mhousealum

So I had the dealer print off the list of items covered in the 55k service and took it to an Indy to service. Cost was $455 vs. $610 at the dealer. Anyways, the main items in the service were spark plug change, engine air filter, and cabin air filter and a bunch of check this and check that. So I got the Q5 (2010 3.2L) back last Saturday afternoon and immediately noticed acceleration was noticeably improved. A google search pretty much stated you shouldn't notice performance increase from a spark plug change, just better starts (particularly cold weather) which wasn't a problem for me. I'm just curious what you guys/gals think and if performance increase is related to spark plug change, maybe 55k is too long to wait. I actually had just under 52k when I had the service performed. Thoughts?

Transfer

I think you can notice improvement with plugs and filter changes. It might be all placebo, but I felt improvement in my M3 after that type of service.

mhousealum

I agree...initial thought was placebo but the key is I had no expectations of any improvement. After 4 days I'm positive it's accelerating better. Still not sure if the plugs or filter are the cause but I'm happy with it.

Eryeal

Pretty sure this kind of thing is a placebo effect. You aren't looking for a noticeable change in acceleration until the service is performed, and because of that, you think there's a change when really there isn't. I mean, even if there was a small positive change, which is much more likely - it would be too small to actually be "noticeable" .. Imagine if you were driving identical two cars - one had 300 HP, one had 305 HP - you aren't going to be able to detect the difference yourself.

uberwgn

It's likely that you are enjoying a benefit from fresh plugs. Not sure why Audi calls for them to be changed at 55k miles. Maybe DI is harder on plugs. Many cars go to 100k miles today on their first set.

My B8 A4 calls for plugs at 35k miles. I changed them out already and they looked pretty good. Didn't notice much change one way or the other.

-hef-

I don't think anything he did would provide a noticeable increase in performance. Only thing I can think of is that he disconnected your battery during the service, which in turn reset your ECU. When that happens, all the learned driving patterns were deleted. So if you drive like an old lady, all that memory of 'i drive slowly/carefully' got dumped and you were back to factory spec, which feels faster.

mhousealum

That's something I didn't think of....I bought the car at 28k so not sure how they drove before me. I'm going to ask him. Thx

mhousealum

Again, I wasn't expecting anything related to acceleration increase. It is definitely there at the low end and even the mid-range. I drove the car since December, 2012 and I def know how it drove. Again, I'm not complaining just trying to figure out why it has improved. It's not a placebo.

- B -

It could be that the air filter was really gunk'd up with dirt...plus new plugs and your actually efficiently breathing and firing again, which makes any acceleration more pronounced...


You may want to check and make sure you have an actual new air filter in the air box, just in case the Indy mechanic forgot the air filter completely, which would make acceleration very noticeable, but also very dangerous.....at least I would if the change in acceleration is a huge change....

Dalancroft

Tires that were under inflated, fouled plugs, clogged air filter, and yes perhaps an ECU remapping would, after service, make any car feel more sprightly.