Audi 80 2.6 avant, won't start

[kitch80]

Hi
I can't start my 1995 Audi 80 2.6 Avant after car was left standing and battery went flat. From doing some research I suspect the crank sensor as i have no fuel pump or spark and the rev counter needle isn't moving when i crank the car over. Does this sound right? I don't have a manual for this car as Haynes didn't produce one so could someone advise me where the sensor is located and if i can change this myself without special tools?
Thanks
Simon

[scotty33]

I think there are 2 crank sensors like the 20v, a reference sensor picks up on a pin mounted to the front face of the flywheel. There is a speed sensor which picks up on the flywheel teeth. They are mounted low on the left side, (at the edge of the flywheel) I believe they are basically the same sensor and can be interchanged, but have colour coded wiring. If that is correct, you should expect the same readings when metered.
There is also a cam position (hall) sensor that is needed to determine whether no 1 is at tdc after an exhaust stroke or compression stroke. This is mounted on the back of cylinder head and tends to be the more troublesome of the 3 (all of which need to be healthy for starting).

http://www.sjmautotechnik.com/trouble_shooting/20vtime.html
http://www.sjmautotechnik.com/trouble_shooting/20vhall.html

Not the same engine but same principle

12v Pages - The Engine - Component Locations (http://www.12v.org/engine/index.php?section=cl&view=rear)

It is worth trying to read fault codes, I guess the easiest way is to buy a VCDS lead also needed is a 2x2 (obd1) - 16pin (obd2) adaptor. VCDS uses 16pin, but these old cars use 2x2 as in the link:

12v Pages - Maintenance (http://www.12v.org/maintenance/dtc.php)

The fault codes should be able to be 'blinked out' if you feel able to rig up a code reader. The instructions in that link won't work as you have no 'malfunction indicator lamp', suggest you try the method used for a 20v (and many other VAG cars of the era):

http://20v.org/fault.htm

The 'diode' in the pic is a l.e.d. which must be the right way around to work. It simulates a malfunction indicator lamp which is actually a 12volt 1.2watt dash lamp, if you use one of these there are no voltage or polarity issues to overcome..
If you look closely, you should see the A1 A2 B1 numbers on the diagnostic plugs.

[kitch80]

Thanks Scotty
Made myself a code reader but was unable to get anything from it using the instructions from http://20v.org/fault.htm. after reading some other posts it seems that without the extra blue socket the codes cannot be obtained without wiring directly into the ECU to implement the missing MIL readout Audifans.net: You are using an invalid IP (http://www.audifans.net/ftopict-5719.html)
The crank and speed sensors on this car seem to have the wiring attached at the sensor (no plug at sensor end) so can't easily be tested for resistance, i can't even see where the cable terminates as it goes back behind the engine somewhere. All in all not very easy to trouble shoot this problem which is a shame as the car ran really well up to this point.
If i invest in a VCDS lead do i need special software on my laptop etc and is this going to work on this model as the code reader came up blank?

Simon

[scotty33]

My 20v's are the early style with only 2 plugs (no blue one) and I can read codes fine. I am not certain that the 20v method works on a V6 but see no reason why it would not? Have you identified the A1 A2 B1 etc on the diagnostic plugs? Is there 12v supply coming through? - blown fuse? Is there continuity to earth - A1 and A2 These are not connected to the ECU, just a power source. The B1 line is what is known as the 'K line' and should be connected to the ECU, may need tracing back, also check the ECU fuses big ones labelled 'moteur' I think. Sadly it is not unheard of for 2.6 ECU's to fail, so I would not rule this out, though more generally this is unusual
I can't answer where the V6 sensor plugs are located, on a 20v they are grouped with the knock sensor plugs and mounted on the bulkhead.
A VCDS lead should work fine, some E bay specials fail but they are very cheap (and often come with software). Gendan are a UK distributor for Genuine ross-tech cables. VCDS Lite is a free download from Ross tech's site. It will do fault codes fine and a few other things besides, I don't see much point in upgrading to the full version of VCDS unless you have other newer VAG group cars to benefit from all the bells and whistles..

What Fast 28 did on Audifans, was 2 stages. The first was to arrange a blink code reader functioning within the dash (basically simulating an american spec 49 state car but fitted with a 'MIL lamp'. The second stage was to upgrade the MIL lamp functionality to give warning when an actual fault occurs. (As a California spec car would behave)

By definition, the first stage 'proves' that it is possible to blink out fault codes. The problem was that at that time the instructions on the 12v.org site were flawed and nobody was able to get a result (in UK), which is why I suggest that the 20v method should work. The technology/method, even the early V6 processor was the same (Hitachi MMS200 same as late 20v!)