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Topic
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The car in question is a 1999 Honda Accord LX+ABS Automatic. F23A1 engine. 250000km on the odometer.
I’ve owned the car since July 2007 with no issues. Originally I would always get anywhere from 9-10L/100km no questions asked. In 2009 during a long 400km trip the car threw a P0171 System Too Lean (Bank 1) code. When returning back home I took the car in to my (previous) mechanic and explained to him what had happened. When arriving to pick the car up I was told he diagnosed the rear o2 sensor (on the cat.converter) being bad/not working and he mentioned the front sensor was acting lazy. He had replaced both sensors with Bosch sensors. A couple of weeks after this my catalytic converter developed a rattle and its substrate was broken inside. I replaced the converter with an aftermarket one and after reading about bosch sensors and Honda not mixing together I replaced both front/back o2 sensors with denso first time fit sensors.
Not long after such fuel consumption kept getting worse and worse going to 11-11.5L/100km and now in 2012 is usually 12-13L/100km. After digging deeper I found out that the p0171 code could’ve been caused by a fault FPR as there is current a valid TSB out for my vehicle model. The fuel pressure regulator was changed with an aftermarket brand and the vacuum lines were rerouted as stated in the TSB. Following this I began getting a p0420 code for the cat.converter performing under threshold. After researching the issue I placed a spark plug non fouler on the o2 in the converter to slightly move it out of exhaust stream as it seems the issue is rather common with aftermarket converters. Since then I have ended up buying and owning almost a little mechanic shop of my own with respect to tools and gone through and checked and replaced the following to no success…
-Plug Wires with NGK HE73 wires
-Plugs with NGK Iridiums
-Cap/Rotor (Aftermarket from rockauto)
-PCV Valve (OEM)
-Both O2 sensors replaced with OEM Honda sensors
-K&N Air Filter(Has been cleaned)
-Tire pressure is kept at 32.5-33psi all around.
-Used fuel injector cleaner such as seafoam, bg44k, STP
-Changed the cat.converter again thinking the 1st aftermarket one was troublesome
-Throttle Body has been cleaned.
-Grounds have been checked and fortified with 0/1GA wire for the battery-chassis & engine-chassis & battery-transmission
-Battery is good and recently replaced
-Car does not burn oil (Oil changed every 3000-4000km)
-No vacuum leaks have been found
-Transmission fluid changed with honda oem fluid once a year
-All wheel bearings show no problems
-Rear drum brakes are not dragging(drums rotate freely about 1.5 turns when spun by hand)
-Compression test shows 210psi all across 4 cylinders when performed on a semi-warm engine(coolant was at about 60C and car had been sitting for about an hour after operating temp)-ECT is at about 88-95C when car is warm.
-Long Term Fuel Trim is at about -7%
-Short Term Fuel Trim at idle is usually discounting anywhere from -7% to -10%
-Ignition timing at idle is usually a variance between 11/12 degrees
-The car is warmed up in the morning no more then 2-3minutes until the coolant needle shows movement
-The car is driven where gear changing happens at no higher then 3000-3200rpm
-At idle(700rpm) the front o2 oscilliates from 0.3 to 0.8v rather slow and at times hangs either up or down. If increasing idle even to 800rpm the o2 then oscillates rather quickly from 0.3-0.8v. The rear o2 shows movement but at a much much smaller range.
-The car starts on the first try whether it be morning/afternoon/night with no hesitation at all.
-There is very very minimal valve tick in the morning on a cold start which disappears once the car is warmed up. Minimal to the point that you need the hood opened and your ear close by to notice it.The car has a SRI(short ram intake), magnaflow catback exhaust…otherwise the engine is stock as a bone.
Any ideas on what I can look for…
This has been an on-going issue for 3 years now and it’s really eating away at me that i cant figure out why.PS. Repair/maintenance history if it is relevant
-Oil changed every 3000-4000kms.
-Tranny fluid changed once a year.
-Coolant/brake/power steering fluid changed every 2 years
-Engine Air filter changed/cleaned every 6months.2007-OEM TimingBelt/Waterpump
2007-NGK Plug Wires(HE73) and NGK Iridium Plugs
2007-PCV Valve
2007-Rear ParkingBrake Cables
2007-Driver tie-rod arm2008-Thermoquiet Front Pads/Rotors
2008-2x Cabin Air Filters2009-1x Front/Rear Denso O2 Sensor
2009-Dizzy Cap & Rotor & Gasket
2009-Wagner Thermoquiet Drums/Shoes2010-Fuel Pressure Regulator
2010-P/S and Alternator Belts
2010-1x Front/Rear OEM O2 Sensor
2010-Front Endlinks
2010-Catalytic Converter
2010-NGK G-Power Sparkplugs
2010-PCV Valve2011-OEM UCA+Ball Joint x2
2011-OEM TieRods x2
2011-1 OEM Stud on Front Driver Corner
2011-Distributor Cap/Rotor/Gasket
2011-Wagner Thermoquiet Pads/Rotors (Front) w. full brake bleeding
2011-OEM Timing Belt, WaterPump, Cam Seal, Crank Seal, Cam Retainer, Tensioner Pulleys & Springs
2011-OEM Clutch 2nd and 3rd switch
2011-Coolant Hose A2012-Upper Rad Hose
2012-Extend exhaust to clear rearlip
2012-Heater to engine inlet hose
2012-OEM Evap canister and shut-off valve
2012-OEM Oil Pressure Switch
2012-TYC KoyoRad Radiator
2012-Distributor inner oring
2012-Driver Side Axle Seal
2012-NGK G Power Spark Plugs
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Replies
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negative numbers below 0% means the computer is subtracting
fuel.This is a lean command for a rich condition.if your o2
sensor voltage is fixed lean.the computer will severely richen up the
the mixture.this will result in poor gas mileage black smoke and poor
low rpm performance.Even though 250000 really isn’t alot for a Honda (especially when maintained properly.) You may want to pull off the oil pan and check as many of the bearings as you can. I would also check the fuel pressure. Even though you used injector cleaner the one or more injectors may not be working properly.
[quote=”college man” post=37780]negative numbers below 0% means the computer is subtracting
fuel.This is a lean command for a rich condition.if your o2
sensor voltage is fixed lean.the computer will severely richen up the
the mixture.this will result in poor gas mileage black smoke and poor
low rpm performance.[/quote]That was my understanding of fuel trim but a shop i spoke to today claimed Hondas are different then other manufacturers and fuel trim on them works opposite…which i found rather weird.
Nonetheless, i’m only experiencing bad gas mileage as otherwise the car feels like brand new performance wise.
[quote=”thisisbuod” post=37786]Even though 250000 really isn’t alot for a Honda (especially when maintained properly.) You may want to pull off the oil pan and check as many of the bearings as you can. I would also check the fuel pressure. Even though you used injector cleaner the one or more injectors may not be working properly.[/quote]
I shall try sourcing a fuel injection tester kit locally and update; wouldn’t a faulty injector show some kind of symptom though? other than the obvious giving me poor gas mileage.
I agree with College Man’s post.
And as long as your o2 sensors are not wide band, they should operate as stated with 0.1 being lean and 0.9 being rich.
Have your checked your MAF for dirt on the heated element? I have seen first hand of people over oiling those K&N filters causing similar issues as well as CEL’s.
Did you have any issues with gas mileage before you installed the aftermarket intake?
I would look at scan tool PID data for o2 voltage and see what readings you have. If there pegged rich, i would create a vacuum leak to see if the voltage changes.
I would also look at post cat. o2 voltage and see if you are having issues with your after market cat.
If you suspect a leaking fuel injector, you could do a injector leak down test if you have the equipment.
The sensors on a 99 accord are not wideband.
As mentioned in the first post…the front o2 oscillates between 0.2-0.8v with the rear o2 oscillating at a much lower range and maintaining more of a solid line. Both o2s have been changed with brand new denso ones and then changed to oem honda ones in the past 2 years. The only weirdness (if i may call it) is that at idle the front o2 will oscillate but at times will hang either up or down for a prolonged period of time. *this only happens at idle and never while driving*
The vehicle does not have a MAF sensor, only has a MAP sensor.
As mentioned the issue has been existing for the past ~3 years with me trying to figure it out. The issue was existent when the car had a stock intake, stock catback exhaust. For the sole reason of overoiling issue i’m actually using a dryflow filter and not an oiled filter.
I’ll post a video snapshot of my current sensor readings at idle/1000/2000/3000rpm and see if i can get ScanXLPro to create a datamapp of STFT in a tad if it may shine any light on the issue.
[quote=”dreamer2355″ post=37805]I agree with College Man’s post.
And as long as your o2 sensors are not wide band, they should operate as stated with 0.1 being lean and 0.9 being rich.
Have your checked your MAF for dirt on the heated element? I have seen first hand of people over oiling those K&N filters causing similar issues as well as CEL’s.
Did you have any issues with gas mileage before you installed the aftermarket intake?
I would look at scan tool PID data for o2 voltage and see what readings you have. If there pegged rich, i would create a vacuum leak to see if the voltage changes.
I would also look at post cat. o2 voltage and see if you are having issues with your after market cat.
If you suspect a leaking fuel injector, you could do a injector leak down test if you have the equipment.
Are you using a scope or graphing meter for your o2 sensor testing?
Seeing as you have a MAP, it wouldn’t hurt to test it with a DVOM and vacuum pump.
Keep us posted 🙂
[quote=”dreamer2355″ post=37828]Are you using a scope or graphing meter for your o2 sensor testing?
Seeing as you have a MAP, it wouldn’t hurt to test it with a DVOM and vacuum pump.
Keep us posted :)[/quote]
O2 graphs are being seen using a OBD2 LiveData scan tool(the tool is a maxidiag jp701) or via a bluetooth obd2 device and torque app on an android tablet/scanxl pro(laptop).
MAP with the car turned off shows 104kpa, which is correct for my location. I’m just uploading a video showing all the sensors I can pull at idle/1000rpm/2000rpm etc
The video shows sensor parameters at idle,1000rpm,2000rpm etc. Please look at bottom right corner for rpm distinction.
http://www.youtube.com/watch?v=NUD_F_6DxYkThe video shows a line graph of STFT at idle from 00:00 to 00:51.
From 00:51 and onwards the rpm have been increased to 1000rpm
http://www.youtube.com/watch?v=r9msNdJk8JoThe video shows a line graph of O2 Sensor B1S1 at idle from 0:00 to 2:15
From 2:15 onwards rpm were increased to around ~1000rpm
http://www.youtube.com/watch?v=NLDwy2oqv00&off the wall thought. have you tested the resistance in the wiring to your o2 sensors? or did the spray down test to see if you have leaking gaskets that arent leaking enough to trip a code? I think i asked that before. otherwise im out of ideas.
this is why i like older cars. poor gas mileage, rip off the emissions, replace the plugs wires cap and rotor, adjust the carb. turn the cat converter into the salvage yard to pay for it all. Though mine is a bit beyond a simple tune up currently.
I suppose you probably would notice your hp being affected if the injectors were bad, unless it is something that has happened gradually (contrary to your statement). Really, anything that would suddenly throw off your mileage would in turn affect the efficiency of your engine. In other words if your mileage goes down your power goes down. The fact that you haven’t noticed power decrease but have noticed efficiency decrease is odd. Maybe double check the integrity of the fuel delivery system; fuel tank leaks, filter, fuel pressure lines and return lines. Have you used any new fuel additives? If you get gas at a “cheapo” station, they don’t always get their gas from the same vendor so their gas quality can fluctuate unlike (for example) shell gas that always comes from the same place.
Lord Ihcalam, I have not tested resistance of o2 wiring but have tried swapping with another new denso first time fit sensor with no difference.
Leakdown test hasnt been done yet as I need to source a tool, and an air compressor to use with it. That being said on more then one testing throughout the 3 past years compression on each cylinder has been at the ~210 mark at all times.
Swapping ECUs i’ve considered in the past its just usually ppl are weary of something happening to theirs in the process
thisisbuod, The weird thing is that all of this mainly started after that p0171 code on a long trip and after the OEM converter beggining to rattle after the o2 sensors/fpr/vacuum lines were changed. It didn’t go from good to crap in a week, it did happen somewhat gradually that in 3 years i’ve gone from 9.5L/100km(24.75MPG) to 13L/100km(18.09MPG) now.
On more then one inspection by both me and mechanics nothing seems out of place or leaking with respect to the gas tank, fuel delivery, fuel return, fuel vapor lines, fuel rail, fuel injector orings. There is no gas smell emitting from the engine compartment when the fuel pump primes even after priming it about 10 times. No smell emitts when the car is running either.
I usually get gas at Shell, and if not Shell or im in dire need and no shell is close enough then will at times go to Petro-Canada. That being said I have tried getting gas from the following stations Shell, Esso, PetroCanada, Husky, CanadianTire, Costco…thinking it might’ve been the gas but no difference occoured with a tank full of gas from either providers.
another thought. did your area require gas companies to reformulate their fuels? my state went to E10 required all year and my mileage dropped noticeably.
[quote=”Lord Ihcalam” post=37895]another thought. did your area require gas companies to reformulate their fuels? my state went to E10 required all year and my mileage dropped noticeably.[/quote]
Well all fuel pumps in here(Toronto, ON CANADA) say “may contain up to 10% ethanol by volume”.
According to Shell, they claim there is no ethanol in the GOLD (Premium) blend and there MAY be 5% in the Silver blend and there MAY be up to 10% in the Bronze blend…however the end result is all left to government agencies.
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