A Rare Simple Fix

I work on my car from time to time mostly when it has issues. I have had one intermittent issue since I got my car a few years ago that I kept putting off looking into. When I finally looked into it the solution turned out to be a simple one.

The problem

The problem happens when it is hot out and the car is hot and I drive the car and park for about half an hour or less. When I start the car after sitting for a short time and the engine is hot, the idle is high, sometimes 2k but sometimes 3k. Another seemingly related issue I was noticing, when I come off the clutch the engine speed would dip before it settled and in rare cases stall. The issue didn't happen when the weather is cold and not when the engine is cool. If the car sits for an hour or more so that it cools down some then the idle is fine.

I ignored it

I ignored the problem for a long time because A. I mostly drive to work park the car and drive home park and repeat. With this use the problem never appears so it is easy to ignore. B. It is cold a good portion of the year so I forget about the issue until the temperature rises.

I was time

I decided I was time to fix the issue. The problem hadn't happened in a while as it was cold out. On one of the first hot days of the year I decided to bring in my car for inspection as it was due. It passed inspection, but I noticed the person who pulled my car out of the bay looking confused and talking to the others after. No one said anything to me about something being off, I got in my car and when I started it, it was idling at 3k which is quite high. It was one of those rare moments of a hot day and the car was only off for a short time for the inspection. No CEL or codes presented or it would not have passed.

I researched it

I looked into possible issues and found a number of suggestions online about possible causes. Popular on the suggestion list was cleaning the idle air control (IAC) and throttle body. Also popular was checking for vacuum leaks and adjusting the throttle cable. I decided I was going to set aside some time and just do all the suggestions and see if that fixed it although I wasn't sure when.

The problem was obvious

As it so happened the light telling me it was time for an oil change came on. knowing that is a quick easy job I picked up the oil and filter to do that after work. I opened the hood with the engine still hot and looked at the throttle body. Upon inspection, it looked like the throttle was not sitting on the idle adjustment screw. I pushed the valve and sure enough their was a gap and the cable was pulling tension. I changed my oil and then went out later after the car had cooled and checked again. Now with the engine cold the throttle valve was sitting on the screw.

I turned the bolts

After a little WD40 I turned the bolts holding the cable sheath, it only took a small amount of adjustment to remove the tension. It took all of 10 minutes and would have been quicker if it wasn't a bit rusted.

The result

The idle is now perfect and stable with no dips or revving. It has been a little over a week and we are going through a heat wave. I have had to run a number of errands and left my car sit hot and started it again a number of times already. Every time the idle is just below 1k where it should be. I also don't see it dip low when I come off the clutch. I am guessing that issue was the computer trying to compensate for a mechanical issue. The problem as best I can tell was that the cable sheath expands and pulls tension when it is hot.

This was one of those rare cases when the solution to a dreaded problem, was simple and quick once I looked into it.