hi G owners besides these codes i want to explain the symptoms, the misfires come and go, sometimes I can hardly accelerate because it misses so bad and sometimes it completely goes away and I can go 100% throttle to redline without any missfires

even when its not misfiring I can feel its down on power. I do not have extensive experience with this car but I do have tons of experience with my DSM mitsu eclipse GST its turbo and putting down over 500 whp and i built the car and even tuned it myself on whats basically a standalone tuning system.

that said one thing thats throwing me off is the front o2 readings under full decel bank 1 reads .7-.8 but bank 2 reads 1.3

and under cursing or idle bank 1 usually reads .5-.6 and bank 2 reads .7-.8

now what I'm used to is the closer to 1 volt the richer the exhaust is and under full decel most cars have 100% fuel cut (except subarus) so for an o2 sensor to read 1.3v under full decel would tell me that that sensor is no good unless thats a normal thing for these cars

even bank 1 seems to be rich under decel which makes me think thats theres also another problem since both are reading rich just bank two may have a bad sensor as well

rear o2 also read a little off onder full decel they rear 0.0v of 0.1v which is good but under cruise they read a bit high usually between .6v and .8v which is a little higher then I would expect.

as for mods on the car its all stock with the exception of a JWT pop charger and the stillen hard intake pipe, it is a revup too

if someone can please let me know what could be causing these problems.

Thanks
Adam

 

Well I went with my gut feeling on this and got a set of HFC,

I swapped them on last night and problem fixed... the driver side cat internal honey comb thing was loose and was sliding back and fourth inside the housing this was bank 2 cat. I'm assuming the excess back pressure is what was causing the misfire, also I believe it cooked the O2 sensor, which is why it reads up to 1.3v, I'm ordering a new sensor and ill post results back into this thread for those with similar problems

 

No one has any insight on any one of my issues? espically the 1.3V o2 or the high volt readings on decel?

 

Check for post MAFleaks on the intake manifold, just one plenum bolt caused my car to throw p0174. EDIT: Check everywhere, not just the plenum. Anywhere where air can get in that is not being metered.

You changed the cats and didn't change the O2 sensors? I would start there, using OEM replacements for pure peace of mind.

 

I ordered a replacement OEM o2 sensor for the side that was clogged and is reading 1.3V. it is getting delivered today. once i swap that one and and see how it behaves ill decided if the other bank needs to be replaced as well, the other side appears to function normally.

ill look for leaks post MAF but I have done zero mods to the IM so I wouldn't expect any issues there but i will rule it out.


does anyone else have there o2 sensors read high volts on decel? is this normal? i see .7v-.9v on decel

 

The hard intake pipe may be a cause, if the breather hose isn't hooked up properly or near the TB there could be a space... Not saying you don't know how to install mods but things come loose and break over time. I do not have experience logging O2 voltage unfortunately but if you are getting a code for a lean condition, while seeing overly rich readings, check that side especially carefully for leaks on both the intake and exhaust side of things.

Let's see how it performs with the new O2 in...

Meanwhile could you give more background info like mileage, gas octane, and any maintenance performed?

 

I put the new O2 in last night, it is doing the same exact thing as before, I guess it wasn't the problem it still show 1.3V under full decel. I'm assuming thats normal i was hoping someone could verify that.

i have just under 130k miles, I always run 91 i just changed the sparkplugs with iridium plugs, i inspected the coil packs they all looked good, no bulging and no oil in spark plug tubes.


in checked everywhere for leaks and even checked all the bolts on the Intake manifold to make sure all bolts were tight, I wasn't able to fine or hear any leaks, I checked the intake pipe and couplers and no leaks, everything is on good and tight and no vaccum leaks.

JWT pop charger is only a year old.

since replacing the cats and i did the plugs at the same time, the cars seemed to retune it self, it would bog under load at 1st and after a couple trips driving it started running good, but it would still hard start.

then i did the reset i read about by pulling 2 different fuses one under the hood and the other in the driver kick panel.

now its running just like it was when i changed the cats, its sluggish under load, but seems to be slowly getting better.

the O2 sensor still has me thrown becasue i have never seen o2 sensors rear over 1V except in boosted cars when you have high egts and high boost on WOT then i have seen 1.1v but does nissan o2 sensors rear reverse where high volt mean high oxygen content

 

OK so I finally figured this out, I had narrowed it down to a fuel pump/pressure issue, so i ordered a GSS250 Walbro fuel pump which is a prefect replacement for our cars and when i pulled the fuel pump housing the housing it self was half way apart and the lower assembly was hanging off and the pressure side of the pump wasnt sealed to the upper section so pressure was constantly bleeding off, the pump was fine but i went ahead and replaced it any way, now that pump is in my friends Mitsu Galant becasue his pump died and the pump are exactly the same.

the only issue I still have it the fuel system isn't staying pressurized does anyone know if theres a check valve of some kind as part of the fuel pump assembly that could need replacing