[Vwdiesel] Rabbit down on power/ mpg

lbaird119 at aol.com lbaird119 at aol.com
Sun Jul 6 15:07:12 PDT 2008

-----Original Message-----
From: Scott Alexander <salex at dsl.cis.upenn.edu>
To: vwdiesel at vwfans.com
Sent: Sun, 6 Jul 2008 12:31 pm
Subject: [Vwdiesel] Rabbit down on power/ mpg

>  It is capable of producing a black cloud out the  
>back.  We checked the compression before getting it running and  
>compression was within spec.  We also set the timing on the fuel  
>pump.  The valve clearance has not been checked although we're not  
>hearing/ seeing any signs of valves incorrectly set.

  There's really no "signs" that the valves are out of adjustment.
It's worth checking.  Blowing black smoke is too much unburned fuel.
If the pump hasn't been dinkeed with (most likely not) then the 
injuecors are likely worn and need rebuilt/replaced.
>Since everything is pretty much opened up, I'm trying to figure out if  
>there's some deeper work that I should do now.  My friend suggests  
>that the rings may be tired.  (He also points out that the oil turns  
>black very quickly.)  Since I fear the injection pump ;), I'm  
>wondering if it's worth having that rebuilt.  I also have a spare that  
>was supposed to be good when pulled that I could swap in as a  
>comparison point.  Of course, we're also at the point where it would  
>be easier than normal to do things like run another compression check.
>Any suggestions on where to look and one to try next?

  Since your compression is good, the rings are likely good.  Oil 
will turn black real fast if you're blowing black so that is likely 
the cause of the lower mpg AND the black oil (but don't they all 
turn the oil black quickly?)  ;-)  Low power could be from 
incorrect timing specs, misadjusted valves, or bad injectors.
Bad injectors would explain both.  Wrong timing specs would 
only make other problems worse, except for the low power.  
It could cause that.  It would be rare for it to be a pump 
problem.  Of course check your air and fuel filter.  Both 
of those could cause the exact same problems.  Air filter is 
obvious.  A dirty fuel filter messes with pump pressures, timing 
and whatnot due to lack of proper internal pressures.

  You want to make sure your pump and timing specs match.  Pump 
could be from another car so cross check your vw part number on 
the pump.  I'm not home currently so I'm not sure where the 
address of my pump list is...

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