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Still getting HORRIBLE fuel mileage please help me



you need to say wideband, not a/f. thats dumb light show that means nothing.

and its not a wideband unless it comes with a o2 sensor for it. and even then, its not gonna tell you where your gas is going.
 
Yeah, what exactly do you plan on doing with it? Where you putting the o2 sensor? What readings do you expect to see?
 
it was 200$ want to make sure i dont run lean. and can use it to tune with later. want to know what the car is actually doing
 
Got wideband in. Took car for drive. Whike cruising it stays 14.5 to 15.1. Usually 14.7 like it should be. At wot it goes to 10.6 isnt that way to rich?
 


Depend on who you ask and what the motor thinks is okay.

Some motors will not accept going leaner than 11.5 or even 11 for that matter.

I personally ran anywhere from 10.7 to 11 in my car, it liked it there and I knew I never had to worry about it being lean. I didnt care that I could try and lean it out by .5 AFR to gain maybe 5-10hp at the most in some ranges of the RPM, I'd rather be safe than sorry.
 
99GPGTP said:
Got wideband in. Took car for drive. Whike cruising it stays 14.5 to 15.1. Usually 14.7 like it should be. At wot it goes to 10.6 isnt that way to rich?
Click to expand...


mine reads the same thing. exactly pretty much. only ive only seen it dip into the 10's once or twice, most of the time its a flat 11 or so wot.
 
Im out of ideas on what to do. Only thing I haven't done is put a stock fuel pump back in car and replace coils and wires. Car runs great. I have noticed in starting to get knock. I think it's coming from supercharger bearings. I have a tan m90 from a 96 Park Avenue. Can I use the snout and impellers in my m90?
 


99GPGTP said:
Im out of ideas on what to do. Only thing I haven't done is put a stock fuel pump back in car and replace coils and wires. Car runs great. I have noticed in starting to get knock. I think it's coming from supercharger bearings. I have a tan m90 from a 96 Park Avenue. Can I use the snout and impellers in my m90?
Click to expand...
Iirc the blower on the 96 Park Ave is a M60 or whatever they used on the Series 1 l67, I don't think it will work.
-Edit I was wrong, it should be an m90 and they should fit.
Sent from A Galaxy Far Far Away
 
Its a series 2 m90 but tan not grey. Its a gen2 m90 if im correct. It has the long snout not the short snout that was used on the m60's. And as far as the rattle. Its a new coupler. I put it on when i put the ported housing on my car. Had belt off yesterday and checked just to see and its not bad.
 
It's the exact same M90 as yours with two exceptions
1. It has thermal paint on it to keep it cooler.
2. It has a vacuum tree by the TB end. Small caps would make it identical to yours.
 
BillBoost37 said:
It's the exact same M90 as yours with two exceptions
1. It has thermal paint on it to keep it cooler.
2. It has a vacuum tree by the TB end. Small caps would make it identical to yours.
Click to expand...

thanks for the info. im gonna dig farther in to it and see its the supercharger bearings its self. and see if thats causing my problem by creating knock and killing mileage. dont see where it would sense i only see knock under boost with heavy load. also gonna try a fuel pump
 


SCOTTYDOGGS, could my rear o2 cause my poor fuel mileage. i havent changed it yet. reminder i dont have a cat anymore.
 
in a 99 your ok with the rear o2. no endless cat test in that year. unless its setting a code for it. no code carry on.

i fully deleted mine, like its not there any more, and my mpg are the same. like i said, all local stop and go im 14 ish and lower if im hard on take off.

even the egr delete, im not seeing any worse mpg. maybe cause its just that bad already? lol

my local driving is crazy tho. if im lucky i get to 35 mph and hit green lights. thing is theres a light or a stop sign every 1/4 mile or less. and you dont always make em.

then all the traffic at rush hour here just idling in traffic i'll watch the avg drop from 16 to 12 in no time. local traffic, aka grid lock pretty much, light to light. you go nowhere fast.
 
thank. i live 8 miles from work and its mostly 45 from here to work and in mornings i hardly catch any lights, i can even set cruise most the way. but on hwy only running 60-70 i still cant get but 19.5-20mpg {not going by gauge on driver info} i actually calculate the mileage.
 
ive done the math way too. every time it comes back to 12 mpg. and thats just sad.

you have tune? zzp canned tunes kill mpg for a lot of cars.
 
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