'91 900 stuttering - Air Mass Sensor?
robobass
normal. In the last week, we could barely get the car to move. Idle
still normal, but like a vacuum leak kind of feeling - major
hesitation when trying to rev. Our guy is always busy busy busy, but
will give us some advice over the phone. He said look for cracked or
disconnected hoses and wires, etc. especially around the AMM.
Everything looks in order, but I unplugged and replugged all
electrical connectors, and blew out the AMM just orally. It ran fine
for a trip around the block. The next day my wife took out the car in
heavy rain, and said she barely made it to her meeting. When she got
home I repeated the process, but also sprayed some WD40 into the AMM
plug, and a little into the device itself for good measure. I know
this is probably inadvisable. I wanted to use tuner or carb cleaner,
but the parts store was closed. Anyway, it worked. The car runs fine
now, but for how long? I can't say for sure that the AMM is the
problem, but it looks this way. There is plenty of spark, and fuel in
the rail. Is a big dose of carb spray at all useful? Also, is there a
way to diagnose the AMM at home? I noticed that the car sure won't run
if the plug is disconnected!
Thanks! I wish I could search old posts, but that doesn't seem
possible right now.
Adrian
like they were saying:
> We started having trouble at low rpm about a month ago. Idle is normal.
...which suggests that the vac and IAC are both fine.
> I noticed that the car sure won't run if the plug is disconnected!
...which suggests that the AMM isn't _totally_ fubar.
Bosch or Lucas injection?
Turbo or n/a?
All the basics are clearly at least roughly right, since it runs and
idles, but have you gone over the ignition and made sure it's all good?
Timed right, advancing correctly, good plugs/HT leads/cap/arm?
A good spray of carb cleaner around the AMM won't hurt anything - I
forget how the Bosch AMM works, but the Lucas meters the air passing
through a small venturi parallel to the main flow - which is worth
getting to.
> Thanks! I wish I could search old posts, but that doesn't seem possible
> right now.
Google seem to have orphaned the groups archive, unfortunately.
robobass
> robobass <robanzello...@googlemail.com> gurgled happily, sounding much
Thanks for the reply. Nonturbo, originally sold and still in Germany,
so I think Bosch. The sensor is a big piece of pipe just past the
filter. I haven't changed the cap/rotor since I got the car two years
ago, but the wires are fairly new. I don't suspect anything in the
ignition chain since the problem has so far been unaffected by
dampness, and actually worsens as the car warms up. The plugs have
seen better days, I must admit, but besides wear, I don't see any
indicators of other problems. Could excessive gap cause problems like
this?
Adrian
like they were saying:
> Thanks for the reply. Nonturbo, originally sold and still in Germany
2.0 or 2.1?
> so I think Bosch.
Yeh, Lucas was only on turbos.
> The plugs have seen better days, I must admit
It's a quick, cheap and easy diagnostic - I'd be doing plugs, cap & rotor
as a matter of course. If it's a 2.1, the ignition's much more complex,
AIUI.
robobass
> robobass <robanzello...@googlemail.com> gurgled happily, sounding much
Yeah, basic 2.0 16v. The parts stores open in the morning. No weekend
hours here! I'll do the plugs/cap/rotor, as a matter of course but I
really think I'm dealing with something electronic, and AMM related.
I'll report back in 24!
Thanks,
Rob
robobass
Well, I changed out the plugs, sprayed out the cap with WD40, and
sprayed a generous dose of carb cleaner into the intake through the
AMM. On a short test drive it runs perfectly. We'll see...
PeterD
I'd suggest replacing the cap and rotor if that helped it. Cap/rotor
is not that expensive.