Thread: N/A Gas Mileage Help

NOTE: In response to Ben's post, I'll be asking one or two questions at a time. The original post has been saved in Notepad. Once my questions have been answered, I'll repost them all with answers. I was hoping to have this sort of thing all together for anyone looking for it, but I see I was too ambitious at once. This is my attempt at fixing that.

Okay, here's the shakedown. My MPGs have been steadily decreasing as of late, I'm down to 22 where I had gotten 27 before doing the same driving daily, and I'm looking for help as to why.

Today's question is:

I'm smelling raw fuel in the c*ckpit upon cold startup. I suspect it's my MAF, but is there anything else that would account for this?

Facts that might be useful:
'91 SE-R, JDM swap in a Cali-spec car
All stock, N/A, no tuning/stock ecu, no wideband.
Have only had car 6 months, and this is my first stick.
New plugs/wires/cap/rotor/fuel filter/tranny fluid/battery
Cleaned MAF and throttle body
Timing at 19*, running 93 octane

alignment is gonna be the biggest problem, noting is worse than tires fighting for the road

alignment my friend... I average about 39 mpg. When I was coming back from TX I hit a tire tread from a truck and it knocked my alignment way off. For those 3 days I was driving with my alignment messed up my car averaged about 24-5 mpg highway. HUGE HUGE drop.

Damn, I thought so. I had a heavy truck coming faster than it looked at me as I was pulling out of a gas station onto a very poorly maintained street. The result was wicked wheel hop as I dropped the clutch to gtfo. So after the alignment, what about the other stuff?

EDIT: Got the alignment done, I was duck-footed front and rear.

truly without tuning devices like a wideband or a tunable ecu, your going to reach a limitation in the ammount of mpg you will be able to see without modifiying the iginiton and fuel maps, if not just the fuel maps.

at best fixing all your problems you are havinig and getting it back to a good running form at best u will probably only see stock mpg.

where as if you get a tunable ecu with a wideband, you can adjust your cruise AFRS and see greater gas mileage when you are crusing, also can adjust at idle to run leaner.

it probably isnt in your range of things to do, but that is the best way to get the greatest gas mileage

Too many questions to answer all at once. Hit us with less please. Re-ask your most important question and then we'll answer that, then ask the next important one. I don't feel like explaining how to drive a car with a manual transmission, how to search for vacuum leaks, and how much pressure to fill up the tires in the same post.

That's exactly my problem. I haven't got much money to throw at this, but I know the gas mileage I'm getting isn't stock, and I'd be happy with stock. That's pretty much what I'm trying to do.

Okay, reformulated the first post. I think smelling raw fuel in the c*ckpit at cold startup is the most important issue to tackle. I appreciate your willingness to help.

Check for leaking injectors. I'm not sure of the best way to do this but you can probably find some ideas if you search the Forums.

Probably not related to the fuel smell, but definitely a must do if you are getting poor fuel economy, is to check your O2 sensor. Again, if you search the forums, you will find instructions on how to do this without any special equipment.

Let us know what you find.

Bill

Smelling fuel in cabin while cold would have me checking the coolant temp sensor (the one that sends a signal to the ECU, not the gauge cluster) for proper operation.

Then I'd check the fuel pump carrier to see if it was sealing in the fuel tank properly, as well as the lines around it. This is under your rear seats.

Next would be to check all fuel lines (feed, return and vapor lines) for leaks. Also the fuel filler pipe. Next would be leaking injector o-rings. Then check MAF for proper operation as well as O2 sensor. I'll see if I can find what the FSM suggests.

Edit: FSM doesn't say anything about smelling fuel in the diagnostics section of the fuel/emissions chapter.