Didn't pull any codes yet, but I'm getting a no-start/sputtering/backfiring condition on a customer's vehicle. The car will crank strong (new battery), but it will sputter/backfire pretty badly. Once in a while, it will fire and rev to around 3500-4K for a second, then die out. I pulled the CPS near the trans, and did the screwdriver test. I'm not seeing 5 volts with the screwdriver in contact with the tab. I see a slight fluctuation of a few hundred milivolts when I pull the screwdriver away, but, we're talking about very miniscule stuff. If I unplug the CPS, I get a solid 5 volts reference.. The ground is good, as is the 12 volt side. I've cleaned the ground terminals, and checked resistance between the plug at the sensor, and the ground terminals.. after cleaning, it was nill, so I know that my ground is good.

Bad sensor?

 

Pull codes.


But also read this.
http://forums.maxima.org/showthread.php?t=338918

 

If you've got a spare CKPS laying around (you did the VQ35 swap into the 240, right?) it's always worth a shot.

But as TunerMaxima3000 said, pulling codes would be your best bet first.

 

I'll go run to Nissan tomorrow and grab the Consult.. I just checked the "usual suspects" this evening, and ran across the sensor. If I unplug the sensor, the backfiring/misfiring stops, and the car cranks strong without starting. I'll check the codes tomorrow, and order a CPS from Nissan. I don't have any VQ30 sensors laying around.. I have tons of VQ35 pieces, but, those won't help.

Compression is solid across the board at 180-190psi.

I do a ton of Spec V (B15) VQ35 swaps, but, I haven't done any RWD stuff as of yet. I was going to build a S13 drag car with a VQ, but, the car has been sitting for almost a year.. I don't have time to work on it.

 

Did the trusty screwdriver method..

Pulled 0101 (P0340)- CAM POS (Phase)

No 0407 though.. odd...The sensor definitely doesn't pull up to 5 volts with the screwdriver touching the magnetic pickup.

I checked for continuity between the cam sensor plug and ECU pins 46 and 47 for the cam phase circuit. Zero resistance, so my line between the 2 points is good. The pins are clean, wires aren't broken going into the contacts. I checked resistance across the sensor, and got 1.501.. not sure if that's within spec or not..? I checked the resistance from the ground wire at the sensor plug to the ground lugs, and noticed just a slight bit of resistance.. (.011). I'll try cleaning up the grounds tomorrow..

Will a bad cam position (phase) sensor cause my symptoms?

 

I've had weird experiences with a bad CPS, and if that's the code you're pulling...

Cost you maybe $10 at a junkyard.

 

I've got one from a DE-K motor sitting in my tool box.. will that work?

 

 

Sweet.. I'll post the results tomorrow..

 

I was just about to say It was your CPS becuase of the backfiring and sputtering and lacking of turning over.

 

I'm going to change the crank ref sensor as well.. since I'm definitely not getting 5 volts when I close the circuit with a screwdriver.. I'm not sure why it's not throwing a code, though..

 

I should have both sensors here shortly.. just waiting on FedEx..

I pulled the old cam position sensor out, because I had a code for it.. however, when I check the resistance across the sensor, it's within spec.. 1,550 ohms. I checked the pins, and they look fine.. I checked the harness from the connector to the ECU, and made sure the connector on the ECU was fully seated. Not sure why I'm getting a code there...? Maybe the sensor is intermittent..? I checked compression on the front 3 cylinders to rule out cam timing.. I'm getting good compression all the way across the board, so I don't think anything is wrong there. I cleaned the ground terminals with spray on terminal cleaner (acid), and sanded down the contact area. I ran a 10 gauge ground wire directly from the ground lug, back to the negative battery post.. Just waiting on my sensors so I can see if that fixes the problem.

Travis

 

replaced the cam position sensor, and the crank position sensor on the bell housing.. Still didn't fix my problem. I was so disgusted this evening, that I didn't even bother to check the codes again.. I'll try again tomorrow..

 

Whos car was this?

Edit: Nevermind I know.