Hello ladies and gents..

This is my first post here; hoping to get additional input on my situation. I have searched all of the threads and noticed this issue isn't uncommon, but I'm hoping someone may have the caveat I need to get my baby back into top condition.

I purchased my 06 G35 Sedan 5AT a few months ago with 110k, and it cranked and ran fine at that time. About a month ago, I changed the engine oil and diff fluid, and right about that same time, I noticed that sometimes the engine took extra long to start. It raised a little concern, and about a week later the CEL came on, with only PO340 showing. Sometimes the VDC and SES lights could come on as well, but not every time. I would sometimes smell fuel after ignition as well.

After searching all these threads, I realized my issue is almost always resolved by replacing the CPS on bank 1. I replaced the sensor with an aftermarket one, and disconnected my battery for a while to reset the ECU. The CEL has remained off, but the hesitation to fire up remains....???

The constants:
1) It always fires right up when completely cold (as in- in the morning after sitting all night.)
2) When it cranks, it runs fine (although it seems like it may not be as powerful as it should be? but maybe that's my persistent lack of satisfaction with anything under 400hp)
3) If it's been running, and I shut it off, it will fire right back up no problem if it has been off less than about 5 minutes.
4) If it's been running, and I shut it off and leave it for more than 5 minutes or so, the issue usually happens. Even as long as several hours later, the issue will happen.

What I have noticed though now is, that I don't experience the extra long cranking before ignition, but I do notice a stumble.. It's like the starter gets the motor to turn over barely enough for it to start, but there's a significant delay before the engine actually cranks, almost like it's not even going to start, then miraculously does.

*** Sorry about the long-winded explanation ***

Is my issue consistent with what others have seen? I just want my vehicle to start up normally, and not worry each time what will happen.

It seems like the timing is off slightly. I was thinking about replacing CPS bank 2 as well, just to be thorough. I seem to recall reading about another sensor (crankshaft something sensor??) that can go bad and cause issues without throwing a code.. Could this be the case?

Thanks in advance for any and all input.

 

I didnt read your whole post I'm sorry. But the sensor doesn't control how much power gets sent to the starter. Replace the battery to get the faster crank.

Hopefully that was your only issue. Sorry if it's not. How does this site not have a mobile app.....

 

Sorry, I should've included that in my post.

It's definitely not the battery. It's only a year old. It feels like a fuel/timing issue. It fires up just fine if its been sitting for a long time, like over night, even freezing temps.. Keep in mind the car runs fine once it fires up.

 

Ok just read your whole post. It's the battery. There isn't anything in between the two. And it runs fine when it starts so it's not anything binding or broken. It's battery,wire,starter. That's it other than a signal wire in the starter.

Replace your battery. It's likely still under warranty.

 

I appreciate your response.. If the battery is bad, I would think that it would have trouble starting after sitting for a while, especially in the cold. It started right up after sitting for 9 days just last week. Also, a while back (before this started) I accidentally left the radio/ignition on for over 3 hours, and it (surprisingly) fired right up with no issue.

The battery and starter are solid. The issue is related to the CPS and the PO340 code.

 

Again, now the issue seems to be less of a delayed start, and more of a stumble after ignition, like its going to die, then comes back from the dead.