Horrible gas milage on my e30? Haelp

[Tree18is]

i read some of the posts, did anyone mention clogged cat? but O2 sensor and Plugs sound really good to me to. weak spark, not being able to burn the fuel?
i dunno, atleast you got a lot of little suggestions, If it was mine i know what i would do.
oh and BTW, the poor MPG was after the Jim C copy cat chip?

[euroshark]

my dads 535i averages like 18mpg... how the hell are you getting 26-27?

I honestly don't know, maybe it just runs top notch? My dad's dirty euro 635CSi gets about 22mpg average... My 533i has a 3.0 bar fpr and the Bosch 4 pintle injectors, and I swear to god, I got 27mpg driving 180 miles into the mountains from Denver with 4 people and 3 good sized bags in the trunk, sometimes in 4th gear flat out to maintain 70mph up those hills!! 11,000 feet of elevation certainly takes a toll on NA powerplants though... I want a turbo. In any case, I regularly get 27mpg if not better.

[silversleeper]

My 3.2 M30 gets 26-27mpg overall...

my dads 535i averages like 18mpg... how the hell are you getting 26-27?



both my 89 325i's average 20 cty / 24 hwy

[SchnellerVert]

O2 sensor, coolant sensor, leaky injectors especially cold start injectors can all cause terrible mileage. Strange that so many people have consumption problems...

He's not the only one. Winter seems to excerbate problems.

[325iCabrio]

If you go with seafoam pull your O2 sensor. I've heard so many stories about it killing them. Although it didn't mine, it's better to be safe than sorry. Of course if you determine that it's bad already, it doesn't matter.

I was wondering about that. I just put in a new O2 sensor and was thinking about doing Seafoam when it warms up. Do you have to plug the O2 hole when you're doing Seafoam?

[lordofthewaters]

TIME FOR SEAFOAM!!!

If you go with seafoam pull your O2 sensor. I've heard so many stories about it killing them. Although it didn't mine, it's better to be safe than sorry. Of course if you determine that it's bad already, it doesn't matter.

[doucy2]

well fixed my leaky muffler, and changed my fuel filter. checking the vac lines this weekend or when i have some spare time.

my check engine light filipped on for just the sec the other day so i put it in accessory mode and checked the code (ended up being for the o2 sensor) would that maybe be causing some probs?

[euroshark]

Nice, another beer avatar! I haven't tried much from Rogue, but what I have tried kicked ass!

I'd just go through and tighten up the 5 or so possible spots for vacuum leaks, and make sure none of the boots are cracked. Definitely check the temp sensor. My dads was malfunctioning due to cold weather and ~28 years of use, and his car went through a gallon of gas in 5 miles! It was not fun.

[KenC]

how would sprayin carb cleaner show any vacuum leaks?

revs will increase when the carb cleaner is sucked into the intake.

[vic_325]

get a can of carb cleaner and check for vacuume leaks.

how would sprayin carb cleaner show any vacuum leaks?

[golde30]

O2 sensor, coolant sensor, leaky injectors especially cold start injectors can all cause terrible mileage. Strange that so many people have consumption problems...

Are any of you getting smoke at idle, acceleration, deceleration?

My 3.2 M30 gets 26-27mpg overall...

no smoke. injectors are low mileage units offa s50. only thing i can think of would be the coolant sensor, as thats the only component that has been mentioned that i havent replaced...

[euroshark]

O2 sensor, coolant sensor, leaky injectors especially cold start injectors can all cause terrible mileage. Strange that so many people have consumption problems...

Are any of you getting smoke at idle, acceleration, deceleration?

My 3.2 M30 gets 26-27mpg overall...

[golde30]

Cary did you put your old ECU and chip back in?

I told you, get a new coolant sensor for the ECU.
get a can of carb cleaner and check for vacuume leaks.
maybe your AFM is jacked? (I have an extra u can have)

Your power doesn't seem any less.(It sounded good on the embarcadero)

TIME FOR SEAFOAM!!!11

OMGZ seaFOAMZZZzzz...

no i didnt put my old ecu with the JC chip back in...too lazy. oh and that fuckin glove box was such a pita to put back in correctly...

how bad was my squat when i was launching? i can hear the rear tires rub when i launch like that:roll: .

[Axxe]

I'm getting about 20 mpg city, 24 mpg highway. This is averaged by adding 15 litres at a time, and driving until the E light kicks on. Not the most accurate, but the OBC isn't exactly a pinacle of accuracy either.

[Mr.SWISS]

Mine sucks too(16-18 ), I think it's that damn chip I had to have!!!!!!!:curse: