another mpg thread...

[TOOLOW91]

So around December of this past year i installed my o/r x pipe and it sounds great had a few exhaust leaks. i sealed them all up, Im not running 02 eliminators, i have 2 non fouler's on the 2 rear 02s and no check engine light.I know the rears do not control fuel trim, but the car has the normal no cat exhaust smell but to me it seems like it runs way rich now.. so my question is what does stangnet think it could be?

only perf. mods are- mac weld ins , k&n fipk, superchips 93 order tune... ( this was all on the car already before the mid pipe) and then i did the mid pipe and fuel mileage took a dump on me

 

[Maxpowers]

How far did you mpg drop?

You must keep in mind that it's winter. The average driver in cold weather allows their car to warm up more in the winter. The cold weather itself will also drop your mpg.

 

[patman0911]

So around December of this past year i installed my o/r x pipe and it sounds great had a few exhaust leaks. i sealed them all up, Im not running 02 eliminators, i have 2 non fouler's on the 2 rear 02s and no check engine light.I know the rears do not control fuel trim, but the car has the normal no cat exhaust smell but to me it seems like it runs way rich now.. so my question is what does stangnet think it could be?

only perf. mods are- mac weld ins , k&n fipk, superchips 93 order tune... ( this was all on the car already before the mid pipe) and then i did the mid pipe and fuel mileage took a dump on me

Non-foulers? Are you talking about something like these:

If so, have they been effective in keeping the CEL light from tripping since you removed the cats? I came across the idea somewhere a while back and it's so simple that it's brilliant (moves the sensors a little ways out of the exhaust stream to slow response) but I didn't know if anyone was actually running them instead of an MIL-eliminator/O2-sim. Did you use two stacked on each rear O2?

Everyone says that the rears don't affect the fuel trims, and they don't directly, but as I understand it, the PCM does run tests using the rears to confirm that the fronts are doing what it thinks their doing so it could indirectly affect the fuel trims if the readings from the rears are off far enough to cause the PCM to apply bad corrections to the fronts. That may explain why some people experience no change in MPG after a midpipe swap (I didn't) and some people inexplicably do.

Did the mid-pipe significantly move the location of the front O2 sensors?

How big a drop in MPG?

Did the gas stations in your area recently switch to a higher blend of ethanol? (that knocked a couple MPG off mine last year)

Did the average daily temps drop a bunch around that time - as Maxpowers noted, MPG drop with really cold weather - takes longer to get up to temp and the colder denser air leads to higher pumping losses too. Mine dropped a good bit when we had a couple weeks of weather in the 20's and 30's recently.

 

[TOOLOW91]

so i haven't measured but next fill up ill watch my mpg and let everyone know..

as far as the fouler's yes those are them and i have 2 stacked on each 02 sensor.. what you do is drill the first one out with a 1/2 inch drill bit . Thats the one you insert the 02 sensor into, then you thread the drilled fouler with your into into the UN drilled one and then the whole stack into your mid pipe.. haven't had a CEL yet and cost me 11 dollars i can crawl under and snap pics if you like...

in theory it works perfect because essentially all the sensor does is sense heat and produces a voltage signal to send back to the ecu and that interprets its values to make sure its measuring accurately and that the cats are doing there job.. more heat is generated with no cats obviously so if you space them out and keep them as cool as they were after your cats you eliminate your light.

and i do understand as far as it being winter but this is winter #2 with the car so i know its behavior very well. i am mechanically inclined (cert diesel mech) but im looking for ideas here because it could be a few things and im a little stumped..

EDIT- and i also may remove one fouler per side because ive been thinking about what youve brought up for a few days now about them indirectly affecting fuel values based on what the ecu sees from the front and rear