Fault Code - Lean Then Cam Position Sensor

[Stutopia]

A couple of weekends ago I stopped after a spirited drive (pulling fine) and when I started her again (still warm), the idle was a bit lumpy, dipping like it was about to stall and then sorting itself out. I finished the drive fine and nothing felt wrong.

 

Last week I got a P0171 - System Too Lean Bank 1 - CEL. I left this on as I wanted it up when I was going to my usual tech.

 

Today, I took the engine cover off and had a listen around the bay for any sounds of an air leak, nothing obvious, though obviously small ones can be hard to pin down.

 

Next door I have a mechanic who kindly had a quick look and when he plugged in his code reader, it was also showing codes for both bank Cam Shaft Position sensors (I don't have the actual codes). I don't know why these weren't showing on my phone, but that's for another thread.

 

He cleared the codes and CEL, but immediately upon restart both Cam Shaft Position sensors are showing on his reader, although the CEL has not returned. He cleared them again and restarted, they returned. It sat quite comfortably and stable at 800rpm idle for 10 minutes.

 

Any thoughts would be hugely welcome.

 

Thanks!

[TT350]

I had this rough idle and dipping revs and same fault code but turned out to be a coil pack.

[Stutopia]

I had this rough idle and dipping revs and same fault code but turned out to be a coil pack.

 

Thanks TT, gives me another line of enquiry. Much appreciated.

[Stutopia]

So I sat for a while and let her idle, once warm, for a good while, no lumps, just a solid 800 rpm. I took a snapshot of some fuel trim data at idle:

 

 

and also some with the cruise set at 40mph

 

 

Car still seems to drive fine? Any thoughts?

[ilogikal1]

Any thoughts?

 

Many. None useful (or even related) to this though. In fact some of them aren't even suitable for the public...

 

 

Sorry, not very helpful I know, but then what else would you expect from me?

[Stutopia]

In case anyone stumbles upon this via search, here's some info.

 

The lean code was dealt with (by accident) when the MAF was cleaned with electrical contact cleaner, as its was reading very high intake temps 60+. No sign of the lean code since (several weeks, many hundreds of miles).

 

The Cam Position Sensor issue culminated in the Zed spitting the dummy out and taking a long while to start (several seconds cranking) and then the next day, flat out refusing to start. Leaving me with this selection of codes, ignore the ASCD switch that's just the cruise control misbehaving after the steering wheel was swapped out, I should have reused my existing switches.

 

 

Fortunately Ewen at Clark Motorsport helpfully supplied a couple of genuine Nissan cam position sensors and the RAC were summoned to relay me to my garage. The very helpful RAC chap felt it was going to be such a PITA to relay my Zed he elected to fit the part on my drive instead. Once the bank 1 sensor was swapped out, she fired up first time no problem. Now i have gone down to just a couple of codes:

 

 

Since the fault originally occurred I have invested in an UpRev cable, so at last I have had a chance to put it to good use and check the codes and also do some logging (more for my learning than anything else).

 

This is a log from after the initial long start but before it refused to start.

 

 

This is after the bank 1 sensor was swapped out. It's gone down from a +60 flatline to a fluctuating -16

 

 

This is a close up of the data without the RPM plotted against a second axis.

 

 

The resolution of data from the UpRev cable into a laptop is incredible, a 10 minute drive generates something ridiculous like 20,000 collection points across about 20 different parameters. It makes my phone code reader look like an abacus. No real idea what any of it means but it's still dead interesting to have a look at the logs it throws out.