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DISCUSSION => General Topics => Topic started by: doucy2 on November 25, 2006, 11:27:42 AM

Title: Horrible gas milage on my 4dr? Help
Post by: doucy2 on November 25, 2006, 11:27:42 AM
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
Title: Mpg
Post by: FL318is on November 25, 2006, 03:47:36 PM
There was a thread awhile back on MPG.  From what I remember the M42 is not the fuel mizer you would expect with a 4 banger.
Title: Horrible gas milage on my 4dr? Help
Post by: doucy2 on November 25, 2006, 06:24:52 PM
would an exahust leak do it, i think mine is leaking its llouder than it should be.
Title: ???????
Post by: FL318is on November 25, 2006, 10:55:42 PM
I guess its possible.  I am no good at mech. Keep bumping til the gear-heads reply.
Title: Horrible gas milage on my 4dr? Help
Post by: Meister on November 26, 2006, 01:53:06 AM
I have an exhaust leak also, and I am only getting about 250 miles on a tank.  I think that might be causing it cuz before i was getting about 300 on a tank..
Title: Horrible gas milage on my 4dr? Help
Post by: gimpy9195 on November 27, 2006, 01:13:44 AM
my exhaust is shot also. and am getting 300 to a tank. my thermostat is stuck open so my car never warms up. I got better gas mileage in the summer to I can assume that I should replace that to get my summer mileage of 400 to a tank.
Title: Horrible gas milage on my 4dr? Help
Post by: Alpine003 on November 27, 2006, 08:26:47 AM
Quote from: doucy2;14412
I'm only getting around 18mpg (thats with the E light on)


I would check out the cause of the E light since this might have something to do with your mileage.

Other than that, check the normal things:
Fuel filter
Spark plug/wires/coils
Clean Fuel Injectors
Coolant Temp Sensor
TB cable and settings
Title: Horrible gas milage on my 4dr? Help
Post by: asubimmer on November 27, 2006, 09:27:03 AM
yeah I suggest anyone who hasn't changed their fuel filters to do it, its cheap and easy.  Chances are yours is prob original...
Title: Horrible gas milage on my 4dr? Help
Post by: sheepdog on November 27, 2006, 01:30:42 PM
Quote from: Alpine003;14495
I would check out the cause of the E light since this might have something to do with your mileage.

Other than that, check the normal things:
Fuel filter
Spark plug/wires/coils
Clean Fuel Injectors
Coolant Temp Sensor
TB cable and settings

Good advice.
All of those can lead to drastic losses.
May want to look into and air filter as well.

Even good platinum plugs can cost you several MPG, when they are good. These motors like normal plugs. Platinum +4 can cost you 4mpg, ask how I know...

If your wires are bad, do the coil on plug conversion, it is cheaper and works better.

Injectors, get some Chevron Techron from Autozone. Get your tank down to 1/4, then add 3/4 of the bottle, drive 30 minutes, then fill the tank, and dump in the rest, this will clean out the injectors and carbon. Also, make sure you are revving up the engine some. For every 10 minutes of city driving, these cars want a minute on the highway above 3k (look in the manual).

Coolant sensor is easy, where is your temp gauge? Around half is good. 1/4 is bad.

Fuel Filter, change it if it is old.
Do it when the car has been off for a while and is cold. Be prepared for a small smelly mess.
Title: Horrible gas milage on my 4dr? Help
Post by: doucy2 on November 27, 2006, 03:57:09 PM
Quote from: sheepdog;14519
Good advice.
All of those can lead to drastic losses.
May want to look into and air filter as well.

Even good platinum plugs can cost you several MPG, when they are good. These motors like normal plugs. Platinum +4 can cost you 4mpg, ask how I know...

If your wires are bad, do the coil on plug conversion, it is cheaper and works better.

Injectors, get some Chevron Techron from Autozone. Get your tank down to 1/4, then add 3/4 of the bottle, drive 30 minutes, then fill the tank, and dump in the rest, this will clean out the injectors and carbon. Also, make sure you are revving up the engine some. For every 10 minutes of city driving, these cars want a minute on the highway above 3k (look in the manual).

Coolant sensor is easy, where is your temp gauge? Around half is good. 1/4 is bad.

Fuel Filter, change it if it is old.
Do it when the car has been off for a while and is cold. Be prepared for a small smelly mess.


Coils and plugs are brand new 1000 miles ago
I'll try that with my injectors
and for my temp gauge when it is warn it stays around 1/4?? what do i need to do to fit it?

I'll change the filter once I get some $$ in my pocket.
Title: Horrible gas milage on my 4dr? Help
Post by: silverblades181 on November 27, 2006, 09:34:45 PM
How old is the thermostat?
Title: Horrible gas milage on my 4dr? Help
Post by: doucy2 on November 28, 2006, 06:13:41 AM
Quote from: silverblades181;14544
How old is the thermostat?


ide assume original?