Hi everyone,

For the past four weeks I have been trying to solve a problem with my '91 245. It runs extremely rich, with black smoke and lots of gas smell out of the exhaust.

I have been to two garages and a dealer, and still no solution. I have had the plugs replaced, the fuel injector temperature sensor replaced, the O2 sensor replaced, the fuel pressure regulator replaced. No improvement. Next I tried to check the cold start valve by unscrewing it from the intake manifold to see if there was gas flowing through at idle. There wasn't so I think that means it's working OK. Can someone confirm this for me?

The mechanics I was working with threw up their hands and said it was either the air mass meter or the ECU, even though I wasn't getting a diagnostic code for an AMM. Unfortunately I am in CA and my car's fuel injection is a Federal/Canadian version, which means that even my local dealer doesn't have a spare AMM or ECU sitting around to try, so they are reluctant to help me out by ordering a part that might sit on the shelf if it doesn't fix my problem.

So I took a chance and found a rebuilt AMM which I popped in today. It got a little better. There is less black smoke, but I still get diagnostic codes for running rich and I can still smell gas in the exhaust.

Any other ideas out there for me before I run this car off a cliff into the Pacific Ocean?

Thanks.

Peter

an exhaust leak upstream from the o2 sensor will send a false lean signal to the computer driving the actual mixture rich.the o2 signal can be checked with a graphing multi-meter.look for a shop with a snap-on vantage and someone that knows how to use it.they should be able to explain to you what they have found and what it means in a way that you can understand.if you can find this you have a good shot at getting your problem solved,whatever it may be.

I'm thinking that the airflow meter is bad. Having had the same car in both Federal and 50-state trim, as I recall the air flow meters are the same. Did you try running without the airflow meter connected? Any improvement? If there is ANY improvement, then there is likely an airflow meter problem. Otherwise there is either a stuck/sticking injector, or the actual injector firing duration part of the EFI computer is askew. Those would be my guesses.
--
1992 940 wagon, very low miles
as well as others.

Peter,you may look at this for you running rich problem,My brother had a simular problem with his '83 240, the engine would actually blubber when cold under accelleration.Anyway to make a long story short I asked him if he had done anything to the car recently and he said that he had replaced the in-tank fuel filter;so I looked at the return hose that comes from the exit side of the fuel pressure regulator and where the hose enters the fuel tank he had kinked this hose so the fuel pressure was too high and causeing the engine to run rich,so rich that even the computer could not compensate enough for normal driveability.So you may want to check your return hose from the fuel rail and the fuel pressure,hope this helps.

Fuel pressure check is a great place to start (and a fuel pressure regulator is a lot cheaper than the AMM). While you're in there, look very closely at the plastic air hose from the AMM to the intake. A lot of them get holes worn in the outside from rubbing against the strut tower. You may have to take it off and hold it up to the light to make sure. Another item to check for vacuum leaks is the intake manifold gaskets... but a car with that problem ought to run lean, perhaps hesitating.
A really good check of your computer and AMM is to try your parts in another, happier car, and see if you can duplicate symptoms. The shop may be unable or unwilling to try this... don't know what to say except perhaps try a different shop. You wouldn't be the first person to have a driveability problem with an 89-up 240 engine computer.... that's why they're expensive.
Good luck!
Rob Bareiss, New London CT