Hi all,

Brick in question is a 1989 740 N/A Bosch.

Got it back from the shop, good news is the new transmission with 47k miles (with lockout torque converter!) works great! Paid a premium for it, but got a warranty.

Bad news is it died at the shop. Pulled the plug on the AMM and it ran better. Put it back in and it ran OK then died. I felt the AMM and it seemed pretty hot. The mechanic felt it and said it seemed like it was running too hot. Air box pre-heater hose has been removed to prevent frying AMMs due to defective airbox thermostats.

I had a spare I had pulled from a boneyard, put it in, vroom a zoom zoom. 15 miles later, it died on the highway. Got it to the shoulder safely, AMM felt hot, I pulled the AMM plug, tried to get home via surface streets.

It died once more with the AMM unplugged. I pulled over and checked codes and got a 1-2-1* Faulty signal to/from Air Mass Meter and a 2-3-4 Throttle Position Switch (TPS) idle signal faulty (which doesn't make sense, because it's a REGINA code, and this is definitely a BOSCH... Wot der fok...)

Anyway, got it home. Drove to the boneyard, and got an AMM from a 94' 940 (surprised to see it was a Bosch system), cleaned it with MAF cleaner, installed it, cleared the codes, drove it around town for a bit, seems like it's OK, idles smooth & steady, good power. Check engine light came on... Then went off. Checked the OBD, no codes. Felt the AMM, it was pretty warm.

So... This is the third AMM I've been through (although the salvage could have been faulty). I'm about ready to learn all about AMMs so I can come up with a way to adapt a $22 Toyota sensor to work on a brick... Unless someone knows where I can get an AMM with a warranty...

Any and all thoughts are much appreciated.

 

one that that will kill AMM/MAF's on non-turbo cars, the heat riser tube coming from the exhaust manifold into the lower airbox... the flap inside the airbox is thermostat controlled, its supposed to be closed except in very cold weather, but they stick open... this lets hot air off the exhaust header into the intake, which both lowers your engines efficiency (horsepower and fuel economy) AND cooks the AMM/MAF. I tend to wire those flappers permanently closed. if you live in a smog-test state you can't remove the heat riser pipe (looks like a clothes dryer vent hose) as thats a checklist item.

 

Yeah, I pulled the air pre-heater hose off both my bricks as I weighed the fuel savings less important than reliability.

If you could check your AMM to see how hot it runs next time you check your oil/trans/whatever, I'd appreciate it. Mine was hot to the point where it was on the edge of not being able to keep my fingers firmly pressed against it.