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View Full Version : Bad Gas Mileage - 23.8mpg avg


cocofunk
12-18-2017, 08:07 PM
I am getting BAAADDD mileage. 23.8mpg.

I have 2 318Ti's now, a 96 Ti and a 95Ti. My 96 gets 31mpg avg, VERY NICE! But it spills a quart of oil every 200 miles on the highway, horrible. I have not figured it out yet, but I am going to go towards the oil filter housing gasket and bushing on that one.

The 95 Ti is my concern right now. It runs well, no oil leak, but just gets Sh** mileage. Issues on the car now are whiny power steering pump. I have already replaced the water pump and the thermostat - NEW. What I could do is the O2 sensor, fuel filter, air filter, and spark plugs. If I do these, should I be back to 31mpg on this car? Or is the powersteering pump really sucking 6mpg on my car?

Dr Shuffles
12-18-2017, 11:06 PM
Bad fuel mileage could be caused by a lot of things. The power steering pump could be the problem, but there's no way to tell. Since you already know it's bad, just replace it. When trying to fix a vague problem like this, it's best to start with the parts that you know are broken, and then do all the normal maintenance type stuff, like changing filters and checking the brakes.

If the O2 sensor went bad, you'd probably get an error code. The error codes are sometimes misleading, but if there's no error at all, I would assume that the sensor is OK.

The fuel filter, air filter and spark plugs should be changed regularly, so if you don't know how old they are, change them. But I wouldn't expect to get 6 MPG from it.

cocofunk
12-19-2017, 09:20 AM
Update. No changes to the PS Pump yet. Changed Spark plugs to NGK Coppers - iridiums were in there, changed the air filter to a better one - maybe newer (pulled it off of my other 318ti), and put in some Lucas Fuel injector cleaner. Jumped immediately from 23.8mgp avg to 29mpg avg! I am not sure if it was all the changes or one of those things - but the truth is it is better. Granted I have only run a quarter tank on it. I will run a couple of full tanks to confirm, but before that happens, I will have also done the fuel filter. I think I might be hitting the 30mpg+ mark soon if all goes well.

FunElan
12-19-2017, 06:04 PM
If the ps pump is whining try adding more fluid to see if it stops. I got a noticeable improvement in MPG when I replaced all of the vacuum hoses. There is a great write up on here about the vacuum "tree" underneath the intake. Very cheap and easy to do.

Seems like maybe having your injectors rebuilt wouldn't be a bad idea. Glad to see that there was at least a jump with those quick changes.

bazar01
12-20-2017, 03:12 PM
Power steering pump can whine if it is sucking air or fluid is foaming.
You may need to pull the reservoir clean it or backflush it. There must be a screen but I am not sure.

paul somlo
12-20-2017, 08:35 PM
Power steering pump can whine if it is sucking air or fluid is foaming.
You may need to pull the reservoir clean it or backflush it. There must be a screen but I am not sure.
The reservoir has an integral filter, not sure that anything can be done to clean it, other than replacing it. As Bazar said, look in the reservoir while the car is idling, see if there's foam. Under normal conditions, the fluid surface in the reservoir should appear "smooth". Foam generally indicates that you're sucking in air somewhere, a hose, a seal, the pump itself.

SSpeedracer
12-21-2017, 10:31 AM
New plugs probably did it. Fuel adative inj cleaner is bull****. Like funelan said ensure no intake or vac leaks and replace hoses as needed. I suffered mpg reduction by blocking off tree and using tubes at tree that inadvertently pinched. Buy a new tree assembly, don't cut corners like I did.