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Discussion Starter · #1 ·
Hi there, my name is nick, I’ve owned my s5 for about 9-10 months now and this is my very First post lol.... sorry, I should have joined earlier but I’ve genuinely had trouble free time with the car so no need to pic the brains of fellow owners :)

so to my problem... I’ve just had car dyno’d basically to see where car was at After a carbon clean (proper one).
Car seems to be about 50 bhp down from the last time it was dynod 5 years ago.
I have a graph from MRC from 2016 when car made 372ps and 480 nm of torque, I think this was achieved after a carbon clean and map tweak.

so tonight it has made 318 bhp and 440 nm @ power station in Tewkesbury.

I know there different dynos but 50 ish bhp difference seems excessive and to be honest the car has never really felt (to me) like it had 370 bhp...

First thing I’m gonna do is get it back to MRC for health check where I believe it will be dynod again.
i’m just wondering if anyone had any ideas what could possibly be the cause for loss of power?

only probs I’ve had with the car is one time last august car completely lost power while driving on motorway, pull on to hard shoulder then tried to restart.... would just turn but not fire. Until 10 mins later sprung back into life then drove perfect again for 5 or so miles then did it again. Did this another 3 times before I got off at services and brimmed it with fuel (already had half a tank). Had diagnostics done when I got home and not a single fault??? Until today it hasn’t done it again, but when operator of dyno pulled it on to the rollers it cut out ...EXACTLY the same as before, would not fire after numerous attempts ?

so guy plugged diagnostics tool in while it was sat there, surprise surprise no faults...
So we left car for 5 or so mins then tried again and fired up no probs.

only Other thing I’ve noticed with car is it seems to take quite a few cranks to start and this is the same whether hot or cold.

which is leading me to think fuelling prob somewhere? Car seems to run perfect though with no misfires and no codes ever popping up??

any inputwill be greatly appreciated 👍

nick
 

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Discussion Starter · #2 ·
Hi there, my name is nick, I’ve owned my s5 for about 9-10 months now and this is my very First post lol.... sorry, I should have joined earlier but I’ve genuinely had trouble free time with the car so no need to pic the brains of fellow owners :)

so to my problem... I’ve just had car dyno’d basically to see where car was at After a carbon clean (proper one).
Car seems to be about 50 bhp down from the last time it was dynod 5 years ago.
I have a graph from MRC from 2016 when car made 372ps and 480 nm of torque, I think this was achieved after a carbon clean and map tweak.

so tonight it has made 318 bhp and 440 nm @ power station in Tewkesbury.

I know there different dynos but 50 ish bhp difference seems excessive and to be honest the car has never really felt (to me) like it had 370 bhp...

First thing I’m gonna do is get it back to MRC for health check where I believe it will be dynod again.
i’m just wondering if anyone had any ideas what could possibly be the cause for loss of power?

only probs I’ve had with the car is one time last august car completely lost power while driving on motorway, pull on to hard shoulder then tried to restart.... would just turn but not fire. Until 10 mins later sprung back into life then drove perfect again for 5 or so miles then did it again. Did this another 3 times before I got off at services and brimmed it with fuel (already had half a tank). Had diagnostics done when I got home and not a single fault??? Until today it hasn’t done it again, but when operator of dyno pulled it on to the rollers it cut out ...EXACTLY the same as before, would not fire after numerous attempts ?

so guy plugged diagnostics tool in while it was sat there, surprise surprise no faults...
So we left car for 5 or so mins then tried again and fired up no probs.

only Other thing I’ve noticed with car is it seems to take quite a few cranks to start and this is the same whether hot or cold.

which is leading me to think fuelling prob somewhere? Car seems to run perfect though with no misfires and no codes ever popping up??

any inputwill be greatly appreciated 👍

nick
Sorry .... car is v8 4.2
 

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Yeah, could be fuel related (pump, injectors)...
it's hard when the older ones don't throw codes when they have an issue...
Do the dyno guys know how to log with vagcom to see fuel loads?

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Audi S5 Black Edition Mrc Stage 2
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Hi Nick it could be crank sensor as they don't always show even when using vagcom. You are right to take it to Mrc for a health check, but don't be surprised if it is running 320 - 330 bhp.
I have taken 2 V8's to Mrc albeit they were S4's and the last one had a carbon clean ,full milltek exhaust with front resonator delete, modified airbox with K&N filter and a stage 1 tweak.
Finger Parallel Document Paper Diagram

As for dynos they will normally vary depending on the set up in place and how skilled the operator is.
Please post your results up when you have been.
 

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Discussion Starter · #5 ·
Thanks for your responses guys... here are the two graphs
yesterdays:
179343


this was from MRC 4.5 years ago:

179344

I’ve emailed MRC to try and get in for health check ASAP.

regarding your 2 s4 v8’s you e taken their, good to know they don’t just fudge the duo results to keep people happy...👍

nick
 

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Have you checked the leads to the plugs etc? I've had power loss on other vehicles (not Audis) and bad leads has been the issue.
 

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Discussion Starter · #7 ·
Have you checked the leads to the plugs etc? I've had power loss on other vehicles (not Audis) and bad leads has been the issue.
dont think I’ve got leads as the coil packs are directly on top of plugs I believe??

got car booked in with MRC on the 28th but in the meantime I’m gonna get fuel filter changed as I believe it prob hasn’t been done for about 3 years atleast.... also gonna get fuel pressures checked at same time.

would be really nice if it was something as straightforward as clogged fuel filter rather than new fuel pumps🙈
Can someone give me a heads up of best place to get new fuel pumps if they are required?
 

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dont think I’ve got leads as the coil packs are directly on top of plugs I believe??

got car booked in with MRC on the 28th but in the meantime I’m gonna get fuel filter changed as I believe it prob hasn’t been done for about 3 years atleast.... also gonna get fuel pressures checked at same time.

would be really nice if it was something as straightforward as clogged fuel filter rather than new fuel pumps🙈
Can someone give me a heads up of best place to get new fuel pumps if they are required?
Same philosophy... bad coil packs.
 

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my previous S4 did that it lost power on the motorway while I was giving the beans, stood hard shoulder for 5 mins restarted was fine drive at steady speed was fine, got is checked out was 1 of the injectors cutting out when under heavy load.
 
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