Possible IAC problem?

[Lazzman]

I was having an idle shudder issue with my explorer. When I brought it to the dealer they told me it was an IAC valve issue and that I should wait until the truck stalled constantly and I had to keep my foot on the brake and the gas to keep it running.

It does the stalling/ shudder thing the most about 5 minutes after starting the truck when it is cold and it has been sitting awhile. After the truck is fully warmed up the shudder only shows up every 3 minutes or so and not to the level of stalling the truck out.

I replaced the three year old Napa IAC with another new Echlin Napa IAC and the truck still had the same shudder problem and weak idle. What are the odds that I have another bad IAC valve from NAPA? Can other components cause a poor idle, assuming that all the obvious components are good i.e. Clean MAF, Good wires and plugs, clean fuel system etc. Do the aftermarket IAC's have high failure rate?

Also one mechanic was certain it was the IAC because he said the idle did not kick up when the A/C was turned on at idle. I guess it is supposed to do this without fail.

I Want to get some advice before I dump another $100 on a Motorcraft IAC and have the same thing happen.

 

[aldive]

I was having an idle shudder issue with my explorer. When I brought it to the dealer they told me it was an IAC valve issue and that I should wait until the truck stalled constantly and I had to keep my foot on the brake and the gas to keep it running.

Man, sorry to hear of another problem you have with that truck. You must have done something bad in another life.

I replaced the three year old Napa IAC with another new Echlin Napa IAC and the truck still had the same shudder problem and weak idle. What are the odds that I have another bad IAC valve from NAPA?

Slim to none, in my opinion.

Can other components cause a poor idle, assuming that all the obvious components are good i.e. Clean MAF, Good wires and plugs, clean fuel system etc.

Yes.

Are the spark plugs firmly attached to the wire? When was fuel filter changed? Have you monotered the function of the O2 sensors with a scanner? Is the MAF functioning properly. What is the fuel pressure at idle? Vacuum leak? Lower intake O rinngs?

Do the aftermarket IAC's have high failure rate?

Not that I am aware of.

Good luck .....

 

[Lazzman]

Thanks Al

 

[BrooklynBay]

Did you do a compression test? Maybe one of the cylinders isn't working properly. Waht about your plugs, and wires? Have you tested each wire for the same level of spark voltage? Maybe some wires aren't providing enough spark. I think you posted someting about your coil pack in another thread last week, unless that was somebody else.

 

[je5]

Lower intake O-rings I "think".

 

[Lazzman]

My plugs, wires and coil pack are all brand new. I had the lower intake gasket recall done about three years ago, could it appear again after the gaskets were change?

One thing that kind of hits the IAC on the head is the fact that the idle does not kick up when the A/C compressor is turned on. My mechanic told me that is a sure sign that the Idle control is bad.

Also it happens the worst 5 minutes after the truck is first started, in the morning or after its sat for a while. After the truck has run for about 20 minutes it is not as frequent.

The shudder is bad and causes the truck to stall out at times. I could be idling at 700rpm then the shudder happens and the RPM"s drop right down. Sometimes the engine catches it and the rpm's shoot up to 1100rpm then level out to normal. Other times it just flat out dies.

Maybe the intake gaskets shrunk after all these miles?

This blows

 

[je5]

I just replaced my lower intake since it didn't cost much more than the o-rings alone. It solved the same problem for me.

 

[aldive]

Have you tested the IAC?

If no, take a look at Dead Link Removed

 

[BrooklynBay]

That is a nice repair article in that link.

 

[Lazzman]

Thanks Al, I was looking for that article. Kind of can't get by the fact that my brand new IAC from Napa was broken when I received it. The odds don't figure.

Je5 is it hard to replace the lower intake? Where are the O-rings located. I always felt it might be a vacum or gasket leak somewhere.

Thanks for the tips.

 

[aldive]

Thanks Al, I was looking for that article. Kind of can't get by the fact that my brand new IAC from Napa was broken when I received it. The odds don't figure.

Je5 is it hard to replace the lower intake? Where are the O-rings located. I always felt it might be a vacum or gasket leak somewhere.

Thanks for the tips.

Have you tested for a vacuum leak?

 

[Lazzman]

I have been told by several of the mechanics that I took it to that I don't have a vacum leak. Should I believe them? I guess I did pay them for their opinions and they are supposedly the experts.

I checked all my hoses and made sure they were connected, thats as far as I can go. What else can be done and is there a way to check and see if my intakes are leaking air?

 

[aldive]

I have been told by several of the mechanics that I took it to that I don't have a vacum leak. Should I believe them? I guess I did pay them for their opinions and they are supposedly the experts.

Are these the same experts that have not been able to solve your other issues? No, I would not believe them. You need to either do it yourself or find a good mechanic in an independent repair facility.

I checked all my hoses and made sure they were connected, thats as far as I can go. What else can be done and is there a way to check and see if my intakes are leaking air?

There are a plethora of threads on lower intake vacuum leak on this forum.

 

[je5]

Lower intake manifold O-rings

Je5 is it hard to replace the lower intake? Where are the O-rings located. I always felt it might be a vacum or gasket leak somewhere.
Thanks for the tips.[/QUOTE]

They are on the upper and lower portion of the lower intake and you need an "T27" tork socket. My lower o-rings were flush with the manifold and therefore not sealing, especially when cold before the aluminum mating surface had time to seal. You could check it cold with propane injection around the base but I would not recommend it. Inexpensive parts and a few hours of "simple" work to replace dictate starting there first. Besides if the repair of three years ago did not use the thicker o-rings then it was not done correctly anyway. I have seen this dilemma dumbfound master mechanics. Just do it or have it done.

 

[Lazzman]

Ok, got any links to where I can get the correct O rings?

 

[aldive]

Your local Ford dealer.

 

[Lazzman]

I don't think it is the lower intake O rings. Back in January of 2002 my Truck was doing the funny high/low rev thing that straigtend out when the truck got warm.

I took it to the dealer and they put in the OOM12 kit with the timing chain fix. I don't know if they put in the lower O rings or lower intake gasket. Just know it was the OOM12 recall kit.

I also hear there is an O ring under the IAC valve. Where is it? My idle is always week and shudders at times especially when cold, so I am convinced there is a vacum or intake leak somewhere.

Perhaps the extra air from the Volant install exposed the failing lower O rings.

How can I be sure they installed the right stuff? One of the parts in the OOM12 was under warranty and they charged me like $120 for the other parts they did.

 

[Lazzman]

Two quick questions will get me on track.

1. Does the lower intake contain both O rings and intake gasket?

2. Does the 00M12 recall contain the new O rings? I never heard about the O rings being replaced but I have heard plenty about the lower gaskets being to small.

I was under the impression the OOM12 just came with the Cam tensioner and lower intake gaskets.

Would appreciate any help.

 

[aldive]

I don't think it is the lower intake O rings. Back in January of 2002 my Truck was doing the funny high/low rev thing that straigtend out when the truck got warm.

Think or know? Have you tested for a vacuum leak? You are just guessing when you don't test.

I also hear there is an O ring under the IAC valve. Where is it?

You just answered your own question ; its under the IAC ( between IAC and intake manifold ). There is a picture in the link I posted above, # 8 ( http://www.ford-trucks.com/article/...er_IAC_Fix.html ).

My idle is always week and shudders at times especially when cold, so I am convinced there is a vacum or intake leak somewhere.

Test, test, test ..... Develop a logical plan for testing and follow it.

Perhaps the extra air from the Volant install exposed the failing lower O rings.

You are really reaching now.

 

[Lazzman]

Yeah, I know- wishful thinking perhaps. I will check for the vacum leak.