Hello, i have a 95 accord 4cyl non vtech, it has 260k miles on it and the last 5k it has slowly gotten worse gas mileage, went from 32mpg down to 27 and on my last tank it got worse then 22mpg. it is 100% highway driving, i only use it to commute home on the weekends. the check engine light came on last night on my way home, i figured that would definatly help me with the problem. when i turned it off and then on again the light was off. it has been really cold (highs in the negatives lowest it got was -21) so maybe it was a misfire that tripped the CEL. my first thought was the o2 sensor, but how can i be sure it is the o2 sensor with out the computer triping a code?

any help would be fantastic
Danny

 

okay, well i pulled the plugs and noticed that they all have black sute all over them, so i am definatly running rich, the question is why? do the fuel pressure regulators tend to go out on these cars? or is it most likely the o2 sensor or another sensor?

thanks
Danny

 

Man your problem is completely legit and your post intelligent and no response, I'm clueless but here is a bump.

 

Any other syntoms? I know I was running rich cos my EGR Valve was blocked with carbon deposits. It starts a knock and the computer will run rich to try and get rid of it. Is everything else ok? Tire pressure? CV Joints good? Suspension Problems? Last time you did a tune up? If your car has that many miles, get some new plugs(inexpensive). I know batterys dont work as good when it gets real cold like that. Again, a little more info. would be appreciated to help you out.

 

It would really help you to get good info if the code that tripped the CEL was known. As long as you haven't cleared the code by pulling the fuse it should be stored in the ECU.
http://members.troublecodes.ne...n.jpg

 

I'm thinking o2.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by walker111 &raquo;</TD></TR><TR><TD CLASS="quote">I'm thinking o2.</TD></TR></TABLE>
I'm waiting for the code LOL

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Next GenRacing &raquo;</TD></TR><TR><TD CLASS="quote">... do the fuel pressure regulators tend to go out on these cars?</TD></TR></TABLE>Pull the vacuum line off the FPR - there should be NO gasoline in that line. If there is, the FPR is ruptured.

Still, READ THE ERROR CODE. It'll be stored so you don't have to catch it while the CEL is on.

 

i haven't checked the codes yet, is there a link to a list of what number is what code?

also i replaced plugs, wires, rotor, and cap about a year and a half ago (40k miles) and i replaced the air filter not to long ago either.

i replaced the plugs before i drove home to my apartment (200 miles) and still poor gas mileage.

i also checked the o2 sensor with a voltmeter and it seem okay, reading .4-.6 volts idling and about .1 volt when i pulled a vacum line.

i will check the codes and post my findings

thanks
Danny

 

first off with THAT MANY MILES you might want to

Fuel Injector cleaning service
test for leaky injectors
O2 is most likely toast if you have never changed it

Now on to some other things that can cause your problem

1. auto or stick?
2. are you getting MASSIVE heat when you put the temp to the highest settings ( you should literally be roasted out of the car)
3. brakes dragging?

If your car is an auto and you are NOT getting heat as described above and your RPMS are approximately 500 higher than they SHOULD BE, change your t-stat (remove it flush system and install new one)


a failing 02 sensor may or may not throw a code but I noticed that when my t-stat was stuck open, my car lost a few mpg and TQ converter was not locking up in colder weather.

change your fuel filter of you have not done that yet (that is one big PITA)

all the advice I give is in addition to what others have said

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Next GenRacing &raquo;</TD></TR><TR><TD CLASS="quote">i haven't checked the codes yet, is there a link to a list of what number is what code?</TD></TR></TABLE>
This is from the Integra board, so a couple codes are missing. For example Integras don't have EGR.
https://honda-tech.com/zerothread?id=978933
Still, post up the number, so we can tell you what's specific to Accord instead of Integra.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Next GenRacing &raquo;</TD></TR><TR><TD CLASS="quote">i also checked the o2 sensor with a voltmeter and it seem okay, reading .4-.6 volts idling and about .1 volt when i pulled a vacum line.</TD></TR></TABLE>Explain your check with a voltmeter. Did you watch the frequency of it swinging up & down? An O2 sensor going bad gets sluggish, doesn't usually give DIFFERENT readings.

 

okay i finally checked my codes and i got code 43 fuel supply system. so what would trip that code? what ever it is it is doing it to all 4 cyl cause every plug looks rich.

i am at a loss to what the computer could sense that would trip that code.

plz help
Danny

 

also i checked the vacuum line on the fpr and was clean no gas..

it is an auto, and i haven't noticed if the overdrive has been kicking on or not, but it does warm up to operating temp pretty fast and stay there (even though the heater isn't that warm)

brakes are fine. i haven't replaced the fuel filter, but would that cause it to trip a code?

let me know what you think
Danny

 

A clogged filter itself wouldn't trip the computer, because there is no sensor for the filter. However, if the FPR is sensing that there is insufficient fule pressure then that would probably trip a code.

 

if you are getting that code its the O2 sensor (unless you get that code and have driveability issues in that case its the fuel system problem), this is according to the Honda Service manual. just replace the O2 sensor get a fuel injection cleaning and it should clear it up

 

If you are not getting roasting your rear off on high heat, replace your t-stat. My guage showed normal until the temp was below 20 and then it would not register at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by YeuEmMaiMai &raquo;</TD></TR><TR><TD CLASS="quote">If you are not getting roasting your rear off on high heat, replace your t-stat...</TD></TR></TABLE>Yeah, if it's not getting as hot as it should, that would also explain using more fuel.

Code 43 is a kind of catch-all code where the ECU can't say one particular sensor or device is bad, but still the operating condition & fuel use doesn't add up correctly. Like PartsHero says, your O2 sensor could be going bad, but still isn't bad enough for the ECU to point to it as the cause of the problem.

Dirty fuel filter might cause 43 also, because the ECU has no direct way to measure the fuel filter. If it causes the fuel pressure to be low, the ECU has to fire the injectors longer (more fuel) to keep the O2 sensor happy. ECU doesn't know exactly why, so it sets code 43.