Hello,

I've noticed a very drastic decline in mpg of my '94 Accord LX MT (210k mi). I can't quite pinpoint when it happened, but it's been this way for approximately the last 300mi, mostly city driving. Whereas previously I could get around 30mpg, I currently get less than 20mpg.


Here's a list of work I've done on the car:

- new air filter, fuel filter and oil filter
- new spark plugs & wires
- new oil temperature sensor
- cleaned EGR ports
- topped up all fluids
- tire pressure at 31psi
- no CEL or other warning lights


Known issues:

- main relay needs resoldering
- brakes need servicing (might be dragging; yet to be determined; possibly started at the same time as mpg decline)
- broken muffler


When the engine is warm, the idle is at about 600 - 700rpm. Currently, the weather starting to shift, but this problem started before any drastic changes in temperature occurred. I've read that a bad O2 sensor might be cause for a decrease in mpg. Seeing how it's never been replaced before, might that solve this issue?


Cheers!!

 

bad o2 could cause a decrease in mpg, but would usually prompt a CEL.

Dragging brakes would definitely cause a loss in mpg. If a brake was in fact dragging I would expect to find unusual amounts of heat in the wheel wells after driving and possibly pulling to one side while driving if its just one brake that is dragging.

 

Quick question about dragging brakes - would they cause a noticeable slowdown when coasting in neutral? I do that quite a bit on downhills, but I can't say I feel any "drag". However, the car's acceleration from stop does seem more sluggish than before.

Any thoughts?

 

perhaps not on a downhill, but probably if you are coasting on flat ground. all depends on the severity of it though.

 

Fuel leakage can cause low MPG. Check fuel lines for leakage (smell or drip). Check fuel injector/fuel rail connection for leakage (sniff and feel for cold spot).

good luck

 

I tried looking this up, but so far no luck. May I know where exactly I should be looking/smelling for leaks? Also, should this be done before or after driving around for a bit?

Thanks!!

 

Anywhere from front-rear on drivers side is where the fuel lines are located in a plastic tray.

Fuel injectors are on the intake manifold and connect to a common fuel rail. It's where the injector meets the rail to look for a leak past an aging oring.

good luck

 

The common area for the fuel line to rust out is at the left rear where the short line from the pump meets the main line to the fuel filter. It is right behind the break area near the trailing arm. I have found that if people smell gas in that area they think that it is from the fuel cap or from spilling a little when filling up. If you fill up the tank and park it overnight you should be able to find the leak if there is one.

The other thing that may be causing your issue that comes to mind is a weak fuel injector resistor.

 

Does/did the car reside in an area where the roads are salted? Of course you should check for leaks but keep in mind O2 sensors get lazy with age and miles. They really can be considered a maintenance item, needing replacing every 100K - 200K miles.

 

I'll check the fuel lines later when I get home. In the meantime, I thought of another symptom - the car has pretty bad acceleration uphill. It wasn't previously as bad, I'm sure. But now, I'm having to drop from 4th to 3rd just to keep at about 35-40mph.


Yes, I live in Michigan, so the winters here are brutal. Salt on the roads all the time. But then again, this car lived here for 3yrs before being stored in a garage last year. I just got the car this summer.