cold idle hunting

[Tbruz]

2003 Explorer Sport(2 door) with a 4.0 engine; 100K miles: NO CODES stored, NO CEL on

1st daily cold start, the idle jumps up to around 2k and then drops to 1100 to 1500 to 900............and so on
Idles steady as a rock after about 30 seconds or on subsequent starts.

Keep reading about intake gaskets going on earlier models but were 2003 also prone to this?
Also only see the lower intake gaskets( 6 individual O gaskets) from Felpro.
Should this vehicle and engine have the upper and lower gaskets?

Feels like I'm trying to force this intake gasket fix work for my particular issue.

Any thoughts appreciated
Thanks
Tbruz

 

[swshawaii]

PCV elbow checked? Does NOT always throw a CEL or P0171/P0174 lean codes. IAC, MAF, and throttle body clean?

http://www.explorerforum.com/forums/showthread.php?t=314670

 

[PAExplorerXLT]

Seems like just about every other Explorer here has this symptom, as does mine. Changed the upper gaskets and a host of other components but made no difference. Took it to another shop and he did a smoke test and said the lowers need to be replaced, for $1200. No thanks. Went back to the first shop and they said they did a smoke test after replacing the upper and they see nothing. They have no idea where the vacuum leak is, if that is what it is. This is a complete mystery.

 

[Tbruz]

Elbow has been replaced, that one threw a code and I followed the awesome adivce of this website to correct it!
I'll be cleaning IAC, MAF and TB over the weekend.

Can anyone confirm this year 2003 Exp Sport 4.0 should have BOTH upper and lower intake/plenum gaskets?
Can't seem to locate the uppers or both on the usual websites like rockauto.
Thanks
Tbruz

 

[rb142]

Your description is exactly what it is supposed to do on a cold start. What is it that you are looking to fix?

 

[Tbruz]

the idle jumps around on 1st stone cold start , doesn't stay elevated and gradually come down.
2000 to 1100 back up to 1500 down to 900 up to 1500 down to 1100 up to 1300 down to 1000....
This is normal??
Thanks
Tbruz

 

[Bobmbx]

the idle jumps around on 1st stone cold start , doesn't stay elevated and gradually come down.
2000 to 1100 back up to 1500 down to 900 up to 1500 down to 1100 up to 1300 down to 1000....
This is normal??
Thanks
Tbruz

Is your AC compressor running when this happens?

 

[Tbruz]

No AC on, its 20 degrees here in the Northeast!
It "hunts " like that for around 30 to 45 seconds then smooths out as it warms up.
Thanks
Tbruz

 

[swshawaii]

Clean the IAC valve first. 15 minutes and some cleaner. GL

http://www.mysporttrac.com/mysporttrac/projects/CleaningIAC/CLEANING_IAC_MOTOR.htm

 

[PAExplorerXLT]

Hunting is not normal and everybody is of the opinion that it is a vacuum leak, but where? I have mine checked top to bottom, including changing the upper intake gasket, IAC, etc. Couldn’t find it. It takes 30 sec. to stabilize so I just have to live it. Above 50 is not an issue.

 

[Tbruz]

PAExplorerXLT
What year is your ride?
Did you clean IAC or replace it?

Intake gaskets replaced upper only? Does yours have lower gaskets?

Thanks
Tbruz

 

[PAExplorerXLT]

Mine is a 98. One of the first thing I did was replacing the IAC. The mechanic who replaced the upper gasket says the lowers are fine. He says he did a smoke test. The shop owner said if the lowers leak it won’t just cause a vacuum leak. I’ll lose coolant too. This is the first time I hear this.

 

[Tbruz]

Issue Resolved

Went out this morning planning on cleaning the everlovin $%$# out of the IAC, TB and MAF in preparation of what seemed like an inevitable intake gaskets R&R.

Looking around at how I was going to approach the removal for cleaning I noticed a tube disconnected between the the air bridge and the intake plenum.
This tube was halfway between the air filter and the MAF.
connected it up, started the car and it fast idled perfectly around 1500-1600 RPMs and gradually and smoothly dropped to 1K-1100 and stayed STEADY with no hunting.

Thinking back to the last time I worked on the vehicle(January 2014 for thermostat housing) I know I replaced everything properly, in fact I'm a little OCD about checking and rechecking things I unplug and/or disconnect.
Then it dawned on me that I had taken the vehicle in for a oil change back in September at one of those quick oil change places and during their high pressure sell job they tried selling me a new air filter for $37.00 (which it didn't need by the way). In all likelihood , they did not reconnect this tube properly or even realize that it came undone as they put the old filter back in.

All is well with the Explorer, for now.
Thanks
Tbruz

 

[swshawaii]

Bet that will be the quickest and cheapest fix you will EVER have. Good guys CAN win sometimes, right? LOL

Clean them anyway, you'll be surprised how much smoother your engine runs if they've never been done before.

 

[lobo411]

The shop owner said if the lowers leak it won’t just cause a vacuum leak. I’ll lose coolant too. This is the first time I hear this.

Find a shop that knows something about cars imo.