decreased MPG after service
 

hi, i just had the 60k mile service done on our 2005 s60 T5 at the dealer and since then noticed a decrease in the MGP - same conditions, same driving style, same area (mostly highway) gives me about 26 MPG instead of the usual 29 to 30 MPG.
does anybody have a similar experience or explanation for that?

thanks

RE: decreased MPG after service
 

Not really maybe they reset the computer and it is still learning to the driving conditions.

RE: decreased MPG after service
 

Yes, I had a similar problem after service was performed on my 2006 S60 2.5T with approximately 49K miles. Do you know if a sensor was changed? I had a sensor replaced and asked the same question. The reply I received from the maintenance shop was thatafter a sensor is changed the mileages will fluctuate.

RE: decreased MPG after service
 

thanks for your answers - gotta go on a 500 mile trip again on tuesday, maybe it'll be different this time - different meaning hopefully better.
according to the receipt there was no sensor changed, but i will call tomorrow and ask anyway.
fritz

RE: decreased MPG after service
 

hi again,
i did my 500 mile trip and it is getting better - not quite where it was before the service, but now about 2 MPG off. what i should have mentioned in my original post is that the front brake pads have been replaced with the service - could it be that they have been rubbing on the rotors and now are getting more clearance or so?
thanks
fritz

RE: decreased MPG after service
 

I doubt that.
I think is it just relearning.

RE: decreased MPG after service
 

A shop just cleaned my MAF and reset the ETM and I noticed that it is getting worse mileage. They said the car has to re-learn how you drive which can take a while. I'd assume that might be why your car is getting poor mileage.

RE: decreased MPG after service
 

The one thing that can really throw off the mileage are spark plugs. If they were changed and the wrong heat range or just the wrong brand plugs installed this will throw the mileage off. Not speaking out of my a*s here. I had the same issue when I installed non-OEM plugs in my Chev truck years ago. Mileage was down probably 5MPG's before I put OEM plugs back in.

RE: decreased MPG after service
 

i took the spark plugs (Bosch Super Plus FR7DC) out to check the gap - they are all at .032 or .033.
i think i read somewhere that it is supposed to be at .028 - would it make a difference to gap them down to that?
one other thing i noticed is that when i park and rev it up to about 3000 RPM and let go of the pedal it does make a - for the lack of better words - burping or farting sound. could that be related to the plugs too?
oh, except for the decreased mileage it runs fine.

thanks

fritz

RE: decreased MPG after service
 

I would regap them and see if it makes them better.

RE: decreased MPG after service
 

thanks tech - after i do this, should i pull the ECU fuse to make it relearn the parameters?

RE: decreased MPG after service
 

I would do that to be safe.

RE: decreased MPG after service
 

I believe FR7DC's are $.99 copper spark plugs that belong in a Kia not a turbo Volvo. The right plugs are platinums from Bosch. Don't know if this will fix the problem but I swear by original equipment spark plugs. See link below.
http://www.fcpgroton.com/product-exe...ategory_id/225

RE: decreased MPG after service
 

here is a little update...
we went on a little road-trip over the last 3 days from fort irwin, ca to albuquerque, mn and then back via sedona, az and the grand canyon to fort irwin.
i did not particularly try to save gas and always went with the max i dared to go - since the limit was 75 mph in arizona and new mexico i did around 83-85 mph for long periods of time and in high elevations of up to 7700 ft (we are at about 1920 ft), it was me and my wife with just a little luggage.
i reset the average mpg counter when we left and didn't touch it on the trip - when we arrived home yesterday we had averaged 28.5 mpg, which i think is pretty good for the driving we did.
i did discover a humming noise though, but that is a different story.....
thanks for all the answers.
fritz