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Hi everyone - first time poster here. I've recently come into ownership of a beautiful 2010 Audi S5 with the 4.2 V8 engine, automatic transmission, sport diff and drive select.

The first thing I noticed was that this car didn't seem as fast as one would expect of an "s" product. I was expecting to be pushed back in my seat, but for the most part only first gear will do that. The remaining power comes on in a smooth and linear fashion - third gear is especially disappointing (feels more like fourth in other cars). It's one of those cars when you don't feel like you're accelerating quickly, but then you look at the dial and you're already over the speed limit.

I looked at the power/torque graph of these motors and it seems there's a rapid incline up to about 3,900 RPM then a linear drop all the way to redline - probably not the most exciting curve in terms of acceleration, and also explains why the latter gears don't feel as quick. I must say, I miss the "dramatic" power curve of single turbo motors - each gear starts off slow then becomes faster as you rev, reaching a "crescendo" before changing gears and going through it all again.

Regardless, I noticed something interesting - after a long drive on highways and coming back into the city, the S5 suddenly felt much more responsive across the rev range.

My first thought is perhaps something in the ignition system - plugs, coilpacks, or carbon buildup. My car doesn't seem to have any misfires or stutters, so I initially ruled those out - but it's still possible. Note that I always drive in Dynamic mode with manual shifting and have also tried turning off ESP to see if that made a difference (it didn't).

Any other ideas? Thanks in advance!
 

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Check out Mat Armstrong on YouTube. He's been doing up an S5 V8.
His latest video might explain why the S5 doesn't feel as fast as it should.
Hopefully he solves the issue with his.
Good luck and welcome to the forum.
 

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S
Check out Mat Armstrong on YouTube. He's been doing up an S5 V8.
His latest video might explain why the S5 doesn't feel as fast as it should.
Hopefully he solves the issue with his.
Good luck and welcome to the forum.
SJ, I’m also watching matts journey with the S5. Interesting he’s lost 100bhp some where. Even after a walnut carbon clean he found about 6bhp.
 

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Interesting indeed! My V8 is the old S4 feels as strong as alot of horses and really picks her feet up so I guess that you have also lost loads of geegees somewhere.....I would firstly have her fully serviced and change all filters and fluids, and then start from there.
 
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Most cars will 'feel' more responsive and eager after a good long drive on the highway, unless they are driven on the highway all the time. It's carbon build up, breathers, fuel line etc etc that clean them selves after a sustained period of driving. When I used to track my cars, the car felt like it had been remapped after a day on track clearing the cobwebs! :)

The FSI engines do suffer from carbon build up and may not show any symptoms, except maybe in the power department. The 4.2 V8 is quite lethargic and no where near as lively as the RS high revving V8.

Only real way to tell is get is diagnostic scanned and possibly on a rolling road to see what actually power it has.

The other thing is, the previous owner may have driven it like Miss Daisy and put regular fuel in it. So putting super in it and giving some spirited driving may wake it up again.

Do as Simon says and get a full service if it hasn't already been done. The B8 A5 and S models will surprise you with how much crap they suck up into the air box and cover the air filter. My A5 TDI V6 air filter looked like it had a 2nd job as a garden vac!
 

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Discussion Starter #6
Thanks for the responses so far - I watched Matt's videos on was surprised at his loss of power (and minimal amount gained back from carbon cleaning). I understand typical powerloss through the drivetrain, but 100hp seemed significant! The car has recently been serviced but I have no records of carbon cleaning. I suppose I should start there, then report back with results!

What are others thoughts on the power delivery of the 4.2 S5?
 

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I changed the coil packs and plugs at 65,000 miles and noticed a big improvement in performance. Not sure how many miles you have on yours or if this has been done before, but its a pretty easy and cheap service. Also added a KN airfilter at that time which I think someone mentioned. And I was always one who would run regular gas through my previous cars. I can tell a difference when I run (and now only run) premium through mine.
 

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Hi, thanks for your post. I have been running premium fuel but admit I have not got a history of coilpacks, plugs and filter replacements. I am going to assume that's an expensive job, mostly for the coilpack prices and then labor (although it looks like you only need to move the overflow tank and airbox to do the job)
 

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Actually really easy to do. $30-50 per coil. Mine threw a code that said I needed to change one and once I saw how cheap they were I just did them all along with the plugs. You just have to move the expansion take to the side as you do the drivers side. You don't have to remove it. And the airbox for the passenger side but its not that bad. If you are comfortable changing plugs you shouldn't have any problem. Might take you 2 hours. Just be careful unhooking the coils from the the plugs. The little tabs are brittle after being hot. I sprayed a little silicone spray on the tabs and that seemed to help.
 

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Sorry, by plugs above I meant the plug that goes from the the wiring harness and plugs into the coil pack. There is a little tab that you have to pull down that allows you to unplug the coil pack from the car.

 

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Something I read a few days ago that might be the reason: exactly how long is your "long" drive? What I read stated that, even though your temp gauge shows full temp, it's measuring the coolant temp, NOT the oil temperature. The oil, and the pan, are a ways away from the combustion action, and take a lot longer to come up to full temp, than the coolant does. And colder oil will present more drag on the bottom of the crank/etc.
If you're in a cold climate, and not feeling the pep until a Highway run, that might be the cause...
 

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Interesting - I found that it was after about 30-40 minutes of driving. I'm in Vancouver, Canada so it's about 5 degrees C at the moment. Could possibly have to do with oil temp too. Thanks for the responses!
 

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I also have a 2010 S5. Bought mine around 55k and now has 75k. When I got it a carbon cleaning had never been done... it was full of gunk. After the carbon clean there was a step change in performance, smoother and no longer fell on its face at lower rpms, but still suffered from higher rpm misfires when pushed. I had been working with a european car 'specialist' and they defaulted to changing plugs and coils, maybe there was a slight improvement but it didn't solve the problem. After troubleshooting myself I replaced the injectors and it runs like I think it should, no more misfires. Mine pulls strongest from 3.5k to 5-6k so my seat of the pants response differs from your description... YMMV. If the previous owner used poor gas or non VW502 approved oils you may be more likely to have gummed up valve pockets and injectors, but if you're not throwing any codes seems like it shouldn't be too bad.
 

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Another possible pointer: what grade engine oil are you running? In your cool climate I guess that you must an oil which copes well from start up even at very low early morning temps?
 

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Hi everyone - first time poster here. I've recently come into ownership of a beautiful 2010 Audi S5 with the 4.2 V8 engine, automatic transmission, sport diff and drive select.

The first thing I noticed was that this car didn't seem as fast as one would expect of an "s" product. I was expecting to be pushed back in my seat, but for the most part only first gear will do that. The remaining power comes on in a smooth and linear fashion - third gear is especially disappointing (feels more like fourth in other cars). It's one of those cars when you don't feel like you're accelerating quickly, but then you look at the dial and you're already over the speed limit.

I looked at the power/torque graph of these motors and it seems there's a rapid incline up to about 3,900 RPM then a linear drop all the way to redline - probably not the most exciting curve in terms of acceleration, and also explains why the latter gears don't feel as quick. I must say, I miss the "dramatic" power curve of single turbo motors - each gear starts off slow then becomes faster as you rev, reaching a "crescendo" before changing gears and going through it all again.

Regardless, I noticed something interesting - after a long drive on highways and coming back into the city, the S5 suddenly felt much more responsive across the rev range.

My first thought is perhaps something in the ignition system - plugs, coilpacks, or carbon buildup. My car doesn't seem to have any misfires or stutters, so I initially ruled those out - but it's still possible. Note that I always drive in Dynamic mode with manual shifting and have also tried turning off ESP to see if that made a difference (it didn't).

Any other ideas? Thanks in advance!
I changed the coil packs and plugs at 65,000 miles and noticed a big improvement in performance. Not sure how many miles you have on yours or if this has been done before, but its a pretty easy and cheap service. Also added a KN airfilter at that time which I think someone mentioned. And I was always one who would run regular gas through my previous cars. I can tell a difference when I run (and now only run) premium through mine.
Just curious I found a set of plugs for $85 same a factory OEM although I hear now if you go in they actually use a different brand but how much did the coil packs and plugs run you in the end? This is the first car I'm trying to do strictly outside any shop or atleast the dealer and I've done everything myself this far saving tons of money this way. Just did a carbon clean last week helped a ton. I'll do it every 10k miles now. Got its 1st carbon cleaning at 86k and MAN it needed it
 

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Go for NGK Iridiums, supposed to have some advantages over platinum which are OEM.
 

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I believe that's what they switched to if you were to go to the dealer today to get it done instead of the old oem. Thx will do
 

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I used the Duralast coil packs from Autozone. 6 pack for $123 and then had to buy 2 more at $31. And I can't remember if I did Iridium or Double Platinum but they are $5-8 each.
 
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