The temp sensor (in a coolant manifold) is an input to a box located behind
the glove compartment. An output of that box provides current to the gray
box on the side of the mixture control unit (differential pressure
regulator). More current = richer mixture. Open circuit = very lean
mixture. The proper / quick check is to measure the current through the
differential pressure regulator but that is difficult to do without the test
jig and a solid electrical theory in mind.. I believe the normal current is
in the 100ma range. It's in the books but they make it harder to find as
time passes.

Doubt that the control box would actually fail unless there has been a major
electrical event. Once I found / replaced an open transistor in the box and
we drove it for years, but I'd purchased that car due to it's having an
electrical fire due to the radiator cooling fan.. Oh those days of $1200
Audi 4000s.

I'd be crawling around under the glove box, looking for where the mice have
been unless you have a Fluke 77 and feel like cutting wires.

mark lemon
Woodward Iowa

<iamsiam@aol.com> wrote in message
news:1170619241.886746.160980@a34g2000cwb.googlegr oups.com...
> Hello Audi 4000 fuel help still needed
>
> Been busy at work, not much time to work on the Audi until last week.
>
> Still having problems getting this car to run, was wondering if there
> are any other ideas out there?
>
> I still can not get the fuel injector unit to shoot fuel into the
> injectors. It still fires fuel to the cold start valve, enough juice
> to run 3-5 seconds.
>
> I checked all fuses, put new ones in the blank spaces.
>
> I checked the fuel injector air-door, it opened fine.
>
> I replaced the entire fuel injector unit with a used one I had from a
> parts lot I bought.
>
> I changed the fuel regulator as well, the one on the injector unit, I
> believe this is the "Differential fuel pressure sensor (just in
> front of fuel distributor." ,that you mentioned
> As far as the "Failing engine temp senso" " the MFTS ", is this the
> same as the temperature sending switch? . Could this really keep the
> fuel injector unit from firing? Can I bypass this to test it?
> There is no massive air leak at the large intake manifold
> The ignition switch is fine, it is new, it is getting power to the
> fuel pump and other systems
>
> Any help would be appreciated!!
>
> Richy Jackson
> On Jan 2, 11:07 pm, "dave AKA vwdoc1" <vwd...@hotmail.com> wrote:
>> Like TonyJ said..............it might be a Failing engine coolant temp
>> sensor (CTS)
>>
>> Or a fuse in the fuse box. It is positioned to look like a spare fuse
>> and
>> many times I will find it missing on a vehicle that is not running right
>> if
>> running at all. 8^o
>> Examine all of the fuses for any broken ones and stick a fuse in all
>> sockets
>> with terminals.
>>
>> Or it could be the ground wire for the fuel pressure regulator is broken
>> and
>> it should be located at the cold start valve.
>>
>> Or it could be a defective fuel distributor.
>>
>> Or it could be a massive air leak at the large intake manifold boots.
>> Maybe
>> a light engine backfire into the intake system along with the gas pedal
>> being depressed might have caused a hose/pipe to pop off creating a large
>> vacuum leak.
>>
>> Or it could be the ign switch not allowing power to the systems when it
>> is
>> in the ON position. Telltale signs would be those red idiot lights not
>> being ON with the ign ON or while cranking over the engine.
>>
>> good luck and let us know what happens!
>> later,
>> dave
>> AKA vwdoc1
>>
>> "TonyJ" <tonyjnos...@nospamvisi.com> wrote in message
>>
>> news:12pk7fqk0hu0s2c@corp.supernews.com...
>>
>>
>>
>>
>>
>> > iams...@aol.com wrote:
>> >> I was wondering of anyone could help me with a problem that suddenly
>> >> developed with my AUDI,
>>
>> >> The car is a 1987 Audi 4000s 1.8L
>> >> Here is the deal, the car will start for second or two, but will not
>> >> rev up, then it dies.
>>
>> >> Fuel pump and filters are new.
>>
>> >> Strong fuel pressure to the Fuel injector unit.
>>
>> >> The injector unit is sending fuel to the cold start valve, but not to
>> >> the cylinders, thus the car will start but will not continue to run.
>> >> The pressure to the cold start valve is strong, but not a drop to the
>> >> fuel injectors.
>>
>> >> I replaced the external fuel regulator with a spare one and checked
>> >> for
>> >> vacuum leaks etc.
>>
>> >> I am not sure where to look from here, internally on the Fuel
>> >> Injection
>> >> Unit, or to a relay or other control.
>>
>> >> As I stated the problem happened overnight.
>>
>> >> Any help would be appreciated.
>> >> I have not used a internet group before, do I hope I am doing this
>> >> right...........
>>
>> >> Thanks,
>>
>> >> Richy Jackson
>>
>> > If the air plate just above the air filter is stuck the injectors will
>> > not
>> > fire. This can be due to vacuum leaks (you checked but check again)
>> > or
>> > deposits on the rod above the plate.
>>
>> > Open air cleaner and reach up into the intake just above. The plate
>> > should
>> > move but with a little pressure. Don't force it.
>>
>> > Other ideas:
>> > Differential fuel pressure sensor (just in front of fuel distributor.
>>
>> > Blown engine management fuse (in the side of the relay box.
>>
>> > Failing engine temp sensor. In the T44s it is called the MFTS and it is
>> > located by the upper radiator hose inlet to the engine.- Hide quoted
>> > text -
>>
>> - Show quoted text -
>
>

 

Try replacing the temperature control switch which could be sending a
false reading to your ECU hence no fuel in cylinders

"TonyJ" wrote
> iamsiam@aol.com wrote:
> > I was wondering of anyone could help me with a problem that
> suddenly
> > developed with my AUDI,
> >
> > The car is a 1987 Audi 4000s 1.8L
> > Here is the deal, the car will start for second or two, but
> will not
> > rev up, then it dies.
> >
> > Fuel pump and filters are new.
> >
> > Strong fuel pressure to the Fuel injector unit.
> >
> > The injector unit is sending fuel to the cold start valve,
> but not to
> > the cylinders, thus the car will start but will not continue
> to run.
> > The pressure to the cold start valve is strong, but not a
> drop to the
> > fuel injectors.
> >
> > I replaced the external fuel regulator with a spare one and
> checked for
> > vacuum leaks etc.
> >
> > I am not sure where to look from here, internally on the
> Fuel Injection
> > Unit, or to a relay or other control.
> >
> > As I stated the problem happened overnight.
> >
> > Any help would be appreciated.
> > I have not used a internet group before, do I hope I am
> doing this
> > right...........
> >
> >
> >
> >
> >
> > Thanks,
> >
> >
> >
> > Richy Jackson
> >
> If the air plate just above the air filter is stuck the
> injectors will not fire.
> This can be due to vacuum leaks (you checked but check
> again) or deposits on
> the rod above the plate.
>
> Open air cleaner and reach up into the intake just above. The
> plate should move
> but with a little pressure. Don't force it.
>
> Other ideas:
> Differential fuel pressure sensor (just in front of fuel
> distributor.
>
> Blown engine management fuse (in the side of the relay box.
>
> Failing engine temp sensor. In the T44s it is called the MFTS
> and it is located
> by the upper radiator hose inlet to the engine.

--
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Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/4000s-fuel...ict202188.html

 

Try replacing the temperature control switch which could be sending a
false reading to your ECU hence no fuel in cylinders

"TonyJ" wrote
> iamsiam@aol.com wrote:
> > I was wondering of anyone could help me with a problem that
> suddenly
> > developed with my AUDI,
> >
> > The car is a 1987 Audi 4000s 1.8L
> > Here is the deal, the car will start for second or two, but
> will not
> > rev up, then it dies.
> >
> > Fuel pump and filters are new.
> >
> > Strong fuel pressure to the Fuel injector unit.
> >
> > The injector unit is sending fuel to the cold start valve,
> but not to
> > the cylinders, thus the car will start but will not continue
> to run.
> > The pressure to the cold start valve is strong, but not a
> drop to the
> > fuel injectors.
> >
> > I replaced the external fuel regulator with a spare one and
> checked for
> > vacuum leaks etc.
> >
> > I am not sure where to look from here, internally on the
> Fuel Injection
> > Unit, or to a relay or other control.
> >
> > As I stated the problem happened overnight.
> >
> > Any help would be appreciated.
> > I have not used a internet group before, do I hope I am
> doing this
> > right...........
> >
> >
> >
> >
> >
> > Thanks,
> >
> >
> >
> > Richy Jackson
> >
> If the air plate just above the air filter is stuck the
> injectors will not fire.
> This can be due to vacuum leaks (you checked but check
> again) or deposits on
> the rod above the plate.
>
> Open air cleaner and reach up into the intake just above. The
> plate should move
> but with a little pressure. Don't force it.
>
> Other ideas:
> Differential fuel pressure sensor (just in front of fuel
> distributor.
>
> Blown engine management fuse (in the side of the relay box.
>
> Failing engine temp sensor. In the T44s it is called the MFTS
> and it is located
> by the upper radiator hose inlet to the engine.

--
Posted at author's request, using http://www.AutoBoardz.com interface
Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/4000s-fuel...ict202188.html

 

Try replacing the temperature control switch which could be sending a
false reading to your ECU hence no fuel in cylinders

"TonyJ" wrote
> iamsiam@aol.com wrote:
> > I was wondering of anyone could help me with a problem that
> suddenly
> > developed with my AUDI,
> >
> > The car is a 1987 Audi 4000s 1.8L
> > Here is the deal, the car will start for second or two, but
> will not
> > rev up, then it dies.
> >
> > Fuel pump and filters are new.
> >
> > Strong fuel pressure to the Fuel injector unit.
> >
> > The injector unit is sending fuel to the cold start valve,
> but not to
> > the cylinders, thus the car will start but will not continue
> to run.
> > The pressure to the cold start valve is strong, but not a
> drop to the
> > fuel injectors.
> >
> > I replaced the external fuel regulator with a spare one and
> checked for
> > vacuum leaks etc.
> >
> > I am not sure where to look from here, internally on the
> Fuel Injection
> > Unit, or to a relay or other control.
> >
> > As I stated the problem happened overnight.
> >
> > Any help would be appreciated.
> > I have not used a internet group before, do I hope I am
> doing this
> > right...........
> >
> >
> >
> >
> >
> > Thanks,
> >
> >
> >
> > Richy Jackson
> >
> If the air plate just above the air filter is stuck the
> injectors will not fire.
> This can be due to vacuum leaks (you checked but check
> again) or deposits on
> the rod above the plate.
>
> Open air cleaner and reach up into the intake just above. The
> plate should move
> but with a little pressure. Don't force it.
>
> Other ideas:
> Differential fuel pressure sensor (just in front of fuel
> distributor.
>
> Blown engine management fuse (in the side of the relay box.
>
> Failing engine temp sensor. In the T44s it is called the MFTS
> and it is located
> by the upper radiator hose inlet to the engine.

--
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Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/4000s-fuel...ict202188.html

 

Try replacing the temperature control switch which could be sending a
false reading to your ECU hence no fuel in cylinders

"TonyJ" wrote
> iamsiam@aol.com wrote:
> > I was wondering of anyone could help me with a problem that
> suddenly
> > developed with my AUDI,
> >
> > The car is a 1987 Audi 4000s 1.8L
> > Here is the deal, the car will start for second or two, but
> will not
> > rev up, then it dies.
> >
> > Fuel pump and filters are new.
> >
> > Strong fuel pressure to the Fuel injector unit.
> >
> > The injector unit is sending fuel to the cold start valve,
> but not to
> > the cylinders, thus the car will start but will not continue
> to run.
> > The pressure to the cold start valve is strong, but not a
> drop to the
> > fuel injectors.
> >
> > I replaced the external fuel regulator with a spare one and
> checked for
> > vacuum leaks etc.
> >
> > I am not sure where to look from here, internally on the
> Fuel Injection
> > Unit, or to a relay or other control.
> >
> > As I stated the problem happened overnight.
> >
> > Any help would be appreciated.
> > I have not used a internet group before, do I hope I am
> doing this
> > right...........
> >
> >
> >
> >
> >
> > Thanks,
> >
> >
> >
> > Richy Jackson
> >
> If the air plate just above the air filter is stuck the
> injectors will not fire.
> This can be due to vacuum leaks (you checked but check
> again) or deposits on
> the rod above the plate.
>
> Open air cleaner and reach up into the intake just above. The
> plate should move
> but with a little pressure. Don't force it.
>
> Other ideas:
> Differential fuel pressure sensor (just in front of fuel
> distributor.
>
> Blown engine management fuse (in the side of the relay box.
>
> Failing engine temp sensor. In the T44s it is called the MFTS
> and it is located
> by the upper radiator hose inlet to the engine.

--
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Articles individually verified to usenet standards. Visit URL to contact author/report abuse
Thread archive: http://www.AutoBoardz.com/4000s-fuel...ict202188.html