This stumble just started all of a sudden. I was slowing in traffic, and had just pulled it down into 2nd then tried accelerating.
The car fell flat on its face.
If you very gradually ease into the throttle it is OK. But, forget "normal" driving.
The idle seems a bit rougher than previously.
Am I looking at a fuel filter change? Or, does anybody have any other suggestions?
Thanks.

You mean that if you accelerate very gently the car will get up to speed and hold there? That doesn't sound like a bad AMM. A failed AMM should give poor running at anything above idle.

Before you spend on a new or rebuilt AMM ($$$) make sure there are no vacuum leaks around the manifold, or air leaks in the accordion ducting from the AMM to the throttle body. There are few bigger frustrations than spending a bunch of cash on a cure, only to find it makes no difference at all.

I had a very similar problem, and after removal and careful inspection, found a split in the ducting, at the 'bottom' of a fold. $5 at the PnP yard for an airtight duct cured it completely.
--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)

volvodad, the car will not pull itself. You can let out the clutch with it idling and it will try to move but, as soon as you touch the gas, the engine dies.
I found the diverter flap stuck wide open for the hot air off the exhaust manifold, and completely blocking the fresh air inlet. I used a heat gun to warm the thermostat and the flap just barely moved.
So, I figure there was a cascade effect. The air box thermostat failed, which allowed all that hot air to cook the AMM.
FCP Groton has already been contacted and the parts are on their way.

Providing that the car doesn't have a 340 in it, the issue could be a failed in-tank fuel pump or hoses leading up to it. Another thought is that the FPR on the fuel rail has failed. The filter could also be an issue. If you are running a 340, well... lets just say you need bigger fuel pumps and fuel lines!

jorrell
--
89 244 171K miles, 92 245 236K miles, 06 XC70, 00 Eclipse custom Turbo setup

jorrell, LOL.

The 340 is in my '73 Dart Sport. I've got a 3/8" ID line with a 68 gph pump feeding the 750 Holley.

Anyway, the Volvo still has its original B230F in it. What really confuses me about this problem with the Volvo is how quickly it started. It was running fine one minute and suddenly started running lousy.
I can let the car idle and slowly ease out the clutch and the car begins moving. However, the moment I touch the throttle the engine dies.
Just curious, is there a way to diagnose the mass air sensor, or whatever that sensor is called that is between the throttle body and the air filter?

Thanks.

If you disconnect the electical connector to the AMM (key off) and it idles fine it is the AMM. You won't be able to drive it very easily it is in a limp home mode and you really do limp. Check the air box thermostat it is probably stuck open allowing hot air off the exhaust manifold to continuously go to the AMM eventually killing it. Sounds like a failed AMM. Dan

Hey pageda, I disconnected the wiring to the AMM and started the engine. It acts just like it did without disconnecting the wiring. Does that indicate a bad AMM to you?
I hate to throw money at a problem, but I don't know any other way to test the AMM.

Thanks.

I have only had one fail, the car would not start until I disconnected the AMM. Then it would idle just fine but was difficult if not nearly impossible to drive.
Yours sounds to me like it is in the failed (limp home mode) when it is connected. See if you get some other opinions on it. At any rate you should have a spare known good AMM in your trunk. Dan

I spoke with a guy tonight who used to run a Volvo shop in Atlanta until about two years ago.
He said all things are pointing to the AMM. I ordered an AMM a few minutes ago.
Plus, through talking with him, I found out the thermostat for the flapper in the air filter housing is bad. It is 90* degrees outside right now and the flap is closed to the outside air and allowing only the heated air in.
I used a heat gun on the thermostat and the flapper never completely closed.
So, I ordered the thermostat, along with other stuff from FCP Groton a little bit ago.

Some of us remove the preheat hose if you are not subject to emissions testing and plug the hole into the airbox. The failed airbox thermostat is known to take out AMMs. Dan

A new AMM did the trick. The car runs great now. I took that diverter flap out of the air box and disconnected the heated air tube as well.
Thanks for all the advice.