1999 4X4 2.7 5spd with P0505 code....Need advice please.

Truck has 244,000 miles on it if that matters....

Problem started about 3 weeks ago....Started it up one morning and got the high idle and it thru the CEL, after it warmed up the serging went away. Light went off on it's own and it started fine for a day or two then the same as before, had the codes checked and P0505 which I know is the idle air control system malfunction. I tried the easy fix of pouring some seafoam down into the hose that goes down to the control valve, that only worked a week and the CEL is back on as well as the high revs when cold starting. It still runs fine after head down the road.

I looked for a How-To... post but all I found were for the V6. I read all the post I could find about the P0505 codes and from those I take it that the idle air control valve may be bad, it could just need cleaning, same thing with the throttle body, the mass air flow sensor may be bad....I checked all the vacuum hoses and they all look good, no cracks anyway.

I'm looking for advice on the best way to tell which of the multitude of things it most likely is....? I hope I have overlooked a good How to.... on removing the throttle body and idle air control valve and someone could post the link here.

Anybody have a list of gaskets and such that would be needed....?

Thank Ya'll in advance....
Brian

 

The throttle plate shaft on the 2.7 can start to stick with age. If it idles high, try manually pushing the throttle closed in the bay or give it a couple taps with the soft side of a hammer. I think I have seen a youtube video that shows the TB sticking and how they fixed it with a spacer. If that isn't the issue, check the PCV or replace it if it's original. Then move towards the IACV since that will be the most expensive part to fix.

 

Thank you for the reply....I looked for the youtube video but didn't find it. Below is the best How To.... vidoe I have found yet.

https://www.youtube.com/watch?v=J2cr3LBPOgQ

Brian

 

https://www.youtube.com/watch?v=IIbTvxR1TQk

This is the video I was remembering

 

Well the CEL went away for about a week....But came back middle of this week.....So I decided to take the throttle body off and clean it and the idle air control valve...Put it all back together and I still have the high revs.....I guess I'll start replacing parts.

Anyone have a clue which I should start with first.....?

Brian

 

I have a new IAC on the way but today on my way to work the high revs never stopped......Then about 5 miles from the office it would also not hold idle.....Without keeping my foot on the gas pedal which is a real pain in traffic with a 5 speed.

My plan to get home is to unhook the electrical connection from the IAC and then move the throttle stop to bring the RPM's up.....Any other way besides having it towed....? My roadside service only tows up to 10 miles and the office is 50 miles from home.

Brian

 

Well I made it home....No revs high or low, but it didn't run right, which I guess is to be expected with the IAC unplugged.

Brian

 

My $48 ebay IAC valve came in Monday....I put it on and the truck runs just fine....Not sure how long this cheap part will last but for 1/5 the price I figured it was worth a shot.

Brian

 

Please keep us updated on whether or not this fixes it for the longer term!

 

Will do....For those that don't know the part number for an automatic is different than a manual....Most of the ones listed on ebay are for automatics. I have no clue if it really makes a difference or not....They look the same to me....I bought the 22270-75040.

Auto--22270-75030
Manual--22270-75040

Brian

 

Well I said I would report back if I had an issue....I have been getting low RPM's at idle and I think it's the IAC again....Not sure yet but I will post back what the issue once I get it fixed. It lasted 5 years if it has gone bad.

 

That it worked this long is quite amazing .

Double check that the firewall is not cracked.

Did it trip the PO505 code again?

 

No CEL and no codes even pending yet.