Audi 100 Won't Start (Not: Vacuum Leak, Fuel Pump Relay, ...)

[Marc Boucher]

By the way I just wanted to comment on how super helpful the members of this
list have been.  I can't believe the time and effort you've given me.
(Ironically my other project today is helping a friend with his home
network...given what he wants to do its been about equally problematic :-)

OK, I've verified that idle switch works...open circuit when on idle and
closed circuit otherwise (note it looks like I may have never used this
switch...not knowing about it, I'd set the idle with the built in set screw.
I've just now backed it off...)   fyi how would you suggest trying to start
the car now i.e. the tow truck had me put the pedal to the floor and turn it
over (which worked there, while being boosted..isn't this to clear a flooded
condition?), but this hasn't worked since.  The occasional time when I can
get it to start now is with no gas applied)

Finally, with regard to http://www.sjmautotechnik.com/100ecuf.html , you
said "Keep in mind that this site is for turbo engines only."  Actually they
have both turbo info and non turbo info (scroll down on this page and you'll
see: http://www.sjmautotechnik.com/trouble2.html).

The link http://www.sjmautotechnik.com/100ecuf.html
is exactly my car, which is:


1990 Audi 100 with NF engine and CIS-E-III
Automatic transmission Front wheel drive (not quatro)
Not Turbo
Built for California emissions (Catalytic Converter, Egr valve)
2.30 liter (141 cu in)
Horsepower: 130 bhp
Compression Ratio: 10.1: 1



Marc


----- Original Message ----- 
From: "SJ" <syljay at optonline.net>
To: "Marc Boucher" <mboucher70 at hotmail.com>
Sent: Tuesday, January 27, 2004 9:11 PM
Subject: Re: Audi 100 Won't Start (Vacuum Leak?)





> Ok continuing on...Here's a few more points/questions:
>
> 1.) if the fuel pump makes a noise when energized and draws six amps, and
> the car occasionally starts and runs for a few minutes, is that really


> enough to rule out fuel pump?
**** I dont know what current it should draw. But, six amps sounds
reasonable.
I'm working on a tester that will measure both fuel pressure and volume of
fuel flow. But thats for another time.
I think there are tests in the bentley for measuring fuel flow. So much fuel
in so many seconds.

>
> 2.) I've never been able to find the O2 sensor (though I know its been
> changed and I know its located on the exhaust manifold...Any tips on
finding
> it?
**** Up on the firewall. Just to the right of the ignition coil. The O2
connector is mounted on a metal bracket. Two white wires go to one connector
 .. these are the O2 sensor heater wires. The sensor wire is a single wire
 .goes to single wire connector. Easy to spot, its out in the open.


>
> 3.) In an earlier email you'd suggested,
> "For the hell of it, next time you start the engine, unplug the connector
at
> the idle switch . .. using a jumper, short the two idle contacts to
simulate
> closed idle sw contacts . . .then start the engine."
>
> I haven't done this  yet...how does this tie in with the testing we're
about
> to do and when should I do it (assuming I only get one good run of the car
> today)
**** First, make sure the switch is working. Test with ohm meter. If it
works, leave it alone. If it doesnt work, the ECU doesnt know that the
engine is idling. Weird things happen like surging. ECU switches to its
"idle map" when that switch is closed.

>
> 4.) I had already thought that mixture might be an issue and attempted to
> follow this article:
> http://www.humanspeakers.com/audi/timing2.htm
> Problem is that I have not yet found the "little hole between the fuel
> distributor and the black rubber intake boot" into which I need to insert
a
> "3mm hex tool".   I will look again.  Does 'hex tool' mean an Allen Key?
**** The idle mixture is the last thing to check. This  almost never fails.
The hole is plugged. Its a small plug located as described. hard to spot .
you need to clean the area first. Then drill out the plug and remove it.
Hex tool is a long allen key . . .T handle.
Forget this until you have exhausted all the other tests.

>
>
> 5.) Finally, the last thing that I thought I'd mention.  In performing the
> "Output" tests from the following url:
> http://www.sjmautotechnik.com/100ecuf.html
> There were a few things that did not exactly perform as the instructions
> stated.  Let me detail:
**** Keep in mind that this site is for turbo engines only. The turbo has a
different ECU, different engine, different plumbing, different fault codes .
etc, etc


>
> Before starting the test...under normal circumstances, once the ignition
is
> engaged, 100mA is measured flowing through the differential pressure
> regulator.
>
> Documentation for testing the differential pressure regulator reads:
>
>  activate the Output Tests, you must first insert the fuse into the fuel
> pump relay, or connect the LED and the jumper wire to short across the
Fault
> Code Connectors as shown and THEN turn on the ignition to start the output
> tests. Remove the fuse or jumper wire after 4 seconds:
> (Test #1)  The code 4341, will be displayed by the fault code light/LED.
The
> Differential Pressure Regulator with have 10 milli amps applied to this
> regulator when the full throttle switch is manually closed. 100 milli amps
> when the throttle switch is open.
> OBSERVED RESULT: As soon as the test began, the Differential pressure
> regulator had 10mA running through it.  Pressing the full throttle switch
> thus resulted in no change.  100mA was only obtained after the test was
> complete.
>
>
> a.. Insert the fuse, or connect the jumper wire again for 4 seconds to go
to
> the next output test:
> (Test #5)  Code 4343,   Close the full throttle switch again, and the
Carbon
> Canister Solenoid valve is cycled on and off.
> OBSERVED RESULT: As soon as the fuse was removed the carbon canister
> solenoid began its cycling.  No action to the full throttle switch was
> required and doing so produced no change in the carbon canister solenoid
>
> a.. Insert the fuse, or connect the jumper wire again for 4 seconds to go
to
> the next output test:
> (Test #2)  Code 4431,  will be displayed. Close the full throttle switch
and
> the Idle Stabilizer valve cycles.
> OBSERVED RESULT: As soon as the fuse was removed the idle stabilizer valve
> began its cycling.  No action to the full throttle switch was required and
> doing so produced no change in the idle stabilizer valve.
>
> a.. Insert the fuse, or connect the jumper wire again for 4 seconds to go
to
> the next output test:
> Test #4)  Code 4443,  Close the full throttle switch and the Cold Start
> Valve will be cycled on and off for 10 seconds
> OBSERVED RESULT: AS EXPECTED.  Unlike the other tests, the Cold Start
Valve
> only began cycling once the full throttle switch had been pressed.  Once
the
> full throttle switch ws pressed, the Cold Start Valve cycled for
> approximately 10 seconds then stopped.
>
>
> My assumption was that these discrepancies between the instructions at
that
> web site and the observed results were either documentation errors or
> changes to the design of the tests.  However its also possible that the
> observed results demonstrate a failure of the differential pressure
> regulator, or the full throttle switch.
>
**** Give me the specs on your car again. year model engine etc
I'll look up the output test procedure in my 90 100 Bentley.

Looks like you  are hooked up to read diff pressure currents. Good.

Will get back to you.