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Jerky when cold

Posted: Mon Nov 06, 2006 9:56 am
by bjacks
Anyone else have this when the car is cold and using light throttle? Kangaroo's mildly up the road, the Mrs even mentioned it so it must be true :D

Fine after a couple of minutes.

Cheers

Ben

Posted: Mon Nov 06, 2006 10:10 am
by DuncanMac
Yup - Mine does it too - especially on these f off freezing mornings. I tend to let it run for a few miutes until it has warmed up a little - minute or two.

Posted: Mon Nov 06, 2006 12:57 pm
by Nipper
Mine does the exact same thing on a really cold morning. It's fine as soon as it starts to warm up. It's obviously a design feature!!!!

Posted: Mon Nov 06, 2006 2:35 pm
by bjacks
Glad it's not just me then!

Feels a tad over-fuelled. I'll see of there's any s/w updates due...

I can't really have it sat in the garage warming up and gassing the baby out!

I hoped he'll have petrol in his blood, but not literally :wink:

Cheers

Ben

PS, on another note, is 2nd gear torque restricted? It doesn't feel as crisp as 3rd.

Posted: Mon Nov 06, 2006 3:19 pm
by PetrolDave
bjacks wrote:Feels a tad over-fuelled.
That's exactly what's happening!

When an engine is cold not all the fuel that is injected is atomised (i.e. ready to burn) so during the cold warm-up period excess fuel has to be injected. It sounds like Audi have not got the excess amount of fuel correct and have gone slightly OTT. Maybe they should map the excess fuelling better i.e. control it using ambient temperature? Or maybe they've got that mapping wrong? Sounds like a case for a software update - though you would have thought the cold weather testing in Finland/Sweden would have shown this problem?

You can tell when the over-fuelling is happening - just listen to the exhaust note. For the first few seconds or minutes (depending on how cold it is) the exhaust note is REALLY loud and crackly, and the engine idle is noticeably faster than normal. This ends quite suddenly and the exhaust goes quieter and the idle speed drops.

Posted: Mon Nov 06, 2006 5:23 pm
by bjacks
A question to the dealer then.

My CSL used to cough and splutter a bit, someone told me that it was because it didn't use a MAF and relied on more of an old-school attitude to fueling. It used to be cured by giving it a tad more throttle, but the RS has much more torque and more throttle equals more speed - which isn't ideal in traffic!

I had assumed the exhaust flaps were opened at startup just to make the car sound nice and put a grin on your face (and make it worthwile spending £55k) :D

Cheers

Ben

Posted: Mon Nov 06, 2006 8:46 pm
by andrei
mine too! even if I wait a little bit untill the rpm is under 1000 still feels "jerky" for a couple of minutes until warms up more.
But still, how it is going to work when outside will be -15 degrees (C) or even lower?
I noticed also some irregularities in suspenssion work when cold (0-3 degrees C) - anyone else?

some noises like it is frozen - you know the exact feeling you have when you change gears when is realy cold outside and the oil is very, very thick

Posted: Tue Nov 07, 2006 9:40 am
by Jezzer
Bjacks, I know you can't compare the RS4 Avant with the CSL but how do you rate them against each other. Just interested in your thoughts as I have made the same move as you.

Posted: Tue Nov 07, 2006 10:17 am
by bjacks
Jezzer wrote:Bjacks, I know you can't compare the RS4 Avant with the CSL but how do you rate them against each other. Just interested in your thoughts as I have made the same move as you.
I remember first jumping into the CSL and wondering how I put up with Audi's dynamics for so long! I actually enjoyed steering and dictating where the car went with the throttle :D With the B5 RS4 I think I enjoyed the straight line grunt most.

The B7 is better than the B5, but the steering feel is still not there. I had a 987 Boxster S with PASM between the CSL and the B7, so I was spoilt with good steering again.

The RS feels stronger in the mid range than the CSL (not suprisingly) and hence is a more useable car. The type of driving I do rarely lets me hang on till the red line as I'm usually in town or on the motorways. The CSL was very perky in the mid range, but absolutly loved to be gunned everywhere. When the cold weather set in, I found it very hard to use much more than part throttle as it would just light up the back end. This meant that I did about 300 miles all winter so it was a waste of time keeping it. When the back stepped out at 70MPH in a straight line due to a change in road surface I decided that enough was enough :shock:

Back to the RS, it doesn't do what the CSL does, but it is not supposed to. This morning I revelled in the heated seats, mid range grunt and 4WD traction. The same kind of journey in the CSL would have been colder, more noisey and slower as it was slippery.

For me it means that I can use it every day of the year without worrying where the next ditch is :wink:

The ride in the RS is pretty harsh with SS+ but hopefully will be worth it when I get somewhere near a track again (hopefully!).



Back on topic, I've not noticed any other creaks and groans but it's not that cold here at the moment and the car lives in the garage.

Still hopped up the road this morning, may have to put some "L" plates on the back :D

Cheers all

Ben