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I took the cam phasers off and disassembled them. There appears to be no damage (cracks, broken bits,...etc). I checked the old ones and the new ones, they all look the same. I'm guessing it wasn't the cam phasers. Should I put the original ones back on or the new (used) ones?
Either would be fine, pick whichever has less apparent wear.
I think the next step (after reassembly) is to just replace the IAT/MAF. You threw a momentary code for it a while back, something might be off with it's data, source a new MAF (IAT is part of the MAF). I think Hitachi was the OEM manufacturer so try to get one of those.
Also replace the ignition condenser.
After that I think you need an actual oil pressure sensor to verify good oil pressure.
At this point the only components you HAVEN'T replaced will be the wiring harness and ECM.
I'm back!!!! Sorry for the hiatus. I just graduated with a Master of Science in Mech Eng. last Saturday... at 40 years old. WOOOO WHOOOOO!!!! I had to stop working on the car to focus on my Thesis last month.
I have not done anything to the car since my last post. However... the P0300 DTC turned off yesterday morning. I rushed to the inspection place and told them to not turn the car off while testing. It passed inspection and then 10 miles later... P0300. At least I don't have to drive in fear of being pulled over for the next 6 months. I honestly think it's a vacuum leak or ECM. I hear a weird air sucking noise when decelerating (why I think it's a vacuum) and also my tire pressure warning light keeps turning on randomly for no reason (why I think it may be ECM), then it's off during my next drive. My tire pressure is fine @35 psi. I'll start fiddling with it Monday... a friend of mine just bought a vacuum leak/smoke tester. We will see if it shows us anything. Still determined to post a solution.
If you hear a hissing on decel it's almost definitely a vacuum leak, when the throttle is closed you have the highest intake vacuum. Also inspect around the brake line to brake booster area. Possibly the booster itself but it seems VERY uncommon for one to fail on these cars.
As for the tire pressure, that's not handled by the ECM, the signal goes to the keyless entry receiver and it sends the data to the BCM where it's processed. Most likely you have an intermittently failing RX or TX at one of the wheels or a battery getting low in the TX. You can see which one is giving the issue next time the tire pressure light turns on by grounding out the TPMS service connector. You need to access the connector first, it's taped to the wiring of the OBD2 harness up under the dash, it's possible to remove it without removing the lower trim piece but it's a VERY VERY tight place to work so you should just remove that panel.
Cut the tape and let the harness hang or tie wrap it to a better more accessible location.
When you tire light turns on again use a piece of wire and ground out that harness ONE TIME for just a second, it's just one wire, this will make the tire pressure light flash a code for which component is the problem, the code flashes like how old OBD1 stuff used to work, it flashes the first digit followed by the second digit, then a long pause before repeating.
So for example code 35 that repeated twice would look like this.
If there are multiple codes it does them one at a time then repeats, so firstcode, short pause, secondcode, long pause to repeat, firstcode, short pause, secondcode, long pause to repeate, etc.
When you're done just turn the ignition off/on to get out of diagnostic mode.
Don't repeatedly ground out the tire pressure service port, if you do it 5 times in a row you put the system into initialization mode for installing new TPMS sensors, then you will have to set the tires to very specific pressure and drive a specific distance to recalibrate the system. If you have a battery going dead and need to replace the sensor you will have to do this anyways, some tire shops have a handheld tool to make this easier or you can do it yourself by following the instructions in this thread.
Sorry for another very long hiatus again. Scored a job and moved from NC to CA. I brought my G35 with me and I still have these issues with notes:
P0300... after all that work at the beginning of the year [6x spark plugs (NGK PLFR5A-11), 6x coil packs (Hitachi IGC0007), valve cover (OEM), timing (OEM), cam-phaser inspection, gallery gasket (OEM), Upstream O2 sensors (DENSO 2345061), Downstream O2 sensors (NTK 24404)] - Completed
Around the time I got it inspected, the P0300 would go off/on intermittently.
After putting the OEM cats back on, p0300 is now on constantly (though I don't think it's causing the issue) ... but the car drives fine (or maybe I've gotten used to driving with a slight almost unnoticeable misfire). Still ridiculously hungry for oil.
Also.. if I prime the fuel pump, the engine seems to turn over and start normal. If I don't prime the fuel pump, the engine seems to struggle slightly.
I have not tried any of the tire pressure tricks... but living in the Bay Area requires long distance driving to explore (45+ minute rides). I've notice that the tire pressure light comes on after about 25-30 minutes of driving and stays on until I turn the car off. When I get back in later on, it's off. If I drive for under 30 minutes, it doesn't come on. How would you know if the battery was going dead in one?
I bought this car in 2012 @87,000 miles. Today it has 213,000+ miles. One major component that I have not changed is the clutch, flywheel, and pressure plate. I have a spare sitting in my storage from z1motorsports. Do you think my flywheel could be wonky after all this time? Note: I had some camshaft sensor issues a few years back. Gonna call a specialist tomorrow... and schedule a diagnostic test.
I think you should pull the fuel pump and see if the strainer baggy has a lot of debris on it, might be getting slightly starved for fuel pressure at higher rpm causing the P0300. However drinking a lot of oil can also cause a misfire as well, compression test to see where you're at, if compression is still good it might be sipping a lot more than it should through the PCV system. Have you cleaned your PCV valve or at least shaken it to make sure it still rattles? This might also contribute to a misfire if the PCV valve is a little stuck open.
I'm leaning towards the fuel pump strainer though especially what you describe about the pump needing to be primed, could be a failing pump too and the relief/check valve is failed and overall delivering less fuel pressure.
As for the tire pressure light, you can put the system in diagnostic mode to see exactly what's triggering that light. The OBD2 data link connector has a single wire harness taped to it directly BEHIND the plug (look up under dash and you'll see it), poke another wire into that single wire TPMS harness and ground it out momentarily to chassis ground (brake pedal bolts works good) and the TPMS light on the dash will start flashing a sort of morse-code that you can reference against this chart from the FSM section WT - Wheels/Tires.
Thanks for this info. Fuel pump (Fuel sending unit) is less than a year old (Hitachi). PCV valve also less than a year old (OEM). I agree, there's something fishy with the fuel... could a erroneous ECM map cause this. I keep saying it could be an ECM (previous owner ran FI setup, I'm not sure how they flashed/tuned the ECM).
The horn turned out to be a blown fuse. Replace the fuse and the horn is working and hasn't blown in 2 days.
Just got the car back from A&J Nissan specialist in San Jose. They charged me $130 for a diagnotic test. They confirmed that my spark plugs and coil packs are fine. They suspect there is a mechanical failure inside the engine. I told them I did a compression test back around March and all cylinders were within +/- 14 psi of each other. I did not perform a leak down test. He told me he notice there was considerable black smoke coming from the right bank and that a leak down test would need to be performed to ensure there weren't any compression leaks (which I'm sure there are, I have bad blow-by where I have to top off oil at least 2-3 times a month). For a compression and leak down test I was quoted $500!!!! They suspect I have leaking valves. I told him that price was outrageous considering the compression/leak down test should have been included with the diagnostics test. None-the-less, paying $500 to uncover a problem that I know exist isn't helpful. My choices now are to get a valve job... which will be probably $2800+. Or swap an engine (MT REV-UP), which will be $4000+. The car drives fine. I just want the check engine light to turn off. If I can do that, I'll drive it into the dirt.
I'm not really concerned about the TPMS, but may attempt messing with it at some point. It doesn't turn on unless I drive longer than 30+ minutes.
At this point I think it makes sense to swap the ECM/BCM, find ones being sold as a pair WITH KEYS so you won't need to reprogram it. Ideally find a car in a local wrecking yard you can pull everything from, unfortunately since you've gone through basically ALL the systems it's almost just throwing parts at the car at this point, my gut is suspecting you have a damaged engine wire harness though since the issue seems to be intermittent... Most likely if the previous owner was FI they likely had an UpRev tune but I don't see any reason why they wouldn't flash back to stock when removing the stuff. Otherwise it's basically leaving $800 worth of equipment on the car.
As for the price on a leakdown and compression test, yeah that's pretty ridiculous, only takes about an hour to do the whole thing.
I saw you said something about the numbers for the compression test, do you have those values still?
I found several ECM/BCM with keys on Ebay ranging from $300 to $700. Haven't pulled the trigger yet. I should mention... the CEL would turn off when oil was running low, once I put more oil in it would come back on and stay on... yet no difference in performance either... I'm not even sure it's misfiring.
Here are the results from my compression test at the beginning of the year.
That's weird, I wonder if you have a cam phase sensor that's a little laggy or a slightly defective crank sensor.
Something you should try first that I'm curious about, remove your spark plugs and set them LOWER than factory spec gap. Factory gap is 0.043, set your gap at 0.030 and see if it makes a difference. This will help pinpoint if it's spark related or not, just be careful with the iridium/platinum tip you can't use one of the "wheel" style gappers to open it up if you close it too much, you need to use pliers (or a ground strap plier, personally I just use regular pliers) to open up the gap. Gently tap the ground strap on a workbench to close it up a little.
This was the engine that had the cracked intake plenum and... an exhaust leak right? Did you ever have the intake and exhaust smoke tested to make sure there's no more leaks?
I can't believe that with as many replaced components and troubleshooting has gone into this car that you're still having issues with the random misfire? Have you ever replaced the crank sensor? The ECU detects the misfire through the crank sensor. is the harness oily? It's at the bottom of the bellhousing and MAYBE it's got just the wrong amount of oil contamination in the harness that's causing a problem? You can buy a replacement crank sensor pigtails and splice it onto the factory wiring.
What about the condition of the flywheel pickup ring? Have you ever removed the crank sensor (or imo it's easier to remove the blank plate from the driver side engine where the starter could alternately mount since it's a much bigger hole) and thoroughly inspected (possibly clean with brake cleaner and a plastic brush) the flywheel ring gear.
Ok because this is starting to bug me too I re-read through the ENTIRE thread...
-New crank sensor harness, clean or at very least INSPECT the entire circumference of the flywheel/crank pickup, personally I would toss in a new crank sensor.
Are there ANY cam sensors that weren't replaced, I saw in a previous post where maybe your exhaust cam sensors weren't replaced?
-Do the spark plug gap change
-Smoke test both intake/exhaust
-Leakdown test, although I don't think this is the issue, the previous owner was definitely FI and might have cooked a valve on cylinder 4 which has intermittently popped up.
Does the engine EVER ping? I know these engines are sort of notorious for it, I'm wondering if you have a damaged knock sensor harness (incredibly common and yours is probably damaged) and/or bad knock sensor that's not pulling timing fast enough (or at all) which is contributing to poor cylinder conditions causing the misfire. It's an easy and fairly inexpensive repair for new knock sensor and new sub harness.
If that doesn't make any change then it's time for a new ECM/BCM/keys AND the ECM harness.
EDIT: Lol at how many times I asked you for the compression test throughout this thread.
Same engine with the cracked upper plenum that was replaced. I cleaned out the Crank sensor harness thoroughly with electrical connector cleaner. And I mean thoroughly. I did not inspect the flywheel/crank pick-up... though it should be noted that the current clutch/flywheel/pressure plate is about over 140k miles old. I have a new exedy clutch/z1 nodular iron flywheel/ and exedy pressure plate. All cam sensors were replaced at the same time in 2020... I bought some auto zone ones initially and I think it was you who convinced me to immediately take them back and get OEM. I replaced intake and exhaust with OEM sensors straight from the dealer. I haven't done an intake/exhaust smoke test, but will look into it. I live in a luxury apartment complex now, no more private garage, so I'm not sure how they'd feel about me working on my car underground in the garage. Any tips on places I can work on my car without bothering anyone? Once I find a place, I'll try your spark plug test.
I'm not sure what pinging is. When I had the manifold off I was considering swapping the knock sensor out, should have just done that. Z1 sells the knock sensor for $195 while rock auto is selling it for $91. Both seemed to be made by NTK. Why is there such a huge price difference? I'll swap these out probably the weekend after next.
Not sure about where to work on your vehicle, I've always lived in a rural area outside town and I have nicknamed my neighbor "Junkyard Don". No one here really cares what you do, maybe create a new thread asking that specific question because I haven't ever seen it specifically addressed before.
Pinging is predetonation, it sounds similar to shaking up an aerosol can of paint, typically you would hear it momentarily while giving the vehicle quite a bit of throttle. Your knock sensor is supposed to be sending a signal back to the ECM every time it detects knock so the ECM can pull ignition timing out of the motor, some engines like the early 2000 LS1 chevy engines were notorious for knocking due to bad knock sensors. The VQ35DE is notorious for knocking and I've always attributed it to the factory defective knock sensor sub harness, the insulation peels off the conductors. If the ECM never gets the signal for knock it's going to keep pushing timing and it creates a poor cylinder combustion cycle which in theory COULD cause the ECM to incorrectly "see" a misfire on the crank sensor because it F's with the oscillating pattern of the crank sensor.
Pinging/knock/predetonation is basically when the cylinder fires BEFORE it reaches top dead center, it tries to force the piston back down even though it's still on the upstroke, it can cause significant amount of damage too but the VQ engines are pretty stout and a lot of them knock regularly.
The ECM monitors the crank sensor (as well as voltage monitoring for the spark plug discharge) for a misfire, the hall effect sensor should be a steady rise and fall of voltage as the crank sensor read the flywheel pickups sweeping across it, in a misfire condition there is a slight pulsation to this pattern since it's not ACTUALLY a smooth 360 turn, it's got 6 pulses of "turns" due to the combustion of each cylinder pushing the flywheel forward to the next point, the ECM is sensitive enough to be able to detect if one cylinder didn't push the flywheel far enough due to... magic... I guess. I just know that it works, I don't know HOW it possibly works to that sensitive of a degree but it does.
If the knock sensor data isn't getting to the ECM to pull back timing, and the engine is pinging which you would typically be able to hear with the windows down, sort of a "clackety" sound when you're giving it a lot of throttle, then that predetonation COULD be causing an arrhythmic crank sensor pulse that the ECM would think was a misfire since the knock sensor data didn't make it to the ECM.
Just my theory on other possible reasons for your P0300.
As for the price difference in the sensors, I'd get the cheaper one, Z1 Is probably selling an actual Nissan Genuine Parts sensor which goes through another layer of quality assurance at Nissan before it's sealed up in a Nissan bag. This increases the cost.
