Horrible gas milage on my e30? Haelp

[doucy2]

my 91 318i with 120k

all city driving buzzing around town, I'm only getting around 18mpg (thats with the E light on) Why would it be getting such poor milage?

I have a Jim C knock off chip and I always put 93 in, so its getting expensive.
Any help

[AndrewBird]

Bad o2 sensor causing the engine to run rich?

[golde30]

i get 16mpg on my 325is. this is after major tune-up(plugs, cap/rotor, O2, Tstat, fuel filter, oil change, coolant flush, air filter), and passed CA smog with flying colors. im stumped.

[jhower08]

dont feel bad guys, i have an 86 325es, ebay chip on 93 octane always. im getting 15 mpg. normal driving including highway. ill be doing 40 in 4th gear at 2 grand and i get 15. its just rediculous. my obc, mpg needle, and gas gauge all seem like theyre working on the same page. would it be the coding plug in the cluster or obc thats doing this to us?

[doucy2]

wow, thats three us up that need some help, anyone??

[O 16581 72452 5]

Exhaust leak?

[jhower08]

Exhaust leak?

not to bash you or anything but there is no way that an exhaust leak would cause this bad of mpg.

[eibowow]

not to bash you or anything but there is no way that an exhaust leak would cause this bad of mpg.

i have an 88 is w/ 91 octane mark d chip and im getting around 19 mpg.

[cahomey]

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

[Tomslide50]

jhower08- An exhaust leak ahead of the O2 sensor(most likely the manifold to downpipe flanges) will pull fresh air in due to the velocity of the exhaust, showing the O2 sensor more air, causing it to think your engine is running lean. It will then adjust the fuel trim and make you run rich, but it will think you're spot on because of the exhaust leak. If you've got that exhaust leak "tick" coming from that area it's definitely worth replacing any bad gaskets. They need it anyway even if it's not your problem.

[Mr.SWISS]

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

[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.

[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: .

[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]

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...