Hey guys, ever since I put on my SMSP setup, i've noticed the gas mileage has taken a turn for the worst. Yes, I knew to expect this so thats not whats bothering me. I recently had it tuned about a month ago (air fuel) on the dyno and everything looked alright. made good power but lost some midrange because I was using an safc instead of a vafc . Anyways, it seems as if ever since the tune itself, i'm slowly losing mileage. I went through a full tank of 93 Premium in about 200-180 miles roughly 1-2 months ago around the tune, mostly highway too. Today, i MIGHT be getting 185, I have to fill up today. I did replace the spark plugs the time of the tune, but I myself have never replaced the fuel filter, and I'm not sure if the previous owner ever did either, although he did take his car to the dealer every maintenance schedule, but who trusts their work. Could it be the PCV, wires, fuel filter?? I just got an oil change too so oil filter shouldn't be a problem. I'm leaning towards replacing the fuel filter, you guys have any other recommendations?? Right now i'm at about 57xxx miles

 

I had ONLY my timing advanced inbetween dyno runs (just for the hell of it) and I had a noticeable power increase but noticed immediately that following week of driving that my gas mileage got worse. So i set it back to factory spec and only advance it for hpde's and such.

So anyway... did you have your (ignition) timing advanced?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Alexander &raquo;</TD></TR><TR><TD CLASS="quote">I had ONLY my timing advanced inbetween dyno runs (just for the hell of it) and I had a noticeable power increase but noticed immediately that following week of driving that my gas mileage got worse. So i set it back to factory spec and only advance it for hpde's and such.

So anyway... did you have your (ignition) timing advanced?</TD></TR></TABLE>


yea man, actually even before the first run the tuner advanced the timing! could that really be the cause of my problem?? The car all does kind of hesitate sometimes when semi-low on gas around the mid RPMs, 4-5k.

 

wow even your mileage before this problem looks to be bad. i get close to 300 miles a tank with moderate driving. sorry i dont know of any solution. good luck

 

Tire pressure plays a big factor in gas mileage. Clogged injector would also cause problems.

 

ouch that SUCKS lol..

i'm having the same problem (but with a different car)...

lots of things can worsen mileage:

- o2 sensor
- fuel pressure regulator (bad shape)
- fuel pump
- spark plug wires, spark plugs, distributor cap + rotor (lack of tune up)
(i know you did ur spark plugs)

- mistuned ignition timing (as mentioned above)
- misadjusted valve clearance
- Oil level (do you check yours?)
- Tire pressure (as mentioned above)
(sorry i'm re-mentioning some things.. it's just flowing thoguh my head)

- check for engine codes, even if the light isn't on. I doubt you have any since you have such low mileage and since you tuned your car.

- High mileage, old motor, worn seals, age&lt;-- which i guess doesn't affect you

- fuel injectors. I know it's been mentioned, but waht you can do is check the resistance to see if any injectors aren't functioning up to par. Just connect a multi meter to the injector.

There's a lot more, but I can't think of any other things... I'll add on later

Fuel Economy problems are a bitch because sometimes the car is running just fine and out of nowhere you get horrible mileage.

I still can't figure out my ****

Good luck.

 

Man thanks, looks like I'll be doing a lot of work to try and find the problem(s). I DO have a Check Engine Light, but thats been on since the header and exhaust have went on, I am using an aftermarket Carsound Cat, and the o2 sensors were extended at the time of the install. I did check the code before the tune and I got CEL 45 for too rich or too lean, had it tuned, went away for a day or two. Been back ever since I will try and check the code again this week and see what it reads now, maybe because the o2 sensors were extented, that messed it up, or just an aftermarket cat is casuing it. Who knows...thanks for everyones input

 

check air filter

 

definately take a look at the check engine light again, it only comes on for emmisions related stuff. I would guess since you got the O2 sensor code last time that it is the same. I would definately check out the connection that was made when the o2 sensor was "lengthend", if that is ok then replace the sensor. Good luck

 

If you have a CEL your car runs in safe mode and will dump more fuel to accomodate. you have an aftermarket cat that seems like it would cause worse mileage also. if your code was too rich/lean, than it seems like you answered your own question.

 

better gas mileage
1. fuel filter
2. plugs
3. air filter
4. pcv valve
5. Go to Acura and get a decarbonization done its like 34.99 and they take off vacuum hoses and get a can of something? and de carbonized your intake manifold i did it and it works!
6.throttle body cleaned
7. can of sea foam in gas.

 

thanks everyone!!! i will definitly be doing these ASAP