with my 3rd gen 4runner where it won't idle at all until it is warmed up. Every day is like this, morning or evening, it takes about 5-10 minutes of revving the engine until it will idle without stalling. Additionally, it will occasionally stall when it is warm and I pull up at a junction or something. Once it is warm and idling the RPM is sitting at 500rpm.

I've searched through the forums and tried a few things suggested from older threads. Put new spark plugs in (NGK) and changed the fuel filter a couple days ago and actually it is now running worse! The old spark plugs were very black and probably hadn't been changed in about 4 years.

Any ideas what could be causing this? Any advice on what we should look for?

Appreciate any help. Thanks

 

[wemslie97]

I would try cleaning your MAF and throttle body. Easy and rewarding!

 

[HiLife]

I would check out the engine temp sensor is within spec with a ohm meter.
It would be good to go through your iac valve to make sure it's not hung up in one position. I would be good to do a good iac cleaning while you're there.

 

[TheDurk]

I would check out the engine temp sensor is within spec with a ohm meter.
It would be good to go through your iac valve to make sure it's not hung up in one position. I would be good to do a good iac cleaning while you're there.

Agree.

On the ECT: put a live scanner on it and see if the sensor reports a cold engine at start-up as it should see what temp it idles at normally. Also note if idle evens out when switching to closed loop, or continues in closed loop. Check carefully for vacuum leaks, the cause of most idle issues.

IAC is also likely issue.

 

[baja1]

you dont even have to remove the IAC just pull off the intake tube exposing the IAC coil. the coil is held on by 2 phillips screws, remove it revealing the armature (looks like a black knob) rotating this will be an idle control, if it doesn't turn the IAC is stuck and needs to be cleaned.

 

[TheDurk]

you dont even have to remove the IAC just pull off the intake tube exposing the IAC coil. the coil is held on by 2 phillips screws, remove it revealing the armature (looks like a black knob) rotating this will be an idle control, if it doesn't turn the IAC is stuck and needs to be cleaned.

Use a JIS driver on those screws or you will strip them...

 

[duffbeer911]

ok thanks guys for these suggestions. Will try some of this today/tomorrow and see how it goes.

 

[alumarine]

Is it throwing any codes?

 

[duffbeer911]

thanks for the replies. Turns out it was the throttle position sensor ... replaced it and everything is running great.

cheers