Question on 740 air mass meter

I have an 89 Volvo 740 GL non-turbo 8-valve sedan. Hard to start,
barely runs unless you give it a lot of gas.... when you put it in
drive it stalls right away. In neutral or park, it won't idle at all,
you have to hold some accelerator all the time, or it will stall. I
read the stored codes out, it has set the code for bad air mass
meter/sensor. I also have a 92 Volvo 740 GL with the turbo engine.
Same type/size, but has a turbo. I don't want to buy a new AMM for the
broke-down 740 sedan, and try it, only to find that there is something
else wrong like a bad connector. Usually these electrical parts are
non-returnable. So does someone know if the AMM in my 740 wagon is the
same AMM used in the 740 sedan? If they are interchangeable, then I
can try the one out of the wagon in the sedan to confirm the fix
before buying a new one.
I know these things have a delicate platinum element in them...is
this something that you shouldn't buy used from a junked car?

 

Check the numbers on them (the last 3 vary from what I have seen)- I
think that the '89 will have an xx7 and the '92 will be an xx6 (or
maybe even the 012), but I am guessing. If the numbers are the same
then they are the same part (well, DUH!). The numbers are lightly
engraved on the flat, black, plastic panel face and can't be seen
unless it is removed.

As far as used ones, most yards will warranty them for 30 days for
credit. I have a few spares I keep around from a local yard. I tested
each one when I got them home and they were all fine.

You could get a used one to verify that this is insdeed the problem
then get the rebuilt one later and keep the used one as a spare.

One thing I have learned about these things is that even a drepair
shop cannot test one for proper operation wihout exchenging it for
another part to see. of course, if it were my shop I would keep spares
on teh shelf for A/B testing so that I could be sure before selling
one to the customer. IF they totally fail the car will go into limp
mode, but there have been two recent cases here on A.A.V that have
shown that this is not normally the case. As they go out they just
send the wrong signal to the computer and so the computer creates the
incorrect mixture and the car runs terribly.

If you have checked the following already:
- cracked intake hose from the AMM to the throttle body
- cracked or disconnected vacuum lines
- Properly operating idle air control valve
....and that is all OK, then it seems that the AMM is the next best
place to look. Logically speaking, it is the most sensitive item in
the system. While you are at it, be sure to check the thermostat in
teh air box. It MUST turn off the hot air from the heat riser once the
car warms up or the AMM will fail in a short time.

Hope that helps....
__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

 

It's a no-brainer to buy a used one, at least to have as a spare. They're
around $300 for a remanufactured part, $15-$30 used, I've always bought used
ones and had good luck. If you're really worried about reliability, buy a
used one for testing, then if that solves the problem buy a new one and
stash the used one in the car as a spare.