Hey guys, I have a 2004 350z that just hit over 70k miles. I just bought the car a week and a half ago and shortly afterwards noticed that the check engine light was on. I read the code and it ended up being the p0172 code.
First thing I did was clean the MAF sensor and although it seemed to have helped the car a little bit the check engine light came back with the same code.
So yesterday I decided I would add seafoam to the gas, but also decided to do the vacuume treatment as well. I used a little less than 1/3 of the can through the vacuume line. Let it sit for 20 min. And then started it and of course all the smoke had come out. Shorty afterwards I took it out for a drive and drove it a bit hard.
When I got to a gas station I had a quarter of a tank of gas and poured 2/3 of the can of seafoam in and put in about $15 of gas which bought be up to a half tank.
After driving around some more I noticed that it was running pretty bad and that most of the time will shut off when it comes to an idle. (I thought that maybe I didnt put in enough gas to mix with the seafoam and went ahead and filled up the tank)
I drove about 55 miles since then and the car is still performing in that same way. I also noticed that its running very rich as where I park in my garage there is black **** all around the floor where my exhaust is.

Right now I figure that maybe the seafoam fouled my plugs so im replacing the plugs right now, but does anyone have any idea what I can do?

 

Ok so I replaced my spark plugs. The old ones were pretty dirty and covered in a really dark ****...I took the car out for a drive and although I can feel it has more power. It still doesnt idle right/ cuts off and sometimes hesitates or feels like it misfires...next im gonna try cleaning the throttle body. I already cleaned my MAF sensor the other day

 

is it throwing any misfire codes?

 

I just got back from my test drive after cleaning the throttle body. It idles a LITTLE better and cuts off less but still cuts off sometimes when idling.
The codes im getting now are
P1271
P1281

 

So you're saying that the only problem before all of your treatments was the CEL, and now you have the sputtering / idling issue?

I would be tempted to fill the tank completely to dilute the seafoam.

 

After researching the codes its basically the air/fuel sensor on both banks of the car.
Is the air/fuel sensor basically a different way of saying oxygen sensor?
Is their any way I can test and clean the oxygen sensors to make sure they are working properly?

 

The only problem Iv had before the treatment was the CEL and it would give me the p0127 code. I did fill the tank completely and have brought it back down to a quarter of a tank today and just now put in another half tank and the issue persist.

 

maybe try cleaning the o2 sensors or replace them.

 

I just jacked the car up (this is my first time working on this car since iv only had it for about a week) and I see 4 oxygen sensors total. 1 on each cat and 1 on each side before the cats. Is that correct?
What can i use to clean the sensors? MAF cleaner?

 

I don't know if the O2 sensors play a roll in how a vehicle runs at idle.

 

My scan tool can also read the o2 sensors. Heres what its reading

O2S11 (V) 0.305
O2S12 (V) 0.280
O2S21 (V) 0.620
O2S22 (V) 0.280

so from the looks of it it looks like maybe the O2S21 is faulty?
But then again im getting codes for both sides and to be honest im not exactly sure what the numbers im looking at mean (im used to working on older cars for the most part) any help is greatly appreciated

 

I cleaned the back 2 O2 sensors that are on the cats, they just mainly had **** all over them. I cleaned them with throttle body cleaner, did a test drive. Not much of a difference.
While I was driving I used my scan tool to see the status of the O2 sensors

O2S11 (V) 0.005
O2S12 (V) 0.960
O2S21 (V) 0.010
O2S22 (V) 0.960

I'm going to let the car cool down and then try the front sensors

 

Well, I couldnt get the other O2 sensors off (they're really tight) so I guess ill finally give in and take it to the dealership >.<
I did do another code reading and im getting p1168 as well now so yeah.
I hope they wont charge me over $600

 

Well i'm afraid I can't offer any help suffice to say that P1168 = closed loop on bank 2 as P1148 = closed loop on bank 1 but you probably know this already, so I'm not sure if you've done more damage trying to remove the O2 sensors or that this is something else has reared its head.

 

How dirty is your air filter?

 

Slight chance u put the MAF sensor backwards accidentally? ._. Sometimes it could be an honest mistake like this that causes problems lol um, after cleaning the TB and the sensor, maybe doing the relearn procedures would help out in ur case. If that's not it, then I guess maybe it could be something wrong with the ECU which would suck... A lot.

 

I think a relearn is a good start.

I doubt there is an issue with his ECU, originally he just had a CEL. It was after his Vacuum and Fuel seafoam treatments that he developed these major issues.

 

True, true. Checking for a vacuum leak would also be a good idea.

 

ok, so I took it to the dealer (mainly cause I couldnt get one of the air/fuel sensors off and yeah i do have the right socket to fit it, but i dont have a lift so it was kind of hard to get to) the dealer replaced one air/fuel sensor that was bad, but the car was still running very rich.
We came to the conclusion that one or more of my fuel injectors are actually stuck open and are constantly pouring in fuel. They said they will be taking a look at them on monday and let me know.
Of course the dealer is overly expensive as ****, but I got such a good deal on the car so **** it.

 

What im thinking is that when I did the seafoam treatment it had actually knocked some gunk or carbon loose and that it got stuck in one or more of the injectors causing it to stay open.