Control Pressure Problem

[lord_verminaard at yahoo.com (Brendan Doyle)]

Found (at least I think) the problem with my '81 as well.  I pulled the top off of the fuel distributor, and sure enough, the pin was sticky as hell.  Also, the little brass nut with the "o" ring on it was completely unscrewed from the gland nut!  Not sure how it was even running at this point.  The roller pivot on the sensor plate was also really gummed up.  Just goes to show, if it looks good on the outside of the part, does not mean it's good on the inside.  Pulled the pin out and cleaned everything up, re-assembled, and started it- cough cough, sputter, dead.  No starty.  Ok, fine, pulled the spark plugs, they were wet.  Well shit.  While I had the plugs out, I thought, why not pull the valve cover and double-check the cam timing.  So I did- and found a few surprises.  First of all, it had a cam oil baffle on it.  Cool!  I also looked at the cam- hmm, it has a "W" stamped on it- it was supposed to be a "G"!  Well shit, feeling sort of ripped off, I looked at the cam
 some more, and instead of the VW stamp on the other end of it, it had "ESTAS".  So it's a re-grind?  I looked at it closer, and wow, the lobes are close to the journal- REALLY close.  WTF?  I grabbed my other stock cam that was laying around and did a side-by side- (or as close as I could check with the cam in the car) the lobes on the stock cam are dwarfed compared to this one.  I know the G-cam was not this big either- as I really had a hard time noticing any difference from a stock to a "g" when they were next to each other.  So what's the biggest cam you can put in a JH head without clearancing  the journals?  Cause I can barely fit the thinnest feeler gauge I have between the lobe and the journal when they are closest to each other.  Maybe that would explain the lack of low-end torque?  :P

Dried the plugs, cranked the engine over a few times without the plugs in it or the fuel relay on.  I also pulled the DPR off of the fuel distributor, and gave the tiny little hex screw on the back of it a 1/4 turn clockwise, hoping this would also fix my upper-rpm lean problem.  Re-assembled everything, and cranked it up- had trouble starting and idling.  I had to turn the mixture screw about 4 turns away from FULL lean before it would run, but it idled well.  My DPR harness broke, so I threw it in the trash and tuned it by ear instead.  It still idles pretty well rich, just shy of smoking a bit at idle, but if I leaned out the idle any more, it would stumble on low-rpm acceleration.  But getting on it full-throttle, it stays rich all the way up to 6,000 rpms.  And it RUNS.  I can tell the exhaust is holding it back now, it still feels like it wants more.

But not all is well.  This morning, I was driving to work, and I felt that sinking feeling again, where coming to a stop the idle will drop below 900 instead of doing what it normally does, and will idle rough.  Sure enough, no power again.  No sputtering, no misfire, just NO power.  I was aggravated, so I shut the car off and re-started it again.  After about 10 seconds of idle hunting, it went back to it's familiar purr and power was restored.  I really wish I knew what the hell was going on, but all I keep thinking about is that nice shiny TDI engine sitting in my garage just waiting for some attention.  ;)

I will recommend to whomever buys this engine and tranny combo from me to take all of the CIS-E crap and throw it in the trash.  I mean, I adore the engineering behind CIS but sometimes it really just makes NO sense.

Brendan

----- Original Message ----
From: C Boyko <roccit_53@xxxxxxxxxxxxxxxxxxxxxxx>
To:  Gordy Stedman  <ydrogs@xxxxxxxxx>
Cc: Scirocco-l@xxxxxxxxxxxx; housecall55@xxxxxxxxx
Sent: Tuesday, June 12, 2007 7:08:15 AM
Subject: Re: Control Pressure Problem

Good for you!! Posting the cure, what an excellent thing that is!. And a 79
Rabbit in a yard? Not around here unless it was MY yard, they crush them
unless they're really new. And my fuel distributor problem didn't show with
the fuel pressure tests, that's interesting. Mine behaved well at idle, but
did not do well under load. Volume tests identified mine (again, they were
fine with the plate just slightly raised).
I'm starting to think this is like "lupus" for our cars, try everything
else, then come around to the diagnosis of bad distributor. Fuel delivery
is there, it's just not right, some of the time. Glad you found it at any
rate, it's SO nice when they finally do what they're capable of.

Cathy

On 1:18 am 06/12/07 "Gordy Stedman" <ydrogs@xxxxxxxxx> wrote:
> Just to add some closure Sean got a used fuel distributor from the
> yard off a 79 rabbit, swapped it out and it starts right up.  Have
> not hooked up the fuel pressure tester to see what the numbers are
> but it responds like a real VW should.  Just need to turn down the
> idle a little and replace noisy wheel bearins.  We think the PO who
> fucked everything up on the car had the wrong fuel distributor on the
> air box. Need to get a photo of the bolt used to hold on the rear
> control arm clamp, yikes.
>
> On 6/3/07, Gordy Stedman <ydrogs@xxxxxxxxx> wrote:
> >
> >  On 6/3/07, Cris Carpenter <housecall55@xxxxxxxxx> wrote:
> > >
> > >  CIS-E and plain CIS are not the same, and an 81 will have only
> > >  one fuel pump. If the control pressures are indeed as high as
> > >  the system pressure, something is blocking the return through
> > >  the control loop. Are you simply substituting one bad WUR for
> > >  another? If the control pressures are that high, it should have
> > >  a real hard time running at all, but especially cold. If you are
> > >  sure you are using a known good WUR, the problem must be the
> fuel distributor. The control loop uses some fuel pressure to hold the
> > >  fuel distributor plunger down. The air flap of the fuel
> > >  distributor has to overcome the control pressure to raise the
> > >  piston and let more fuel to the injectors. The control pressure
> > >  is lower when cold by virtue of the WUR bleeding it off through
> > >  the return circuit back to the tank, allowing the piston to ride
> > >  higher and let more fuel to the injectors until the engine
> starts to warm up. But both the feed and return side of the warm-up
> > >  loop on an 81 goes through the fuel
> > >  distributor. If you are acccurately testing the control
> > >  pressures (I've seen people set it up wrong), have tried a known
> > >  good WUR, and you still have control pressures that high, the
> > > problem must be the fuel distributor.
> > >  Cris
> >
> >  That was what we were coming up as a conclusion also. Thanks for
> >  the detailed explanation.  It does run badly when cold and would
> >  not start at all until we fixed the cold start injector circuit.
> >  We will be swapping out the fuel distributor, maybe complete air
> >  box assembely sometime this week. Hope it works.
> >  --
> >  Gordy
> >  MK1 x 5
> >
>
>
>
> --
> Gordy
> MK1 x 5
> _______________________________________________
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> Scirocco-l@xxxxxxxxxxxx
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