81 Scirocco smog check fixes update

Is there a vacuum hose under the throttle body? Maybe it is off.
Maybe a closer inspection of the throttle body! Gasket is ok?
How did you check that both throttle plates were closed?
Test the idle with the accelerator cable off of the throttle linkage.
I remember seeing an intake manifold loose on a 1981 Cabriolet. That really
messed up its idle!
Does the engine die if you remove the main intake boot on top of the fuel
distributor?

Running out of ideas here!

"nutso fasst" > wrote in message
...
>
> "dave AKA vwdoc1" > wrote in message
> ...
>> Keep looking! :-)
>
> I checked the AAV (closed when hot). I blocked the intake hose from the
> AAV
> to ensure the AAV was sealing OK. I blocked the hose to the distributor
> timing retard and brake booster (thus increasing idle speed because timing
> advances quite a bit). I checked the idle air screw for seating using a
> pen
> light and dental mirror (don't see any damage). Throttle butterflies fully
> closed. I ran propane around everything again. Opened a vacuum line and
> sprayed propane around it just to confirm rpms went up.
>
> From where comes air that burns the fuel to idle fast and blow my cool?
>
> This engine is supposed to be timed with vacuum hoses attached to
> distributor. But changing CO changes manifold vacuum which changes timing
> which changes idle speed which changes...
>
> (Oops. Slick little wet spot under the car. Never noticed that clutch-side
> crank seal leak before.)
>
>

With a high idle you only have to check for leaks after the throttle body!
All the stuf before the t.body has only effect on fuel, advance etc. So
inspect the whole intake manifold and all it's attachments.

SFC

"nutso fasst" > schreef in bericht
...
>
> "dave AKA vwdoc1" > wrote in message
> ...
>> Keep looking! :-)
>
> I checked the AAV (closed when hot). I blocked the intake hose from the
> AAV
> to ensure the AAV was sealing OK. I blocked the hose to the distributor
> timing retard and brake booster (thus increasing idle speed because timing
> advances quite a bit). I checked the idle air screw for seating using a
> pen
> light and dental mirror (don't see any damage). Throttle butterflies fully
> closed. I ran propane around everything again. Opened a vacuum line and
> sprayed propane around it just to confirm rpms went up.
>
> From where comes air that burns the fuel to idle fast and blow my cool?
>
> This engine is supposed to be timed with vacuum hoses attached to
> distributor. But changing CO changes manifold vacuum which changes timing
> which changes idle speed which changes...
>
> (Oops. Slick little wet spot under the car. Never noticed that clutch-side
> crank seal leak before.)
>
>

Pull the plug out of the old hose and stick it in the new hose. It was
just a metal plug inside the old hose so it should come out. Leaky
valve cover? As the other person mentioned false air somewhere. Have
you tried to squish the valve cover hose flat to see if the idle
changes?

Did you plug the vacuum hose to the brake booster? I do not recall if
that is hard plastic but you do not want to squeeze a hard plastic
hose shut.

On my old cars I had to replace all the little plastic vacuum lines.
They were all brittle. You can get that stuff at a good auto parts
house. I used to grab those lines when I was in the junk yard.

If your hood is original and not butchered there should be a vacuum
hose diagram listing every hose. It may not list every plug or cork
that may be there to block of unused vacuum sources. Triple check that
every line starts at the correct port and finishes at the correct
place. Block off the line that goes to the golf ball vacuum reservoir
on the hood which also goes to the inside the car vacuum system to
control air flow. You do have the golf ball reservoir on the hood?

Have you made sure that the air flow sensor moves freely? There is a
procedure in the Bentley for that. I had a fuel distributor plate mess
up in my 84. I tried to fix it but a trip to the junkyard to get a
distributor from an 85 with some other spare parts fixed the problem.
I spent a few hours at one guy's house trying to figure out a starting
problem that was fixed when the fuel distributor was changed. Please
do not start messing with this stuff as you may introduce yet another
problem. It is easy to goof up when you start messing with that
distributor.

When you attach a timing light to the distributor and apply vacuum to
the vacuum advance line does it advance? Does it go back when you
remove the vacuum? When you attach vacuum to the vacuum retard does it
retard? Does it go back when vacuum is released?

So you don't live where Dave, Jim, SFC, Nate or any other folks who
really know VWs live?

On Sat, 27 Sep 2008 08:54:24 -0700, "nutso fasst"
> wrote:

>
>"Jim Behning" > wrote in message
.. .
>> No, your memory is correct. I think there was a metal plug with a hole
>> in the middle. So instead of that hose being 13 mm ID it was 3 mm or
>> something like that. Just for fun he could get a big C clamp or an
>> alligator nose Vise Grip to close off that hose. That would almost
>> simulate the missing plug. If the idle drops way down you found one of
>> your problems. Once again it could be a lot of problems, not just one.
>
>I inspected the hose with a strong penlight. The plug with the hole is
>there. I felt a plug in the new hose as well, but the old is more
>restrictive. I can see light through the small hole but there's apparently
>crankcase vapor residue and simply shooting carb cleaner through doesn't
>remove it completely. Clearly though, this is 'measured air' that is going
>into the manifold, so perhaps the engine can't be shut down with the idle
>air screw alone.
>
>Anyway, I'm now back to square 173 and will continue working at it today.
>One thought that comes in answer to "how could fixes and cleaning make
>things worse?" is the possibility someone screwed the idle screw in too hard
>at some point and damaged the seat such that it can't be closed. The crud I
>cleaned out was acting as a restriction. I wish I'd looked at that more
>carefully when I had the throttle body off.
>
>nf
>

"SFC" > wrote in message
.. .
> With a high idle you only have to check for leaks after the throttle body!
> All the stuf before the t.body has only effect on fuel, advance etc. So
> inspect the whole intake manifold and all it's attachments.

I noticed that:
(1) a small leak in the intake manifold (remove small hose) raises idle
speed
(2) a large leak (remove large hose) stalls the engine
(3) a small leak before the throttle body slows the idle
(4) a large leak (open a rubber boot) stalls the engine

#4 had to be the case. Without vacuum in the intake tube, how can the air
sensor plate lift enough to supply fuel to the injectors?

I suspect the crack in the plastic intake tube occurred after the first smog
check (failed for HC only). Vacuum dropped at the air sensor and caused a
leaner fuel/air mixture which explains the big rise in NOx. By the time of
the third test the crack had opened even more, giving the 'gross polluter'
rating for NOx.

With the idle air screw fully closed, the AAV fully closed, and the throttle
plates fully closed, there should be no vacuum at the air sensor plate and
the engine shouldn't run even if there are leaks elsewhere in the manifold,
correct? So the basic problem is either leakage through the throttle body
from the intake tube or an AAV that leaks even when closed. The throttle
plates seal tightly enough to dam up carb cleaner in the venturis and the
air screw looks to be sealing OK. So maybe I should recheck the AAV.

I noticed the idle drop briefly when the cooling fan came on but turning on
the lights has no effect.

If I up the CO enough to get a smooth hot idle (1050-1100 rpm) and then the
engine is allowed to cool completely so the AAV is open, the cold engine
idles at about 800 rpm initially, and then rises to 1050-1100 after 5
minutes or so as the AAV closes.

If I lower the CO to get the hot idle below 1K, and then shut off the engine
and allow it to cool for a while but not so long that the AAV opens, and
then start the engine, it hardly idles and needs to be run for a minute
before it will idle OK.

The diagram inside the hood shows the plastic "on/off" valve to which the
distributor advance vacuum hose attaches. The output hose from the valve
goes to a "carbon cannister." Other small hoses are still a mystery.

The air flow sensor plate appears to be at the top of the 5mm tolerance (top
of plate at narrowest opening). Maybe I should lower it slightly and see
what happens. (I'm measuring it with key off. The Clymer manual gives a
complicated procedure using a fuel pressure gauge and a special VW tool.)

Thanks much to all who have taken the time to offer insight into this
problem. If I don't find a 'good' fix soon, I'm going to set the CO lean
enough to idle <1K and get an 'off-line' smog check.

nf

On Mon, 29 Sep 2008 14:32:59 -0700, "nutso fasst"
> wrote:

>
>"SFC" > wrote in message
. ..
>> With a high idle you only have to check for leaks after the throttle body!
>> All the stuf before the t.body has only effect on fuel, advance etc. So
>> inspect the whole intake manifold and all it's attachments.
>
>I noticed that:
>(1) a small leak in the intake manifold (remove small hose) raises idle
>speed
>(2) a large leak (remove large hose) stalls the engine
>(3) a small leak before the throttle body slows the idle
>(4) a large leak (open a rubber boot) stalls the engine
>
>#4 had to be the case. Without vacuum in the intake tube, how can the air
>sensor plate lift enough to supply fuel to the injectors?
>
>I suspect the crack in the plastic intake tube occurred after the first smog
>check (failed for HC only). Vacuum dropped at the air sensor and caused a
>leaner fuel/air mixture which explains the big rise in NOx. By the time of
>the third test the crack had opened even more, giving the 'gross polluter'
>rating for NOx.
>
>With the idle air screw fully closed, the AAV fully closed, and the throttle
>plates fully closed, there should be no vacuum at the air sensor plate and
>the engine shouldn't run even if there are leaks elsewhere in the manifold,
>correct? So the basic problem is either leakage through the throttle body
>from the intake tube or an AAV that leaks even when closed. The throttle
>plates seal tightly enough to dam up carb cleaner in the venturis and the
>air screw looks to be sealing OK. So maybe I should recheck the AAV.
>
>I noticed the idle drop briefly when the cooling fan came on but turning on
>the lights has no effect.
>
>If I up the CO enough to get a smooth hot idle (1050-1100 rpm) and then the
>engine is allowed to cool completely so the AAV is open, the cold engine
>idles at about 800 rpm initially, and then rises to 1050-1100 after 5
>minutes or so as the AAV closes.
>
>If I lower the CO to get the hot idle below 1K, and then shut off the engine
>and allow it to cool for a while but not so long that the AAV opens, and
>then start the engine, it hardly idles and needs to be run for a minute
>before it will idle OK.
>
>The diagram inside the hood shows the plastic "on/off" valve to which the
>distributor advance vacuum hose attaches. The output hose from the valve
>goes to a "carbon cannister." Other small hoses are still a mystery.
>
>The air flow sensor plate appears to be at the top of the 5mm tolerance (top
>of plate at narrowest opening). Maybe I should lower it slightly and see
>what happens. (I'm measuring it with key off. The Clymer manual gives a
>complicated procedure using a fuel pressure gauge and a special VW tool.)
>
>Thanks much to all who have taken the time to offer insight into this
>problem. If I don't find a 'good' fix soon, I'm going to set the CO lean
>enough to idle <1K and get an 'off-line' smog check.
>
>nf
>
the aav is not airtight. There is nothing to really check. You
visually look to see that it closes.

You do not adjust idle speed with CO adjustments.

Throttle plates are not supposed to be totally closed otherwise they
wear out the housing. They are cracked open just a tiny bit.

Why don't you take a picture of the hose diagram on the hood and post
it along with a picture of your engine compartment. Kodak has a free
picture gallery that I use.

I saw no posting about trying to install your restrictor from the old
crankcase vent hose into the new crankcase vent hose.

"Jim Behning" > wrote in message
...

> the aav is not airtight. There is nothing to really check. You
> visually look to see that it closes.

Which I did. And it does. If it is not airtight then I think I'm OK there. I
had the hose off the closed AAV and blocked it to the manifold. This
decreased idle speed slightly. But there was a bit of vacuum at the closed
AAV. When I blocked the hole to the AAV the idle speed increased slightly.
All in all, completely blocking the closed AAV produced almost no change in
idle speed.

> You do not adjust idle speed with CO adjustments.

Taking CO lean brings idle speed down. Idle speed >1K is immediate smog test
fail.

> Throttle plates are not supposed to be totally closed otherwise they
> wear out the housing. They are cracked open just a tiny bit.

Many years ago I took this car to a BMW 'mechanic'. I don't remember what
was wrong with the engine, but when I picked up the car the idle was bad.
The 'mechanic' told me the engine was near death (115K mi). When I got home
I discovered the idle stop screw had been screwed out and the throttle plate
was sticking in the venturi. That made me aware of the purpose of the stop
screw. Both throttle plates now close as much as possible without sticking.

> Why don't you take a picture of the hose diagram on the hood and post
> it along with a picture of your engine compartment. Kodak has a free
> picture gallery that I use.

I already posted a link to pictures of my engine compartment. They're at:
http://hpaa.com/autos
Looking closely at the diagram I see the 'mystery hoses' are for the air
conditioner. I turned the stop valve around so those lines are blocked. (I
disconnected the air conditioner long ago.) Too dark to take pics of the
diagram right now, my DV camera has no light.

> I saw no posting about trying to install your restrictor from the old
> crankcase vent hose into the new crankcase vent hose.

Apparently you aren't seeing all of my posts. I did not buy the new hose.
There is nothing wrong with the old one. The only difference is that the
restrictor in my hose is more restrictive than the restrictor in the new
one.

nf

It has been too long for me, since I have not seen one of these in 10-15
years. lol
So I am not sure if the PCV is routed correctly. I guess it is, since you
have owned the car since new or close to new.

Those little hoses in the upper picture should go to the vacuum reservoir
and the heater controls inside the car.

If you have plugged ALL of the hoses at the same time and dialed the idle
screw all the way in and you still have a high idle and no intake manifold
leaks then............
throttle body.

If the intake manifold gasket is blown at the bottom will propane still be
sucked in?

I should have some spare throttle bodys if you need one. I was about to
recycle a lot of the stuff I have in my basement that I probably won't need
ever again!
Are you sure that your secondary throttle plate is free and fully closing?
I have had to free up many of them that were sticking from corrosion.

I vote you take off that TB again and inspect it and test it!

JMHO
--
later,
(One out of many daves)

"nutso fasst" > wrote in message
...
>
> "Jim Behning" > wrote in
> message
> ...
>
>> the aav is not airtight. There is nothing to really check. You
>> visually look to see that it closes.
>
> Which I did. And it does. If it is not airtight then I think I'm OK there.
> I
> had the hose off the closed AAV and blocked it to the manifold. This
> decreased idle speed slightly. But there was a bit of vacuum at the closed
> AAV. When I blocked the hole to the AAV the idle speed increased slightly.
> All in all, completely blocking the closed AAV produced almost no change
> in
> idle speed.
>
>> You do not adjust idle speed with CO adjustments.
>
> Taking CO lean brings idle speed down. Idle speed >1K is immediate smog
> test
> fail.
>
>> Throttle plates are not supposed to be totally closed otherwise they
>> wear out the housing. They are cracked open just a tiny bit.
>
> Many years ago I took this car to a BMW 'mechanic'. I don't remember what
> was wrong with the engine, but when I picked up the car the idle was bad.
> The 'mechanic' told me the engine was near death (115K mi). When I got
> home
> I discovered the idle stop screw had been screwed out and the throttle
> plate
> was sticking in the venturi. That made me aware of the purpose of the stop
> screw. Both throttle plates now close as much as possible without
> sticking.
>
>> Why don't you take a picture of the hose diagram on the hood and post
>> it along with a picture of your engine compartment. Kodak has a free
>> picture gallery that I use.
>
> I already posted a link to pictures of my engine compartment. They're at:
> http://hpaa.com/autos
> Looking closely at the diagram I see the 'mystery hoses' are for the air
> conditioner. I turned the stop valve around so those lines are blocked. (I
> disconnected the air conditioner long ago.) Too dark to take pics of the
> diagram right now, my DV camera has no light.
>
>> I saw no posting about trying to install your restrictor from the old
>> crankcase vent hose into the new crankcase vent hose.
>
> Apparently you aren't seeing all of my posts. I did not buy the new hose.
> There is nothing wrong with the old one. The only difference is that the
> restrictor in my hose is more restrictive than the restrictor in the new
> one.
>
> nf
>
>

> I noticed that:
> (1) a small leak in the intake manifold (remove small hose) raises idle
> speed
That's normal..

> (2) a large leak (remove large hose) stalls the engine
To little air flow passing the meter, so not enough fuel...

> (3) a small leak before the throttle body slows the idle
Less airflow passing the meter, so leaner mixture

> (4) a large leak (open a rubber boot) stalls the engine
No air flow passing the meter, so no fuel...

> #4 had to be the case. Without vacuum in the intake tube, how can the air
> sensor plate lift enough to supply fuel to the injectors?
I agree, altough it's hardly a vacuum, more to do with flow.

> With the idle air screw fully closed, the AAV fully closed, and the
> throttle
> plates fully closed, there should be no vacuum at the air sensor plate and
> the engine shouldn't run even if there are leaks elsewhere in the
> manifold,
> correct?

Yes, no air passing the air meter meanse no fuel injection..

> The diagram inside the hood shows the plastic "on/off" valve to which the
> distributor advance vacuum hose attaches. The output hose from the valve
> goes to a "carbon cannister." Other small hoses are still a mystery.

Could be a vac. line going to the instr. panel. This is used for measuring
fuel comsumption.
Does it have MFA (small computer showing oil temp, speed etc)?

>
> The air flow sensor plate appears to be at the top of the 5mm tolerance
> (top
> of plate at narrowest opening). Maybe I should lower it slightly and see
> what happens.

No, this is good. Tolerance is between the top of the cyl. part and 0,5mm
below it.

SFC

You block vacuum lines with a screw or a bolt. That little thing you
turned around is a check valve. It will not function as a plug with
any guaranteed performance. Just remove it and stick a screw in the
hose. read further for my ideas on that line.

Your pictures are missing a lot of hoses. Well maybe not as I turn the
page in my Bentley. There should be a T in the vacuum
advance/Evaporative emission control valve/vacuum port after throttle
plates, or is it before the throttle plates. Looks like after the
plates but I can't tell without a throttle body in my hand.

I think you are working off the center diagram on my page 2 unless you
have EGR.

http://www.brookridgemorgans.com/jim/VWVacuum.JPG or
http://www.brookridgemorgans.com/jim/VWVacuum2.jpg

Your first picture shows what you believe to be hoses for the AC and
vent control system. That hose heading to the left or to the front of
the car should be attached to a vacuum reservoir. On my Rabbits that
reservoir was attached to the hood with two rubber straps and looked
like a bunch of golf balls. I do not recall looking under the hood of
a Sirocco with AC to know what your reservoir is supposed to look
like. Just put a screw in the vacuum hose just before the T to block
that all off.

That set of black hoses with the T fitting where one to the right goes
to the check valve and off to the ventilation controls. Might as well
block it before that check valve. The left side of the T goes to the
vacuum retard on the distributor. Make sure you have no leaks with
your Mighty Vac.

I do not have any throttle bodies laying around anymore. There may be
ports on the throttle body that are supposed to be capped off with
rubber plugs if not used. Make sure they are capped. The vacuum
advance in the picture shows it sourcing from as close to the intake
manifold as possible but off the throttle body. Make sure it is on the
correct port.

Are the hoses to the charcoal canister and the accumulator tank in
perfect shape? Have you eliminated them during your troubleshooting
with big plugs?

You may not be understanding what I said about CO adjustments. Yes
playing with the CO will make differences in the idle speed. That is
not how you adjust the CO. You get out your dwell meter and set it
accordingly. Of course you cannot ever properly set the CO with false
air leaks. I can adjust the idle speed of my car with the gear shifter
and the clutch. I just put the car in gear. Let out the clutch a bit
with the parking brake en gauged. The idle speed adjusts. :-)

Engine compartment looks to be in pretty good shape.

On Mon, 29 Sep 2008 18:24:39 -0700, "nutso fasst"
> wrote:

>
>"Jim Behning" > wrote in message
.. .
>
>> the aav is not airtight. There is nothing to really check. You
>> visually look to see that it closes.
>
>Which I did. And it does. If it is not airtight then I think I'm OK there. I
>had the hose off the closed AAV and blocked it to the manifold. This
>decreased idle speed slightly. But there was a bit of vacuum at the closed
>AAV. When I blocked the hole to the AAV the idle speed increased slightly.
>All in all, completely blocking the closed AAV produced almost no change in
>idle speed.
>
>> You do not adjust idle speed with CO adjustments.
>
>Taking CO lean brings idle speed down. Idle speed >1K is immediate smog test
>fail.
>
>> Throttle plates are not supposed to be totally closed otherwise they
>> wear out the housing. They are cracked open just a tiny bit.
>
>Many years ago I took this car to a BMW 'mechanic'. I don't remember what
>was wrong with the engine, but when I picked up the car the idle was bad.
>The 'mechanic' told me the engine was near death (115K mi). When I got home
>I discovered the idle stop screw had been screwed out and the throttle plate
>was sticking in the venturi. That made me aware of the purpose of the stop
>screw. Both throttle plates now close as much as possible without sticking.
>
>> Why don't you take a picture of the hose diagram on the hood and post
>> it along with a picture of your engine compartment. Kodak has a free
>> picture gallery that I use.
>
>I already posted a link to pictures of my engine compartment. They're at:
>http://hpaa.com/autos
>Looking closely at the diagram I see the 'mystery hoses' are for the air
>conditioner. I turned the stop valve around so those lines are blocked. (I
>disconnected the air conditioner long ago.) Too dark to take pics of the
>diagram right now, my DV camera has no light.
>
>> I saw no posting about trying to install your restrictor from the old
>> crankcase vent hose into the new crankcase vent hose.
>
>Apparently you aren't seeing all of my posts. I did not buy the new hose.
>There is nothing wrong with the old one. The only difference is that the
>restrictor in my hose is more restrictive than the restrictor in the new
>one.
>
>nf
>

OK, I bypassed the A/C hose completely (vacuum reservoir is in the front of
the right wheel well, BTW). The center diagram you posted is not quite
right. See additional photos - including the diagram inside the hood - at
http://hpaa.com/autos

The vacuum advance is the only hose connection on the throttle body. The
tiny hole is just outside the throttle plate. There is no measureable vacuum
until the throttle is opened.

Hoses to the charcoal canister look good. I don't think that line's at
fault. Sucking on the vacuum hose that goes to the on/off valve for the
charcoal canister causes idle speed to increase. I need to find some rubber
plugs.

I understand what you meant regarding idle and CO. But I really want to get
this car smogged so I can get current tags (registration paid, tags pending
smog check). Ol' lady can't/won't drive my truck and I'm tired of being a
chaffeur.

Question regarding the dwell meter CO adjust: 49-state spec is 1.5% CO.
California spec is .3% CO. Shouldn't the dwell be different for Calif. cars?

nf