Engine still wont start from cold

[AUDIS2avant]

I have just today changed the hall sensor and no help there, any better ideas this time guys?

[UrS4boy]

Symptoms again are?

[AUDIS2avant]

when the engine is cold, and temp is below 0 then no start, is it above just 2-3 degrees then it starts just fine

[UrS4boy]

when the engine is cold, and temp is below 0 then no start, is it above just 2-3 degrees then it starts just fine

But it still cranks below 0 C? Just not firing?

You need to establish that a) the fuel pump is working below 0 C and b) you have spark. It has to be one or the other (obviously). My bet is on the fuel pump. Or perhaps a sticky fuel pump relay. If the J17 FP relay doesn't work, then lots of things don't work, at least with an ABY/AAN. Follow the link below for more info:

http://forums.audiworld.com/s4s6/msgs/133907.phtml

[AUDIS2avant]

hmm, when it started thie afternoon after some time, it was bouncing up and down a little, thought it was the generator or a bellt first but maybe it´s the fuel pump relay then.
Yes it crancks just fine, but just wont start

[AUDIS2avant]

Ok, have checked the fueling today, and there is no priming but the pump runs when i cranck the car, is this right?

[Knight Rider S4]

Get the car on vag.com ASAP and see what codes you get ..help you along a bit better as the trial and error way can be very expensive way of doing things

[AUDIS2avant]

i know, but a vagcom test in denmark coasts 130£ and 140£ pr hour and they dont even know the car very good so i´m gonna check what i can my self first
Btw, where can i find the resistance on each sensor?
Tried to search but cant find it

[Jas11n]

Ok, have checked the fueling today, and there is no priming but the pump runs when i cranck the car, is this right?

Yes, that's right. ABY doesn't prime the pump.

[AUDIS2avant]

Ok super.
Have measured some sensors also
IAT sensor 453ohm
Speed and cranck sensor 900-933ohm

tried to cranck it after i fetteled with the cranck sensor and it tried to start but with some HUGE misfires, so maybe a cranck sensor?

[Knight Rider S4]

Cheapest way to read the codes is buy this
http://cgi.ebay.co.uk/UNIVERSAL-OBD2...1%7C240%3A1308

and this
http://cgi.ebay.com/2x2-2-way-OBD2-A...713.m153.l1262


And post up the codes and hopefully straight forward fix from then


Cheers

[AUDIS2avant]

Knight rider: thanx m8, have bought it now, was just what i was looking for

I found an old friend today, that had a vag-com and we put it on the tester and got a LOT of fault codes, but after resetting them nothing came up again accept one 00532 low supply voltage (i think this was after the car just stalled on the freeway)
But we are gonna test it again in a few days

[AUDIS2avant]

there was also a misread from the mfts sensor i think, the gauge inside the car showed 92` (first dash after 90`) and the fan had just startet when it said 101` on the coolant temp on the vag-com??

[UrS4boy]

Ok super.
Have measured some sensors also
IAT sensor 453ohm
Speed and cranck sensor 900-933ohm

tried to cranck it after i fetteled with the cranck sensor and it tried to start but with some HUGE misfires, so maybe a cranck sensor?

G4 and G28 speed and crank sensors should be about 900-1000 ohms of resistance on both of them (and they are interchangable)

IAT sensor resistance is a function of temperature, as shown in this graph (from SJM Autotechnik via S2central):

[AUDIS2avant]

that looks about right, iat is showing the right temp then.