[T3] Cylinder Performance

[Adriel Rowley]

----------------------------------------
> From: jadney at vwtype3.org
> To: type3 at vwtype3.org
> Date: Sat, 18 Jun 2011 06:34:10 -0500
> Subject: Re: [T3] Cylinder Performance
>
> On 17 Jun 2011 at 18:00, Adriel Rowley wrote:
>
> > Pulled number three and was fouled: black as coal.  Wire wheeled it,
> > and reinstalled.
>
> Cleaning a spark plug with a wire brush will leave metal tracks on
> the insulator which will often allow the spark to go to ground along
> the surface of the insulator rather than jumping the gap. You might
> want to replace that plug now, or swap it with a different cylinder
> to see if the problem moves.
>
Good to know about the brush, but I used a wheel, which if I understand
correctly, is fine to do.  Why could I not clean it?

I use a wire wheel as it cleans the spark plug, rather than having it 
take up landfill space. ;)  Is there a better way to clean them?

> > Checked four, and was clean as it was when I put it in less than 25
> > miles ago (unknown hours though).  Therefor, figured number three must
> > be getting too much fuel,
>
> Black plugs usually mean that the cylinder is not firing at all. This
> would be due to lack of spark, lack of fuel, or lack of compression.
> Check the resistance of all 4 SP wires.
>
It was not firing prior to cleaning.  I thought fouling was do to over 
richness of the mixture, thus why I changed the fuel injector.  So, we
now know we have fuel.  Will check compression, but my meter cannot 
measure wire resistance for some reason.  I do have the wonderful spark
plug wires you rebuild for me, but so nice I put them in a safe place...

> > checked number three injector beside four.  Got a bit of a stream
> > rather than number four's fog.  So, swapped to another injector but
> > did not test, ASSuming it was fine.  However, with engine running,
> > still is not quite right.  Pulled the number three spark plug wire
> > from the distributor cap, I get about half the response as I do from
> > the others.  I do notice the spark is brighter than before, but hard
> > to be sure in bright light.  I am now thinking after all the sitting
> > with gasoline the injector did in its life, might need cleaning.  So
> > sending out a set to be tested and cleaned, since I have heard this
> > strong recommendation many times but thought all was fine.  Lesson
> > learned: prevent rather than fix.
>
> In 40 years, I don't think I've ever had to replace an injector due
> to a bad spray pattern, only due to leaking gas externally. If you're
> having spray pattern problems, it makes me think that you've either
> got dirt getting in there or water that's causing rust. Make sure
> your overflow hose is good, or repaired, and change your fuel filter.
>
Overflow is good, however water could have been in the tank.  Here in
the land of Socialism and wacko tree huggers, they put corn in the fuel.
I get a great magazine called "Skinned Knuckles", and one of the 
articles was discussing how the ethanol absorbs water, then gets 
saturated to the point where the fuel then has water in it.  This can 
happen as the fuel cap sealing ring is dried out and also in a moist 
climate being by the coast.  The fuel was over a year old, but no 
longer drain fuel as there is no way to dispose of it other than adding 
it to the drained oil to be recycled.  The time I did that, they 
wondered why the oil smelled so bad but I just laughed and left; could 
have been an issue. I did have an improvement in performance when I put 
fresh fuel in.  I did take Bob's advice and put in fuel dryer/cleaner, 
but have not driven it since, though thinking I will today (been paying
bills long distance).

Sunday I will be at Oma's house for Father's day, so will round up all 
the fuel injectors and send them off to be cleaned to be sure all rust 
is removed.  Plus, then can be sure flow rates are within proper range 
of each other, especially the rebuilt units (you had mentioned prior 
they may be an issue so going to just get flow rate measured).

What should I do in the future to prevent the fuel getting moister in 
it?  The last time I looked in the tank a couple years ago, there was 
some rust.  Will this be an issue in the future?

> Your injectors should all be BOSCH with yellow bodies and part number
> ending in 007.
>
They are 007, as I checked when I get them.  If they are not, I would have
tossed them (no one wanted the L-Jetronic injectors).  Might have some 
early black bodies, I.I.R.C..

> > My question is how much of an affect does variations in spray (already
> > know what streaming does) have on cylinder performance, i.e.
> > variations of fine atomization.
>
> I've never seen the spray pattern be very important. Since the spray
> just goes onto the intake valve, the combustion chamber never sees
> that pattern. My guess is that the pattern might have more to do with
> cold starts in cold weather but becomes irrelevant once the intake
> valve warms up.
>
I thought the chamber at one point does see the pattern: thank you for 
clarifying this.  Cold starts is the same answer I got on theSamba.  It is 
the time where I am doing my observations.  Was a bit nervous to drive it 
out of perfect tune.

> > Also, what about spark plug gap?  I am using the disk gapper, so
> > thinking I could be in the range of 28 to 30 thousandths, and do not
> > know if this is something to be aware of.
>
> Try reducing the gap a bit, to more like .024". Sometimes the larger
> gaps make it more likely that the spark will "leak" out somewhere
> else before it gets to the plug.
>
For some reason, I thought the gap was 0.028...  Will close it down.



Thank you so very much!
Adriel