5.5 gen Maxima tune-up, now no start :(

[bartZ32tt]

Background: 125k miles, 6-spd transmission, completely stock (prior). Ran well (no SES light/codes) but a tad sluggish, IMO. My exhaust blew out, so I figured it was replacement/upgrade/tune-up time.

What I did: changed spark plugs (NGK IFR5AIX-11), installed OBX headers with new gaskets, new Walker OEM catback with new gaskets, new valve cover (the one by firewall) since it was old, new upper plenum gasket, extended both primary o2 sensors via crimp-connectors, brand new Bosch secondary o2 sensors (no o2 simulator).

Problem: cranks and doesn't start. Verified spark on one cylinder (got too late to check others). Checked SES light for codes: getting 10 slow blinks, 3 fast blinks, 4 fast blinks, 10 fast blinks (and repeats from here). I assume this to be code P0340 - correct? Would this cause a no-start condition?

Additional information:
-I used crimp connectors to extend the o2 sensors because I was unable to solder the stainless steel wires. I did not keep track of the order of the two white wires. Does their order of connection to the plug matter?
-when I removed my rear-center coil, there was oil all over the outside of it. Didn't look like any oil got inside where it contacts the spark plug though. I cleaned the cylinder out the best I could and maintained order of coilpacks upon reassembly.
-All spark plugs were in terrible shape, believe they were original.
-Unknown age of all coilpacks. Like I said, car threw no codes before though, and I verified 2 of the coilpacks' resistance was within spec, so I reused all of them.


Any help is greatly appreciated as I continue trouble-shooting on my own.

[frapjap]

Welcome to NICO!
Sounds like a bummer of a problem.
The first thing you might do is check to make sure all of your grounds are grounded. Maybe you missed one when you removed the coil packs.

After that, definitely check into the wiring of the 02 sensor. My guess is that it matters, but check the link to the FSM in my signature.

[PapaSmurf2k3]

O2 sensor shouldn't prevent it from starting.
Did you mix up the wiring on your coils/plugs? If they aren't firing at the right time, you've got a problem.
Have you confirmed you're getting fuel?
Could always try putting some fuel down a vacuum line, or spraying some starting fluid in there to see if it starts... can't imagine why that would have changed, but you never know.

[NutriaforBreakfast]

What about the connection to the camshaft position sensor?
Could the security system be activated?