Nissan 350Z VQ35DE

I have a problem with starting. Sometimes the car starts right away, and sometimes it cranks but doesn’t start, as long as I hold the starter it won’t start, I have to let go and make another attempt or two and it starts straight away.

I used the trigger settings from basemap, I have the car tuned, everything works perfectly. I checked the ignition with the lamp and it’s OK. I have synchronization on cam tooth 24, the scoop looks good. The only problem is starting it. It looks like it doesn’t sync as it should every time, even though I have “synchronization” in the log.

The car is taking part in the rally in a few days, do you have any ideas on what to look for?

project, log and scoope

I can’t decide looking at the logs if its losing sync or the cold start fueling just needs adjusting. Are you cycling the key quickly in these logs?

Battery voltage is dipping into the 6V at times, this is low and especially with 12V hall sensors like the VQ has that may be too low.

Is the scope log you posted at cranking speed or engine running?

Hi! Thank you, I didn’t pay attention to the battery voltage because the starter turns quickly. But maybe the voltage disappears at the EMU BLACK itself - I will check it.

As for cold start fueling, I have already checked 50 options, no matter how many ms of fuel injection I have, the car does not start. It literally happens randomly.

I tried from 2ms to even 8ms. This is not the first car I have made, we have been doing this for several years, but I have never had such a problem. Usually, however, we have a 60-2 trigger, and here there is a specific trigger and maybe something is wrong with the flywheel. This is a rally car, with a Quaife sequential gearbox. However, when checking with the strobe lamp, when it starts, the ignition matches the lamp. Maybe I’ll check the ignition with the lamp when trying to start, to see if anything changes.

When it comes to trying to start it, it looks like this: I turn on the starter and hold it for 10 seconds and the engine will not start. Then I take a break for 2 seconds and on the next attempt the car starts after a few revolutions of the crankshaft. The engine will run for a while, I turn it off and it will either start immediately or I can crank it for 10-15 seconds and nothing. Only interrupting the cycle and restarting it and re-synchronizing it causes the car to start.

the scoop is when the engine is running, so I’ll see what happens if it doesn’t start.

The log shows “cam sec. trigger sync” that when synchronization appears, from the value 0 tooth, first for a while it becomes 16 tooth and only then 24 tooth and after a few seconds the engine starts.

We use the engine harness from the car, it is not a new harness. We connected it according to the pinout from the p&p adapter.

I’ve found the Black to very voltage stable, even down to 6V. The sensors I have less experience with how they handle low voltage conditions.

Your tune has quite a lot less fuel on cranking compared to the Ecumaster supplied basemap, though I usually find their maps quite rich anyway. Prime pulse really helps with low temps, and batching the injectors can add a lot of fuel quickly. Especially with a trigger setup like the stock VQ, the ecu doesn’t know engine position until the cam sync’s its spinning for a bit before firing the injectors at all. I know aftermarket flywheels can be an issue on these cars since the crank trigger is on the flywheel and tolerances are critical.

I’m not 100% sure on this but the cam sync tooth may need to change based on oil pressure being this is a VVT engine. With no oil pressure the ecu can’t control the cam, once the engine is spinning fast enough to generate oil pressure it locks onto 24 degrees, but thats a hunch of what’s happening in the background when you select the “350Z trigger type”

Lol a 60-2 or 36-1 would be a simpler setup.

I know these sensors do fail, I’ve yet to do a standalone on one and have the sensors fail but stock ecu cars many times they have trouble starting and replacing the crank and cam as a pair is the solve. Hall effect are a bit less resilient to heat

Overall, in my opinion, this car needs to be disassembled and reassembled. It’s a freshly purchased car and its condition is average, but that doesn’t change the fact that it needs to be repaired somehow :smiley: so that it can take part in a rally in a few days, and then you can move on.

I would like to do this starting, because it may be problematic during the rally.

I’m just wondering if it’s a problem with the oil pressure on the VVT, because it looks a bit like that, but the car has an oil pressure sensor and the pressure is 6bar (on the crankshaft) as soon as the engine turns a few revolutions.

Oddly enough, there were no such problems on the OEM ECU. Perhaps the OEM ECU copes better with any deviations in the trigger during startup.

I did notice your scope log and the one supplied in the same folder as the basemap differ ever so slightly.
I asked what rpm yours was taken thinking maybe that’s the difference, but yours has the Crank and Cam teeth aligned, where theirs does not.

In my experience OEM ecu’s are better at ‘coping’ with deviations in trigger vs ecumaster. Not sure if its just good at ignoring them and the standalone isn’t or if oem hardware is just more finely tuned to deal with one engine’s specific deviations.

If you an oscilloscope you can put onto the crank and cam sensors, verify that when the ecu is losing sync on cranking that its still seeing a signal.

Problem is either the ecu’s interpretation of the signals or that its not receiving any.

There’s is a few instances on your log of a “false secondary trigger, filtered” error. That’s another area to explore

I will make a new scope, because in our engine I need to have a slightly different camshaft offset than in the basemap. I physically checked the timing and it is fine, but when I started the engine on BASEMAP, CAM1 with VVT turned off had a value of -8 degrees, and cam2 had a value of +2 degrees. I thought that maybe the camshafts were physically moved, but I removed the valve covers and measured the valve lift at TDC for the 1st cylinder on the 1st head, and for the 4th cylinder on the 2nd head, because in both cases the crankshaft can be precisely positioned at TDC.

So it turned out that both CAM1 and CAM2 open by the same amount when the piston is at TDC, and VVT does not work, so after starting the engine and turning off VVT, I had to make an offset correction so that 0 was zero.