kicker99chevy Posted March 1, 2011 Report Share Posted March 1, 2011 ok im puzzled first off i gotta say i basiclly dont know a thing about car engines but here is my question i have a 99 chevy monte carlo with the 3.8 v6 in it on average i was getting around 24 or 25 mpg now it gets about 20mpg i live in minnesota and iv been told the cold can cause it to drop iv also just got the tranny flushed new spark plugs its got good tires with the correct air pressure its got a fairly new air filter its got a new mass airflow censor but i have no idea what else could cause it to drop from 24 to 25 all the way down to 20 mpgs can anybody help me out Quote Link to comment Share on other sites More sharing options...
JaM Customs aka mprete Posted March 1, 2011 Report Share Posted March 1, 2011 could be the cold, and do you start it up and let it get warm before you drive it?? that uses gas and doesnt add mileage making it seem like worse gas mileage. Quote 2001 dodge ram 2500 quad cab 5.9L V8 my build logs... dodge build http://www.stevemeadedesigns.com/board/topic/94914-mpretes-2001-dodge-ram-2500-quad-cab-build-log/ trik build http://www.stevemeadedesigns.com/board/topic/94447-trik-build/page__p__1298547__hl__trik__fromsearch__1entry1298547 box building thread- very cool designs (PICS!!!) http://www.stevemeadedesigns.com/board/topic/95713-2d-or-3d-box-pics/page__gopid__1318152entry1318152 i am a mechanic, pm me if you have questions or anything. Link to comment Share on other sites More sharing options...
HotRodHam Posted March 1, 2011 Report Share Posted March 1, 2011 my car did this so i replaced my gas cap and it went back to normal. idk if thats ur problem but that was mine Quote 18" Sundown Zv4 D2JL 1000/1 V1XS Power D3200 Link to comment Share on other sites More sharing options...
BulletInjection Posted March 1, 2011 Report Share Posted March 1, 2011 Cold weather Quote My build: http://www.stevemeadedesigns.com/board/ind...8920&st=100 http://www.youtube.com/Bulletinjection Link to comment Share on other sites More sharing options...
sprkn_ranger Posted March 1, 2011 Report Share Posted March 1, 2011 Have you replaced your fuel filter? That can cause it. Also I know it sounds dumb but weight can be an issue, have you put anything heavy in the trunk recently? It takes more horsepower to move extra weight. Also you mentioned you put new spark plugs in, if they aren't capped properly that can make a difference too, even if they are "pre gapped" you should always re gap them to the proper specs cause during shipping and whatnot they can be dropped causing the gap to change. Quote Check out my build log! 4 Havocs in a blowthrough http://www.stevemeadedesigns.com/board/topic/187506-sprkn-rangers-blowthrough-build/ Link to comment Share on other sites More sharing options...
Rebel4055 Posted March 1, 2011 Report Share Posted March 1, 2011 Change your plug wires too. Quote Rest In Peace mother. January 22, 1955 - February 14, 2013 http://www.stevemeadedesigns.com/board/user/35351-megrch/ Link to comment Share on other sites More sharing options...
BeachJoshua Posted March 1, 2011 Report Share Posted March 1, 2011 Did the use the correct weight of tranny fluid? Quote | S-10 | 4.5^3 ft | 33Hz | SAE-1000D @ 1 Ohm | 2 SA-12s | SPL: 143.7 Sealed | 153.4 Port Wars Link to comment Share on other sites More sharing options...
UnderLoK Posted March 1, 2011 Report Share Posted March 1, 2011 (edited) o2 sensor could be going... Edited out the rest as you already said it Edited March 1, 2011 by UnderLoK Quote If at first you do not succeed, you are doing it wrong! -ARSCheck out my walled TBSS build over here4 Fi Team 18s on 2 Cactus K9 DS18 doors on 2 MBQ 1Ks, Vifa pillars on a STL4.500 Pioneer X8500 6 XS Power D7500, 1 3400S Second Skin 2 270a Mechman Alts Link to comment Share on other sites More sharing options...
white4d96 Posted March 2, 2011 Report Share Posted March 2, 2011 I wouldn't call 24-5 to 20 massive sucking. Sounds to me like you changed driving style or are making shorter trips. During the winter I go from getting 21-22 to as low as 16 because I let my car warm up and don't take as many long trips. Quote Too many projects, too little time... Link to comment Share on other sites More sharing options...
captainhook426 Posted March 2, 2011 Report Share Posted March 2, 2011 it's not super-charged by any chance is it? A small vacuum leak could cause that problem, fuel filter, and those motors are really really bad about blowing up the intake gasket (especially with the orange coolant). If you have a platinum or iridium spark plug you DO NOT want to even attempt to re-gap them, you will more than likely ruin the plugs all together! Quote Next time she tries to punch you in the stomach, whip your wiener out and chase her around. Show her who's boss. Link to comment Share on other sites More sharing options...
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