Idle air control valve or oxygen sensor or what?

I have a 1995 VW Golf GL, automatic. BION, it has only about
30,000 miles on it. I always warm it up and I replace the oil
and filter every 6 months. Every 2-3 years I do a basic tune-up
because it has always run very well and I use it so little it
makes no sense to change spark plugs which have 2,000 miles on
them, etc.

It started running slightly unevenly about a year ago, a couple
of partial tune-ups, injector washings, and other stuff
mechanics do seem to have fixed it.

A month ago or so it started dying on the road. Sometimes it
would start again, but then it wouldn't. So I had it towed to my
garage.

The (13 year old) coil was replaced. It died after 6 months, a
new one was put in ten days ago. It died within a week, a new
one was put in at no charge. So far so good.

In the meantime - for about the last month or so - the car
started idling rough - the needle moves between 650 and 850 - it
NEVER did that before - it /used/ to /run/ a bit unevenly but
the tune-ups, injector washing etc. appear to have fixed it. It
rusn fine at normal driving speeds.

It also failed air check for the first time EVER - the CO
emissions were too high, between 1.5 and 4.5 - depending on who
messed with the distributor before. They have to be under 1 or
it doesn't pass. Luckily (?) I live in a place where you can
"help out" a guy and get a sticker no matter WHAT the readings
are. Since I drive the car twice a week at most, I can't even
feel guilty about it.

Several people told me to change the oxygen sensor.

At the end of a tiring day of messing about with all this, I was
passing by a small garage and they put a scanner on it and it
said 00525 - lambda sensor. So the guy said to get a new oxygen
sensor.

My regular garage - who so far have been the best garage I have
ever been to in my life (yes, I know...) - put /their/ scanner
on it and /it/ said that the idle air control valve needed
adjusting - so they adjusted it and it ran like a dream for
about 30 miles. (It always runs like new after they fix
something - until the next time.)

So, now it has again started to idle roughly - MUCH more so than
before - the needle actually dropped down to about 400 at one
time! It never goes higher than 850, and I understand "normal"
is 750-800 and that's what it has always been.

The only thing that has occurred to me is that the scanner MAY
have indicated IACV /and-or/ oxygen sensor as being faulty since
logic would suggest (of course, logic rarely applies to car
repairs) the symptoms may be similar. Not that this gets me
anywhere, still, a thought.

As you can tell, I know almost nothing about cars. Is the valve
faulty and should it be replaced? WHY did it work great for 30
miles and then got MUCH worse? Is there an adjustment screw and
a "fix in place" screw and they forgot to tighten that 2nd
screw? Or should I replace the oxygen sensor?

Or what?

Any help would be greatly appreciated.

I believe that you are running an aftermarket ign coil. I have not seen
many or any of those survive for long. I have seen them died within a week
and never last past 1 year. I refuse to use them!!!
I ONLY purchase them from the dealer to get their TEMIK brand.


"vampire chicken" <drinking DeleteThis @the.coop> wrote in message
news:Xns9AAFAE3D2FBCvamchi@66.250.146.158...
>I have a 1995 VW Golf GL, automatic. BION, it has only about
> 30,000 miles on it. I always warm it up and I replace the oil
> and filter every 6 months. Every 2-3 years I do a basic tune-up
> because it has always run very well and I use it so little it
> makes no sense to change spark plugs which have 2,000 miles on
> them, etc.
>
> It started running slightly unevenly about a year ago, a couple
> of partial tune-ups, injector washings, and other stuff
> mechanics do seem to have fixed it.
>
> A month ago or so it started dying on the road. Sometimes it
> would start again, but then it wouldn't. So I had it towed to my
> garage.
>
> The (13 year old) coil was replaced. It died after 6 months, a
> new one was put in ten days ago. It died within a week, a new
> one was put in at no charge. So far so good.
>
> In the meantime - for about the last month or so - the car
> started idling rough - the needle moves between 650 and 850 - it
> NEVER did that before - it /used/ to /run/ a bit unevenly but
> the tune-ups, injector washing etc. appear to have fixed it. It
> rusn fine at normal driving speeds.
>
> It also failed air check for the first time EVER - the CO
> emissions were too high, between 1.5 and 4.5 - depending on who
> messed with the distributor before. They have to be under 1 or
> it doesn't pass. Luckily (?) I live in a place where you can
> "help out" a guy and get a sticker no matter WHAT the readings
> are. Since I drive the car twice a week at most, I can't even
> feel guilty about it.
>
> Several people told me to change the oxygen sensor.
>
> At the end of a tiring day of messing about with all this, I was
> passing by a small garage and they put a scanner on it and it
> said 00525 - lambda sensor. So the guy said to get a new oxygen
> sensor.
>
> My regular garage - who so far have been the best garage I have
> ever been to in my life (yes, I know...) - put /their/ scanner
> on it and /it/ said that the idle air control valve needed
> adjusting - so they adjusted it and it ran like a dream for
> about 30 miles. (It always runs like new after they fix
> something - until the next time.)
>
> So, now it has again started to idle roughly - MUCH more so than
> before - the needle actually dropped down to about 400 at one
> time! It never goes higher than 850, and I understand "normal"
> is 750-800 and that's what it has always been.
>
> The only thing that has occurred to me is that the scanner MAY
> have indicated IACV /and-or/ oxygen sensor as being faulty since
> logic would suggest (of course, logic rarely applies to car
> repairs) the symptoms may be similar. Not that this gets me
> anywhere, still, a thought.
>
> As you can tell, I know almost nothing about cars. Is the valve
> faulty and should it be replaced? WHY did it work great for 30
> miles and then got MUCH worse? Is there an adjustment screw and
> a "fix in place" screw and they forgot to tighten that 2nd
> screw? Or should I replace the oxygen sensor?
>
> Or what?
>
> Any help would be greatly appreciated.