e30 cat

[jdbmw325is]

i have a 1989 325is and it doesn't have a cat. will this make cause me to get poor gas mileage? plus what should a 1989 325is get on average in the city?

[Naplm00]

prob anywhere from 18-25 depending on how you drive auto/stick

[dashboardmonkey]

about 15 mpg

[nando]

about 15 mpg

huh?

[dashboardmonkey]

huh?

well that's what i get anyway

i drive it pretty hard tho

[Mike325]

You will not get worse gas mileage without it. Because the car is obd1, the o2 sensor is before the cat only and will not care if there is a cat or not. The exhaust will actually have slightly less restriction because there is no cat, so mileage should stay close to stock or tiny bit better.

[nando]

well that's what i get anyway

i drive it pretty hard tho

I have a thirsty 2.8 liter and on it's worst day I don't get less than 18. lol

well, except on the track when it's like 8-12..

[ck_taft325is]

15mpg is pretty low there. My '88 iS cammed, chipped and running 19lb injectors only got down to 17-22mpg and I flogged it routinely.

[jdbmw325is]

i put 8 gallons in and got about 150 mile that is about 17 or 18 miles per gallon. i was confused because my OBC was reading 10.5 or so. as i looked further into it i realized that the read out was 10.5 L:100. i found out that that is letters per 100 kilometers.

[allwheeldrive]

In the winter i'm down around 22-23 mpg. Summer i'm up around 25mpg.

[pporcaro]

I'm down around 15 mpg in my eta. But that's because im missing things like the o2 sensor and what not.

[bimma360]

I have a thirsty 2.8 liter and on it's worst day I don't get less than 18. lol

well, except on the track when it's like 8-12..

Yeah 18 or 19 is about what i get when i'm foot heavy... and the car runs rich on boost. 15mpg is just nuts.

Dave

[moatilliatta]

no cat < Fuel mileage

[stumble_t]

Please correct me if im wrong but...
How does a cat effect gas mileage on a pre OBD car???
An OXYGEN SENSOR will effect fuel economy not a cat. The cat does NOTHING to effect fuel trim.
If the car had a post cat O2 sensor it would effect fuel trim but our cars only have one and its BEFORE the cat.

[nando]

a reduction in exhaust backpressure could make it run a little leaner.. but if you just removed the cat and left everything else stock, you probably couldn't measure the difference.