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Re: [T3] Fastback Progress <a bit long>


On 6 Jan 2002, at 1:51, Christopher Sheridan wrote:

> At one listmembers suggestion I also disconnected the
> fuel line heading into the CSI, not just the mpc. and plugged it up.
> The engine immediately had a great high idle, then I realized that I
> needed to plug up the CSI end as well, which I then did, the idle
> returned to it's lower missing state. Would all CSI with no fuel hose
> on them suck vacuum like that, or just leaky ones?

You should not have to plug the hose (I'm assuming the electrical 
plug was still out so we can be SURE that it was not being 
actuated.) If leaving the hose unplugged gave you a high idle that 
went away when you plugged it, then it is leaking. This is a little 
hard to imagine, because the leak you are describing here sounds 
like a BIG leak, compared to, say, that created by the idle air 
screw. I have a hard time imaging that much air getting thru a 
normal CSV even if it was stuck fully open.

> So with that disconnected and plugged, I tried to readjust the idle
> but found the same inability. Got it to idle at 950 roughly only with
> the idle screw all the way out where I could wiggle it with my hand.
> Not so much good. So I screwed it back down and settle for toggling
> between 950 and 1050 (at the higher end the engine is making a sort of
> muffled grinding sound which corresponds to the moments the rpms move
> over 1000, this is a clue, but I don't have the solution)

That's a bit high, but it should still not be hard to get it to do this. 
The grinding sound is concerning, but it could be any number of 
things, some major, most minor.

> I run the motor and pull each SPwire off the cap one at a time and
> each one causes a noticeable drop in RPM. I then pull one day old plug
> out and its not black, in fact it looks hardly used, more of the color
> of the stuff they coat heads with when you get them back from the
> rebuilder, so those look okay I don't change them. Check the dwell
> -tonight its a steady 47 degrees, needle barely moves at high rpms.
> Check the voltage at the coil its 13.7.

All sounds fine.

> Jim the chassis number on this fastback starts with 3102 and I think
> its a 70, but was suprised when I discovered the engine code is for a
> 1972 type 3. The distributor is either for a 70 or 72 I'm not sure
> which one I have in there. when I turn the key first I hear something
> turn on humming then as I keep turning I hear one definitive click.
> I'm not sure if this is 2 clicks or one, but I wouldn't be suprised if
> the wires on the starter are wrong - there are at least 2 wires
> plugged to the solenoid though I haven't looked too closely at them
> lately.

It is possible that you have a complete 72 engine. If so, you need 
to check out the special instructions for timing a 72. One of the 
things that marks a 72 is that this is the ONLY FI year where the 
vacuum advance can has 2 connections (adv and retard.) They 
each have to be hooked up the the right places and they have to be 
working right to do the timing. This also points out the possibility 
that some of your FI parts may be 72 and some 70. There are 
enough differences that this could cause problems.

It actually sounds like you are getting both clicks. The first click 
occurs as all the dash/idiot lights come on. Go out there and try 
this and keep in mind that the dash lights themselves don't make 
any noise when they come on. What you're watching for is NOT a 
matter of turning the key farther, it is strictly a matter of time. You 
simply turn the key from OFF to ON (don't go to START) and 
listen. It may help to do this with your eyes closed and to hold your 
keys so they don't jangle and confuse the first click.

The hum you hear is most likely the fuel pump running. In doing 
this test it will only run in the ~1 second time between the 2 clicks. 
If you hear the 2 clicks with the pump running in between, then 
your system, including the wires to the starter, is connected 
properly.

> Left on the table is a suggestion to turn the fuel pressure back up a
> bit from 28 to avoid vapor lock - say to 30...I certainly don't want
> vapor lock. Another suggestion to swap out the pressure switch.

Such a suggestion can only stem from an improper understanding 
of vapor lock: You can't get actual vapor lock with the FI setup, and 
the thing you CAN get won't be helped by upping the fuel pressure.

You may need to do an inventory of exactly which FI items are 
installed on your car. The ones to check are the brain, pressure 
sensor, distributor (vac adv can), and temp switch. We don't have a 
pressure switch, but you probably meant the pressure sensor.

> 70 fastback


-
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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