1990 240 Idle and Performance problem

[trashy]

Started driving my old Volvo while getting my truck repaired. It was running fine, but I decided that it was time to do a bit of work on it since I don't know the maintenance history on it. The first thing I did was snug up the belts since they were squealing a little bit. I then drove down to the auto parts store and bought a distributor cap, rotor, plugs and plug wires for it. It ran fine while I made the trip there and back.

Get home, changed the above parts and thought all was well. Drove to work the next day, and noticed a really rough idle if I was stopped at a stop light. Other than the rough idle, the car seems to run just fine. I figured maybe I had a wire loose, and re-checked them, but the problem persists.

I did some reading here on the forum, and figured maybe I had some kind of air flow problem, so I cleaned the MAF and replaced the air filter. My next plan is to clean the throttle body and go from there. The symptoms kind of point to some kind of vacuum issue to me. The air filter and MAF cleaning seemed to help a bit in the morning when it was slightly cooler out, but in the afternoon when it was hot out, the same rough idle was there.

I then got the bright idea to check for fault codes. With the limited time that I had, I checked and in port 2 I got 3-1-1 and port 6 got 1-1-1.

My question is, what would the 3-1-1 code point to?

My plan of action at this point is to go forward with cleaning the throttle body and possibly replace some of the older vacuum hoses in the car. Any other pointers as to what could cause this?

[broke wagon]

Here's a link to obd codes, http://www.volvoclub.org.uk/faq/EngineOBDCodes.html
The air box thermosat valve might be faulty. If it's not working the valve will fail in the pre-heated air position. You could take the cover off the air filter while the engine is cold and see if the valve has the air flow open or closed. If its closed thats the pre-heated air position.
If you cleaned the throttle body make sure you adjust the throttle position sensor. I had forgot to do that and it seemed to help.
good luck

[trashy]

First of all, thank you for the reply broke wagon. I more-or-less ruled out the air box thermostat because I don't have the hose that runs from it to the exhaust manifold. Living in Florida, I don't think I really need it right away.

Here is what I did this morning.

Pulled throttle body and cleaned it. While it was off I did resistance checks on the throttle switch, and it checked out fine.

Replaced all of the vacuum hoses that I could with the exception of the larger hose that runs to the flame trap (on order). The vacuum hoses were in poor shape, and I even found a couple that were cracked/split.

Cleaned the flame trap.

Adjusted the throttle switch to spec when putting everything back together. Cleaned up the airbox and intake hose, as well as re-cleaned the MAF with MAF cleaner.

Started the car up, and the same rough idle was still there.

I then started researching some of the other tests to run on the system, then said to myself "self, it was not idling like this until you replaced some parts". So I put the old spark plug wires back on it, no change. I then pulled the spark plugs to inspect and double check the gap on them. Plug number 3 had very little gap! I don't remember dropping it when I was doing the installation, and I'm almost positive that I checked the gap prior to installing them.

Started it up and it's now purring like a kitten. Took it for a test drive, and it seems to be running better than ever.

Lesson learned - Always go back to the last thing that was done prior to a problem cropping up.

On a side note. While I had things apart I bought some engine foam cleaner from NAPA and sprayed it on the VERY dirty engine block according to the directions. After letting it sit for 15 min. I rinsed it off, and the grease/oil/grime came right off! It's pretty good stuff!