I have a 96'accord ex 4-cylinder F22B1 Man.tran with 173,000 miles in it and this car is giving me hell! my problem is that my check engine light (code po301) keeps showing up everytime i bring my car back to Seattle area or at sea level. it seems odd because my car would work great once i reset my DTC up on higher elevation in Washington state and on my way home to Montana. it would be no problem there.but once i get back to sea level(seattle/Bremerton or any place here at sea level my CEL would come back on with the same code(#1 cylinder Misfire) this happens everytime i travel home and back. I replaced my spark plugs, plugwires, distro cap, rotor,fuel filter(cause my fuel economy is bad) ultrasonically cleaned all my injectors,replace O2 sensor, MAP sensor,cleaned my EGR passageway and replace EGR too, and the last thing i've replace because everyone i spoke to that i mentioned my problem thinks it might be my Barometric sensor is bad because of the change of altitude and the problem only occurs once i am at sea level is my ECM. cause the Baro sensor is said to be inside the ECM itself. BUT! that to did not work either. the same problem is still there.... and by the way it also does the same thing with my speedometer,i replace my VSS in march when it started to "work/not work" but at home (montana and upper elevation area) it works 95% of the time. I do not know what else i could do to this car,i like the car a lot but as i said i feel like i'm driving a V8 with its crappy fuel economy. the car runs fine but its the fuel mileage i'm getting from it. Please i need help with this one,i've taken my car to the dealership and other shops but they could not give me any answers but "i'm not sure " replies and $100+ each per diagnostic session,i'm so broke!!

 

been thinking about it for a little and i will continue thinking about your problem, and im sure some of our heavy hitters will take up my slack. but i have come up with these ideas.

compression check for burnt valves caused by overtightening.
check fuel pressure for faulty regulator
an actual bad injector (they dont just get dirty)
excessive combustion deposits

 

i am a bit puzzled on this one.. i have to do some digging around...........by the way what plugs did you install???

you need to do some testing yourself,,,, ,the eliminating process..


# 1 ..,when car misfires,, get a screwdriver and put the metal part on inject # 1, the other in your hear and listen for a click from the injector, do it to at least another injector and compare...

# 2 ,, remove the plug from cyl # 1 and see how it is firing, too rich ? lean ? swap it with cyl # 2 and see if misfire follows the plug or stays with cyl # 1

# 3 if it stays on # 1 .. try a different plug wire.........if still there

# 4 .., do a compression chk,,, leakage test..

try these and post results,,,,,,,,,,,,,,,,,in the mean time i will see if i can find any info on the subject

Also, make sure that the throttle body is clean , remove the intake tube, and clean all inside the throttle body with carb cleaner, clean all the passages.. Being at seal level the car is going to run leaner so we want to make sure we can give this baby as much fuel as we can..
remove the map sensor and clean the passage as well.

 

thanks for the reply, i've done the compression test already and it was in spec, i have the denso spark plugs in there and the injectors are clicking as they should. i'll clean the throttle body as you mentioned.i l also replaced the map sensor vacuum hose just in case it could be leaking but that did not help either. hope you dig some more about this,thanks!

 

Did you check the plug from cyl 1? The way that plug looks (whether it's too lean, or if it has carbon deposits, or even if it's normal) can shed a lot of light on the situation.

Good luck with your dilema, I'm sure the helpful advice you get here will fix the problem.

 

are you talking about if its firing too lean,too rich? how can i tell if it is? the spark plugs are fairly new(replace in feb 06). thanks.

 

This is pretty wierd problem. When you change elevation the outside pressure changes as well so i'm thinking that has something to do with it. The really wierd thing is that one of your cylinders is misfiring. If the pressure was the sole problem, then all the cylinders should be misfiring since they are subjected to the same pressure. I don't think its gonna be any of the sensors because first of all it looks liek you replaced all teh important sensors but also if the sensor was doing something goofy then all the cylinders would be affected, not just #1. I would try taking the battery cables off when you are at sea level and putting them back on. When did the problem start or has it always been that way?

 

Yeah, you can take the spark plug out and actually look at it to see if you are running rich, lean, or stoich...

Get your hands on a haynes manual, since they have a very handy pictures of spark plug conditions on the back page. Or see if any of these fit your plug's description:

Normal: Brown to Grayish tan color with some slight wear. Overall ceramic portion appears white or off white (not black or ashy)

Too Rich: Dry soot on plug. Black carbon may coat the electrode or ceramic.

Too lean: Electrode may be melted. Insulators cracking or chipped. A blistered white insulator and eroded electrode is also an indicator of a lean mix.

a mix that's too rich or too lean can cause misfiring, and the plug will surely tell you this. If the plug looks normal (compare it to another if cyl 1 is the only one misfiring), then I would swap it out with another cylinders plug like deserthonda said and see if the misfire goes to cyl 2 or happens again at cyl 1.

 

the problem started back in jan '06 when i drove this car to seattle from montana(i bought the car there) originally the codes were po301,302 and the random misfire code. i've replaced things i needed to correct this problem and i eliminated 2 of the 3 codes,but the po301 is still there. i know that it is weird since it only comes back on at sea level.i've cleared the codes by a scantool, removing back up radio fuse for ten seconds and removing the negative cable of my battery,but once i start driving again in within 5 miles or less my CEL would come back on.

 

i inspected my plugs and they were normal,i switched my #2 plug with #1 because both look the same but is still misfire on #1 cylinder when the CEL light came back on.