Crank, no start (yay!)
 

So, I’ve gone back to the harness and ECU that came with my car. (I’m installing a non-rev engine in my 06 6MT because of reasons.)

Now, the car cranks, but won’t start. I can connect to the ECU with my scanner, and see code for the exhaust VVT stuff (which isn’t present on this engine, no surprise there) and one for the fuel level sensor, P0462. That one is odd, because the fuel gauge is working correctly.

I *just* finished putting the original wiring harness back in, so it’s possible I missed a connection. However, were that the case, I wouldn’t expect the gauge to work. Hmmm.

I removed the #1 ignition coil from the block, popped in a spare spark plug, and cranked the engine. No spark. I verified that I’m getting +12v on the that connector with a multimeter.

This implies, at least to me, that the ECU isn’t sending a spark command. So, why would that be?

The bright red light on the dash to the left of the instrument cluster - the one that flashes when the key isn’t in the car - is on, solid red. The only thing I’ve found so far in the manual about this indicates that the key isn’t registered. (Either key - I’ve tried both.)

Nav, radio, everything else works fine. I can lock and unlock with the remote. I even reprogrammed the remote using one of these keys. (Lock the doors, stick the key in six times, hazards flash, etc.)

So, my question is: how can I rule the anti theft crap out as the cause of the problem? If it is anti theft, why would the car let me program a remote if it doesn’t recognize the key?

This is the ECU that came with the car, original keys. The car sat for about two years without a battery. I suppose it’s possible that the ECU “forgot” the keys, I really don’t know much about that system. If it’s some sort of rolling code than the keys would also have to keep a charge, which seems like poor design.

HELP. PLEASE.

Programming the fob has nothing to do with security recognizing the transmitter in the physical key itself.

Solid light means the NATS is triggered but I thought NATS would disable cranking the motor as well? Maybe I'm wrong.

Also, the rev up ECU will NOT work with a non rev motor, it requires a signal from all cam sensors in order to fire the injectors and ignition coil packs. Without a signal from all 4 cam phase sensors it won't fire, non rev ECU only reads 2 cam phase sensors.

Since the old engine is still sitting here, dutifully supplying replacemrnt bolts and misc bits, I went ahead and pulled the cam actuators and sensors and plugged them up to the car.

https://cimg4.ibsrv.net/gimg/g35driv...623bcc37c.jpeg


(Side note:!nice magnets, I may have a use for those later!)

All the codes are gone save the fuel level sensor - and the gauge stubbornly insists on reporting an accurate fuel level - and still no spark.

Also: the car will crank even with the ECU completely removed. So, Cranking doesn't preclude NATS preemption.

Thanks again for your help. I owe you beer.

If it's solid red you might need the keys reprogrammed. I think it allows a crank without spark, but I could be wrong and it's a no crank at all. Either way a solid red light is a NATs trigger and probably needs to be fixed by the dealer or locksmith the right tools.

Can you verify all the cam and the crank sensors are sending output? Does the RPM needle move when you crank the engine?

I'll check it when I get back to the car in a few days. It's stored at my father's place about 100 miles from me, had to come back home this morning to see my wife & kids and get some actual Real Life Stuff (tm) done.

Are the keys registered with / identified by the BCM or ECM?

Another question would be whether the dealer can program the keys without the entire car. As in, if I took them the ECM and/or BCM and the keys, could they hook it up and program it? Or do I have to tow the entire car, which isn't entirely reassembled and is 70 miles from the nearest Infiniti dealer?

I'll call them, but in my experience, dealers aren't all that willing to address unusual requests like this.

Yeah what you're doing wouldn't even work regardless of NATS, the engine doesn't necessarily need to see the sensor itself it needs the SIGNAL from the sensor passing the pickups on the camshaft, the sensor is just the middleman so the ECU knows exactly where the intake/exhaust cams/crank are in their rotational cycle. Once all conditions are met and it knows exactly where the crank/intake cams/exhaust cams are at in relation to one another THEN it sends the signal to spark/fuel at the correct moment in time.

The sensors just allow it to read the cam/crank positions, if those exhaust cams never move (because the part is literally just sitting stationary) it still won't fire.

The components that make up NATS, key, antenna located on the lock cylinder, BCM, ECU, wiring. It could be any of them causing the issue or (as I suspect) it's because the ECU doesn't see the exhaust cams.

The dealership needs to be able to access the ECU/BCM in order to program the keys, they do this via the OBD2 port so if you could supply all the components including the wiring harness I suppose it's possible?

Also, any NISSAN dealership can perform the required service, not just Infiniti.

Okay, since I’m crazy, I:

Yanked the harness again. This is not a fun process with the engine in the car.

Hooked it back up to the old engine, which is strapped to a pallet. I should’ve taken a picture of this, but my phone was dead. :P

Extended the grounds, tested for continuity - all good.

Tested power at the coils - happy +12V. I can talk to the ECU/ECM/whatever they’re calling it this week and it’s happy.

No spark. No fuel.

I have a friend with a CONSULT II which I’m borrowing this weekend, will see what I can see.

And, while I’m at it:

Passive sensors are funny things. The ECU can read it and attempt to determine where the cams are. But, I know from personal experience that this car will start with the cam actuators and sensors completely disconnected. It won’t run *well* at higher RPM, but it WILL start. Also, the sensors can’t really send good data until the engine is spinning. It’s similar in principle to running open-loop until the O2 sensors get up to temp, but a few seconds instead of minutes.

The crank sensor is a different beast. The computer needs to know its position in order to know when to spark. Testing that is next on my list, need to find my o-scope in the garage. (I switched from firmware to software / graphics dev years ago, a lot of my EE skills and equipment have atrophied.)

Going back to the shop this weekend, will reprogram the keys and hook up the CAN sniffer to see what all the sensors are doing. That should help.

Again, thank you, everyone, for your time and input. Much appreciated.

PS: WEIRD: I can open the trunk with the fob and the switch on the dash, but not the button in the tail light. This indicates a harness break or disconnection. Hmm. Given the fuel level sensor code, which also requires talking to something at the back of the car where the gas tank is, I’m reasonably certain that I’m missing a connection, or have a bad ground somewhere.

I have three grounds connected. How many are there?

So, as I posted elsewhere,

The car runs. Using the non-rev engine, rev-up harness, and non-rev ECM, it starts and runs. Pretty smoothly, actually.

Thats is the weirdest combination of components and the last thing I'd expect to work.

The G35 ECM (code UM) won't communicate with the G35 BCM, but the 350Z ECM (code FJ) does.

I'd like to find another (affordable) UM ECM to test with as I suspect that is the culprit. I plan to swap the rev-up heads onto to this engine over the winter, I just don't have the time to do it right now and the car needs to be mobile in the meantime. Leaving the non-rev heads and ECM in the car doesn't seem like the greatest idea, especially when I one day sell the car. (I'm keeping a full record of all of this for the next owner. I've been burned on used car purchases before, and I'd never knowingly screw someone else over. I like to be able to sleep at night.)

I've read here that the VQ heads can't be resurfaced. How accurate is this? Is it due to valve/piston clearance, materials used or what?

The good news is the probably won't NEED to be shaved, they have a very rigid design but it's also probably the most finicky set if heads about proper torque pattern and preload. iirc it needs to be torqued in 3 steps.

My Solstice was the same way. I have ARP head studs on that one. Torque in three steps, to 25, 60 and finally 80#. If you do it in the wrong order, it'll warp the head. (Like the VQ35, it's an all-aluminum engine.)

There's something to be said for iron heads and block. Sure, it weighs 50% more and heat distribution sort of sucks, but, hey, they're resilient.

Are the head bolts on the VQ torque-to-yield?

Depends on the studs (stock ones YES), there's a few options for the VQ and it's strongly recommended to look into using the HR gasket not the VQ gasket due to some improvements. It requires a mild amount of dremel work to use the HR gasket but it's worth the effort especially if you plan on adding power to the motor.

Two things:

Item 1:

I bench-tested the G35 ECM - the one that’s not working - and found it’s not sending on the CAN lines. It’s weird, but such is life. I’m more surprised that the 350Z ECM will run the engine using the G35 harness. :\

Item 2:

Okay, I’m going to go ahead and swap the heads and put the rev-up heads on this engine. I need to go over them with a feeler gauge and have a long conversation with the valves, but they look ok (visually, but I can’t eyeball 2/1000ths.)

Question: how difficult is this to do with the engine in the car? I’ve read through the FSM but I’m getting dizzy following all the links.

I once rebuilt the engine in my Z32 TT. It sort of worked when it was done, but the most complicated thing I’d done before that was a Skyline caliper upgrade. Working on my US cars is simple by comparison. (Why, oh why, did they put every freaking harness connector on with the push-tab TOWARDS the thing it’s mounted to instead of outward? I just about cut part of the harness the other day to get that connector that’s on top of the transmission on the back. My hands aren’t exactly large, and I could not, for the life of me, get that little !#@$!! Off.

I can pull the engine again if necessary, but I’d (obviously) rather not.

Advice?

What will I need besides new head gaskets? New head bolts? I’m not building a track car, not interested in adding go-fast parts or building it for boost.

Thanks.

what would it mean if the RPM needle doesnt move while cranking?

Typically it means a failed crank sensor, that's where engine rpm data is derived from.