P0302 Cylinder Misfire

SouthArk370Z

Possibly a wiring problem. FSM (link in my sig) has wiring diagrams and will tell you what kind of signal to look for at the injector. Also lots troubleshooting procedures.

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Capncorroded

With my situation last year I diagnosed it as the ECM. The dealer confirmed it with consult and swapped it out. Luckily I still had a warranty. No problems since.

My theory about why it went "possibly", was error on my part and leaving the key fob in the cup holder during storage. Ive always left the keys in my stored vehicles, and completely forgot about how there is a "wake up" of some features when the fob is in range.

SonicVQ

If you want to troubleshoot the ignition coils, you will need to scope the current of each ignition coil on the primary (low voltage side) typically the coil ground.

When you look at all 6 waveforms, you will quickly find out which one is different and that is the bad one.

If haven't used a scope or don't have access to one, then you might want to take it in to a good shop.

Hug0

Thanks for advices.

SonicVQ:Coils are OK. Also I am 100% sure, that problem is only on cylinder 4.

I tried some troubleshooting. Can somebody tell me what is condenser with connector F8? And where I can find it? I can´t find any pictures of it. I know what it should be, but I cant find it anywhere :/

SonicVQ

The condenser is difficult to find as it is taped to the wiring harness that is under the upper intake.



This is what it looks like:

Attached Images

	1.jpg (208.0 KB, 98 views)
	2.jpg (28.0 KB, 95 views)

Hug0

Thank you!!!!

Little progress: I tried osciloscope today. On cylinders which are OK, there is 5-6V signal on signal wire on coils. On fourth cylinder, there si similar signal, but only 2-2,5V.
Wire from ECM to coil plug seems to be OK (checked with multimeter).

I really hoped, that problem is caused by bad wire, but It kinda looks like ECM problem

Should I try to change signal wire from ECM to coil? According to my uncle (electrician) wire is 99% OK.

SonicVQ

Now that you have a scope, I think the next step is determine bad coil, vs bad wire/ecu.

Set up the scope and get a screen capture (use phone if there isn't a built in function) of cylinder #4 signal wire and either #2 or #6 ignition coil.

Move ignition coil #4 to #2 or #6, and take screen shots again.

Compare the pictures and see if the lower voltage signal wire moves to #2 or #6 or stays on #4. (posting the pictures would also be helpful to me)

• If the low voltage signal moves with the coil, I would suspect a bad coil.
•*If the low voltage signal stays on cylinder #4:
• check coil ground and 12volt supply

Since the original problem got worse after changing the plugs, I would focus on the wiring and check connectors for burnt or bent pins.

When checking wire resistance, it is important to keep in mind that the meter uses a very small current for the resistance test. The ignition coils uses a fairly high amperage of about 12 amps for 0.005 seconds when at idle. (I have scoped my G37's ignition coils)

This can result in the meter showing a good connection, but it may not be a good enough connection for the current draw of the coil.

Additional thought:
Over the years I have tried to help many people with car/engine problems.
About half the time, aftermarket add-ons have directly or indirectly caused the issue.
Melted wires, wires pulled too tight and break internally, loose connections, missing grounds, etc.

With this in mind, please double check any modifications that have been done looking for the items mentioned above.

Hug0

Unfortunatelly, I don´t have a scope. My uncle has really old one, so I went to his place and we checked it there.

I took some videos, but I need to check if they are OK.

I changed coils (#2 to #4 and back) before and there was no change. I also tried create spark between coil with sparkplug and ground. On #2 coil socket, there was pretty nice spark, on #4 socket (same coil and sparkplug used) there was none. #4 coil is now brand new from NGK (there was some chinese piece of sh*t from previous owner).
Should I check this again with scope?

I checked 12V and ground and it was OK. I will double check that.

According to mods, I think that only one electric related is Uprev tune. I tried 3 different maps without any change.

I would like to change signal wire, but I am not sure if I can change it myself.

I checked all grounds I could find and clear them. Wires looks OK, there is no obvious tension (but I know, they still can be damaged).

SonicVQ

If you haven't already, disconnect the ECU and the ignition coil #4. Check the resistance between #4 signal wire and ground. It should be open.

I think the next step would be to temporarily run a wire from the ECU to the signal wire on the ignition coil.

Use the factory shop manual to find the location of the cylinder #4 ignition coil wire. On my 2011 G37 it is pin #11 and the wire is green. The 370 might be the same or different.


At the ECU tap into the #4 coil wire and run it to the signal wire on #4 ignition coil. Since this is just a test, make it easy for yourself and run the wire out the window to the engine.

** Make sure to use a wire that is about as thick as what is already there. **

The point of the test is to have a known good wire between the ECU and ignition coil #4 signal wire.

• Test for spark strength (like you did before) and compare it to #2 or #6
• Start the engine and check to see if it is running on all 6 cylinders.

I wish you luck and let me know the results.

Hug0

Hi, little update...

It is open.. No shortage there.

If I connect wire to ECU socket with needle or something, there is no change.
Unfortunatelly, I don´t have that small pins to change whole wire without damaging original one.

I don´t want to cut original wire.
Unfortunatelly I can´t find that small pins anywhere.

Btw: we tried to check voltage with scope by putting needle into ECU socket and there was also only 2V.

I will let you know results after I´ll find correct pins and do a proper test with new wire.

Hug0

So, here is little update...

I found used ECU socket and coil socket.
So I took new cable and solder pins to it.

And suprisingly new cable did not make any change..
I took it and replace wire for cylinder 2, just to know if my made wire works and it does work fine...

Now it looks like, that all coil wires are OK. There is 12V with ignition, ground is OK and now I can tell that signal wire is also OK.

Unfortunatelly this leads me to ECU...

sportsman2003

Look on Ebay. I have seen ECU's for $100.00

SonicVQ

I think you are right.
Ebay is a good source for inexpensive ECUs. I have purchased them for as low $50 US (plus shipping, duty and taxes of $50 to Canada, so $100 total)

I believe you will need to have the VIN re-programmed, and re-sync the ECU and BCM so your intelligent keys will work and you can start the car.

-OR-
you can unsolder the EEPROM (95320 4Kb) and move it to the replacement ECU.

-OR-
you can read the old EEPROM and write to the replacement ECU EEPROM.


Good luck!

Hug0

Thanks!

That is what I am little aware. Immo and ECU settings.

I have MPPS cable with software for downloading and uploading ECU sw (I used it for my VW and BMW), so I am thinking, that I will duplicate my ECU to new one. But I don´t know how about immobiliser?

Also I have ECU MEC107-390 and only one available localy is MEC107-070. I can´t find any info about compatibility.
its around $200

also I can force VIN into ECU thru Uprev SW.

SonicVQ

The "MEC107" is not the part number, it is more like a production number.

You need to find out the ECU ID of your existing ECU. It will be something like "6GC2A"

This can be done with an cheap ELM327 OBD scanner and an app like:
• OBD Fusion (in diagnostic reports, under calibration ID)
• NDS III (Android Only and bluetooth OBD scanner only)
• Torque Pro (Android Only under Adapter settings)

The actual part number for your ECU is 23703 + ECU ID, for example: 23703-1UX0A
IF your ECU ID is 1UX0A.

As far as I know, the 370 and G37 use the same hardware for the ECU, but have different programming in the ROM and in the EEPROM that is not part of the SH7059 processor, but a separate 8 pin IC.

You will need to copy the ECU ROMs programming and write it to the new ECU.
I don't think your MPPS cable will work on a Nissan / Hitachi / Renesas ECU.

Also, you will need to copy or move the 8 pin EEPROM that holds the key IDs, VIN and other stuff.

I think your best option is to contact "ByThaBay" (Nissan 370Z Forum - View Profile: ByThaBay).

I think he can provide a pre-programmed ECU that you can just swap in.