This is somewhat OT because these came out of my Tacoma 2.7 that I'm having issues with.....See pics below. I'll post the issues I'm having at the bottom. I trust Ya'll, I'm not getting much help on the Tacoma board.














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.


Part 2...
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.

Part 3...
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.

I did make it home and the high or low revs didn't happen
on the way home so I know it's the IAC unit that is causing it....I just don't know if it's bad or it's getting bad signals from the ECM.

OK back to work....
Brian

 

Most likely a bad IAC and I think most shops would start by replacing it before doing any further diagnostics.

Not sure why you posted the pics of the spark plugs, but they look fine. A bit worn, but air-fuel mix looks good and no excessive oil.

 

I thought I might have had a blown head gasket.... Went thru many of the same issues on my last Toyota and that's what's it was in it.

Thank you for taking the time to reply
Brian

 

How many miles are on your engine? A split vacuum hose would give the same "high idle speed" as a bad IAC motor so I would check the vacuum hoses first just because hoses are usually the first things to fail under a hot hood. Remember, vacuum hoses always split where they're plugged on to a nipple; especially those near the greatest source of heat because heat hardens them.

As far as your spark plugs go I would switch to iridium plugs because they last almost forever.

 

w/zwede
when was the last time your Tb was cleaned out? Do you have any vacuum leaks?

 

244,000 miles on truck....TB and IAC cleaned last Saturday. I have check for vacuum leaks but I will double check again.

Brian

 

The new IAC valve did the trick....I'm not sure how long it will last because I used a cheap ebay $48 part instead of a $250 parts store one.....So far so good.

Brian