P1606 VVEL issue/code

mendoza_ms

February 20, 2018

Replaced the Cam sensors but she didn't idle right this morning. Starting to get really tired of borrowing the wife's car - she is too as she can't leave the house nowadays. I need to fix this ASAP. Starting to consider taking it to the stealership or trading it in for a new ride altogether...

February 21, 2018

Tried troubleshooting after work. I noticed that the voltage dropped quickly after idling and shutting off the engine, so I decided to do a full stress test of the electrical system.

What I did was I let the car idle for 3-4 mins, then I started turning on the accessories - High beams, A/C, Defroster, Hazards, Heated seats, blasting stereo on full bass, etc. Normal voltage while driving is usually 14.5v. With everything else running it dropped to 14.1v over 1-2 minutes. Then I turned off accessories and let the car idle so the battery could recover before shutting it off again.

After shutting it off, I switched the ignition to the "ON" position without starting the engine so I could run my code reader and I noticed it dropped from 12.7v all the way to 12.2v within about a minute. That didn't look right so I switched it off and used a DMM (voltmeter) to read the voltage off the battery directly and it was reading 12.13v, which is below spec.

After this discovery I ran the code reader and started/idled some more and got the same P1606 and P1606 pending with an additional P0300 and a random U1024 and P1421.

I checked my yellow top Optima battery's date of manufacture and reads 05/2013. The Optima website says battery life can range anywhere from 18 months all the way up to 4 years - depending on operating temperatures and whether or not the battery is properly maintained by the Alternator, etc:

https://www.optimabatteries.com/en-u...r-battery-last

I'm hoping the battery is the root cause - it seems like it would be time to replace it, but the symptoms don't add up. I really don't know anymore... I'm a former Computer Science/Electrical Engineering student, a full time web developer and consider myself proficient with tools and technology but I'm just out of ideas now and really tired of this. I don't want to get rid of my Z...

Any help would be appreciated at this point...

aireoh

i have a friend that’s having the exact same problem and symptoms. i’m gonna keep researching the forums, but hopefully you find a solution brother.

__________________
FBO, Cammed, E85, 12.6 1/4 mile

Vorex

Did either of you have any luck finding root cause? I'm having the same intermittent issue. Typically if I leave it alone overnight it just works. I fidgeted with the MAF and camshaft sensor connectors one time thinking that actually did something (the next morning) but I think it's just time (or ambient temperature) that solves it.

mendoza_ms

Vorex, yeah that was my experience as well. Typically the symptoms would go away overnight or after a day or so.

My understanding is that the capacitors and inductors inside the relays discharge and reset over time. Relays are basically made of light metals, plastic and ceramic so it makes sense that extreme temperatures would negatively affect them (mainly heat), but that's probably not the root cause.

My 370z is a 2009 and since it's a first generation model some parts are more likely to fail since the engineers don't have all the bugs worked out yet. If your car is newer, I would buy a brand new relay and replace the VVEL relay with that one, disconnect your car battery for a few minutes, plug it back in and drive modestly for a bit before pushing it harder.

Here's a video that you may find useful:
https://www.youtube.com/watch?v=DWmt6gorzUg