Quick question while I'm waiting to reassemble. Are the parts circled in red OEM

• Upper Circle - some sort of EVAP/Purge system filter ANSWER: That is the EVAP Purge Resonator (OEM).
• Lower Circle - heat shield covering fuel line from fuel damper and the EVAP/purge line ANSWER: This heat shield is not OEM and is attached to the fire wall with chicken wire .
  • I will uninstall this and mount it on a proper bracket.

 

I'm back. So I removed that heat shield and who ever had the car before me took the OEM fuel line out, bent it to the shape they wanted and reinstalled it. When I tried to replace the the fuel damper it wouldn't reach the quick connect. So I went out and bought a tube bender... long story short. I bent/kinked/destroyed the fuel line. I took an Uber out to LKQ cut about 4 feet of fuel line off a G35 coupe along with the bracket. Brought it back home, cleaned it, and installed with a compression fitting and it works like a charm. Fuel system is back to OEM, with exception to that compression fitting.

P0024 has also been resolved with reinstalling the the slack tensioner and timing chain. No more knocking noise. The car is very quiet now and calmer, but it gets loud after 3000 rpms with the new exhaust. There's not much roughness in the idle anymore, but you can still feel a very very slight misfire...

P0300 is still there. With all the components I've replaced, I think it's boiling down to three things.

1. Vacuum leak that I cannot see. (I've taken the upper/lower plenum off multiple times and I've never replaced the gasket that mates between the lower plenum and the intake manifold... I saw someone with a 4runner generating a P0300 that had this problem - link). I'll spray some throttle body cleaner as best I can in that area to see if there is any change in RPMs.
2. While under the car, I notice I've only replace 3 O2 sensors within the last 2 years. B2S2 is still the original 2005 sensor. I've order a new NTK one from RockAuto... though I doubt this will improve any because of the integrated no-foulers on the HFC should make this a mute point.
3. ECM - I could be fighting with the ECM. I really hope this isn't the issue. It's obvious the previous owner had a FI setup, which means he would have tuned it. I hope they didn't damage the ECM.

After I install the B2S2 O2 sensor and the intake manifold gasket... if it doesn't fix the P0300, I'm taking it back to Soho motorsports for another diagnostic.

Should I get the OEM gasket or the Motordyne Iso Thermal Lower Intake Plenum Gasket

 

Those gaskets are all metal reusable ones. I would just pull the plenum apart and inspect before replacing anything.

I would replace the injectors, the previous owner was definitely FI it's obvious because of the hole they cut for the intercooler piping and you have no idea what leftover injectors were installed.

If that doesn't do it then look into getting the ECM reflashed by Nissan/Infiniti. Should just be a 1 hour service charge for a reflash.

 

I've already purchased a new OEM metal intake gasket (should be here tomorrow)... I remember the current one has its coating chipping near the 7th and 8th nuts and you could see the metal gasket layers were separating a little. Probably a good idea to replace it.

Injectors
Question: Do the RevUp and Non-RevUp use different OEM fuel injectors? I suspected that the fuel injectors were bad a little over a year so I pulled 6 fuel injectors off a DE sedan and replaced 3 of the injectors that were super dirty. The ones off my RevUp and the Non-RevUp sedan looked identical and most G35/350z threads say they're the same. But when I go to Z1's website I notice they ask if you have a RevUp or Non-RevUp when attempting to purchase. Currently there are 3 original RevUp fuel injectors and 3 sedan Non-RevUp fuel injectors installed (since over a year ago). Maintenance starts early tomorrow morning. My plan is to test (resistance and 12 volt operation) and flush the RevUP injectors and reinstall them. If the original RevUp injectors fail any test, I'll use all sedan Non-RevUp (tested and flushed). I'll purchase new ones if neither pass testing.

 

I am at the start of this journey is sounds like with my 2008 g35 sport sedan. About to replace my catalytic converters this weekend with test pipes due to passenger side over heating cat. I've replaced 2 cam shaft sensors and the crank shaft sensor, replaced ignition coils, and plugs twice. I've basically been around the vehicle since day one as it was my mothers who had it serviced at the dealership so previous owner problems are out of the question. I bought it around 140k miles and have done all the maintenance thus far (just brake pads, alternator, a/c condenser, cabin filters, rear diff and oil fluid, **** like that). If you had any advice to offer as far as limiting the amount of parts to throw at this car what would it be? Was timing chain tensioners worth it? Throwing the P0300 code with left sided cat clogged as mentioned above, have not replace any o2 sensors as of yet. I did learn from all this that i need to do a reset after removing throttle bodies which i definitely did do recently changing ignition coils and plugs but nothing i have done yet has fixed random misfire and ***** getting worse.

 

How do you know your passenger side cat is overheating? If that's the case you probably have a clogged cat... which would need to be replace... and will hopefully solve your P0300. Make sure you have non-fouler bungs integrated into your test pipes or you may generate some new misfire codes. My advice, what I should have done after my first post... take it to a dealer or a nissan/infiniti specialist for a proper diagnostic. Spending the $150 - $200 for a Consult II or III diagnostic will be well worth it rather than throwing over $1200 worth of parts at it just to find out it's something small like a gasket, O2 sensor, or cam sensor... or finding out your engine is toast and that $1200 could have gone towards a used low mileage engine or new car. My G has over 200k miles on it. My gallery gasket was blown, since I had to remove the timing chain cover, I figured I might as well replace the timing chain components (even thought they all looked like they were in good condition).

 

Quick Update: Installed a new B2S2 O2 sensor. Reset the CEL and went for a 10 minute drive. Checked for codes and now I'm getting a pending CEL P0304. This happened before, then it went away leaving the P0300. Maybe something with Cylinder 4 is the culprit. I will be doing the injector stuff I mentioned before later... got some papers to write.

 

I realized yesterday that I forgot to tighten the clamp where the intake meets the throttle body. I corrected that and now p0304 is gone, but P0300 is still there. I called back up to Soho motorsports to tell them that the gallery gasket and timing chain components were installed but I'm still getting a P0300. They initially said I didn't set the timing correctly, but I know I did (minus not setting the slack tensioner). I told him that I'm confident the timing is correct. Then he says "how long have you had the P0300" and I was like "It's been continuously on since August." The then tells me it's probably the camshaft sprockets are worn out from running with low oil pressure for that long. I really, really, really do not want to open up that timing cover again. It is such a pain from start to finish. Not to mention my A/C clutch is not engaging anymore. Does anyone think a camshaft sprocket could generate a P0300?

Just looked at prices on a new exhaust camshaft sprockets. They are at almost $900 each.

 

If you only threw the code at high rpm when the engine was revved but not at idle I'd POSSIBLY suspect the sprocket, but since it does it at idle I'm pretty suspect about that.

If you clear the code while the engine is running does it immediately come back? If not exactly WHEN does the code come back, that will help narrow down exactly when it's triggering which will help narrow down exactly what is causing it.

You can clear codes with the BAFX bluetooth adapter and the Android Torque Pro app, personally I would keep the adapter plugged in every time the car was getting turned on just so you can clear codes and try to replicate the EXACT scenario which causes it to turn on.

 

If I clear the code it comes back intermittently. For example, Sunday, I cleared the code, drove 24 miles round trip to my favorite coffee spot (maybe 14 miles highway), no pending or confirmed codes. I get back to doing school work for 4 hours and decide to grab some food, 8 mile round trip. When I get home I decided to run the scanner and I have a pending P0300. Ate my food, and then went out for a 5 min test drive and the CEL light came on. Today (Monday) I cleared the code, drove to get lunch (3 mile drive) and the CEL on one trip. I'll post some freeze frames on my next post.

Update:
I kept reading the service manual about inspecting the coil packs. One part said to inspect the condenser. I'm like what the hell does the A/C condenser have to do with the coil packs. So there's this thing called a Condenser Ignition Coil. Mine was hidden and wrapped onto the main wiring harness with electrical tape right above the Bank 1 coil packs. I removed the electrical tape to expose the condenser ignition coil and harness. There was brown fluid oozing out of both ends of wire harness and also in the condenser ignition coil. It's a pretty cheap part, so I'm gonna wait until the morning and see if the Nissan dealer up the street has any. Clean up the harness and see what happens. That can't be dielectric grease, can it? It's really greasy. (Cleric, just saw your other post from last year explaining what this is... so essentially it's a capacitor that works as a coil pack "spark" regulator, right?).



Back of Condenser Ignition Coil harness. I'm not sure what all that brown gunk is and not really sure how to clean it.

Front of Condenser Ignition Coil harness. Gunk is caked inside of the harness bad.

Condenser Ignition Coil harness. Seems it was burning up.



Opened the condenser ignition coil and it was fried.

 

Holy crap, someone smothered the ever living F out of that thing with dielectric???

This COULD possibly be the culprit and yes they are very inexpensive. I'm leaning more towards a coil pack failing caused the condenser to fail which then causes intermittent spark issues because it's no longer able to rapidly discharge properly.

Basically it allows a large reservoir of electrical current to be stored up in the circuit, when the coil pack discharges it draws from this reservoir which then rapidly fills back up. The current draw of 6 coil packs all firing intermittently causes a "ripple" in the current, imagine waves on water, if you created another wave that would slam against the ones already in the water it creates a disturbance which can effect the flow. If you have a deep river of current it's not an issue, if you have a very shallow stream it can cause a momentary loss of water as one wave slams into the next.

This is more or less what the capacitor is doing, allowing for a larger volume of current to prevent hard cycling on the coil pack because it WILL cook coils by opening them without the current behind it, the voltage will spike to make the arc, create extra heat in the winding on the coil pack.

Don't be surprised if you do possibly have a coil pack issue that exists after you replace the condenser, I would give them all a very good visual inspection particularly for heat discoloration on the contact spring that's up inside the well boot, use a flashlight, if it looks brown/orange-ish replace it, that's usually where the damage STARTS.

 

Thanks... awesome explanation. It definitely shows you are an electrician or electrical engineer. P0304 has been popping up intermittently over the last couple of days. I went in to check the coil and spark plug today and that's when I saw the condenser/capacitor inspection in the FSM. I just checked coils 2, 4, and 6... no discoloration on the coil spring, it's dry and silver. I don't know if the brown goop is aged moisture/water, or dielectric grease... the electrical tape looked OEM. I think I'm the first person ever to service it. Is there usually dielectric grease in this connection? I saw some other 350z post were OP said that water poured out when he removed the electrical tape and connector. He was confused on how water got into the connection.

 

Yeah that's not a connection that normally would get wet unless you wash the engine bay which I am STRONGLY opposed to btw.

I've seen that kind of sludge in the field before (electrician, not an engineer, but naturally curious). It's just an abundance of dielectric that's a decade old and probably got really hot.

When you replace it wipe all that crap off, then apply a VERY thin layer of electrical anti-oxidation grease on the harness when you plug the new one in. If you want to make it a bit more moisture resistant you can wrap it tightly in electrical tape but that's probably unnecessary because it's supposed to be dry in the engine bay as long as you have the lower cover on and aren't spraying water in the bay. You probably won't even need to add more dielectric because there's so much up in the harness.

 

I pulled the terminals out of the harness. Cleaned out the harness and terminals and got pretty much all of the dielectric out. There's probably a very thin coat left on the terminals, so I'll leave them as they are. I don't have any anti-oxidation grease on hand, I'll have to grab some tomorrow.

 

Glad you found it, btw that dielectric grease is in fact factory. My 240SX and Silvia all use that same part and are pretty coated with that stuff. I'd pick up a tube at local auto parts store and lube it up when you install the fresh one. Feel free to go to town like they did at the factory in my opinion. Cleric provided a pretty good breakdown of what that thing does.