View Full Version : Recommendations for maintenance - 2015 S4 54k miles
SteveYem
03-18-2019, 10:16 AM
My 2015 S4 is currently around the 54k mile mark, out of factory warranty, and I'm not quite ready to move onto something else yet. Meanwhile, for the past couple years I've been living with this car having this sort of cycling / stumbling idle coupled with lousier than normal gas mileage, as well as some coolant consumption. I presented all of these issues to the Audi dealer while I was within the warranty period and after checking out the car they responded with "everything appears to be operating within normal parameters". I know it's not normal because up to a certain point it didn't behave this way, nor did my B8 S4 that preceded it. Maybe it's an intake valve carbon buildup issue if nothing else, but in any case I'm thinking that the supercharger has to come off.
Since it looks like I will be holding onto this car for a little while longer I am looking to put some money in for maintenance to (hopefully) get back up to running like new. I am planning to use an independent shop to do the work I am thinking to have them do the following:
* Walnut blast cleaning of the intake valves
* Replace the thermostat
* Replace the PCV valve
* Replace the supercharger belt (I already have a new one laying around with a Stage 2 pulley that I might also have them install while the SC is out...)
Is there anything else I should have them do while they have the supercharger removed?
Chris@EPL
03-18-2019, 10:18 AM
Audi calls for plugs every 55k miles. With tuned cars we see that they need to be every 25-35k miles. We recommend the NGK PFR8S8EG gapped down to .026".
SteveYem
03-18-2019, 10:22 AM
Audi calls for plugs every 55k miles. With tuned cars we see that they need to be every 25-35k miles. We recommend the NGK PFR8S8EG gapped down to .026".
Thanks Chris. I did swap in a set of those plugs, gapped to .026" per your advice, back around the 35k mile mark but based on your input it seems I'm due for it again. I may DIY it again before taking the car in for this other work if I'm feeling motivated.
B0bbyB0b
03-18-2019, 10:23 AM
I know my 2014 has a little bit of a rough idle and was always told that is the behavior of the motor...it is a 90 degree vs 60 degree and that is typical.
SteveYem
03-18-2019, 10:29 AM
I know my 2014 has a little bit of a rough idle and was always told that is the behavior of the motor...it is a 90 degree vs 60 degree and that is typical.
I've heard the same and I understand the rough idle, but mine is a bit different. It sort of cycles and has this periodic "stumble", almost like there is a valve somewhere opening and closing. From the outside of the car the exhaust note sort of fades out periodically. I posted about it here: https://www.audizine.com/forum/showthread.php/818390-Rough-and-erratic-idle-2015-S4
Here again, the Audi dealer told me it's "operating within normal parameters" but it just doesn't seem right.
v36sedan
03-18-2019, 04:47 PM
Pcv, coolant line, thermostat, spark plugs, all belts
eugkim
03-19-2019, 05:01 AM
Water pump?
Acejam
03-19-2019, 04:02 PM
I've heard the same and I understand the rough idle, but mine is a bit different. It sort of cycles and has this periodic "stumble", almost like there is a valve somewhere opening and closing. From the outside of the car the exhaust note sort of fades out periodically. I posted about it here: https://www.audizine.com/forum/showthread.php/818390-Rough-and-erratic-idle-2015-S4
Here again, the Audi dealer told me it's "operating within normal parameters" but it just doesn't seem right.
This sounds and looks exactly like a vacuum leak. Triple check your intake hoses, even the ones you didn’t touch when installing that intake. Perhaps one of the ECS nipples or tubes is cracked, it wouldn’t be the first time.
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SteveYem
03-19-2019, 05:19 PM
This sounds and looks exactly like a vacuum leak. Triple check your intake hoses, even the ones you didn’t touch when installing that intake. Perhaps one of the ECS nipples or tubes is cracked, it wouldn’t be the first time.
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Interesting. My first ECS intake tube developed a crack at the vacuum line nope, but the replacement one appears to be good still. Maybe there is some other line leaking as you suggested. I’m taking my car in to the shop next week and I’ll mention this.
Edit- would a vacuum leak typically also cause decreased gas mileage, delayed/laggy throttle response and perceivable decrease in power output?
sacandagaD
03-20-2019, 08:12 AM
Audi calls for plugs every 55k miles. With tuned cars we see that they need to be every 25-35k miles. We recommend the NGK PFR8S8EG gapped down to .026".
Chris- Would you suggest that for a piggy tune as well?
Chris@EPL
03-20-2019, 08:15 AM
Chris- Would you suggest that for a piggy tune as well?
I would not suggest a piggie back tune, ;)
I too have had the cycling / stumbling idle, but from reading it seems our engines dont idle the smoothest and is normal behavior.
sacandagaD
03-20-2019, 08:44 AM
I would not suggest a piggie back tune, ;)
Lmao! How about if one were using a piggy now and planning to go to an EPL Stage 1 tune just as soon as they hit 50k, when their warranty ends?
Chris@EPL
03-20-2019, 08:46 AM
Lmao! How about if one were using a piggy now and planning to go to an EPL Stage 1 tune just as soon as they hit 50k, when their warranty ends?
Yes I would recommend the same plugs and gap.
SteveYem
03-27-2019, 06:44 AM
I am currently at an independent shop and the tech checked the pressure at the oil cap (put an oil cap on with a pressure tap in it) and found that the pressure fluctuated, but on average registered very high vacuum. I could not see the max reading on the manometer, but it pegged it out fully. He checked it a few time by disconnecting and reconnecting the tube from his oil cap pressure tap to the manometer and a couple times the vacuum looked normal, but the rest of the tries it maxed out the manometer.
Does this indicated anything to anyone?