Bad Gas Milage...Don't know why

Custom_V6_Limited_SE · Post by **Custom_V6_Limited_SE** » May 2nd, 2006, 11:28 am

I used to get up to 30mpg in my car, now, I'm down to 19.5. I have replaced both O2 sensors already and that didn't fix it. I also bypassed my EGR and that didn't fix it (although it is noticably more powerful).

jschrauwen · Post by **jschrauwen** » May 2nd, 2006, 12:09 pm

Made no mention of spark plug type, gap and condition when inspecting. No mention of type of filter system - oem airbox & filter, a CAI?? If CAI, type, routing and termination of filter? Is it safe to assume that this just happened over night or rather was there a few mods or tinkering done prior up to this realization. A few gaps to fill in the picture would help. If you said this over the phone a Mazda mechanic he would probably need more info....... so do we.

Chemical · Post by **Chemical** » May 2nd, 2006, 8:07 pm

An earlier thread also mentioned tyre pressure- I took his advice and mine were low so now getting a few more miles per tank. Also is'nt it true that MX3's are set to run rich from the factory? I've looked at the online manual to see about backing the regulator off but don't have a fuel pressure gauge.

hgallegos915 · Post by **hgallegos915** » May 2nd, 2006, 10:35 pm

Just do the regular tune up and dont floor it alot. check for FUEL LEAKS. Usually our fuel pressure regulator will die for no reason. bleh... check codes. Possibly you are in limp mode. replace fuel filter.

Custom_V6_Limited_SE · Post by **Custom_V6_Limited_SE** » May 3rd, 2006, 2:02 pm

I have a CAI that goes behind the driver's headlight. Spark plugs are pretty new. And it had a tune up somewhere around 6 months ago. I declined from 30mpg to 19.5mpg over a period of about two months. As I said, new O2's. I am still waiting for an adjustable FPR that I got off of eBay (don't buy from BNR Racing). Mayby I will try the fuel filter.

Custom_V6_Limited_SE · Post by **Custom_V6_Limited_SE** » May 4th, 2006, 1:26 pm

Well, I was more carefull on the accelerator (touch it and shift at 3000) and I think I'm up to 24.5mpg. Still waiting on my Adjustable FPR anf Fuel Filter.

blueskyguy007 · Post by **blueskyguy007** » May 4th, 2006, 2:09 pm

Has anyone noticed any drop in fuel economy since they changed all of americas fuel to ethenol? I think maybe I'm just trippin like I'm placeboin lol..but I was thinking maybe that might had something to do with it. Have you changed oil recently..I know my 1st car I didn't change the oil and let it go down to 1 quart (it leaked..I was stupid and 16) but it made my compression suck and I noticed a BIG difference in fuel economy.

~peace

Custom_V6_Limited_SE · Post by **Custom_V6_Limited_SE** » May 4th, 2006, 2:49 pm

I replace it every 2000 miles with fully synthectic 10w30 Mobile 1 oil (I'm changing it today). My car doesn't leak oil and I check it often.