me and my buddy are trying to get his g35 running smoothly, we put a new motor in it a few months back and it ran hot, we narrowed it down to a head gasket, replaced that, then we had timing issues so we re-timed it. Now we have it all back together and it wont start. At first we weren't getting any spark what so ever, but now when we unplug the bank 2 cam sensor it will start and run, just poorly. Any ideas?

 

First thing it sounds like is that cam sensor is dead. With a replacement motor, I would replace both cam sensors to start.
Also check your variable VVT and make sure they are clean. Replacement motors sometimes have those a little gunked up from sitting so long.

Finally, what codes are you currently throwing, there have to be some.

 

forgot to mention that but there is a u1000 code, which makes 0 sense because im able to communicate with all modules and the only thing i could find abt that code is the IPCM going bad which means nothing would work what so every, which everything does, just doesnt fire

 

Did you pull the IPCM? Underneath if the hole is plugged it fills with water, shorting out the IPCM. Check ignition relay as well.

 

i dont believe it could be the IPCM judging that everything still works. all relays and fuses are good, remember, The car will crank and run, poorly, if we un plug the bank 2 cam sensor, if we connect it back while its running it will still run just still poorly. Just once we turn it off then try and crank it again, connected, it will not start, just turn over

 

I believe, but not 100% sure, once you start the car, if a sensor is dead or unplugged, it is mostly ignored until the car is restarted. I would at the very least replace that sensor with a new one to see if it behaves.
Are you saying you get no other errors except the U1000.

When you replaced the engine , did you switch ECU and use the one it came with the new engine? Or still the original?

Is this a JDM motor? Meaning could you have a bunch of sensors that are not behaving correctly for this car? Can you swap sensors with the original engine?

 

we replaced the cam sensor, still the same issue, but now it isnt throwing a cam code or a u1000, this motor is out of a 350z, when we originally got it in, it ran fine, just had a leaky head gasket, we replaced it and now were having all these issues

 

OK, so help me make sure of what you have and haven't done to the car

1 - Do you have the ECU that came with the engine?
2 - Is the engine exactly the same? Not a revup? or from a different year car?
3 - Have you replaced all the hoses and gaskets when doing the swap that could be suspect? valve cover gasket, valve to valve hose, intake gasket?
4 - Have you verified by pulling at testing the VVT solenoids to validate they are moving? Also looking inside are they clogged?
5 - have you reset the ECU to relearn the motor
6 - What do your upstream and downstream O2's look like, do they show rich or too lean? Anything unusual?
7 - Have you verified ALL the grounds are done. There are a bunch, like the ones attached to the front of the engine, and the ground strap on the side
8 - Could there be old shitty gas in the car?
9 - Have you validated the fuel injectors and their pressure? Did you bring over the original ones to the new replacement engine
10 - have you changed the plugs? Are they the correct gap and type? Have you validated spark to each one?
11 - Any leaks with the air intake? Does the car run any differently if you unplug the sensor from the intake hose?

 

1. no this is the ecu that came with the G
2. yes, same exact engine, just from a 350z (non revup)
3. we replaced any bad hoses and all gaskets are new
4. yes
5. yes
6. they are all showing lean, we havent been able to see what the are while running
7. yes, we have went over them 1,000 times
8. we just put new gas in it
9. yes and yes
10. yes, yes and yes
11. no leaks and not sure

our instructor is dead set on it being a loose or faulty ground but we have no clue where it could be

 

we are running a false lean, making it run super rich

 

For a rich/lean extreme condition like this, I tend to put in a pressure regulator and adjust the pressure to get it to fall in line. Unless you have a programmer in which you could adjust up or down the injectors until it read correctly.

At this point, if he is convinced is a ground, then my thinking is:

1-Have you tested the grounds at the ECU first? Meaning both the ground wire that is usually attached to the outside of the ECU as well as the black ground wires in the harness.
2-Then, have you taken apart the harness to pin each one at each end? This is a slow process but you might have one of the pins loose and that's why it's not grounding correctly
3-If you unplug the cam sensor and it runs, what errors does it show besides the cam sensor error?
4- Could there still be a timing error with the cam or crankshaft/timing chain? You don't have to be very far off to get it to not start

 

dont believe we have a way to regulate fuel pressure but i’ll talk to my buddy about getting a FPR

1-Yes, as far as we can see every ground is good, ECU grounds and harness grounds.
2-we haven't taken it apart but we have tested all the pins in the connectors, we noticed one thing, which is weird, bank 2 cam sensor gets a signal pulse on the 5 volt reference wire, bank 1, on the other hand, doesn't. Bank 1 is the good sensor, bank 2 is the one throwing the code.
3-Bank 2 cam sensor is the only code it is throwing.
4- I believe we are starting to narrow it down to timing or a bad intake cam, This specific intake cam came off the original motor because we broke the one off the new motor, would you think it being from another motor could throw it off? Is there that small of a difference between a 350z vq35de and a g35 vq35de for it to not want to run unless it isnt getting a signal?

 

Those sensors can be wonky. I don't exactly understnad why there are so many shitty ones made, but I've definitely seen people swap 2 or three to get one to work well. Unless OEM, be suspicious of them.

 

Same for my audi.
It was hit or miss, but less so once I made sure I got parts through Rock Auto...got smp (standard motors).
There seems to be a QC issue with these sensors industry wide...I blame China.

 

I would replace both cam and the crank sensor with Hitachi (they were the OEM manufacturer for the sensor). Definitely don't use any aftermarket sensors for those, Hitachi or OEM Genuine Nissan only. I am also strongly opposed to using the cam/crank sensors that come with used engines. You have no clue if they're any good.

Do you have an oscilloscope? You can verify the cam and crank sensors are sending the correct pulses to the ECM by backprobing the ECM while you crank the engine then comparing the reading to the service manual. They have a picture of the pulses under the DTC codes for cam and crank sensors in section EC - Engine Controls. I think it's P0340 and P0345 for the cam sensors, P0335 for the crank sensor.

As far as the cam sensors go, pin 3 (pink wire) should have 12vdc, pin 1 (black wire) is ground source so test for 12vdc against that pin. Pin 2 (yellow or orange depending on sensor) is the signal back to the ECM.

You can't really test for voltage on the signal wire since it's a hall effect signal, need to check it using an oscilloscope. Sometimes an analog meter will be able to pick up the rise/fall of zero to 5vdc signal but most DMM's can't.

As for the replacement intake cam, as long as it was from the correct bank you should be good. Normal OEM cams have a pink stripe for intake, orange stripe for exhaust. Right bank 1 is stamped RE, left bank 2 is stamped LH. I would double check to make sure the correct cam was installed unless you're 100% certain you don't accidentally have two left or two right cams.

Ground wiring, there should be a larger gauge bonding jumper from the timing chain cover on the bank1 side that lands on the chassis directly below the coolant reservoir. If it's not there you can temporarily use something like 6AWG wire or larger and just make a jumper from the engine to the battery negative.

If you're using the injectors that came with the donor engine that could DEFINITELY be the issue. Never reuse donor injectors without flow testing them first.