I am in the process of replacing what I believe to be a failed air mass meter in my '92 non-turbo 240. Will know for certain after it arrives in the mail in the next day or two. While waiting for my purchase to show up in the mail box, I've been reading numerous posts and other info and have noticed that a failure of the hot/cold air delivery through the flapper valve in the air box is often cited as contributing to failure.

What condition contributes to the amm failure? An always hot air delivery or all cold air w/ no warm start up? The warm air hose and metal "deflector" that fits on the exhaust manifold are missing on my car. If a failed air valve which sends only hot air to the amm is the culprit, is it OK to run without the warm start-up air hardware? I understand that the absence of the warm air at start-up will affect emissions and driveability but I can live with those issues until such time I buy and refit the warm air "deflector" and pipe.

Thanks.

I still have my preheat hose hooked up but I replace the airbox thermostat every time I change the air filter as a precautionary measure.
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Mike F - 1984 244 DL - 317,000 miles
Original engine, transmission, drive train, starter
Undergoing reconstructive surgery with POR-15

1972 142 S - The Yellow Brick - 135,000 miles
All stock except for Weber Carb. B20B engine. M40

If you don't have visual emissions inspection, just remove the hose and plug the hole in the airbox. If you do, block the airflow and replace the hose.
Hose or not does not affect running or warmup.
Dan

With the pre-heat hose in place and a failed open air flap (the only failure mode of the thermostat), the AMM will cook. Cold will not hurt the AMM. The LH 2.4 system AMM does have a life span, perhaps you just found it!

jorrell
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92 245 317K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently being enjoyed!