Hello everyone. I’m new to the Z community and have owned my Z for about 8 months now. I have a 2003 350z with 118000 miles that recently started stalling out for what seems as no good reason. Engine mods include Injen COI, plenum spacer, and Invidia Gemini/Cat delete.

It all started when I did my valve cover replacement. I replaced 1 coil pack that was leaking at the seal as well as all the spark plugs with OEM Nissan ones. When I hooked everything back up she ran great! I did the ECU reset and drove 100 miles continuously, doing both highway and city driving. I continued to drive it for the next few days racking up a total of around 200-250 miles. Then one day I pulled off my street and it stalled out and would not start again. After a few more tries it started as nothing was wrong. Ever since that day the car randomly stalls, at idle AND while driving for seemingly no good reason. The car has no issue starting, sounds good and then randomly it’ll misfire a few times and then, it dies. Usually after it stops, 90% of the time it’ll start right back up, the other 10% it’ll crank/no start, and after a few minutes will start right back up. I can’t find any vaccuum leaks, I have ruled out VVT solenoids, MAF, O2 sensors have proper voltage and fuel trim readings. Engine Idles around 625-650 which seems low. I have no way to test AFR but it seems rich judging off smells and some buildup on exhaust tips (not sure if thats normal when Catless) when it stalls, the oil, battery, and cel light all come on and then turn right back off when started again, also it does not throw a code neither before/after stalling.

I included some screenshots from my OBD reader if that provides any info.

 

no codes?

 

Nope. None. CEL pops up after it stalls but then on startup it goes away.

 

sounds like cam/crank sensor issues. Check everything in the engine bay. Even battery terminals for corrosion or lose wires anything.

 

This was the first rabbit hole I went down, I actually replaced the battery and terminals as a whole a few weeks back. I’ve heard these cars don’t always throw CEL all the time for crank/cam so I’ll look into that

 

The cam and/or crank sensors can start failing without causing the CEL to come on, so it's best to get the codes read to see if anything is stored. Sometimes when one or more fail hard enough to cause the CEL to come on, it's too late and you're stranded.

If it is, replace with OEM.

As for the idle, it should be 650 +/- 50 rpm, so you're fine there.

A common mistake is to mix up the wiring harnesses for the ignition coils whenever replacing the valve covers, but since you drove for about 200-250 miles without incident, I doubt it's that.

 

finally got around to changing the cam sensors.
same issue. ☹️

 

Car stalls randomly at idle or high speeds. Engine runs perfectly fine. Ruled out battery & alternator & belts.
Replaced coil packs and spark plugs just under a month ago. Started stalling last week and has died 4 times since then.

2003 350z VQ35DE 171k Miles

 

Same thing happened to me.



 

Post 6 told you what you need to know