I see that there are a bunch of random misfire threads on here and other forums, but still can't seem to get a clear cut answer. I have an 05 AT coupe with about 138k miles on it. It ran perfect up until i decided to give it an oil change.

I always knew I had an oil leak problem as i would see a pool of oil on the floor every time i parked. So i went ahead and got a oil cooler o ring, bought some oil and a filter and decided to do my first ever oil change. Being excited and all, i took my sweet time and made sure everything was done right. Since there was a lot of oil under the car, i cleaned up everything with some brake clean to get rid of the gunk. Went ahead and started with the oil change and then replaced the oil cooler o ring. Didn't take off the cooler just twisted it to expose the back side. Screwed it back into place and torqued to spec, and finished with the oil change. Added 5 quarts of 5w-30 and all went well.

Turned on my car and i immediately saw the SES light flash on. Got a little worried but then i realized like an idiot i forgot to plug the MAF sensor back into its place before turning on the car. (I removed my intake to clean up some oil by the dipstick.) So im thinking okay the light will turn off. It drove fine but then here's where the problem started. Driving home from work, i realized that the car would jerk and sputter when im waiting at a red light. But when driving it, it seemed pretty fine. I realized that a lot of smoke was coming out of the exhaust. Took it to a mechanic to read out a code and he got random misfire.

Now i know random misfire can occur from bad spark plugs, coils, vacuum leak, etc. But this was never an issue up until when i did the oil change and o ring replacement. My mechanic said it would take him a day or two to check through everything to figure out the problem, but not until next week. Could the fact that i cleaned under my car with brake clean (there are a few of electrical plugs down there) or anything with the MAF sensor plug not being put back before turning on the car have anything to do with it? Or is it just a coincidence that a misfire would occur RIGHT AFTER i did the oil change, o ring replacement, intake removal?

I'm going to change the spark plugs and check the coils but i really don't see how that correlates with what i did with the car.

 

Odds are if you took your intake off you probably didn't put it back on securely and you're getting a large vacuum leak. Double check everything, I know myself have had issues where it connects to the throttle body. There is also a PCV hose on the back of the intake tube make sure that's connected.

 

Would that itself cause such a problem? (The jerking/sputtering and misfiring)

 

Yep, a large vacuum leak can cause the symptoms you're experiencing. You should throw a code though P0174 or P0171 running too lean, I think are the numbers. I had a leak at the o-ring between the brake booster and master cylinder. Took me forever to find it, since it was a hard leak to trace. I was getting crappy gas mileage, stumbling at idle, P0300 (random misfire) occasionally, revving up/down, and a consistent P0174.

Another possibility is maybe your MAF got damaged somehow when you took it out? If you have a bad MAF you won't get a code, but your car will run like shiiite. That's a 300 dollar replacement, so don't go running to that yet (I did and now I'm stuck with an extra one).

I'd say vacuum leak though, since it happens mostly at idle and seems to be fine when driving.

 

As far as what the mechanic told me, he only said random misfire (P0300) and didnt tell me any other codes. Maybe it's just that? I'll probably go to an auto parts store to get a second reading and see if i get any other code. But I'm definitely experiencing what you just mentioned. When i took out the intake, i placed the air filter box on the ground as i do normally, maybe the impact of me placing it on the ground messed it up? Lol, at this point I'm taking anything into account. Maybe some dirt got into the sensor. I'll probably try cleaning the sensor with some MAF cleaner. But yeah, its odd that it drives perfectly fine, dont feel any loss of power or any oddness even when driving around 70-80 on the freeway. So i can probably conclude its something to do with the intake. Wont know until i become a detective and investigate.

I appreciate the help! I'll keep this thread updated if i figure out whats wrong (hopefully nothing too serious, broke college student problems lol).

 

Erase the code, see if it comes back. (to confirm the issue)

 

The code was erased actually and it drove fine. But when I (accidentally) ran over a pot hole, the SES light came back on. And the poor idling/jerking clogging started to occur again. Not sure if its just a coincidence or maybe there's something that's not in place tight enough.

 

Was it the same error code? P0300?

If hitting a bump caused it to come back. I'd suggest some electrical connection might be loose and bumps are triggering it.

 

Okay so now its getting even more weird. I just turned on my car leaving from school and the SES light is still on but the car runs fine. I went to autozone to pull the code, and this time I didn't get random misfire, but now I got P0011; Intake valve timing control performance. Does that have anything to do with the MAF sensor?

The code by definition says code P0011 indicated that the Bank 1 Intake Camshaft Position timing was advanced beyond limits for a predetermined period of time.

 

Page 168-172

http://www.nicoclub.com/FSM/G35/Seda...5_Sedan/ec.pdf

 

So it basically it says

• Check camshaft sensor
• Check crankshaft sensor
• Check timing chain
• Check IVT valve
• Check camshaft (where you have to practically partially disassemble the engine)

And basically replace anything thats bad. Does that sound accurate?

 

What year is your car?

 

Its a 2005 AT coupe

 

Well, the only thing you've done recently is an oil change correct? Any different oil? or a different filter?

Only reason I ask is that sometimes, a Cam position code can be tripped for not doing an oil change soon enough. Usually it's not an issue on the G35 as most people here overmaintain. However, on the Altima, where people drive 19000 miles without changing the oil, it frequently comes up. Usually the first thing suggested when a Cam code (or code related to cam position sensor) comes up is to change the oil.

Not saying to go change your oil...but there might be a correlation between your recent oil change, and this code.

I sure as hell wouldn't pull the engine apart to check the camshaft just yet, but I'd def check oil level first, and then start checking the sensors

 

Yeah, only an oil change. I always had it done at some oil change place but this time i decided to do it myself because god knows what crap they would put in. I put in 5 quarts synthetic 5w-30 mobil oil with a mobil filter. I also replaced the o ring by the oil cooler because i was leaking a whole bunch of oil. I had to constantly top it off with conventional 5w-30, (going to top if off with synthetic now if i still see oil leaking or oil consumption).

Usually i replace the oil every 3000 miles but the last time i went to get the oil changed, they told me to replace it at 4000. I didnt wait the 4000 mile mark though, i changed it at 3400. Im thinking theres a correlation as well because this never happened before. I would assume it would happen before fixing the o ring because the oil would be low. But with 5 quarts and a fixed oil leak? Spraying brake clean by the pan and surroundings wouldnt cause a problem would it?

I'll probably start off with replacing the oil again, maybe not using the full 5 quarts. Just 4.5 and see where it goes. Honestly dont know what to do with this fairly fresh oil i just put in lol. Recycle i guess.

And then maybe get a new camshaft sensor for bank 1?