Ok, I have an '03 touring Z and I just had my stock clutch and flywheel replaced with a JWT clutch and a Nismo Flywheel (didn't want a ton of chatter from the JWT flywheel).

Anyway, had a mechanic friend of mine do the install because my local dealership quoted me just under a grand to do the swap.

When we started the car we got the SES light, Slip light, and VDC off light. It was throwing the crank position sensor code and on top of that the Tach is fluttering, or jumping around alot (its just the tach you can tell the engine rpm is normal).

Any ideas as to what has caused this?

I think he indexed the flywheel wrong but he thinks he got it right. I just want to know if there are any other possibilities before we tear back into the trans.

Also, if it is indexed wrong. How would we know where to put it if we dont know the exact position the stock one came off?

Thanks,
A

 

There is a pin that protrudes from the crank shaft that has to line up with the small hole on the back of the flywheel. That could be your problem. Also make sure the crank angle sensor and cam position sensors are all plugged in. Another possibility is that the crank angle sensor was damaged or has gone bad.

I'm guessing the flywheel was not lined up properly as the engine RPM is stable (because it can determine the position of the crank through the cam sensors) but the tach is getting 2 different RPM signals (one from the crank sensor and one from the cam sensors) instead of 2 of the same RPM signals. I would guess that the computer is getting the same reading from all the cam sensors and thus the ECU determines that the crank sensor is the odd one out (ie: flywheel not clocked properly and telling the computer the crank is in a given position when it is actually not). That would explain the Crank sensor code if it is not the sensor going/gone bad.

 

Thanks,

I need to talk to him about that dowl pin in the back of the crank.

Also, when we started the engine the flywheel struck the crank position sensor and scarred it. We initailly thought that was the problem so I replaced the crank sensor and re-shimmed so that it wasnt getting hit by the flywheel. I thought it was wierd that the flywheel hit the sensor in the first place. That should not have happened unless the Nismo flywheel was a larger diameter than the stock flywheel. Right?

Thoughts.......

 

well you should not have to shim it. so that tells me right there they did not line the dowl pin up. looks like someone has to pull the tranny again.

 

flywheel was installed wrong.

 

Yea, the sensor should not have to be shimmed, although I haven't installed a nismo flywheel. However, that definitely doesn't sound right as the few JWT flywheels I have done have not needed the sensor to be shimmed. Flywheel is most likely installed wrong.

 

Ok, that confirms what I was thinking. Im fine with pulling the trans agian.

With the dowl pin on the back of the crank there should only be one way the flywheel can possible even be installed right? Because there is only one dowl pin alignment hole in the flywheel. So if he got the flywheel in to begin with the crank must have been missing the dowl pin.

 

Well S***, talked to NISMO and they said that if the flywheel was not aligned correctly with the dowel pin then you should not be able to go to full throttle which I can do.

Also, back to the re-shimming of the crack position sensor. Even if the flywheel was installed incorrectly it still should never hit that crank position sensor due to the fact that is perfectly round. So that leads me to believe the diameter of the NISMO one is slightly larger. Maybe a factory f*** up.

Thoughts?

 

just check the diameter when you pull it. im sure its fine. if the dowel isnt aligned, it could be sitting at a messed up angle which caused it to strike. or perhaps you dropped a bolt in there or something and thats what originally hit the crank sensor.

i wouldnt worry about it, meaning that... when you take it all apart, im sure it will be clear as day what was going on to cause the issues.

IIRC, the JWT flywheel has 2 usable positions for the dowel, for different VQ applications... perhaps he used the wrong dowel opening if your flywheel has the 2 holes.

 

Thank You, great explanation!

 

edited: nevermind

 

Ok. Swapped flywheels. In case anybody is interested or they have the same problem down the road there was a small dent in the reader ring of the flywheel causing it to change the air gap between the crank position sensor and therefore screwing with the tach.

Went to JWT. Much Better! Should have done this in the first place. Chatter even at idle is hard to notice. Accelleration much better!