Slow start

[Mg74]

Had the same issue and fitted a 16mm2 earth cable from negative battery terminal below bonnet across to a bolt on the engine and problem sorted.

[Georgeq7]

I am having similar issues where the car will seem like the battery is dead with the first and sometimes second attempt to start then will spin over and start no problem. I added 2 extra earth cables to the engine but it hasn’t helped. I am wondering if it could be a poor earth at the battery or where the earth cable connects from the battery to the body. This is a very frustrating problem. 

[Henrik S]

On 10/26/2017 at 8:25 PM, Bigdave1230 said:

Recently the car has been giving the impression of a flat battery when trying to start. It would turnover a couple of times but very very slowly. Turning the ignition off and then on again and the car would turn over slowly and then speed up and start but this may take a few attempts. It gave all the impressions of a poor starter motor. But having fitted one on a previous Q7 I know this is a 4 hour job and even with a decent discount is still over £200 for the unit. So decided to ring a local auto electrician that could hopefully diagnose exactly the part that needed replacing. (Vagcom showed nothing amiss by the way).

 He turned up and checked the car over and said that the cars alternator was charging the battery at around 13.6v. This is a indication of a poor earth and fitted another earth cable from the earth point under the bonnet used for jump starting to the engine manifold. Said he’s fitted loads as it’s a well known problem within VAG that the earths corrode over time and need cleaning. The car now charges at just over 14v and starts better than it ever did less than 2 seconds from turning the key. Turns over faster than my mates 2011 and 2014 Q7’s. Cost £10 for the earth cable and £40 for callout Including 1 hours labour. 

Hope this is helpful to anybody with a similar problem.

 

 

I had to create an account here just to say THANK YOU!

 

I had the same problem, took a 16mm2 battery cable and connected it between the negative batterypost in the engine bay as you described, and the other end to the exhaust manifold. A big difference!

[Steve Q]

3 hours ago, Henrik S said:

I had to create an account here just to say THANK YOU!

 

I had the same problem, took a 16mm2 battery cable and connected it between the negative batterypost in the engine bay as you described, and the other end to the exhaust manifold. A big difference!

You're welcome. Pleased to hear this forum helped you 🙂

[supernovauk]

On 2/16/2022 at 8:51 AM, Henrik S said:

I had to create an account here just to say THANK YOU

 

I had the same problem, took a 16mm2 battery cable and connected it between the negative batterypost in the engine bay as you described, and the other end to the exhaust manifold. A big difference!

Hi have the same earth problem as it has lazy start like battery flat or sometimes not even turning over, I connect a jump lead from negative post under bonnet to the engine and starts so is definitely earth problem, Where is the best place on engine to add an extra earth as it is a Q7 just like yours and noticed you said made a big difference Thanks

[Nickie94]

Hi, I have just brought an Audi Q7 2007 and have a similiar issue where it is very sluggish to start and seems like it is draining the battery. I have seen this thread and checked my engine to find I don't have that earth cable from the neg point to the manifold. Anyone know if this could be my cause and need one fitting? Thank you

[Magnet]

Hello Nickie, 

Many thanks for joining, 

It certainly sounds as if adding an additional earth lead has worked, so I guess it’s a case of biting the bullet and giving it a try -assuming the battery is as serviceable as it should be. 
Kind regards,

Gareth. 

 

[ikkia-alpha]

Trying to Fit an Earth Cable as demonstrated in the pic. Could anyone help with the socket size please ? what mm of Triple Square Spline is that ?

[Magnet]

Hello Ark,

Thanks for being in touch.

Hopefully someone might come along with the answer for you, but I must expose my lack of knowledge with the terminology - Triple Square Spline - used on your side of the world Ark. 

I’m wondering if that translates to Allen Key as I know them-? 

Kind regards,

Gareth. 

 

[ikkia-alpha]

Hey Magnet, maybe the bit is called 12 points (or XZN) as opposed to Hex (6point) ? 

Anyway, just wanna say that I have the same hot slow start issue, and mechanic asked me to change battery.

I'm not convinced as I do not have the issue when engine is cold.  

I fixed my slow start by following this thread and add the earth strap.

My theory is that the earthing issue is exuberated when engine is hot as the resistance goes up, and voltage on start motor goes below the required voltage. 

[Magnet]

Thanks Ark, but still none the wiser with the different terminologies on the opposite side of the globe. It’s surprising how much we don’t know! 
Great to hear you solved your problem by adding the extra earthing strap, but apologies but I must admit I’m not following the logic of the (contact?) resistance increasing with temperature, but….

Kind regards,

Gareth. 

[ikkia-alpha]

I think what I had in mind was that the existing earthing cable underneath the car is worn down, but not completely disconnected. 

So when the temperature is low, the car still somewhat have an OK earth. I checked my engine to car body resistance, it was 0.2omh when cold, I guess its acceptable. 

When the engine bay warms up, and the existing earth cable heats up as current flow through the cable. Metal resistance (ohm) goes up as temperature goes up. As a result, more voltage drop. 

this youtube video is pretty revalent. He used the thermo gun to check the earth cable temp under the car

 

Edited May 17, 2023 by ikkia-alpha

[Magnet]

Thanks Ark, but still not following that logic, but it really doesn’t matter since you have now sorted the issue, and that’s the most important thing. 

[Robsi98]

Having the same issue

on stop start it’s sometimes throwing all the dash lights up and once in a blue moon not starting at all , just fitted earth hopefully will sort ,seems more power to starter 

[Bigdave1230]

My 2014 did something similar when I got it. The start stop often had the deactivated symbol on the dash and on the occasion it did work it didn’t restart the car and would beep and put error lights on the dash. Turning the ignition off and back on would restart it but slowly. That was caused by a faulty battery. Replaced and it’s been fine since.

[a6blacked007]

I have also notice this once or twice is it possible just to clean surface of connection points with ie sandpaper etc ... 

[Bigdave1230]

Yes but the earths that corrode are accessible from under the car and aren’t the easiest to get to but yeah you can clean them up. 
Easiest thing to do is get a jump lead and put it from somewhere metal on the engine and the negative terminal under the bonnet on the passenger side and try starting the car to see if it makes a difference. If it turns over quicker then it looks like the earths are corroded.