Help With Falling MPG?
Thread Starter
Junior Member
Joined: Mar 2008
Posts: 18
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From: New Hampshire
2002 E55 AMG, 1985 380SL
Help With Falling MPG?
Hi all... I have noticed that about since winter (dec/jan) up here in New Hampshire I have lost about 2-3 mpg average. There has been no noticeable loss of performance, and I haven't noticed a change in my driving habits at all. Used to get 21-22, now getting 18-20 combined city/highway (~75% highway). A couple weeks ago my CEL came on once indicated MAF issues, and shut off. I cleaned the MAF anyway and haven't seen any real improvement in MPG (did notice performance boost). I threw in a bottle of Techron in my last tank and just filled up a new one today. Hoping that'll help.
Any suggestions on what could cause a loss of MPG like this? I know it's not a lot, but it just seems kinda weird. Thanks.
Any suggestions on what could cause a loss of MPG like this? I know it's not a lot, but it just seems kinda weird. Thanks.
MBWorld Fanatic!
Joined: Nov 2008
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210 55
Yap, the MAF sensor cause this issue, maybe not affect the engine power at this time but they start to get more gas & more gas & more gas & you notice the power loss with the time (maybe 1 week, maybe 1 month or maybe 1 year) this sensors have this problem, at cold start your engine works fine? or you notice some faulty power?
Thread Starter
Junior Member
Joined: Mar 2008
Posts: 18
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From: New Hampshire
2002 E55 AMG, 1985 380SL
I avoid ethanol when possible, and fill up only with top tier fuels. I did just get new tires (toyo proxes 4), which may be it because the MPG loss was a sudden drop, not a slow fall. Also, my engine runs just fine at cold start, and power seems to be fine for now. I'll probably replace the MAF in the spring anyways. Seems ok for now though... I'll keep an eye on things. Thanks for the help all.
Super Member
Joined: Apr 2007
Posts: 749
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From: The Bay. We Fresh.
2008 W211 E63
i run toyo t1rs in Cali and still get 20-22 mpg at around 75% freeway driving. i did however get much worse mileage when my MAF crapped out. I found that cleaning it doesn't do much. Have a MB shop check it out. There is range (i think its between 1 and 1.1) that the MAF should be running at. Anything outside of that range and the MAF need to be replaced. When I replaced mine it was running at 1.30. As SOON as I changed it the power and MPG came back.
Thread Starter
Junior Member
Joined: Mar 2008
Posts: 18
Likes: 0
From: New Hampshire
2002 E55 AMG, 1985 380SL
i run toyo t1rs in Cali and still get 20-22 mpg at around 75% freeway driving. i did however get much worse mileage when my MAF crapped out. I found that cleaning it doesn't do much. Have a MB shop check it out. There is range (i think its between 1 and 1.1) that the MAF should be running at. Anything outside of that range and the MAF need to be replaced. When I replaced mine it was running at 1.30. As SOON as I changed it the power and MPG came back.
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MBWorld Fanatic!
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From: Chicago, IL
02 996 Turbo, 05 CLK55 AMG
I don't drive my car in winter but I know that few of my friends where complaining about the same thing ... loss in MPG during winter season ...
Last edited by SaMaS; Feb 13, 2009 at 10:40 AM.
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Joined: Dec 2005
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From: Fort Worth, TX
2011 GL550, 2004 Audi S4 v8
I had the same exact tires for winter, and I was in Portland, ME...I used to get 22mpg. I seriously doubt it's the tires...and yes, this was on my E55. I'd look into the MAF.
Thread Starter
Junior Member
Joined: Mar 2008
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From: New Hampshire
2002 E55 AMG, 1985 380SL
yeah i'll probably end up changing my maf anyways... just passed 72000k which seems like quite a while for one of those troublesome little guys. I wonder if the extreme cold can effect mpgs... it's been a brutal winter up here, and the change in MPG happened around the same time as the change in weather. Thanks again all.
