Audi A6 Avant Ignition no-go!.

Hi, My formerly, till this afternoon, trusty old steed 1995 vintage, was going fine till I parked up and went to re-light a few hours later and simply no-go!.

A bit of investigation revealed that there was no sparks to be found anywhere. Fortunately I happened to have some tools with me and a multi meter and discovered that there were around 11 volts on the two coil primary windings. I was offered a lift back home and I seemed to remember that some Audis had problems with ignition coil failures so with not that much to loose, I took the coil off and bought it back home and a few checks with a multi meter revealed the right , according the Haynes manual, resistance's.

However I connected the coil across a small 12 volt battery and took another bit of wire from the HT output terminal and formed a small "spark gap" with that to one of the other primary terminals, and when you "flick" the wire from the battery onto the primary terminals there is only a tiny feeble 1 millimetre long spark.

I would have thought that this should be a lot more than that and suspect that perhaps the coil has "shorted turns" perhaps?.

Anyone else had a similar experience with this sort of problem on these cars?.

TIA....

Reply to
tony sayer
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...or the battery is flat. Just a thought.

Reply to
Conor

Which engine?!?!

If its the inline 4 2litre, then almost certainly its the amp mounted under /next to the coil.

Tim..

Reply to
Tim (remove obvious)

unless you introduce a condenser as well then you will only get a feeble spark.

is the cambelt still intact and turning? they usually fail at start up.

otherwise it is connections, immobiliser, crank sensor, ign module, etc.

if you are in the aa get them out.

mrcheerful

Reply to
mrcheerful

In article , mrcheerful . writes

Yes in fact further experimentation revealed that adding a cap across the coil did indeed get it better. But in the original design thats not there is it?, it seems that the ignition amplifier is just a simple semi conductor switch that takes the output of the ECU and "amplifies" the switching pulse from that..

Just a well they fail then!!. The distributor is going round so its OK..

Yep,

Actually went back to site this am and re fitted coil etc and switched on and started first time and been running ever since!. Took a scope to the ign amp input and output and very much as expected low amplitude slightly sloped pulse and on the output side much larger with some ripple and overshoot and big fat sparks!..

Mystery. absolute mystery!,suppose something is intermittent or the immobiliser has got its nickers in a twist. Wonder if it might be due to being parked right next to a radio transmitter site, 'tho nothing would have changed since yesterday afternoon!!!..

Thanks to all who replied on group and via e-mail!....

Reply to
tony sayer

: Yes in fact further experimentation revealed that adding a cap across the coil : did indeed get it better. But in the original design thats not there is it?, : it seems that the ignition amplifier is just a simple semi conductor switch : that takes the output of the ECU and "amplifies" the switching pulse from : that..

I'm pretty sure there will be a big capacitor somewhere in the ignition amplifier.

Ian

Reply to
Ian Johnston

In article , Ian Johnston writes

Can't be all that much as there seems sod all room in that unit!

cheers

Reply to
tony sayer

No, as the ECU performs the condensor-esque control of the LT side of the coil.

Tim..

Reply to
Tim..

In article , Tim.. writes

Err right;!, when is the ECU anyway?...

Reply to
tony sayer

When is the ECU. Most of the time I would think...

Under the scuttle panel, base of the windscreen passenger side. Be very sure it is not cracked / damaged and replaced properly as I've known several die from water ingress caused from broken / missing panel.

Tim..

Reply to
Tim (remove obvious)

Modern car HT systems don't just switch the volts to the LT side of the coil - likely to be a capacitive discharge type?

Reply to
Dave Plowman (News)

Just let you all know, if it is the coil pack that is faulty VAG now give a lifetime warranty on Coil Packs & Air Bags

Our 2002 VW Golf 1.8T with 185,000 miles had a faulty Coil Pack last week & we contacted VW Customer Services after remember the thing about Audi's & enquired if they offered anything as a gesture of goodwill & we were told by Customer Services that it would be replaced by our local VW dealer FOC which was done on Thursday

Reply to
A C

In article , A C writes

Actually its been fine ever since the other day!!!.

Perhaps there was a UFO nearby that was sucking all the power out of the air;-)

Reply to
tony sayer

In article , tony sayer writes

O dear!, same again. Have my suspicions that the immobiliser may have something to do with this!.

Anyone know where its kept?, bl**dy Haynes manual isn't any help, just saying "refer to your VAG dealer";-!....

Reply to
tony sayer

It's built into the enginemanagement system. You can extract the codes with Vag-Com or any decent independent VW garage can do so.

Reply to
Duncan Wood

Thanks for that. In fact I had a vehicle sparks round today and once again its behaving itself!!, though the did say there were problems in its memory with a few things and didn't want to justify changing them on spec, so he's deleted the "history" and said if it packs up somewhere just call and he'll come along and read it again!....

Reply to
tony sayer

And as a follow up to this one. Vehicle sparks fitted a new ignition switch as he said that the contacts were a known problem and sure enough they did look rather burnt and manky and, there was an Audi recall on vehicles from that year, which was alleged to cause some problems this motah had experenc3ed over the years odd shenanigans with windows and flashers etc, and I don't think this one was done.

Anyway drove around fine till Saturday nite when it cut out and came back and then cut out again and wouldn't restart. Towed home as was only just down the road. Wouldn't start when cold few tests were done distributor pronounced finally deceased new one fitted and all is fine now so fingers crossed:)

And thats to all who replied....

Reply to
tony sayer

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