Cranks but won't start
 

hey guys I'm an experienced mechanic, but this car has got me stumped.

06 350z - Came to my shop as a no start diagnosis. Here is what I have done so far, any help is really appreciated !


Car cranks over strongly but won't start, and hardly even hiccups, doesn't want to start. When you put the gas pedal all the way down it seems like it hiccups a bit, trying to start ever so slightly.

I pulled all the wires, checking for spark at each one, wires have spark, and are in the correct order.

Pulled plugs and replaced with new

Fuel pump can be heard priming.

Sprayed starting fluid down into the intake via the throttle body, and also directly into the spark plug wells when I changed the plugs, no change at all.

Battery is good and charged

No check engine codes, and no security light. Trouble lights come on normally when you turn the key to power, then go off.


Really stumped here. Figured since I can see spark, it must be fuel/air, but no reaction to the starting fluid.


Anybody have any ideas?

AP104 Does NOT fit 2006 350Z. I'd suggest sticking with the OEM NGK plugs.
https://cimg7.ibsrv.net/gimg/my350z....8c0aabc78e.png

Im sorry I actually listed the wrong plugs! I did a 06 Taurus the same day and had the plugs in my head from that car. It got the correct plugs, still no idea whats up with it. At this point I'm thinking head gasket or internal issues in the motor, the oil has a strange smell to it. Not typical oil/coolant mix or gas/oil mix smell, but it is semi sweet smelling.

have you done a compression check?

Not yet, was trying to eliminate the superficial parts/possibilities first before checking the motor itself, but its looking like somethings going on in that motor unless I'm missing something..

If the ECU was bad, there would likely be some signs elsewhere right? Check engine light, no spark, something? Everything seems totally normal aside from the oil smell and the no start.

Have you read diagnostic codes? Like P1610-1615?

It has no codes...

When I need to have my car towed by AAA when I move, I unplug the ecm. The car will attempt to start, but will never start, so I get the tow. It tries to crank over so the tow driver won't try to jump the battery.

So maybe an issue with communications to the ecm. Check the ipdm and it's relays. I also fried my ecm once, took a heck of a while to diagnose, but the car would try to crank over but never would.