16 MPG? Suggestions?

[EatsHondas]

So u guys think its unlikely not the FPR?

OEM FPR runs $110 on PelicanParts, up to you whether you wanna replace it or not. If the engine runs smoothly and the plugs aren't black, I'd skip it.

[Kozworth]

coolant temp sensor, I read a kid said he replaced his and it gained performance. I guess if you have a cts that is reading incorrectly, as in reading lower, the car will add more fuel because it thinks its in open loop. The pcm will add more fuel to help warm up the engine quicker.

I would also recommend checking compression. If you have excessive wear on the valves/seats, rings, etc, you will lose compression and power. Might not seem too obvious, but it can rob you of performance. I had an e36 with low compression on cyl 3, but all the others were good. The car wasnt the best mpg wise, but it still felt like it pulled decent (maybe just a hair sluggish). Might be hard to notice a weaker engine with an auto trans.

[BROKINBIMMER]

Did you mention if you replaced/rebuilt/had cleaned your injectors?

I replaced the o rings and pintles but not the filters. Also, I did soak the injectors in laquer thinner and used compressed air to clean them the following morning. I know this is not as good as sending them out for a rebuild, what do you think?

[NoSnowJustIce]

I'm averaging 22mpg with my m20b25 with mostly city driving, and oldddd o2 sensor, afm, injectors and spark plugs, but chipped dme running 92 octane with a 3.73lsd 5 speed manual, heavy foot. I live around lots of hills too
I hope to be getting 25 with a good tune up, so I hope you can fix your issue too.

[BROKINBIMMER]

New ignition wires helped out a lot

[dsphil]

Unless I can do something about the stop signs every 900feet, my b25 will keep getting 18mpg unless I drive my b27 which can get 23mpg.

[nickmcc92]

Now I'm at 14.7 mpg. Wow

[Tstarkey24]

My 92 325i is 5 speed and i get about the same, now my 87 325es got about 30+ mpg and that had a intake exhaust and chip in it i had to run 92oct but it got great gas mileage so 16 to 20 mpg might just be what they get.

[BROKINBIMMER]

Have you raised your mpg? I'm also getting around 14-16 mpg city driving auto transmission.

No. I've replaced just about everything that could effect it's efficiency except for the plug wires. I'm not even sure they will make a difference...

[nickmcc92]

Have you raised your mpg? I'm also getting around 14-16 mpg city driving auto transmission.

[BROKINBIMMER]

You did not say whether you replaced the injectors or not. If you still have bad mpg then check to make sure that the car does not have 19lb injectors running with stock chip. Have you removed the spark plugs to see if they are fouled with fuel? Looking at the spark plugs can tell you a lot about how your engine is running.

Factory injectors

[dnguyen1963]

You did not say whether you replaced the injectors or not. If you still have bad mpg then check to make sure that the car does not have 19lb injectors running with stock chip. Have you removed the spark plugs to see if they are fouled with fuel? Looking at the spark plugs can tell you a lot about how your engine is running.

[BROKINBIMMER]

Gas mileage still blows

[BROKINBIMMER]

No, mine is a 3.73. Here is a bit of info about diff that might be useful...


U.S. E30s:

318i/is

1984-1985 - 3.64 (84 open for Auto)
1991 - 4.10 (Manual)



318ic

1991-1992 - 4.27 (Manual w/ LSD option)


325

1988 - 2.93


325e/es

1984 - 1985 - 2.79 w/ LSD option
1986 - 1987 - 2.93 (es = LSD)


325i/is/ic

1987 - 1988 - 3.73 (is = LSD)
1988 - 3.73 (Automatic; iS = LSD)
1989 - 1993 - 3.73 (Manual; is = LSD)
1989 - 1992 - 4.10 (Automatic; is = LSD)


325iX

1988 - 3.91
1989 - 1991 - 3.91 (Manual)
1989 - 1991 - 4.10 (Automatic)



M3

1988 - 1991 - 4.10
1988 - 1991 - 4.45 (rare)


325i Touring

3.91 (LSD = option)

Well the 3.73 rear diff makes a pretty considerable difference in RPm's at cruising speeds. Hopefully I'll be able to pick one up during/after the swap.

[dnguyen1963]

So you swapped the diff with a 4.10? I will be doing a 5speed conversion soon and was worried that my gas mileage will get even worse...

No, mine is a 3.73. Here is a bit of info about diff that might be useful...


U.S. E30s:

318i/is

1984-1985 - 3.64 (84 open for Auto)
1991 - 4.10 (Manual)



318ic

1991-1992 - 4.27 (Manual w/ LSD option)


325

1988 - 2.93


325e/es

1984 - 1985 - 2.79 w/ LSD option
1986 - 1987 - 2.93 (es = LSD)


325i/is/ic

1987 - 1988 - 3.73 (is = LSD)
1988 - 3.73 (Automatic; iS = LSD)
1989 - 1993 - 3.73 (Manual; is = LSD)
1989 - 1992 - 4.10 (Automatic; is = LSD)


325iX

1988 - 3.91
1989 - 1991 - 3.91 (Manual)
1989 - 1991 - 4.10 (Automatic)



M3

1988 - 1991 - 4.10
1988 - 1991 - 4.45 (rare)


325i Touring

3.91 (LSD = option)