Delayed Start on My RS4

[PetrolDave]

The immobiliser system on the B7 needs the key to be within a few inches of the key barrel to detect it, and the transponder in the key is passive.

The Audi immobiliser allows the starter to turn and the engine to start, but it will stop within a few seconds if the key isn't recognised. Your symptoms are completely different to this so it's not the Audi immobiliser.

Another possibility is that either the ignition switch or the starter switch are faulty - but those are not common problems so I still have the tracker immobiliser as my number 1 suspect.

[neckarsulm]

Another possibility is that either the ignition switch or the starter switch are faulty - but those are not common problems so I still have the tracker immobiliser as my number 1 suspect.

Dave, the fact it takes longer to start when its been left is making me think it's less likely to be the remote immobilisation.
I was thinking battery maybe?

[PetrolDave]

First post in this thread says "battery is fine" though?

[neckarsulm]

batteries do the weirdest things though.
I was looking at a B6 S4 which would flash brake warning on startup, always started OK.
Problem was that the battery while in good order was too low spec so current draw to starter affected the other electronics
My point being that for what they cost its worth a go if investigation can get expensive

[PetrolDave]

My point being that for what they cost its worth a go if investigation can get expensive

I'm with you there.

If the battery hasn't had a load test done on it as part of the investigation then it's NOT safe to assume that the battery is fine.

Even the highest spec car batteries only have a guarantee of 5 years, and some RS4s are now older than that - so their batteries are on "borrowed time".

My RS4 will be 5 years old this Summer, and if I get any electrical problems the FIRST thing I'll be doing is fitting a new battery.

[Ice_Coffee]

What you say is true,but one of the heaviest loads for a battery is cranking the engine, and going at it for minutes at a time indicates an excellent battery to me !

[Timster]

Oh nice one Mr Coffee... now look what you've done: You've mentioned Batteries and Loads !!!

Now Arthur's going to come along and discuss the various load coefficients of Lead Acid vs Nickel Cadmium vs Lithium Ion vs the primary school ~ potato battery. (remember those?)

[Ice_Coffee]

lol , I welcome arthurs schooling, I always feel a bit more enlightened afterwards, even if some of it goes over my head. TBH it also goes to show the caliber of people on this forum, there are quite a few clever kiddies on here which is not surprising, taking into account the vehicle we own.

[PetrolDave]

What you say is true,but one of the heaviest loads for a battery is cranking the engine, and going at it for minutes at a time indicates an excellent battery to me !

But going at it for a while can lead to sulphation of the plates which increases the internal resistance of the battery, so the battery could become a "victim" of the original problem.

[adsgreen]

Cranking is tough but dependant on the way the ignition system is controlled and what is set to drop out during cranking it can mean that whilst the engine turns over there's not enough left to properly start the car.
I'd agree with the above - for the cost of a new battery it would be worth checking.

[B7RSX]

Right... ok guys.

Was an interesting read thanks. What i will do then.. change that battery. You guys are right that for the cost of a new battery it would be worth checking. It cant be the remote immobilisation from the tracker just doesnt make sense because i have to switch it off from the laptop and plus the fact once the cars been started it starts fine throughout the day. Only in mornings or if its been left for a few days it takes forever to start.

Drove it today after a few days... man its EPIC! Wouldnt change it for anything else. Still grinning from it.

[B7RSX]

Saying that where is the best place for get a good OEM (ish) battery from? Except the stealers!

[Ice_Coffee]

I don't know but according to VCDS I can code the car for the best battery recharging algorithims, based on manufacturer. All the big manufacturers are listed as options, Varta, Bosch etc etc

[PetrolDave]

I don't know but according to VCDS I can code the car for the best battery recharging algorithims, based on manufacturer. All the big manufacturers are listed as options, Varta, Bosch etc etc

That only applies to cars with MMI - it doesn't apply to the B7.

[neckarsulm]

Saying that where is the best place for get a good OEM (ish) battery from? Except the stealers!

I got an 096 Bosch S3 from Euro Car Parts for about £65, not sure which one is in our cars but 096 is big