Idle air control valve or oxygen sensor or what?

Just take a look yourself and see if it is a TEMIK.
Lift the hood and follow the center wire from the distributor to the coil.
Takes 10 seconds. ;-)
You don't want an aftermarket one, not just German, not OEM, not HUGO, not
BERU, only TEMIK!!
The aftermarket coils can even spark but the spark might be weak creating a
lot of running problems or non-starting problems.

I will wait for your visual confirmation.

"Madesio" > wrote in message
...
> On 01 Jun 2008 00:09:37 GMT, vampire chicken >
> wrote:
>
>>"dave AKA vwdoc1" > wrote in
>>news >>
>>> 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.
>>
>>The garage assured me it was the German original one, but I'll
>>pay heed to your warning, and maybe try to get a good look at
>>it.
>
> I've come across aftermarket coils that have failed on a regular basis
> as well.
>
> On another note, are there any stored fault codes? I'd have to assume
> no, because I see no mention of it. If that be the case, I'd be
> investigating a possibly failing fuel pump. It could be cutting out
> under certain circumstances causing the car to stall.

"dave AKA vwdoc1" > wrote in
:

> Oh well that blew my theory. lol

OH NO! And here I thought it was solved!

> I would probably not think it was the coil now with a new
> Temic there.

Even a Mexican one? AFAIK, the previous 2 (one lasted 6 months,
one about a week) were the same ones. The /original/ lasted over
12 years - but for all I know it may have been a Mexican one as
well! Still, I think it might be worth checking to see if any
real Bosch Temics can be found.

> So maybe like others have said, fuel pump, fuel filter, 02
> sensor, etc.

Fuel pump and fuel filter were changed not that long ago.

I did (while still groping around in the dark) find an original
Bosch o2 sensor for a really good price. I'm tempted to get it,
although my garage guy says "if it runs OK, why spend the
money?". But it's NOT running OK /again/! So maybe it IS the
damn o2 sensor, as the scanner in that one garage indicated. MY
garage's scanner said, first time, coil, second time, AIV. So
maybe similar symptoms can cause very different diagnostics from
different scanners and it IS the o2 sensor???

I will also ask if they just "adjusted" the air valve or whether
they actually cleaned it properly as well. Although they really
are a pretty conscientious garage.

> :-( I have taken out some Bosch Platinum
> Spark Plugs that were causing horrible running problems in
> engines.

This gets worse and worse!

I /believe/ they put in some Japanese spark plugs last time they
changed them and washed the injectors, etc. The dist. parts are
new as well, but I have not inquired into their /exact/ origin.

At least, AFAIK, there are NO Chinese parts in the car.

> I use the long life original spark plugs and Bosch
> distributor caps and rotors. The aftermarket distributor
> rotors can also cause some hard-to-find running problems.
> With excellent quality parts installed hopefully you don't
> have to worry about those parts too while searching for the
> main problem(s). ;-)

I'll see what I can do.

> Diagnostic Trouble Codes (faults) are usually stored in the
> car's computer which might require a scanner to read the
> codes. I don't think your car will blink out the codes for
> you so a special scanner is needed. I believe you have a
> 1995 Golf, I don't think Autozone or other stores can read
> your OBD-I system. They can only read the OBD-II systems
> AFAIK.

I'll see what my garage says.

I'm tired of waiting for the tow trucks with everyone honking at
me!

> Good luck!

I'm going to need it, it seems.

Thanks again very much for your help!
vc

Oh well that blew my theory. lol
I would probably not think it was the coil now with a new Temic there.

So maybe like others have said, fuel pump, fuel filter, 02 sensor, etc. :-(
I have taken out some Bosch Platinum Spark Plugs that were causing horrible
running problems in engines.
I use the long life original spark plugs and Bosch distributor caps and
rotors. The aftermarket distributor rotors can also cause some hard-to-find
running problems.
With excellent quality parts installed hopefully you don't have to worry
about those parts too while searching for the main problem(s). ;-)

Diagnostic Trouble Codes (faults) are usually stored in the car's computer
which might require a scanner to read the codes. I don't think your car
will blink out the codes for you so a special scanner is needed. I believe
you have a 1995 Golf, I don't think Autozone or other stores can read your
OBD-I system. They can only read the OBD-II systems AFAIK.

Good luck!
--
later,
dave
(One out of many daves)

"vampire chicken" > wrote in message
...
> vampire chicken > wrote in
> :
>
>>> You don't want an aftermarket one, not just German, not
>>> OEM, not HUGO, not BERU, only TEMIK!!
>
> Well, it's a Temic, but it's "Made in Mexico". Brazil and Mexico
> manufacture an enormous amount of VW's and many parts come from
> there as well. I guess I'll have to look for a real German Bosch
> Temic - I hope I can find one.
>
> Right?
>
> Thanks again for all your time.
> vc

I don't believe Temic is related to Bosch. It's just another elec. auto
parts manf.

SFC

"vampire chicken" > schreef in bericht
...
> vampire chicken > wrote in
> :
>
>>> You don't want an aftermarket one, not just German, not
>>> OEM, not HUGO, not BERU, only TEMIK!!
>
> Well, it's a Temic, but it's "Made in Mexico". Brazil and Mexico
> manufacture an enormous amount of VW's and many parts come from
> there as well. I guess I'll have to look for a real German Bosch
> Temic - I hope I can find one.
>
> Right?
>
> Thanks again for all your time.
> vc

"SFC" > wrote in
:

> I don't believe Temic is related to Bosch. It's just
> another elec. auto parts manf.
>
> SFC

You are correct, I just got confused while Googling. Actually it
/appears/ that a lot of Temics DO seem to come from China these
days - as if /anything/ didn't - so I guess I should be glad I
have a Mexican one.

This whole thing is very very sad. I hesitate to say too much, because the
most obvious comment is, the people who are alleged "mechanics" are plain
and simple incompetent. First off, if you have a very high CO level that
indicates the car is running rich. A faulty distributor or ignition coil
will not cause you to run rich. Faulty timing might if its EXTREMELY bad
but thats detectable with a timing light.

I'd suspect a clogged fuel filter and/or the O2 sensor. A car with 30k
miles on it shouldn't have a messed up O2 sensor though. On the other
hand, driving a car 2300 miles a year is very tough on a car. Thats 44
miles per week. If you can get 400 miles on a tank, that means you are
on average going at least 9 weeks between refuels. Gas does degrade,
and humidity condenses in the gas tank which just sits there and nastifies
your gas.

That said, if it were me, I'd positively diagnose it, and if you can't do
that, take it to someone who is willing to, and not just throw parts at
it, or guess about it because it will never get fixed that way, and you'll
never be sure. You can positively diagnose the problem if its a faulty
sensor, period.

BTW, Temic is a German company, as is Beru and Bosch, they are all completely
seperate companies.

> wrote in
:

> This whole thing is very very sad.

Thank you for your empathy.

> I hesitate to say too
> much, because the most obvious comment is, the people who
> are alleged "mechanics" are plain and simple incompetent.

I have found this out, even though I have only owned 3 cars in
my life. I once had a VOLVO dealer set the idle on a Volvo stick
shift station wagon to 2000 RPM, so I had to step on the gas AND
on the brake to have it idle normally! The hills and mountains
were especially enjoyable!

> First off, if you have a very high CO level that indicates
> the car is running rich. A faulty distributor or ignition
> coil will not cause you to run rich. Faulty timing might
> if its EXTREMELY bad but thats detectable with a timing
> light.

The permissible aircheck CO level was just lowered from 2 to 1 -
6 months ago my car passed with flying colors. Now my CO
emission level was between 1.5 and 4.5 (per ?) depending on the
2000/4000 RPM readings and depending on whether the "mechanics"
who do these things here messed with the timing first. FWIW, it
was BETTER (under '2' /both/ RPM's) /before/ they slowed it
down!

Still, they ALL said I need a new 0² sensor, as the plug-in
scanner whose reading I /personally/ saw did. But my mechanic
said it was the coil - so I have a 3rd coil in 6 months or so. A
Temic (albeit a Mexican one as I assume the others were, but no
has said anything about that making them worthless) - which
impressed me - I had never heard of Temic let alone that it was
"the only coil to get" until Dave replied to me. OTOH, 3 Temics
in 6 months is NOT so impressive. OTOH, the original lasted over
12 years but who knows what THAT was and where it was made?

I am tempted to buy a real Bosch 0² sensor but my garage says
not to waste the money if the car runs OK. It will be cheaper
than taking it to a dealer for a (hopefully accurate) diagnostic
but at this point (see below) I am just going to wait until the
next disaster strikes.

The current situation is:

It ran GREAT for the first 5 miles after they put in the 3rd
coil and adjusted the AIV.

Then when I started it next day it started instantly (as it
ALWAYS has) but idled even MORE roughly than before! The needle
actually went down to 400 at one point! But it ran fine,
although I /fully/ expected total disaster at some point.

The next day it started, idled and ran just perfectly - and I
stopped and started about 4 or 5 times that day.

> I'd suspect a clogged fuel filter and/or the O2 sensor. A
> car with 30k miles on it shouldn't have a messed up O2
> sensor though.

Yes, I read they last 60K miles.

> On the other hand, driving a car 2300 miles
> a year is very tough on a car. Thats 44 miles per week.

Sometimes it's 10 miles a week, sometimes it's 80. There's
nothing I can do - I am not going to drive it just for the sake
of putting miles on it, right? I live in a huge city with
horrible traffic. It's hell.

As I said, I always warm it up and religiously change
oil/filters. It has always run perfectly well, and when I
started having some problems about a year ago, another garage
cleaned the injectors and a few other things. It was OK for a
few weeks, than it started up again.

I was recommended /this/ garage. They tuned it up, put Bosch
spark plugs in (Dave - I was wrong, Bosch, not Japanese, I
checked the invoice), new dist. cap and rotor, re-cleaned the
injectors, and a few other things (I am reasonably sure they
checked the fuel filter, which was changed a couple of years ago
anyway along with the fuel pump - original German pump was
installed [then THAT garage closed down, of course].).

Anyway, after these guys did all that, it ran better than it has
//EVER// run. (I have been driving it since the car was about 3
years old, for about 10 years now.)

> If you can get 400 miles on a tank, that means you are on
> average going at least 9 weeks between refuels.

The tank is about 15 gallons and I seem to get about 16-20 mpg.
It's always been that - AFAICT because since I drive it so
little I never paid much attention to the gas consumption.

It does vary, but I am sure I have gone 5-8 weeks with no
refill. The gas gauge is a little "moody", and it' not worth
getting into the tank to fix it. But I believe I get more like
200-250 miles per tank. I fill it up full every 100 miles or so
and it usually takes 4-5 gallons to get it full. I reset the
"trip meter" to judge when to fill up.

My garage told me I have to run about 150 miles on it before
they can do a new accurate scanner reading. That's how I knew
last week that I got about 20 mpg - I wrote down the numbers.
The BAD news is that was 90% on the freeway!!!!

> Gas does
> degrade, and humidity condenses in the gas tank which just
> sits there and nastifies your gas.

Well, I didn't know that, and it sounds bad, but short of
stuffing a petrol-resistant rubber bag inside the tank and
inflating it so the tank capacity is reduced to 5 gallons, what
can I do?

> That said, if it were me, I'd positively diagnose it, and
> if you can't do that,

*I* personally certainly can't do it. I have learned more about
this car in this thread than I ever knew before.

> take it to someone who is willing to,
> and not just throw parts at it, or guess about it because
> it will never get fixed that way, and you'll never be sure.

These ARE words of wisdom and I appreciate them.

AT /this/ moment it seems fine. Maybe the super-erratic idling
(which only happened once since the last service) was just the
new coil/AIV adjusting themselves to their "new home" (I know, I
sound like an idiot). If it screws up again, depending on what
my garage says THEN, I MAY bite the bullet and take it to a VW
dealer. If anyone can /positively/ diagnose it, /they/ should be
able to. It will probably cost me 1/8 the current worth of the
car, but that's still better than buying a new one.

> You can positively diagnose the problem if its a faulty
> sensor, period.

Well, as I said, a garage I happened to be passing by at the end
of a hellish day (and figured, what the hell, let's see what
/they/ say) did a scanner reading and it indicated the 0² sensor
as bad.

But MY garage said THEIR scanner indicated a faulty AIV, and
that they adjusted it and also put in a new coil (another
Mexican Temic) since the coil had just died at the same time,
more or less. (Good thing insurance includes towing.)

> BTW, Temic is a German company, as is Beru and Bosch, they
> are all completely separate companies.

Thanks, I got confused when Googling.

Thanks for your comments. I will keep you "posted".

Regards
vc

On Wed, 04 Jun 2008 02:12:14 +0100, vampire chicken >
wrote:

> > wrote in
> :
>
>> This whole thing is very very sad.
>
> Thank you for your empathy.
>
>> I hesitate to say too
>> much, because the most obvious comment is, the people who
>> are alleged "mechanics" are plain and simple incompetent.
>
> I have found this out, even though I have only owned 3 cars in
> my life. I once had a VOLVO dealer set the idle on a Volvo stick
> shift station wagon to 2000 RPM, so I had to step on the gas AND
> on the brake to have it idle normally! The hills and mountains
> were especially enjoyable!
>
>> First off, if you have a very high CO level that indicates
>> the car is running rich. A faulty distributor or ignition
>> coil will not cause you to run rich. Faulty timing might
>> if its EXTREMELY bad but thats detectable with a timing
>> light.
>
> The permissible aircheck CO level was just lowered from 2 to 1 -
> 6 months ago my car passed with flying colors. Now my CO
> emission level was between 1.5 and 4.5 (per ?) depending on the
> 2000/4000 RPM readings and depending on whether the "mechanics"
> who do these things here messed with the timing first. FWIW, it
> was BETTER (under '2' /both/ RPM's) /before/ they slowed it
> down!
>
> Still, they ALL said I need a new 0² sensor, as the plug-in
> scanner whose reading I /personally/ saw did. But my mechanic
> said it was the coil - so I have a 3rd coil in 6 months or so. A
> Temic (albeit a Mexican one as I assume the others were, but no
> has said anything about that making them worthless) - which
> impressed me - I had never heard of Temic let alone that it was
> "the only coil to get" until Dave replied to me. OTOH, 3 Temics
> in 6 months is NOT so impressive. OTOH, the original lasted over
> 12 years but who knows what THAT was and where it was made?
>
> I am tempted to buy a real Bosch 0² sensor but my garage says
> not to waste the money if the car runs OK. It will be cheaper
> than taking it to a dealer for a (hopefully accurate) diagnostic
> but at this point (see below) I am just going to wait until the
> next disaster strikes.
>
> The current situation is:
>
> It ran GREAT for the first 5 miles after they put in the 3rd
> coil and adjusted the AIV.
>
> Then when I started it next day it started instantly (as it
> ALWAYS has) but idled even MORE roughly than before! The needle
> actually went down to 400 at one point! But it ran fine,
> although I /fully/ expected total disaster at some point.
>
> The next day it started, idled and ran just perfectly - and I
> stopped and started about 4 or 5 times that day.
>
>> I'd suspect a clogged fuel filter and/or the O2 sensor. A
>> car with 30k miles on it shouldn't have a messed up O2
>> sensor though.
>
> Yes, I read they last 60K miles.
>
>> On the other hand, driving a car 2300 miles
>> a year is very tough on a car. Thats 44 miles per week.
>
> Sometimes it's 10 miles a week, sometimes it's 80. There's
> nothing I can do - I am not going to drive it just for the sake
> of putting miles on it, right? I live in a huge city with
> horrible traffic. It's hell.
>
> As I said, I always warm it up and religiously change
> oil/filters. It has always run perfectly well, and when I
> started having some problems about a year ago, another garage
> cleaned the injectors and a few other things. It was OK for a
> few weeks, than it started up again.
>
> I was recommended /this/ garage. They tuned it up, put Bosch
> spark plugs in (Dave - I was wrong, Bosch, not Japanese, I
> checked the invoice), new dist. cap and rotor, re-cleaned the
> injectors, and a few other things (I am reasonably sure they
> checked the fuel filter, which was changed a couple of years ago
> anyway along with the fuel pump - original German pump was
> installed [then THAT garage closed down, of course].).
>
> Anyway, after these guys did all that, it ran better than it has
> //EVER// run. (I have been driving it since the car was about 3
> years old, for about 10 years now.)
>
>> If you can get 400 miles on a tank, that means you are on
>> average going at least 9 weeks between refuels.
>
> The tank is about 15 gallons and I seem to get about 16-20 mpg.
> It's always been that - AFAICT because since I drive it so
> little I never paid much attention to the gas consumption.
>
> It does vary, but I am sure I have gone 5-8 weeks with no
> refill. The gas gauge is a little "moody", and it' not worth
> getting into the tank to fix it. But I believe I get more like
> 200-250 miles per tank. I fill it up full every 100 miles or so
> and it usually takes 4-5 gallons to get it full. I reset the
> "trip meter" to judge when to fill up.
>
> My garage told me I have to run about 150 miles on it before
> they can do a new accurate scanner reading. That's how I knew
> last week that I got about 20 mpg - I wrote down the numbers.
> The BAD news is that was 90% on the freeway!!!!
>
>> Gas does
>> degrade, and humidity condenses in the gas tank which just
>> sits there and nastifies your gas.
>
> Well, I didn't know that, and it sounds bad, but short of
> stuffing a petrol-resistant rubber bag inside the tank and
> inflating it so the tank capacity is reduced to 5 gallons, what
> can I do?
>
>> That said, if it were me, I'd positively diagnose it, and
>> if you can't do that,
>
> *I* personally certainly can't do it. I have learned more about
> this car in this thread than I ever knew before.
>
>> take it to someone who is willing to,
>> and not just throw parts at it, or guess about it because
>> it will never get fixed that way, and you'll never be sure.
>
> These ARE words of wisdom and I appreciate them.
>
> AT /this/ moment it seems fine. Maybe the super-erratic idling
> (which only happened once since the last service) was just the
> new coil/AIV adjusting themselves to their "new home" (I know, I
> sound like an idiot). If it screws up again, depending on what
> my garage says THEN, I MAY bite the bullet and take it to a VW
> dealer. If anyone can /positively/ diagnose it, /they/ should be
> able to. It will probably cost me 1/8 the current worth of the
> car, but that's still better than buying a new one.
>
>> You can positively diagnose the problem if its a faulty
>> sensor, period.
>
> Well, as I said, a garage I happened to be passing by at the end
> of a hellish day (and figured, what the hell, let's see what
> /they/ say) did a scanner reading and it indicated the 0² sensor
> as bad.
>
> But MY garage said THEIR scanner indicated a faulty AIV, and
> that they adjusted it and also put in a new coil (another
> Mexican Temic) since the coil had just died at the same time,
> more or less. (Good thing insurance includes towing.)
>
>> BTW, Temic is a German company, as is Beru and Bosch, they
>> are all completely separate companies.
>
> Thanks, I got confused when Googling.
>
> Thanks for your comments. I will keep you "posted".
>
> Regards
> vc

If you're going to keep it find somebody with or buy vag-com, it lets you
read all the faults yourself, it's better than generic scanners and as
good if not better than the vw one on a car that age. A new O2 sensor is
cheaper than a dealer scan though.

vampire chicken wrote:
> 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 would be looking at the egr valve and maybe replacing the iacv.

In rec.autos.makers.vw.watercooled vampire chicken > wrote:
> > wrote in
> :
>
>> This whole thing is very very sad.
>
> Thank you for your empathy.
>
>> I hesitate to say too
>> much, because the most obvious comment is, the people who
>> are alleged "mechanics" are plain and simple incompetent.
>
> I have found this out, even though I have only owned 3 cars in
> my life. I once had a VOLVO dealer set the idle on a Volvo stick
> shift station wagon to 2000 RPM, so I had to step on the gas AND
> on the brake to have it idle normally! The hills and mountains
> were especially enjoyable!
>
>> First off, if you have a very high CO level that indicates
>> the car is running rich. A faulty distributor or ignition
>> coil will not cause you to run rich. Faulty timing might
>> if its EXTREMELY bad but thats detectable with a timing
>> light.
>
> The permissible aircheck CO level was just lowered from 2 to 1 -
> 6 months ago my car passed with flying colors. Now my CO
> emission level was between 1.5 and 4.5 (per ?) depending on the
> 2000/4000 RPM readings and depending on whether the "mechanics"
> who do these things here messed with the timing first. FWIW, it
> was BETTER (under '2' /both/ RPM's) /before/ they slowed it
> down!

I'm assuming that the CO level you are referring to is % CO. 1% CO is
very rich. 4.5% is beyond absurd and is a clear indicator something
very blatant is wrong. The last emissions test I performed on my 86
Jetta was 0.00% CO. There's no reason that a properly functioning car
should be above about .15%, and if you are above .5% something is most
likely wrong. Your abysmal fuel economy (and yes, 20 mpg mostly highway
is abysmal, it should be more like 30 mpg) is also a clear indicator you
are running rich.

The idle air control valve, and the timing, and distributor, and the blah
blah blah don't affect this. What can affect it? Dity fuel injectors,
a clogged fuel filter, bad pressure regulator, bad mass airflow sensor (MAF),
bad O2 sensor, and bad coolant temp sensors would be the most obvious causes,
a bad ground could also be to blame. All of these can be checked, and
relatively easily. For example. Put a pressure gauge on the fuel rail
and measure fuel pressure with the pump on. It should reach whatever is
specified in the manual. Turn off the pump. It should stay there. If
you have a pressure gauge which can reference the intake manifold then you
can try measuring with the engine running. The O2 sensor can be checked on
an oscilloscope. The coolant temp sensor can be checked with a multimeter,
as can the MAF most likely (if not an oscilloscope should work). The
fuel filter can be just replaced since its cheap and easy enough, if
you seriously suspect it (and I would if the fuel pressure is too low,
especially when the engine is running).

It sounds like you've been driving around like this for a while, its likely
you have destroyed the catalytic converter by doing this. Be prepared for
that.

>
> Still, they ALL said I need a new 0? sensor, as the plug-in
> scanner whose reading I /personally/ saw did. But my mechanic
> said it was the coil - so I have a 3rd coil in 6 months or so. A
> Temic (albeit a Mexican one as I assume the others were, but no
> has said anything about that making them worthless) - which
> impressed me - I had never heard of Temic let alone that it was
> "the only coil to get" until Dave replied to me. OTOH, 3 Temics
> in 6 months is NOT so impressive. OTOH, the original lasted over
> 12 years but who knows what THAT was and where it was made?

No computer can say you need a new O2 sensor. The computer can say that the
output of the O2 sensor is not what it expects. It is then up to an
educated person to determine why based on performing additional tests.
Bad grounds, or air leaks could cause a properly functioning O2 sensor to
have faulty readings as could other scenarios such as a totally busted
pressure regulator that puts the pressure up so much that the computer can't
adequately lean it to compensate. That last one would have a proper reading
but it wouldn't be what the computer expects, and in fact its the pressure
regulator that has the problem, not the O2 sensor.

As for a coil. The coil is extremely unlikely to cause a high CO reading.
I'm curious how this "mechanic" diagnosed a faulty coil as being to blame
for your cars problem, or how you've gone through 3 of them. To me this
would be a red flag that he's replacing the wrong part. I have heard
rebuilt aftermarket alternators and starters are unreliable, but I am much
more suspicious of a bunch of brand new Temic coils being bad.

> I am tempted to buy a real Bosch 0? sensor but my garage says
> not to waste the money if the car runs OK. It will be cheaper
> than taking it to a dealer for a (hopefully accurate) diagnostic
> but at this point (see below) I am just going to wait until the
> next disaster strikes.

Thats a very very very bad idea. An oxygen sensor will probably cost $60
($30 if you get a universal Bosch sensor). The next disaster will almost
certainly be a screwed up catalytic converter if you continue to run rich,
and you don't want to know how much that will cost. Knowing what is
wrong with your car and fixing it is worth something in terms of piece of
mind. If I had to guess, all these mechanics you have been taking it to
(the one who keeps replacing your coil, the ones who are cleaning your
injectors, etc, etc) are just jerking you around cause they don't know.
If you don't fix it properly for real, this is going to continue forever
and you may as well just get rid of the car now.

> The current situation is:
>
> It ran GREAT for the first 5 miles after they put in the 3rd
> coil and adjusted the AIV.
>
> Then when I started it next day it started instantly (as it
> ALWAYS has) but idled even MORE roughly than before! The needle
> actually went down to 400 at one point! But it ran fine,
> although I /fully/ expected total disaster at some point.

Right, so the idle stabalizer valve and the coil had nothing to do with
the problem. Clearly, yet they keep screwing around with this crap. I
don't know where you are, but you sound more American than British, so
if we are talking a base model 95 US Jetta. I don't even know what the
heck an adjustment is. I've never owned one, but I do have the service
manual, I don't recall hearing of an adjustment, and all the idle stabalizer
valves on A2 cars didn't have adjustments. What the heck would you adjust
anyway? On the A2, sometimes you would adjust the throttle stop position
to get the ECU to provide the right duty cycle to the ISV, but there was
no adjustment on the valve. Yet another thing I have to wonder about.

> The next day it started, idled and ran just perfectly - and I
> stopped and started about 4 or 5 times that day.
>
>> I'd suspect a clogged fuel filter and/or the O2 sensor. A
>> car with 30k miles on it shouldn't have a messed up O2
>> sensor though.
>
> Yes, I read they last 60K miles.

It depends on the model year. Presumably you have a heated O2 sensor.
The 60k miles thing is essentially an EPA recommendation that the vehicle
manufacturers are required to parrot. If the car is otherwise operating
properly, its very possible that the O2 sensor could last 150k miles. Looking
at the output of the O2 sensor and coolant temp sensor would be very
instructive here.

>> On the other hand, driving a car 2300 miles
>> a year is very tough on a car. Thats 44 miles per week.
>
> Sometimes it's 10 miles a week, sometimes it's 80. There's
> nothing I can do - I am not going to drive it just for the sake
> of putting miles on it, right? I live in a huge city with
> horrible traffic. It's hell.

I understand. You just need to understand its hell on the car. Maybe you
should consider an electric vehicle. Oh wait.. there aren't any yet.

> As I said, I always warm it up and religiously change
> oil/filters. It has always run perfectly well, and when I
> started having some problems about a year ago, another garage
> cleaned the injectors and a few other things. It was OK for a
> few weeks, than it started up again.

Warming up a car is just a good way to waste gas. The car is adequately
warmed up within 20 seconds of driving. Just don't drive it hard for the
first couple minutes.

> I was recommended /this/ garage. They tuned it up, put Bosch
> spark plugs in (Dave - I was wrong, Bosch, not Japanese, I
> checked the invoice), new dist. cap and rotor, re-cleaned the
> injectors, and a few other things (I am reasonably sure they
> checked the fuel filter, which was changed a couple of years ago
> anyway along with the fuel pump - original German pump was
> installed [then THAT garage closed down, of course].).
>
> Anyway, after these guys did all that, it ran better than it has
> //EVER// run. (I have been driving it since the car was about 3
> years old, for about 10 years now.)

> Well, I didn't know that, and it sounds bad, but short of
> stuffing a petrol-resistant rubber bag inside the tank and
> inflating it so the tank capacity is reduced to 5 gallons, what
> can I do?

Honestly, based your usage model... There really isn't much you can do.
Uh oh wait... you said petrol... Now I'm wondering if you are in the UK.
Ugh... I don't know how similar the engine electronics on a UK A3 is
to the US one. The A2's were probably quite different.

>> That said, if it were me, I'd positively diagnose it, and
>> if you can't do that,
>
> *I* personally certainly can't do it. I have learned more about
> this car in this thread than I ever knew before.
>
>> take it to someone who is willing to,
>> and not just throw parts at it, or guess about it because
>> it will never get fixed that way, and you'll never be sure.
>
> These ARE words of wisdom and I appreciate them.
>
> AT /this/ moment it seems fine. Maybe the super-erratic idling
> (which only happened once since the last service) was just the
> new coil/AIV adjusting themselves to their "new home" (I know, I
> sound like an idiot). If it screws up again, depending on what
> my garage says THEN, I MAY bite the bullet and take it to a VW
> dealer. If anyone can /positively/ diagnose it, /they/ should be
> able to. It will probably cost me 1/8 the current worth of the
> car, but that's still better than buying a new one.

Well, since I have no idea what adjustment you can do to the idle stabalizer
valve, I can't comment on that one, but the coil absolutely has no adjustment
and I think its unlikely the engine computer would compensate one way or
another based on replacing the coil.

There are people other than VW dealers who could do this, but I would
strongly recommend someone who specializes in Volkswagens. Heck, at one
point I knew more about my specific car than most VW trained mechanics
who did nothing but VWs all day long. You might just ask if there's someone
local who could take a look at it. Being a VW dealer is no guarantee of
good service, sadly enough.

>> You can positively diagnose the problem if its a faulty
>> sensor, period.
>
> Well, as I said, a garage I happened to be passing by at the end
> of a hellish day (and figured, what the hell, let's see what
> /they/ say) did a scanner reading and it indicated the 0? sensor
> as bad.

A scanner reading is not a positive diagnosis. Its an indicator the
computer thinks something is wrong. Likelyhood is that if the
computer thinks something is wrong, there is something wrong, but it
may not be what it looks like.