Non runner after hall sensor replacement' Gti 97 8v.

[Christo77]

Hi all,
I have a few problems to sort out with my 8valve, main one is that i've just replaced the hall sensor on the dizzy..now the thing wont start'
The timing marks were all correct and set at TDC before removal.. is there a procedure necessary for resetting engine management ecu?  maybe thats the problem..
I have browsed the site pretty well but apologies if i've missed something obvious..
Any help would be great thanks..

Christo77

[AudiA8Quattro]

Is there a spark coming from the ht leads?

[Christo77]

Hi..thanks for the response..
Yes, although i didn't actually check the leads individually i assumed the spark was there as before as it did splutter the last time i tried to start it.. it just wont have it though' a splutter is all she'll do now!
I even put the old sensor back in thinking i had a faulty new one..no such luck' lol
Any other ideas?  cheers 

[AudiA8Quattro]

Why did you replace the hall sender in the first place? no spark?
There is a tdc mark on the dizzy body, have you lined up all the static marks? ie. cam, crank and dizzy.
I would re-check them.

[Christo77]

Basically it was running ok but do have a bit of a misfire hitting the accelerator quickly and a flat spot at about 3.500 rpm.. with the info i've gathered, the hall sensor was the next thing as a possible cause after new plugs, leads, rotor arm, dizzy cap, fuel relay, water temp sensor, clean out the throttle body, check pipework for leaks, and a couple of other things i cant think of now..
Yes all the static marks were lined up ok and the rotor arm pointing toward the mark on the dizzy body..
Working through the whole thing twice i'm pretty sure i've set it up ok..but you right i will re check it..
Thanks again..

[AudiA8Quattro]

Its easily to get the rotor arm 180 degrees out.
Other suggestions, does the fuel pump prime? tried doing a compression test?

[Christo77]

Mm there's a point about the rotor arm, still i cant see how i would have made that mistake...Gonna go have a soak in the bath and think about that one...lol
Your other suggestions not checked but tomorrow'..I hope i'll have made some progress..
I thought this was going to be quite a job but it's not at all really..and i'm standing there trying to see what i've done wrong but cant see anything'  You've got the timing marks crank and cam pulleys, timing on the dizzy and one connector to deal with'.. thats it!
Oh well i'm off to scratch my head
Appreciate the help audi100Quatro
I'll update tomorrow hopefully with better news
Cheers

[Len]

Instead of hall sender ya should have tried changing the ECU relay first!

ECU can be partly reset by disconnecting the battery completely for approx 15 mins.

[Christo77]

Hi again,  all sorted!
The last time i offered the dizzy back into the housing i noticed that the rotor arm wasn't pointing quite where it should be'  taking the thing out a couple of times and putting it back in again the rotor arm seemed to move a bit further away each time from the scribe on the dizzy body'..assuming it cant fit any other way in it goes for good!  that is until some good fella mentions about it being easy to fit wrong 180 degrees out! 
So, set up the crank and cam pulleys again, off comes the dizzy cap and there's the rotor arm pointing towards 8.Oclock!!  No 2 HT lead i think..
I think there's a bit of confusion when looking at the position of the rotor arm in relation to No 1 HT lead in that it's supposed to be a little bit passed that point if things are set up right..so i understand now'.. correct me if i'm wrong,
I have to say it does run even smoother now, although being glad it's running again it can be easy to get carried away with enthusiasm mixed in with relief! lol

Thanks for helping audi

[AudiA8Quattro]

No problem mate 
I had a similar problem when working on a 5 cylinder Audi a couple of years back, after a head rebuild/cam belt/dizzy replacement, its easy to get it wrong. If in doubt always double check