i have a 97 runner with the 3.4. i recently replaced my fuel filter and cleaned and re-oiled my k&n. started with 0305(misfire cyl5), then got 0300(multiple misfire) and 0301(misfire cyl1). i changed the plugs, boots and wires. i used oem NGK dual electrode plugs. no improvement in conditions. next was new coils for cyl1 and cyl5. again no improvement. thinking at this point i had no electrical issues i deemed it a fuel delivery issue and added a gumout total fuel system cleaner to half a tank, hoping it was merely a dirty fuel rail or set of injectors. SOME improvement temporarily and then back to what it was. so continuing on i figured "great i got dirty gas and i should just get some octane booster and be done with it. again nothing. i cleaned the MAF sensor with CDC mafs cleaner, again no improvement. i'm almost at the end of my rope. somewhere in the middle of all of that i got a p0171 bank 1 too lean. i think because my intake tube was loose. i also got p0130 sensor circuit bank 1 and p0133 sensor circuit bank 1 slow response. anybody got any ideas? going to try to reset the ECM with a positive terminal pull tomorrow(1-5-11)

 

Have you changed your fuel filler? And I would service your injectors. I would start with these

 

did the fuel filter before all this started. do you have a link for the injectors?

 

Are you missing any coolant?

 

not to the best of my knowledge. also another code today p0135 heater circuit bank 1 sensor 1

 

Check that O2 sensor, it is most likely the cause of all your problems.



INSPECTION
(Bank 1 Sensor 1, Bank 1 Sensor 2)

INSPECT HEATER RESISTANCE OF HEATED OXYGEN SENSORS

(a) Disconnect the oxygen sensor connector.

Bank 1 Sensor 1


Bank 1 Sensor 2



(b) Using an ohmmeter, measure the resistance between the terminals +B and HT.

Resistance: At 20°C (68°F): 11 - 16 ohm

If the resistance is not as specified, replace the sensor.

Torque: 20 N.m (200 kgf.cm, 14 ft.lbf)

(c) Reconnect the oxygen sensor connector.

CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. This characteristic is used to detect the oxygen concentration in the exhaust gas and provide feedback to the computer for control of the air-fuel ratio.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen sensor informs the ECM of the LEAN condition (small electromotive force: 0 V).
When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio the oxygen concentration in the exhaust gas in reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive force: 1V). The ECM judges by the electromotive force from the oxygen sensor whether the air-fuel ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor causes output of abnormal electromotive force, the ECM is unable to perform accurate air-fuel ratio control. The heated oxygen sensors include a heater which heats the Zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temp. of the exhaust gas is low) current flows to the heater to heat the sensor for accurate oxygen concentration detection.

 

james woods, if it works i may send you a six pack in the mail.

 

How did your fuel filter look? Did it have rust or dirt in in it? You may have knocked some loose while replacing it and have clogged your injector screens.

 

it wasn't that bad looking to be honest. i changed it because i had no history of it being done. i also cleaned the hell out of the mafs with a q-tip today. i'm about 48 hours from biting the bullet and going to the dealership.

 

anyone else have any ideas?

 

Sounds like oxygen sensor, did you replace it yet or not?

And toyota has a carbon cleaning for the fuel injectors where they hook up a machine directly to the fuel rail. It's a lot more effective than anything you can put in the tank which gets diluted by the gas.


EDIT: You can disconnect the o2 sensor and see how it runs without it because that should throw it into open loop I believe. That will tell you alot if it runs better without the o2 sensor connected. (And it would be the first one before the cat, just use a flat head push the clip back a bit and disconnect the electrical connector)

 

replaced. still misses. things i haven't checked are the fuel delivery, timing belt, ecm. i did all the easy (and not necessarily cheap) things. i replaced the Fuel filter, plugs, boots, wires, coil packs to cyl 1 and cyl 5, and the pre-cat 02 sensor. and i cleaned the crap out of the MAF sensor

 

Yeah I would check your fuel delivery. It sounds like it started right after you replaced the fuel filter. Oh and get rid of that K&N filter, time after time I have seen them deposit oil on the MAF. Get an OEM filter. Hope your truck feels better.

 

thx dew!

 

and the answer was a bad fuel injector on cylinder 5. as soon as i had it all buttoned back up after removing the upper half of the intake and popping the fuel rail, she ran like a champ. my guess is that the old injector was malfunctioning and stuck open dumping enough fuel in the cylinder to cause the constant miss. she seems good as new! thanks to everyone for all the advice.

 

How does that explain the P0301(misfire cyl1) or the P0300?

 

p0300 is a multiple cylinder misfire. p0301 is the code for a misfire in cylinder one, right? so, think about it this way... the fuel rail is like a big loop starting at 5 and continuing past 3, then 1, then jumps from the passenger side of the engine (bank 1) to 2 then 4, then 6(bank 2). after cylinder 6 is the fuel pressure regulator before the return line runs back to the fuel tank. if cylinder 5 was stuck open (which it was) the entire fuel rail after cylinder 5 would get some wonky numbers for the exact pressure at each cylinder.

 

Yeah, that makes sense I guess.

 

I had the same problem as the 1, 3 and 5 cylinders are on the passenger side the multi miss fire I found was due to the cam having jumped a tooth. Bank 1 too lean is due (in my case) to the passenger side head, cam being off by 2 teeth. I tried every thing you have done and this is what fixed it.

 

had the exact same set of codes right before i did my injectors.