I've got a '92 240 Wagon (B230F, LH Jetronic 2.4) 245,000 miles. I'd like some tips on how to troubleshoot the check engine code: 2-2-1 Fuel system compensating for extremely rich or extremely lean running condition at cruise. This is the only socket #2 triggered code stored.

The car always starts, holds an idle and runs okay. I believe it is a lean condition, since the plugs aren't fouled, they have a tannish tint to the insulators, but I can smell gasoline on all of them, when I pull them after running the engine for a little while.

How should I proceed to analyze this situation?

 

Is fuel economy still acceptable? If teh computer is setting lean or rich at cruise, it doesn't mean dripping wet rich or melting pistons lean, it just means it's outside the oxygen senros's parameters, which is a very narrow band near the perfect mixture.
I would reset teh ECU and see if teh code comes back. If it does, and fuel economy is good, Id likely throw a new O2 sensor at it. They do have a service life and often with older engines and management systems, fuel codes are thrown by an old or lazy O2 sensor.

Regards, Andrew.

 

Thanks for the reply Andrew.

Truthfully, the fuel economy isn't great and has seemed to decline over the last few months. What concerned me is the "raw" gas smell and wet threads on the spark plugs when i pulled them yesterday. Although it has high mileage, this engine has maintained its compression and never excessively consumed oil and I'd hate to have gasoline mixing with the oil if that's a possibility here. I was thinking about the O2 sensor, so I'll look into that.

 

from http://www.brickboard.com/FAQ/700-90...neOBDCodes.htm

Fuel trim (lambda control) too lean at part load Lean; air leak; low fuel pressure; bad AMM

 

Thanks bubba240. This is a very educational link that gives me a clear direction to follow. The check engine is on and I need to get the car inspected.

Can the AMM in this car be cleaned? With my other car (Mercury Mystique, V6), I can clean the sensor wire to eliminate lean error codes. I'm not sure if this applies to the Volvo.

 

maybe spray something on the intake manafold gasket or injector o-ring seals ... my guess is you have a bad leak. Look for holes is the tube that connects the air mass meter to the throtle body.

 

I did find a broken vacuum tube. It was one of the the two tubes coming off the top of the throttle body. It is one of those hard plastic tubes and it was just hanging loose. I don't know where it was going to. However, I plugged it to see if that made a difference.

Strangely, the error code changed from 2-2-1 to 2-3-1. I reset the check engine and drove the car around. It hasn't yet come back on. Anyway, after looking at the state of the engine, I'm thinking of replacing gaskets and hoses and O-rings as a maintenance task. I bought the car a few months ago after a twenty-year hiatus from Volvos. The last Volvo I had was an '83 245, B21. So I have some differences to learn in some of its systems, while most are pleasantly familiar.

 

On my 86 the hard vacuum line goes to the ignition computer .. not sure about the 92 ...