[T3] gas mileage, voltage, etc.

[Jim Adney]

On 23 Jun 2017 at 16:32, Daniel Nohejl wrote:

> Okay, so I went back out to the car and gave another look and would you believe that the MPS hose WAS actually disconnected from the plenum? When I looked at it yesterday, it was after the first really loud pop out the exhaust and I´d only driven a few hundred yards. I guess by the time I got back to my house it had vibrated further away b/c itTMs pretty obvious in this pic:
> 
> https://www.thesamba.com/vw/forum/album_page.php?pic_id=1659004
> 
> Oops. 

I never put a clamp on that hose, because there's no pressure on it, but I do 
run it down BETWEEN the 2 air runners, which keeps it aligned and headed 
straight to its port on the  IAD. If your 5/16 hose is loose on that port, you 
should try a different hose.

Having that hose off won't hurt the MAP sensor, but it will run very rich, 
putting gas in the oil and dirtying up the plugs. I would suggest taking it out 
where you can drive at highway speeds for a half hour to see if that cleans 
them up.

Spark plugs have a self cleaning temperature range. If you can keep the 
engine running with the plugs in that range, the porcelain insulator will clean 
itself off. Only the insulator color is important; you can ignore the color of the 
threaded steel sleeve around it. If the insulator doesn't get hot enough, it will 
soot up; if it gets too hot, the ceramic will be damaged. All this is why there 
are different heat range plugs, so it's important to use plugs that are 
appropriate for your engine and the use you give it.

> Well, I also checked the #3 spark plug and while it was pretty black,
> there was a fair amount of almost chocolate brown on the electrode
> area too. I wasn´t too worried so I put it back and didn´t check the
> others b/c after realizing the MPS hose had come off I figured I´d
> found the answer to all my problems. 
> 
> The car started up right away and it idled normally: the exhaust note
> was right and it was appropriately lumpy for a cold start. Then,
> instead of the idle climbing, it got lumpier and lumpier and slower
> and slower until it just stalled. Then it´d start but stall right
> away. Then it wouldn´t start. Now, it´s at a point where it´ll only
> stay idling if I keep my foot on the pedal.

It's quite possible that with the hose connected and the mixture right the 
engine how warms up enough to get the AAR fully closed. If the hose was 
loose the last time you set the idle, there was extra air getting in there, so 
the idle is now set so low that it's not enough to keep the engine running. 

Reset the idle. Take it for a drive. I suspect it will now be fine.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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