I've been doing some searching in regard to my CEL. 0171 & 0174. It appears that I have a vacum leak. I have two questions. First how do I check the intake manifold gaskets? I keep seeing this mentioned but I'm not sure how to check. Second: I've heard a strange whistling sound that sounds like its coming from the passenger side of the truck. Maybe under the dash... Are there any likely vac lines or motors under the dash that are common problems? I'd like a general idea before I start tearing **** apart. Thanks.

 

I had the same codes come up. it was my maf sensor I changed it but you came clean it

 

That's been cleaned. I cleaned it when I removed the K&N filter. Thanks for the suggestion.

I was poking around (literally) under the hood yesterday and stuck my finger through a vacuum hose. I replaced it and cleared the code. If the CEL doesn't come back on the way home from work I'll call it good as far as this issue.

 

The Ford's post -2000 Vacuum lines have a 10 year life span, common issue.

There are a few ways to check gaskets.
All require engine to be idling.
1. Can of Quick Start(ether) or Carb Cleaner, spray it around gaskets and listen for RPM change, downside is that this stuff is flammable, which is the point, so cold engine is best.

2. Propane bottle with a hose, run hose around gaskets and listen for RPM change, less flammable but still need to be careful.

3. Spray bottle of soapy water, spray around gasket areas listen for change in RPM.

Lower intake, upper intake and throttle body are common leak points.

On MAF sensor systems ANY air coming in that doesn't pass thru the MAF sensor can throw off the fuel/air mix, so the large air tube needs to be air tight.

 

Thank you for the response. I was actually thinking of removing the belt (so the fan wasn't running) and holding incense around the intake to see if it sucked in the smoke.

 

Yes that might work, hard to get the smoke were you want it through.

A cigar and a hose might be better, that way you can blow the smoke where you want it, behind wires and "stuff".

And with a cigar, I think Scotch or Bourbon is required, but that could be a Local requirement

 

I like the way you think. Bourbon it is!

 

Ok, I've put over 100 miles on it since I changed the vacuum hose. All is well. CEL is gone, my idle is steady and not bouncing and I feel like my power went up along with my gas milage (still on the same tank so I haven't checked).

Thanks for the responses!