ok, im posting this for vitaminZ, he isnt able to get to a computer right now and is concerned about his ride. he has an 04 350z 6 sp, turbonetics without cats, alphawerks headers, and tanabe exhaust. he was away from his car for a few months. He just got back in town and the battery was dead, changed battery and it's ok now. But he's getting a CEL and the car is ideling weird. with the CEL, the car will idel up and down, mostly in the 16's on the innovate gauge. The CEL went away on it's own once and the idle was fine again. then the code came back and idle started acting up again. He just got the codes checked and they were P0300 (random misfire) and P0171 (Fuel System Lean, Bank 1). Can anyone post here why this could be happening ? He hasnt reset the ecu yet, something i think should be done to help fix the issue but some extra help is needed. Thanks guys.

 

If he doesnt have a return fuel system and bigger injectors . My guess would be a fuel injector is clogged on bank 1 .

 

+1, i need to get a fuel return system as well. the p300 code is the "TN kit" code, everyone, I have spoken to gets it.

 

P300 is the code most are getting with a return system and injectors also

 

anybody? i am more concerned about the P0171 code. How many have got it and what was done to fix it? thanks.

 

P0300 is nothing I'm more worried about the other code. I wold get a new battery. Charging batteries after a long period is not the way to go. I did that after my deployment and I don't think it works well. How much gas was left in the car? I would absolutely get all the fuel out of the car and start with a fresh tank.

 

there is a new battery in already. i have an optima red top on its way. i left the car with a quarter tank but my room mate took the car and put $12 in it. not sure how long ago, i have to ask him. i am thinking the gas is old though. i was gone for three months. i have about a quarter of a tank left to burn now. when i left for my deployment i had driven the Z with the TN kit for @900 miles without any codes. as soon as i turned it on after installing the new battery, the SES light was on. it went out on its own but returned. i erased the codes and it came back on after @ an hour.

 

if the car was sitting for months......the entire fuel system should be cleaned out, injectors and all, because that probably gummed up something pretty heavily.

 

Yeah your supposed to leave like NO gas or as little as possible. Gas breaks down easily over time and its likely you have gunked up the fuel system. Definitely syphon or run the car out of fuel if you can ASAP.

 

would some fuel injector cleaner help his situation ? and maybe go put some better gas in it ?

 

If it was me personally (my car did something similar after a month at the body shop but not quite as bad) I would get a gas can and a couple gallons of premium and syphon the old crap out of the tank and put in the new... I would also still run some injector cleaner through there as well though...

 

might be an injector stuck slap it and it will free up

 

first step should be to take off the plenum and inspect the injectors correct. im sure he'll do that, he loves taking his car apart and putting it back together anyway. come over this afternoon and we'll do it at my house.

 

car sat for 3 months but was started and run for @20 minutes 1-2 times a month. i left the Z with just at a quarter of a tank of gas. my room mates said the gas light came on so they put @ $12 dollars of premium (93). check engine light has ben going in and out. it is out right now. i have a new tank of gas and i changed the oil. the light went back out before i did the aformentioned. i will try some injector cleaner as well. hopefully all is good now. the car still idles lean from time to time. it used to not do that.

 

Light came back on i need to read the code to see if it is just the random misfire code, the running lean on bank 1 code or both again.

 

Slap the injector with a tool and it might clear up... actually does it sound like it is missing when you rev it? the injector might not be the prob

 

i am not hearing anything out of the ordinary. i will try to pay more attention though.

 

The 0300 code is pretty common for highly modded cars. There are some that get that code even when N/A. I'm more worried that the car is not running right. Is it acting properly under boost? What are your AFRs showing under boost and how much boost. Also how much vacuum are you seeing at idle? What is steady AFR at idle and what does it jump to?

 

P0300 is multi cylinder misfire, not random cylinder. the reason this code is probably coming on is because of the fuel system lean on bank one code. depriving a bank of fuel will cause more than one cylinder to misfire.

Now why is the first bank not getting enough fuel is the question. its too bad the injectors are sooo hidden, you could listen to them and find which ones are not firing........

 

i think you may be wrong CLETUS, here is a link to all of the engine codes from the infinity web site.

https://my350z.com/forum/showthread....ighlight=p0171


P0300 Random Misfire