ickythump Posted October 30, 2012 Report Share Posted October 30, 2012 (edited) Hi all, i have experienced a very pretty bad decrease in mpg's from22-23 city to about 18-19...nothing really seems amiss, oil was recently changed and air filter not dirty...hasn't lost any power, doesn't idle too high, and rpm's are where they normally at each speed (eg 1,500 @ 60mph).....any thoughts?? Edited October 30, 2012 by ickythump Quote Link to comment Share on other sites More sharing options...
c_bova Posted October 30, 2012 Report Share Posted October 30, 2012 since it has gotten cold it could be that the gas stations switched to their winter grade fuel which is known to cause mpg to drop as well as the fact it is colder and takes longer for engine to warm up to optimal running temps. that combination will definitely drop your mpgs. Quote Link to comment Share on other sites More sharing options...
akirby Posted October 30, 2012 Report Share Posted October 30, 2012 Have you changed tires recently? Check tire air pressure. Could be a combination of low tire pressures and winter fuel. A dirty air filter won't affect fuel economy. It's also possible you got some bad gas. Quote Link to comment Share on other sites More sharing options...
blankster Posted October 30, 2012 Report Share Posted October 30, 2012 Did they put the correct viscosity of oil in? Quote Link to comment Share on other sites More sharing options...
ickythump Posted October 30, 2012 Author Report Share Posted October 30, 2012 I don't know anything about "winter fuel" but i filled my tank from Buffalo to NYC and in Pennsylvania a few weeks ago which is when i noticed the drop on hwy first...any way i would be able to find out what kind of oil they used?? It was my first oil change, dealer gave me free coupon, or I'd have done it myself Quote Link to comment Share on other sites More sharing options...
Feirstein Posted October 30, 2012 Report Share Posted October 30, 2012 How many miles on the vehicle? Often a drop in mpg is associated with a bad O2 sensor, although today I would think the engine light would indicate this. Have the engine codes pulled to see if it shows any issues. 1 Quote Link to comment Share on other sites More sharing options...
ickythump Posted October 31, 2012 Author Report Share Posted October 31, 2012 95k....never should have bought such a high millage vehicle but, oh well.....no engine light on, will computer know of any issues but not display light? (also, sync has the diagnostic feature but it never works for me!!) Quote Link to comment Share on other sites More sharing options...
akirby Posted October 31, 2012 Report Share Posted October 31, 2012 Check the receipt from the oil change if you still have it. If it started suddenly then it's either the fuel, the oil or both. The O2 sensor would degrade over time or throw a code and light immediately. Quote Link to comment Share on other sites More sharing options...
ickythump Posted October 31, 2012 Author Report Share Posted October 31, 2012 I have it I'll check it, never paid for an oil change so didn't think to look, stupid of me...yea it happened abruptly after oil but i didn't consider they could have screwed up such a simple process....thanks for all the tips guys!! Quote Link to comment Share on other sites More sharing options...
akirby Posted October 31, 2012 Report Share Posted October 31, 2012 I'd get it changed again and make sure they use Motorcraft synthetic blend 5W-20. 1 Quote Link to comment Share on other sites More sharing options...
c_bova Posted October 31, 2012 Report Share Posted October 31, 2012 they might have even set your tire pressure incorrectly, I've known plenty of places that have done that. Quote Link to comment Share on other sites More sharing options...
ickythump Posted November 2, 2012 Author Report Share Posted November 2, 2012 Idk if anyone will be following still, but after filling up with premium and adding "professional grade" (taken with a grain of salt) fuel injector cleaner, i have seen a marked improvement in fuel economy.....not sure which helped, going to try different gas, but hey premium only 4.50 more a fill so.... Quote Link to comment Share on other sites More sharing options...
akirby Posted November 2, 2012 Report Share Posted November 2, 2012 If premium fuel helped then there is something wrong with the engine. Quote Link to comment Share on other sites More sharing options...
c_bova Posted November 2, 2012 Report Share Posted November 2, 2012 (edited) fouled spark plugs or dirty injectors Edited November 2, 2012 by c_bova Quote Link to comment Share on other sites More sharing options...
RJG Posted November 3, 2012 Report Share Posted November 3, 2012 If premium fuel helped then there is something wrong with the engine. Correct. If anything you should get better economy with 87. The ingredients they put in gas to make premium, taking out some of the volatility so as to not ignite early, also takes out some of it's energy content. Probably not enough to be measurable. If heads and pistons gumed up with carbon, effectively raising compression, maybe 91 runs better, but wouldn't improve economy. Also like akirby says, dirty air filter won't cause poor economy with modern vehicles either. Perhaps cleaning the injectors was the ticket. I wouldn't think difference of say 5-20 to 5-30 would really affect economy....although I use the Ford 5-20. If mine....would hook it to a diagnostic tool and look for codes. Quote Link to comment Share on other sites More sharing options...
akirby Posted November 3, 2012 Report Share Posted November 3, 2012 I wouldn't think difference of say 5-20 to 5-30 would really affect economy....although I use the Ford 5-20. Ford switched from 5W-30 to 5W-20 specifically for better fuel economy. Although it wouldn't be more than a few tenths of a mpg. Although if they used 10w-40 that might be more noticeable (and detrimental). Quote Link to comment Share on other sites More sharing options...
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