P0340
 

Hi all,

Just going to dump my problems here...

Driving home the other day, everything seems fine until the freeway onramp when I lose all power. It feels like the fuel starvation problem that I've experienced before, and I am low on fuel.. so I coast off the freeway, and eventually it gets some power back, but it's extremely jerky and definitely not a fuel starvation problem now.

I limp back to a parking lot. The idle is not smooth and bouncing between 800-1400, and it won't rev past 3.5k at all. When I tested revving it, TCS and slip lights also come on. I turn the engine off, try to turn it back on, it will crank but not fire.

Eventually I get a code reader working and see P0300 and P0340 - Camshaft position sensor error. Check the forums and see a few posts that mention unplugging the sensors might work. I clear the DTCs and try it:

Both sensors plugged in - won't start

Bank 2 unplugged - won't start

Bank 1 unplugged - will start, but cranks for much longer than normal, and is in limp mode and won't rev past 3.5k, but the idle is smooth, and everything feels fine otherwise! This has been reproducible every time.

I swapped the left and right sensors, both looked clean and the problem is still exactly the same, and not P0345, and still runs with only bank 2 plugged in, so I think both of the sensors themselves are working.

I probed all connections with a multimeter at both harnesses for OC, SC, and the signal, at the sensors themselves, and in the ECM harness and everything looks fine, and the left & right banks match, giving more evidence that it's not a sensor or electrical problem. I don't have a scope, but the signals are 5V when off and jump around near 4.5V when the engine is running, which is what you'd expect from working sensors.

I feel like I've eliminated any electrical problems, and could it really be a timing problem since the engine runs fine and smooth up to 3.5k in limp mode? But will keep looking.. I've ordered a scope to check the actual signals, and will try to remove the timing cover to inspect the camshaft gears and timing chain this weekend. Most of the other threads I saw didn't post resolutions. I'm hoping I can fix this myself and not have to take it to a dealer :P

Car is tuned with JWT intakes, Nismo exhaust, oil cooler, 60k miles.

Other threads:

http://www.the370z.com/engine-drivet...t-skidpad.html
http://www.the370z.com/engine-drivet...ode-p0340.html
http://www.the370z.com/nissan-370z-w...ont-start.html
http://www.the370z.com/nissan-370z-g...-ak370z-4.html
http://www.the370z.com/nissan-370z-w...-z-issues.html
http://www.the370z.com/nissan-370z-w...ont-start.html

When a problem doesn't move side to side, then the problem is usually wire/ECM related. Try removing the negative terminal from the battery, step on the brake pedal for 10 to 15 seconds (I don't remember exactly, there is a thread somewhere) to clear memory, then reattach cable. Try restarting the car and see what happens with both sensors plugged in. I doubt you have a timing chain issue, the car wouldn't run at all if it jumped time. If you have access to a good scanner (snap-on, MAC or Consult), that might help. GL.

The ECU seems to have an issue with bank 1 and may see it off timing for some reason and wont let you start to protect motor.
But when bank 1 signal is completely missing it uses bank 2 to work out timing for bank1 (only an approx.)and runs in limp mode. Which is why it cranks for longer.
You may have an issue with the variable valve timing on bank 1 or even jumped a tooth on the timing chain. Or ECU/wiring issues.
Could be few others things as well.
Your best to take car to an auto electrician

Thanks guys! I will double check all the wiring tomorrow when I get a scope, but so far everything still seems OK and the problem repeats even after resetting everything.

I discovered last night that the car was super low on oil.. it took almost 2 quarts before getting back up to normal :eek: and was pretty dirty. I did an oil change, but the problem persists. The low oil makes me think it could be an actual VVT problem like a gallery not getting enough oil pressure or tensioner getting clogged or something like the other threads mentioned. I'm trying to think of ways to verify the VVT before committing to tearing it all apart.

I think I found something interesting.

I checked all the signals with a scope and they all look OK individually:

Attachment 139823

bank 1 at sensor
Attachment 139813

bank 2 at sensor
Attachment 139814

bank 1 at ECU
Attachment 139816

bank 2 at ECU
Attachment 139817

Attachment 139824

crankshaft at ECU
Attachment 139818

And then I noticed this drawing in the manual and decided to test both channels:

Attachment 139825
Attachment 139819
Attachment 139820
Attachment 139821
Attachment 139822

It looks like bank2 is advanced about 2ms relative to bank1, if they're supposed to be lined up like the manual shows. this would be about 5 degrees.

I also tested phase vs crank, but these did not vary at all with RPM. maybe IVT doesn't kick in before 3500, or the ecu disables it entirely in limp mode.

I'm not really sure the 5 degree out of phase is an error or not without knowing exactly what the gears look like, but this timing could be off.

Show us pic of crank sensor vs cam phase bank1 at idle.

Sorry didn’t get a pic, but bank1 started about 4 notches into the 10 notch pattern in the crank, and bank2 was 3 notches in. i’m not sure where the zero point should be or what the expected timing at idle is. Will get a pic tomorrow.

Like you were saying. Both banks should be the same, just shifted 360 degrees.

Can you see the timing chain when the cam sensors are removed. I think there's a colored chain line that lines up with mark in the cam pulley.

Anyway first verify chain timing if off and why before opening engine up. Could also be a stretched chain due to high mileage. This would explain the variation in timing between banks 1 and 2.

How many miles on this car and how often is oil changed?

I think car will also run with both cam sensors unplugged. Try it.

And do remember this engine is an interference one so if it is jumping teeth due to loose chain you could damage engine beyond repair.

https://www.youtube.com/watch?v=GnW2NclDbi0

And

http://www.the370z.com/engine-drivet...ing-chain.html

Thanks for the links. The car won't fire with both unplugged even after clearing and resetting everything.

These are vs bank2 but shows the phase offset

Attachment 139845

Attachment 139846

I borrowed a friend's working G37 for a few minutes and got these traces of camshaft bank 1 vs bank 2

Attachment 139850

Attachment 139851

I think this seems to confirm that my timing is in fact off somehow, so I'll have to open it up.

Yep, seem to be off by a lot. Next is to work out why?

Best to open up and see for yourself. Or get a quote to fix.

Remember to replace oil gallery gasket as this was an issue with the 08/09 models.
And something about the screws also going loose. Find out how to replace properly if you are going to replace.

And turn engine over 4 times manually and rechecking timing before closing it up.
You may need to replace chain guides a well if they are worn.

How many miles on car? Water pump replacement might be a good idea.

Very cool diagnostic you ran there. There are threads here on replacing the oil gallery gaskets. I did it myself a year ago, happy to answer any questions.

You can get a gasket kit from ConceptZPerformance. And if you have $$ laying around, might be worth it to figure out what else you'd like done "while you're in there." I ended up relooming and tucking all the bay wires, replacing the belt, etc. Maybe an upgraded oil pump?...

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