Air Mass Meter Questions

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2stepme

I had a starting problem with a 1995 Volvo 940. Once started the car
would run fine. The problem was intermittent at first. On one
occasion it was very difficult to start but did start. A few weeks
later the car would not start but after sitting for several hours it
did start. A mechanic replaced the Air Mass Meter. When I got the car
back it would not start but it had been raining. Over a four day
period it would not start but at the end of the fourth day (one day
with no rain) the car did start but after a great deal of effort. I
gave the car back to my daughter and that day again it would not start.
I took the car to a different mechanic and they found a wire to the
coil that was bad. I have the wire and the connector to the coil is
falling apart. After replacing the wire the car has started every
time. They also replace the fuel pump relay but said this was probably
not the problem.

What I would like to know is:

1. What are the symptoms of a bad Air Mass Meter?
2. Once it goes bad if it creates a starting problem does that mean it
is difficult to start or will not start?
3. If a starting problem occurs caused by the Air Mass Meter, will the
problem be intermittent or will it be continuous?
4. After the car is started, if the car is running smoothly does this
indicate that the Air Mass Meter is probably good?
5. Will a bad Air Mass Meter give the same symptoms as a disconnected
Air Mass Meter ("limp-home" mode)?
6. If you get a code from a diagnostic computer does this mean that the
part is definitely bad?

Also if there are sources such as a manual that I will find this
information please tell me where to look.

Thanks so much ... Michael
 
I had a starting problem with a 1995 Volvo 940. Once started the car
would run fine. The problem was intermittent at first. On one
occasion it was very difficult to start but did start. A few weeks
later the car would not start but after sitting for several hours it
did start. A mechanic replaced the Air Mass Meter. When I got the
car back it would not start but it had been raining.
Click to expand...

That's no excuse. A car should start equally well whether it is raining
or sunny.
Over a four day period it would not start but at the end of the
fourth day (one day with no rain) the car did start but after a great
deal of effort. I gave the car back to my daughter and that day
again it would not start.
I took the car to a different mechanic and they found a wire to the
coil that was bad. I have the wire and the connector to the coil is
falling apart. After replacing the wire the car has started every
time. They also replace the fuel pump relay but said this was
probably not the problem.
Click to expand...

Failure to start in wet weather is pretty typically of disintegrating
ignition wires and/or cracked distributor crack. Other electrical
insulation failures can cause problems too.
What I would like to know is:

1. What are the symptoms of a bad Air Mass Meter?
Click to expand...

http://www.vlvworld.com/indexframe.html?VolvoRepairManual/Section_2_5.htm

http://www.volvoclub.org.uk/faq/EngineFuelinjection.html#TechnicalNoteson
AMMCalibration

http://www.swedishbricks.com/700900FAQ/FAQSummary1.html

From your description I am not convinced that the AMM needed to be
replaced. However, could be that you had two things go wrong with the
car. Hope this helps!
 
I went to
http://www.vlvworld.com/indexframe.html?VolvoRepairManual/Section_2_5.htm
It said: "A faulty AMM can cause no start faults or 'stall' the car
when it's running." I am wondering what a "no start fault" is? Does
this mean the car is difficult to start or does it mean that the car
will not start? Is the starting problem permanent or intermittent?
Also can this problem be detected and/or confirmed with one of those
code readers that you plug into the car?

Thanks again ... Michael
 
Hi Michael,

"No Start Fault" can certainly mean that the car will not start. I
experienced this recently with my '93 245 Classic.
I pulled out the AMM plug, pushed it in and pulled it out ten times. (A
Volvo technician had recommended this procedure to me earlier for just such
a problem.) It worked. The engine turned over and started immediately.

BTW, an excellent maintenance routine is to repeat the above but with the
application of contact cleaner to the contacts beforehand. To finish the
job coat the contacts with dielectric grease.

Good Luck.
Andy I.


:I went to
: http://www.vlvworld.com/indexframe.html?VolvoRepairManual/Section_2_5.htm
: It said: "A faulty AMM can cause no start faults or 'stall' the car
: when it's running." I am wondering what a "no start fault" is? Does
: this mean the car is difficult to start or does it mean that the car
: will not start? Is the starting problem permanent or intermittent?
: Also can this problem be detected and/or confirmed with one of those
: code readers that you plug into the car?
:
: Thanks again ... Michael
:
: Tim McNamara wrote:
: > In article <[email protected]>,
: > [email protected] wrote:
: >
: > > I had a starting problem with a 1995 Volvo 940. Once started the car
: > > would run fine. The problem was intermittent at first. On one
: > > occasion it was very difficult to start but did start. A few weeks
: > > later the car would not start but after sitting for several hours it
: > > did start. A mechanic replaced the Air Mass Meter. When I got the
: > > car back it would not start but it had been raining.
: >
: > That's no excuse. A car should start equally well whether it is raining
: > or sunny.
: >
: > > Over a four day period it would not start but at the end of the
: > > fourth day (one day with no rain) the car did start but after a great
: > > deal of effort. I gave the car back to my daughter and that day
: > > again it would not start.
: > > I took the car to a different mechanic and they found a wire to the
: > > coil that was bad. I have the wire and the connector to the coil is
: > > falling apart. After replacing the wire the car has started every
: > > time. They also replace the fuel pump relay but said this was
: > > probably not the problem.
: >
: > Failure to start in wet weather is pretty typically of disintegrating
: > ignition wires and/or cracked distributor crack. Other electrical
: > insulation failures can cause problems too.
: >
: > > What I would like to know is:
: > >
: > > 1. What are the symptoms of a bad Air Mass Meter?
: >
: >
http://www.vlvworld.com/indexframe.html?VolvoRepairManual/Section_2_5.htm
: >
: >
http://www.volvoclub.org.uk/faq/EngineFuelinjection.html#TechnicalNoteson
: > AMMCalibration
: >
: > http://www.swedishbricks.com/700900FAQ/FAQSummary1.html
: >
: > From your description I am not convinced that the AMM needed to be
: > replaced. However, could be that you had two things go wrong with the
: > car. Hope this helps!
:
 
1. What are the symptoms of a bad Air Mass Meter?
Click to expand...

Usually the motor will start and die, if you unplug the AMM it will
start and run, but you will get poor throttle response, substantially
increased fuel consumption and poor emissions.

2. Once it goes bad if it creates a starting problem does that mean it
is difficult to start or will not start?
Click to expand...

Normally the car will still start just fine, it just won't keep running.
Sometimes it will not start at all.
3. If a starting problem occurs caused by the Air Mass Meter, will the
problem be intermittent or will it be continuous?
Click to expand...

Normally starts out intermittant, then becomes continuous, but it can go
from running fine to not running at all in an instant depending on how
the AMM fails.
4. After the car is started, if the car is running smoothly does this
indicate that the Air Mass Meter is probably good?
Click to expand...

Yes, whey they fail, they make the engine run poorly all around.
5. Will a bad Air Mass Meter give the same symptoms as a disconnected
Air Mass Meter ("limp-home" mode)?
Click to expand...

Not the ones I've had fail, in theory it could happen though.
6. If you get a code from a diagnostic computer does this mean that the
part is definitely bad?
Click to expand...

Certainly not, I find the codes are right about half the time, other
times it's the wiring or a vacuum leak.


Your symptoms sound exactly like a bad high tension lead, which is what
the second mechanic replaced. The AMM was 99% likely just fine.
 
Andy said:
"No Start Fault" can certainly mean that the car will not start. I
experienced this recently with my '93 245 Classic.
I pulled out the AMM plug, pushed it in and pulled it out ten times. (A
Volvo technician had recommended this procedure to me earlier for just such
a problem.) It worked. The engine turned over and started immediately.

BTW, an excellent maintenance routine is to repeat the above but with the
application of contact cleaner to the contacts beforehand. To finish the
job coat the contacts with dielectric grease.
Click to expand...

I solved a similar problem years ago with a TBI Reliant with a 2.2L
engine. It would not start in wet, foggy weather. The Chrysler dealer
replaced one computer and it ran fine - until the next time it was foggy
and raining. Then they wanted to charge for another "scan" and part as
the second scan said the 2nd computer (part) was faulty.

I went to Radio Shack and bought a spray can of contact cleaner and
cleaned all computer "plugs" as well as every plug that i could find on
the wiring harness - including the one to the distributor. I put grease
on the plugs going into the "computer".

That was the LAST time I had a no-start problem with the vehicle (rain
or shine) until I totalled the vehicle ;-)

Ken, Canada
 
To those components, Ken, I can recommend the same treatment for those
notoriously troublesome fuses in the 240 series, 'tho' in that case a
preliminary fine-wire brushing to remove corrosion deposits is a good idea.
Better still, scrap all these fuses with the grey-colored zinc-alloy ends
and substitute copper/brass ended types (available at outlets catering to
VW, not Volvo sad to say..........). Follow up with the contact cleaner/
dielectric grease routine.
Same for the contacts in the fusebox.

Happy Motoring.
Andy I.


: Andy wrote:
:
: > "No Start Fault" can certainly mean that the car will not start. I
: > experienced this recently with my '93 245 Classic.
: > I pulled out the AMM plug, pushed it in and pulled it out ten times. (A
: > Volvo technician had recommended this procedure to me earlier for just
such
: > a problem.) It worked. The engine turned over and started immediately.
: >
: > BTW, an excellent maintenance routine is to repeat the above but with
the
: > application of contact cleaner to the contacts beforehand. To finish
the
: > job coat the contacts with dielectric grease.
:
: I solved a similar problem years ago with a TBI Reliant with a 2.2L
: engine. It would not start in wet, foggy weather. The Chrysler dealer
: replaced one computer and it ran fine - until the next time it was foggy
: and raining. Then they wanted to charge for another "scan" and part as
: the second scan said the 2nd computer (part) was faulty.
:
: I went to Radio Shack and bought a spray can of contact cleaner and
: cleaned all computer "plugs" as well as every plug that i could find on
: the wiring harness - including the one to the distributor. I put grease
: on the plugs going into the "computer".
:
: That was the LAST time I had a no-start problem with the vehicle (rain
: or shine) until I totalled the vehicle ;-)
:
: Ken, Canada
 
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