[Vwdiesel] Why gasss cars mpg sucks (fwd)

Roger Brown r.c.brown at ieee.org
Sat May 14 00:23:51 EDT 2005

Shawn Wright wrote:
> On 14 May 2005 at 0:01, Libbybapa at wmconnect.com <Libbybapa at wmconnect.com> wrote:
>>In a message dated 5/13/05 8:58:35 PM US Mountain Standard Time, 
>>Libbybapa at wmconnect.com writes:
>>>>how  do I know ? ----- I shut fuel solenoid off going down a big hill.
>>>How did the car respond?
>>If it didn't respond poorly, wouldn't it be possible to cut the fuel any time
>>the accelerator lever is in the idle position and the rpm's are above idle, to
>>save fuel of course.  
> I wonder if this is how it is done in the TDIs. It would seem to be a fairly simple thing 
> to design, perhaps using the dynamic oil pressure circuit which triggers at 2000rpm, 
> or just working off the tach signal. But I wonder if prolonged fuel cutoff at highway 
> speeds could cause fuel starvation in the pump, ie: lack of lubrication? I don't know if 
> the location of the solenoid poses a problem in this way or not...

Should no be a problem, at least on the IDIs.  The fuel cutoff solenoid is really mis-named, when off it just bleeds the fuel 
off the pump and returns it to the tank,  Since the pressure inside the pump can't get high enough to break open the injectors, 
the fuel seems to be cut off, at least as far as the injectors see it.


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