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1991 745 Turbo SE has been stalling at traffic lights, but only about 1 or 2 times a week. It is hot here in North Florida, and the worst of the stalling was when the temps were 99 deg. +, so I wrote it off to misadjusted idle and the heavy load on the engine when the A/C compressor and electric aux. radiator fan kicked in at the same time.
But, she also has had a slight shudder, like very quickly lifting foot off of gas then putting it back down again at highway cruise. But much shorter/faster than a human could do it. Again, was with A/C running, so I thought that was it.
Then, Friday, she stalled at a traffic light, started right back up just fine, then did the little shudder thing at highway cruise, but with the A/C off.
This morning, the "Check Engine" light went on. When my wife got the car home, the error code from the fuel injection computer was 1-2-1, or faulty signal from the Air Mass Meter. Meaning either wiring or failing AMM. This code will turn on the "Check Engine" light.
After resetting and erasing the codes, I unplugged and replugged the AMM plug, and started her up. No codes/no check engine light.
She has run pretty well during all this, and always restarts promptly when she stalls. Air filter is about a year old, and should not be too dirty yet.
EDIT to add: Have done the tests, per FAQ. Ground to AMM connector terminal 1 is 0.00 ohms, or perfect. Voltage, at idle, AMM connected, to terminal 3 is 2.54 volts. FAQ says "approximately" 2.3V. Is 2.54V okay? This is with a HP DMM that is pretty accurate. Disconnecting the AMM makes it stumble badly for a second, then she picks up and idles just about as well as with the AMM connected. Hmmm. I lack the courage to try to drive it with the AMM disconnected. Should I try it and see if it runs better without the AMM? [end Edit]
Does this mean that I should order a new/rebuilt AMM, or look for something else. Also, will it strand my family by failing suddenly now, or will it continue to fail gracefully and let me have the time to get a new AMM here.
Given the known flakeyness of the 740 fuel injection system, I'd also hate to order a $300+ AMM only to have it be light oxidation on the connector, or something else. Do the above described symptoms sound like a failing AMM, or more like something else?
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Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)
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