Alright so I got the engine replaced on my 08 FX35 awhile back and ever since I've had P0335 code. The shop did a **** job but I didnt have many options at the time.

So I replaced the crank sensor and cam sensors with OEM parts. After troubleshooting myself a little more, I finally took it to my mechanic. He took a hard look at things and he said the wire from the Crankshaft sensor to the ECM was pinched and he replaced the entire wire. Then he noticed the engine ground wasn't connected so he took care of that. When I left the shop he told me to drive the car for 150 miles so the car could relearn. The P0335 code was still on the car, so I erased that code and went driving. The car was driving amazing, everything was great. After 80 miles, I stopped to get gas and when I restarted my car the P0335 code went on again. Even with the code on the car was driving great. So this morning I jumped in it and the code was still on, I started driving it and my RPM's were jumping like crazy when I was accelerating. The car also wouldnt accelerate very well at all.

Before I left the shop, he did tell me the check engine light would probably come back. He went over a few options of what could still be wrong. He said, it would be a good thing if it was P0335 because he thinks we need to replace the throttle body unit.

What's everyone's thoughts on this? What should I do next? I can replace the throttle body myself but would that even make a difference? I just need to talk this out with someone because I'm going crazy with this car right now..

 

P0355 means the ECM cannot communicate properly with the crankshaft position sensor. It has absolutely nothing whatsoever to do with the throttle body.

Either the problem is:

-The crank sensor, if you purchased a GENUINE NISSAN OEM PART then it's probably not the crank sensor however you may have gotten a defective/malfunctioning unit.

-The wiring going back to the ECM, there are 3 wires on the CKP sensor harness, one of them goes directly to the chassis ground and the other TWO go back to the ECM. Verify the chassis ground wire (black wire) is actually grounded properly and doesn't have a bunch of corrosion on it. Also verify the harness itself isn't damaged/corroded/or has bent pins.

-The installer didn't properly clock the flexplate when installing the new motor. Theoretically you could install the flex plate in any orientation, however there is an ALIGNMENT DOWEL on the crankshaft that must match up to the matching hole on the flex plate, it's definitely possible to install the flexplate wrong though. Typically this causes the motor to run very poorly but not always.

-"Drive for 150 miles to let the car relearn" is an absolute MYTH, any mechanic that tells you this doesn't know what they're talking about. The only thing the ECM "learns" is the long term fuel trim which is a way for the ECM to account for variation in injector flow rate (as they get older they typically flow less) and minor vacuum leaks that develop over time.

You need a new mechanic, I strongly recommend taking the vehicle to Nissan for a 1 hour diagnostic, usually they're able to find the problem very quickly since the dealership Consult-III tool has a build in oscilloscope so they can see the actual data being sent back from the CKP sensor.

My gut feeling is there's still a ground disconnected, there should be a large jumper connected to the right side of the motor on the timing cover (USDM that's the passenger side) and it bolts to the chassis in front of the right side wheel well below the coolant reservoir on the DE motors. I think the HR motors it's in the same place.

 

Also did YOU supply the new crank sensor or was this something that the mechanic supplied? These engines are very notorious for not playing nice with ANY aftermarket sensors and require an actual Nissan OEM sensor (costs about $120) or a Hitachi (the OEM manufacturer for the sensor) which runs about $80.

If he purchased the so-called Genuine Nissan OEM sensor from eBay I can practically guarantee it's a fake. Their marketplace is flooded with fake "Genuine Nissan Parts".

 

Yeah, I bought all Hitachi sensors and installed them myself

 

When I erased the P0335 code and drove last night it ran great. Today I cant drive it. While trying to accelerate, the car is struggling hard and the RPM's are jumping especially between 2-3000. Maybe I will look into some of your suggestions tomorrow and see what I can confirm. I will say I dont know much about wiring.

Good idea to do the Nissan diagnostic, I'll give them a call Monday morning. I appreciate the advice!

 

Since your problem sounds erratic, I would highly suspect its a grounding issue. As Cleric mentioned, check the small ground wires on the front of the timing cover. There is also a skinny ground strap on the driver side rear of the engine on the valve cover. Might be worth checking all the other grounds since the engine was replaced, maybe they missed something. I'd check continuity with the ground wire on the crank sensor harness to the ground on the battery. IMO These cars have a 'weak' grounding setup OEM. Common aftermarket mod is a grounding kit:
https://www.z1motorsports.com/boost-...it-p-8252.html
I made one DIY for about $40, I ran one ground strap from the (-) battery terminal to the front timing cover, and another from the chassis ground (under the coolant reservoir) to one of the starter bolts.
Most noticeable difference was the transmission shifting and manual mode responsiveness. Engine responsiveness isn't noticeable. The stereo does play louder too!

 

The grounding setup was fine when the cars were new, they have NOT aged gracefully though.

 

Thanks for all the advice - I dont know the locations of all the ground wires and I cant seem to find that information online. Like I said before I suck at wiring, I need pictures haha So I scheduled a diagnostic with Nissan this afternoon. I hope I will finally know one way or another what the hell is wrong.

 

As I recall, the wire on the left runs to underneath the coolant reservoir on G35's, not sure about the FX.
The two in the middle are very small/thin wires, but are important to provide ground to some sensors.

 

Ok I found the 3 on the engine and the one on the left hand side on the wheel well. They all look fine to me..

 

Also, my mechanic said he reconnected a ground. I’m guessing that was the one on the wheel well because you can see grinder marks. If I drove awhile with that ground disconnected, would it have effected anything I could check?

 

It looks like this is the ground wire that my crankshaft sensor goes into. I would have to pull the dash to access this right?

 

Well this is what Nissan told me..

 

That one you circled in yellow on the left is actually the HEADLIGHT ground, the engine/chassis primary bonding jumper is down lower and it has a 2-hole lug bolting it to the chassis. On the G35 it's directly below the coolant reservoir and further down the chassis almost directly below that headlight ground.

 

I’m guessing this is it. This is probably the worst looking ground I’ve found so far.