So I had my clutch/fw replaced not too long ago.. Exedy OEM Clutch with an ACT flywheel. After installing the flywheel, however, the car would crank but not start. After getting a code for a malfunctioning Crank Position Sensor, I ended up putting a spacer on the bolt holding the CPS into the bell housing. That just barely solved the problem.. even though it allows my car to start, it takes about 4-5 seconds to crank up.

I gave the dealer $110 tor run it through, and they told me I simply needed to replace the CPS.. Waste of money. I bought a new one just in case, turned out to be another $waste. I just got done replacing it, same issues.

What could be the problem, and how can I solve it?

 

Search the Maintain or Engine/Drivetrain forum. Sounds like the issue where the clutch was not installed properly. IIRC it has something to do with position of clutch relative to crank

 

are you sure the flywheel was put in the right position. there are 2 notches, from FWD and 1 for RWD. easy to put in wrong spot and get those exact problems you are facing.

 

^^What he said.

 

in your case: i don't think it could be a flywheel position issue.
i've had this happen before to me recently

if the flywheel position was messed then i don't think the car would even start at all with the spacer you put on. what it looks like is a defective timing ring on your new ACT flywheel.

IIRC the timing ring has 10 notches a space, 10 notches a space, then another 10 notches and a space (10-10-10). if there is any sort of surface defect then the crank position sensor could read that as an extra notches then say WTF and shut the car off when you crank it on starting.

by adding the spacer onto the nut holding the sensor you are effectively moving the sensor out so it doesn't see those surface defects on the timing ring so its only seeing those notches. however if you move it too far then it doesn't see the notches that you want to see, namely 10-10-10.

what i would to do confirm this is to remove that spacer and replace the CPS in the bell housing. next have a tech hook up a scope to the CPS and have someone crank the motor by hand with a wrench, then count the spikes shown by the scope - you should see 10-10-10. if you see anything else then your ring is bad.

if you purchased the flywheel from ACT you can call up their tech line and try to get them to send you a replacement ring...thats what jim wolf did for me.

 

Hey bro how did you end up fixing this I'm having this same problem

 

Unplug the crank sensor. If the car starts but won't rev, the flywheel is on wrong. There's a pin on the crank and a hole in the flywheel. They need to be lined up.

 

Hey guys,

since I am new here but I know that a new thread might not be worth it, this one looks quite similar. I have a good one for you, several shops and dealer couldn't figure it out yet.

So some half a year ago my 2005 350z stalled and showed a code of a faulty crankshaft position sensor just a week or so before my couple thousand miles trip. Quickly got it to a shop, ordered a new aftermarket one fitted and it didn't work. Tried another one. Then we took several from Infinitis or Muranos, can't remember now - didn't work. Then we took an old OEM one from my friends Z and it worked. Great! Thing is, not so great since after my trip, OEM CPS came to the dealer and the car doesn't even start with it. They ordered a new one thinking it was a bad part but nothing... Problem is that I have to return the part to my friend since he will begin building his car soon and I want the new one without any mileage. All of this was after a new clutch kit was installed and the flywheel refurbished. But it wasn't immediate, there was some time between clutch+flywheel and CPS problems. I will check my billings to see how many days are between them, but it is close. I have searched through forums and most of these problems (Zs not starting with CPS codes) seem to be about bad flywheel fitment or smth similar. But why is my car running on my friend's OEM CPS? Out of 4-6 CPS, it's the only one that works. The dealer tried experimenting and putting the new OEM a bit closer or further out of its fitment and then the car started. But they didn't have time to do any more tests if it doesn't stall when driving and etc. I have seen that small spacers help sometimes. What is the logic behind this, could this help? And I might be feeling some lack of power with friends sensor when accelarating in linearity.

Would appreciate your thoughts since lots of time and money was spent on this single problem

 

Have you ruled out a short in the circuit? I had the same code some time ago, but it wasn't the ckps that was the issue, rather, it was one of the cables, it had become frayed right at the connector housing and was barely contacting the terminal pin inside. Check your connector to see if it's damaged. Do you know how to check for continuity?

 

Me and the shop haven't thought of it I guess, since it wouldn't explain why the friend's part is working in my car. Also, my car with friend's sensor is working without any codes. When we put new OEM one (which technically should be exactly the same as in the friend's Z), then the car doesn't start and shows the code. Interesting, since my car is 2005 and his 2003, but the shop and dealer said that the part numbers are the same.
Obviously, we will try checking it out if it was the case in your car. How to check the continuity? Thanks in advance! Did you spot it accidentally or did you try changing to the new sensor and it didn't work as well?

 

Have you tried all the diagnostic procedures outlined here?

http://www.nicoclub.com/manuals/350Z/coupe/2005/ec.pdf

Start on page 321 and keep reading. Since it's a hall effect sensor, the distance between the sensor and the cog wheel is definitely important. Optimally, you should hook it up to an oscilloscope to see if the waveform's R-R intervals and voltage peaks in open and closed loop match up to the waveforms displayed on page 324 in the FSM linked above.

If the sensor's reading fine, then you work backwards from there to the IPDM and ECU, checking each harness connector along the way. If everything looks good, then it's possible the cog itself is screwed up somehow (though it's hard to imagine that would be the case.) Go here to figure that one out:

http://www.nicoclub.com/manuals/350Z/coupe/2005/em.pdf

It might be time-consuming or you might get lucky and figure it out right away. Throwing parts from different cars on your Z it isn't really going to get you anywhere. Make sure you order the correct CKP Sensor that matches your VIN from an OE Nissan parts source if it turns out that the sensor itself has failed based on what the scope tells you.

 

I spotted it when I changed to kinetix HFCs, and soldered the wires to the terminal pins. You can check for continuity with a multimeter, but it's a little tedious to do it because you need to disconnect the ECM, and run a wire from the corresponding terminals for the ckps, all the way out to the ckps connector, since the multimeter cables are not long enough.

 

Hey there, thanks for all your help. I want to stress that the sensor was OEM and the dealer checked my VIN from the start of this problem. A couple weeks ago the problem was finally fixed with a spacer.

 

A spacer for the ckps?

 

you are avoiding the elephant in the room. Drop the tranny and double check the FW install.