8 Mpg!!!!!

[chehsgsx]

ok so im only getting 8 mpg i have a small boost leak that i will fix asap but im also on my second maf my first maf just was dead ( i believe the car was in a front end accident not bad though) so i bought one from the junk yard only problem when i tap on the maf while the car is running the ideal changes so do i have another bad maf?????? the only other mod i have is an n1 cat back and down pipe ( down pipe leaks ### its a stupid no name ebay one) could this lead to bad mpg any help would be great i cant adored to fill up 3 times a week anymore

 

[DSM_PWR]

wow 8mpg YIKES!

is it possilbe to do a log reading? head to autozone and see if both your o2 sensors are working, my friend had same problem and just ended up bein his front o2. I also believe boost leaks can lead to low gas but not exactly sure...

 

[V8notENUF]

Is your blow off valve recirculated? And as for the downpipe, alot have had success from the ebay downpipes/catbacks, it's probably something an exhaust shop could fix relatively cheap. Also check your front o2 sensor, that's what determines your a/f ratio.

 

[nfernotalon]

Damn, no its not the DP, probably your o2 sensors, or the MAF

 

[chehsgsx]

well the problem with the dp is that its 3 inch at the flange so it doesn't want to seal and my bov does not vent i did my hw on that one and i replace the o2 about a year ago would it go bad that quick??

 

[V8notENUF]

Damn, no its not the DP, probably your o2 sensors, or the MAF

Never said it was his DP, just pointing out the fact that not all ebay DP's are trash. Could really be a number of things, injector stuck open, o2, poorly hacked maf, etc. As for the boost leak, the maf meters the air entering the turbo and makes corrections to determin proper a/f. Once the air is past the maf and altered via either atmospheric bov release or a boost leak, there is no sensor to make up for that lost air that the ecu has already added fuel for, therefore idle surges and the engine runs rich. Just my .02.

 

[nfernotalon]

The OP thought it was not you

 

[DSM_PWR]

i replace the o2 about a year ago would it go bad that quick??

I belive so... race gas for example

 

[mitsocruiser]

damn and I thought 12 miles to the gallon was bad

 

[chehsgsx]

ok so change the o2 and the maf is not hacked so idk whats bad and good wit them in my older car the maf was built proof u could hit it all u want wit no change in ideal and if it went bad the car wouldn't start but these cars are different and harder to spot a problem i also dont have the second o2 in because i dont have a cat is this bad?? oh and just as a side not when i to a boost leak test i have to put the tester on the end of my inter cooler intake pipe because if i include the turbo i can not build any boost on the gauge just kinda wondering y this is and if it can have an effect

 

[DSM_PWR]

you actually can start the car without having a maf, although you will get idle surge, anyone who's ever taken off the intake pipe and forgotten to plug back in the maf plug will tell you that

but i would suggest just boost leaking from the turbo inlet, i believe i do it at 15psi? dont remember but seems about right.

so you replaced the o2 and nothing changed?? are you able to head to autozone/advancedauto/oreily/napa to use a logger?

 

[chehsgsx]

i have a data logger and it only has the code for the second o2 below thresh hold. ok so im going to replace the o2 and im gona try to find a good maf ( any one got one)also i will try to do a boost leak check today and see if thats all good

 

[nfernotalon]

Im sure thats your problem

 

[Artago]

Would a faulty rear O2 cause these problems though? I thought the rear O2 is just there to monitor the efficiency of the cat and plays no part on how the car runs. That's what I thought at least.

 

[Sinner]

umm 8mpg....I know this might sound weird but your not supposed to hold down all of the pedals at once, you just need to hit the gas to make it go forward and THEN the brakes to slow you down.

seriously is that thing smoking a lot to get that kind of mileage, maybe smell lots of unburned gas out of the exhaust.

 

[BoostedPhoenix]

Rear O2 is just for catalyst efficiency, but even if the front one was bad you should do better than that on economy. My 1g had a fouled O2 and i still got 12-15 mpg depending how i was driving (city or highway). That MAF should not change the way the car runs just by hitting it, fix your boost leak and get another MAF in there. The MAF is the biggest factor in calculating fuel delivery so that sounds like your best place to start.

 

[chehsgsx]

ok update time i have many leaks
im leaking at the biss and the tps also leaking thought on of my intake pipes. ok now for the weird ones im leaking from the adjustment screw on my bov valve? and the pcv valve will only hold the boost for a little bit then it relieves the pressure ( it's a brand new pcv). any clues to why it would do this? is that normal. ok so my question now is if i can use o rings for the tps seals? iv heard of doing this instead of buying the expensive tps seals. just wondering if its ok to do and if it is what size o rings should i buy?... also what kind of seal does the biss have. o ring? if so, size??? thanks for the help