OK so I get my L back from the dealer cause the #3 plug blew.

All is fixed.

Well now when I'm at a complete stop and i turn the heat on I can hear a tick and then the rpm goes from 600 rpm to 400 and back up. It's almost like the truck is about to shut off. This is only happening when the heat is on. The idle is rough as heck too. None of this was happening when I brought the truck in and now it comes back like this.

My dealer says if it was their fault that they will fix it. We all know where that ends up.

Anyone have any ideas what it could be?

 

So many diff things it could be ?
A loose Vac line or Plug Connector they maybe didn't
get back on 100%. First thing I would do is check all the
obvious stuff like that yourself.

Then there is the possibility they screwed up the spark plug
install. Just cause they work for Ford surly DOES NOT mean
they know what they're doing. We have actually had a few
members go to Ford to get plugs done, and Ford screwed
it up BIG TIME. One poor guy I think had like 2 or three
broken tips, and a few loose plugs

It sounds like a plug issue to me.
BTW
DID THEY GIVE YOU NEW HEADS ??? or one Head ???
or fix the spit one ???

 

IAC, idle air controller. Small cylindrical thing, clean it out with some carb clean and see if it helps. It'll be in between a tube from the intake bypassing the throttle plate and going back into the main intake.

 

YA OR THAT,
oops, forgot to mention the Idle Adjustment Control
Good Call grinomyte,
mine screwed up when my L was less than a year old.
And that is what it did, the idle would race up and down,
BUT ONLY ON START UP's, AND ON COLD MORNINGS ????
A matter of fact I think I'll clean it today again.

Here's a picture, takes all of 10 minutes to do start to finish




I filled it up with Alcohol, and let it soak. Then I used cue tips and got it spotless inside. I ended up with a sink full of yick and many dirty cue tips when I was done.

 

If you suspect your IAC and it very well could be here are a few checks to insure it is operating correctly.

1. Unplug connector to IAC.

2. Turn ignition switch to on (truck NOT running)

3. Measure the voltage at the IAC connector (the plug, not the IAC valve itself)

4. There should be approx. 10.5 – 12.5vdc (This tells you the PCM is sending the correct voltage and the PCM is good)

5. If that is good, turn ignition switch off

6. Next, check resistance of the IAC circuit

7. Measure the resistance between to two electrical terminals on the IAC valve.

8. Resistance should be between 6 – 13 ohms.

9. Next check to insure the IAC circuit is not shorted to ground.

10. Measure resistance from one of the IAC valve electrical terminals and the IAC valve body.

11. Resistance should be 10,000 ohms or greater.

12. More then likely if it is very dirty inside with carbon it will measure less then 10,000 ohms.

13. Clean it out real good like Rob mentioned and then measure again.


Just seems like lately a lot of people are having problems with the IAC valves…

 

They just did the time sert on #3 cylinder.


I can't imagine it being the IAC cause it was just changed out about 5 k ago.

What gets me is that it's only when the heat is on. I'll go clean the IAC anyway.

 

If it is only when the heat is on then I, like you, don't think it is your IAC. It does seem odd...

 

Read this post and decided to clean mine. Seemed like a simple thing to do so I did it. Thanks for the pics, Rob.

I also found the source of my recent 'gas smell in the cab'. Last time I checked my plugs I inadvertantly ripped the PCV valve out of the valve cover while doing #3. Never knew it until just now when I was cleaning up some accessible stuff while the IAC was removed. Looked down and saw it laying there. Cool.

One less thing to worry about.