Here's a strange one for you. Yesterday my 93 940 NA is running fine. Today it has a strange rattle at idle. Sounds like the exhaust pipes rattling but not at the back of the engine. Once I accelerate the rattle goes away. Take my foot off the pedal and the rattle returns. Acceleration is terrible in the low gears and low speed. Enging noise is different too, higher pitch, like it's working too hard. Once at freeway speed, everything seems normal. A few years back my 240 did something similar without the rattle part. Turned out to be the AMM.

Anyone have a clue? What should I look at first. As always, thanks in advance.

Luke
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89 240 190K, 93 940 80K

Check to see if your catalytic converter is shot. The insides could be what you hear rattling and poor engine performance could be due to the cat. being plugged.

That's a great idea. When I bought the car three months ago, the mechanic who checked it out for me told me he thought the catalytic converted didn't look to good. I had forgotten about that. Anyone have any suggestions about removing or replacing catalytic converters?
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89 240 190K, 93 940 80K

It depends on how it's installed. If it's clamped at both ends then removal may be a little difficult. At work we heat them with a torch and hit them with a hammer to break them loose of the exhaust pipe. Care needs to be taken that the exhaust pipe is not too badly mis-shapen from the heating and hammering. If, on the other hand, it is flanged (held in with bolts) then the worst case scenario would be the flange bolts breaking and needing replacement. Also you will probably need matching gaskets for this type of repair. I had a flanged at both ends cat go bad in my wagon. I bought a universal fit from NAPA with a matched flange for the front but straght pipe out the rear. I cut the flange off the old cat and welded it onto the new one, after careful measurement, and saved quite a bit of $$ by not having to buy from a dealer.

Sure nuff, it was a bad catalytic converter. Good to go today. Drives like a dream. Thanks for the superb diagnosis.
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89 240 190K, 93 940 80K