trini_350z

Hey guys i need some help here.
Sent my 2003 Track 350z to do an engine re haul (all gaskets , seals etc)
when i got it back , car worked good for 2 days

One night while parked up i felt the idle change when i watched my tac i saw the idle was fluctuating alot and i could feel the engine was idling rough. I thought it was just a fuel choke or so and i decided to take the car for a run. Everytime i stop and the car starts to idle , you feel the problem. After about 10 mins the SES light came on (P0306) cleared the code and went home. Next morning i started the car ... no problems . i drove to work and everything was normal . That night on my way home SES again (P0306). When the car came to a standstill i noticed the same problem (idling bad) . I took the car back to the people that did the engine re haul and they said there is no problems and they dont have room to take the car right now. I took the car by a next mechanic a couple days later he said it wa ready to come and collect. Car worked good by him , i drove home (40-45miles) no problems .. next morning still no problems .. that night as i started the car (P0300) i took a freeze frame (posted below)

The new mechanic doesnt have space to take the car in right now and i need help to fix this. Listed below is everything i tried including the freeze frame data and observations


While i was getting P0306 i swapped spark plug and coil pack 5 & 6 (same problem)
Cleaned air filter
Cleaned TB

Not too sure what the mechanic did to clear the P0306

Now i have P0300

Observations -
1. Mainly happens at night
2. Exhaust smell is VERY strong (you cannot stand up behind the car while it is running)
3.Engine makes a different/weird noise while car is giving the problem (sounds like something is loose and shaking up)
4. Oil pressure drops while car is giving the problem
5. **Car doesnt do system check when ignition is turned on (5 beeps) but the first guage does the full cycle.. Car just doesnt beep**

Stock engine and ECU
90,000miles
CATS removed at 60k TP installed

Freeze frame data -

TROUBLE CODE P0300
FUEL SYS1 NA
FUEL SYS2 NA
CALC LOAD % 20.7
COOLANT TEMP 109F
ST FTRM1 % 24.9
LT FTRM1 % 2.3
ST FTRM2 % 24.9
LT FTRM2 % 0
ENGINE RPM 1000
VEH SPEED 0

Live Data - (after i cleared SES)

FUEL SYS1 CL,USING H02S
FUEL SYS2 CL,USING H02S

COOLANT TEMP 185F
ST FTRM1 % 11.7~
LT FTRM1 % 2.3~
ST FTRM2 % 2.3~
LT FTRM2 % -0.7 (doesnt fluctuate)
ENGINE RPM 688~
VEH SPEED 0
IGN ADV DEG 19~
IAT 147F
MAF LB/MIN 0.6~
ABSLY TPS% 0.7~
02S11 .010 V 17.9%
02S12 .07 V NA%
02S21 .01 V 5.4%
02S22 .08 V NA%
OBD2 STAT OBD2-CALIF

ericjackson

iTrader: (2)

not sure about the code. unless the timing chain wasnt put on right. also, try the throttle body relearn procedure. that fixed my idle problem after i rebuilt the engine. but the shop that did the work needs to own up and fix it right. or id be asking for some money back.

id be willing to bet the timing chain is off. it can be a hassle if you arent paying attention.

bealljk

iTrader: (13)

It was a few years back but I pulled P0306 and it was an issue with the cam shaft position sensors…I can look at my paper work tonight if you like. Both were replaced and the code never came back.

trini_350z

Thanks ericjackson will look into that

I am kinda leaning to a bad o2 sensor.

Before i left work last night i decided to just check the car for fault codes (SES was off)
i pulled a p0171 code and cleared it. About 1 minute later ... SES came on i got P0300
When i got home i checked the engine for vacuum leaks and i also took out and tested the PCV valve. The very stong gas smell coming from the exhaust made me stop what i was doing and lean towards the O2 sensor .. You literally cannot stand behind the car while it is idling

I checked Plugs , Coil Packs , MAF , PCV valve

Can someone give me some advice on the O2 sensor causing this strong gas scent coming from the exhaust

trini_350z

Thanks for the info but i recently changed both cam position sensors and crank position sensor

andz33

iTrader: (3)

P0306 is a mis fire on the #6 cylinder. P0300 is a multiple cylinder mis fire. I would get a new coil pack for the #6 cylinder.

andz33

iTrader: (3)

Strong gas smell is caused by the #6 cylinder not firing because it has no spark to ignite the chamber. To test your coil packs and see if it's really bad just swap one cylinder to another and then you'll get a code for that cylinder which in turn will tell you it's a bad coil pack.

trini_350z

I swapped spark plug & coil pack 5 and 6 already

andz33

iTrader: (3)

Are you still getting the same code?

trini_350z

I got it twice after the swap ..

After the last mechanic did some work on it (checked and cleaned injectors , maf , tb etc.) all i am getting now is P0300 & P0171

andz33

iTrader: (3)

Have you done the ecu reset procedure not just clearing it on the obd2 reader?
I would reset the ecu and have it relearn the system.

trini_350z

Yes i did

trini_350z

What caught my eyes are the readings i am getting from the scan tool

this was taken 22nd FEB
02S11 .010 V 17.9%
02S12 .07 V NA%
02S21 .010 V 5.4%
02S22 .08 V NA%

This was taken 5 mins ago
02S11 .020 V 7.8%
02S12 .100 V NA%
02S21 .030 V 16.3%
02S22 .080 V NA%

Why does 2 of them have NA% ?

Is this common ?

trini_350z

Just an update ..


Turns out i have a blown head gasket

Found coolant and oil mixing and my radiator is back pressuring coolant is spraying out the over flow bottle

I am taking it by the mechanic tomorrow night

Will give everyone an update

superd806

Did you ever figure out what was throwing the p0306 code