1998 740il MPG QUESTION

[multiplug]

60000 miles in great condition,always serviced on time and seems to be running great but I am getting terrible mpg,about 12 mpg!

Driving normally,no speeding.

Any thoughts

Cheers

 

[mytan85_325e]

Wow...that's bad...I average 19 mpg on a 1997 740il with 154000 miles. I drive on the freeway 100 miles a day and average around 75mph.

 

[multiplug]

what the hell can it be??

 

[mytan85_325e]

I had my oxygen sensor, plugs and air filter replaced as per the owners manual and I have always averaged decent MPG. My 01 530i with 60k gets 23mpg and my 1991 325i Cabrio with 207k get 28mpg.

 

[multiplug]

what mpg do you get on your 740il?

 

[RossW]

Plugged Cats?

 

[multiplug]

plugged cats,could you elaborate on that.
Cheers

 

[andreyiv]

When the catalytic converters get plugged up the engine has to work harder then before. Sometimes its so bad that the car won't go above 40mph.

At least thats what I thought RossW meant.

 

[multiplug]

I have done quite a bit of research on this,it seems on average the mpg for this vehicle is 15mpg.http://www.bmwboard.com/forum/newreply.php?do=newreply&noquote=1&p=172703#

 

[E38]

I have a 1998 735iL with 125,000 miles.Freeway driving returns 23.3 mpg and city driving gives 19.5 mpg.I am in Australia

 

[cai]

I think this car is too young to have plugged catalytic converters. My guess is on the oxygen sensors; I have heard that they can cause this kind of problem because the fuel mixture gets screwed-up. I am not sure whether a diagnostic tool will be able to tell you anything, but if you have one, hook it to the car and see if it returns a code. Although, I recall hearing, that an oxygen sensor failure will trigger a check engine light and you do not mention the display of any messages or lights. Also, as someone else said before, check the condition of your air filter.

 

[datant]

my 95 with just inder 300K gets about 12-20 depending on how I run her. I normally rag the sh!t out of it so my MPG sucks and I probably need to change the CC like some of the other posts have mentioned. Wonder how many hunderds that will be or will a cheapy do?

 

[E38]

Please explain",rag the shit out of it so my MPG sucks".Whereabouts do you put the rag in the exhaust system?

 

[datant]

it was just a way of saying I have a heavy foot, no rag needed in the exhaust system it is probably clogged enough already.

 

[theref]

My 98 750IL car with just 42.5Kmi needed a right cat replacement. The fuel mileage went into the mid-20s after replacement. Previously, it was in the low teens. It also needed a new T-stat but that would have minor impact on mileage.

 

[datant]

how much was the labor on your cat conveter, did you get it done at a local shop or a BMW dealership?

 

[theref]

It was done at the dealer during the course of other service. It was not expected but the tech found the rattling sound that means the inside had broken up. Labor was $210 and the cat was $1115. Now I wonder about the driver side one.

 

[datant]

ouch that one hurt, I'm still curious if I can buy an aftermarket Caddy Convert on ebay and will it fit and not trip my check engine light and other problems. I'm sure it's past time to do this I'm just not ready to spend that much on this right now.

 

[theref]

Try the Flowmaster or Universal as mentioned on other BMW boards. About $200 each.

 

[multiplug]

how many miles do you usually get before having to replace a cat converter?

I am only at 62000.