2008 V70 with 3.2 six cylinder engine & 129,000 miles. I would like to change the crankshaft position sensor. Can someone tell me its location and what components must be removed to access it?

 

Why do you want to replace it? I'd bet it isn't your problem.

 

Two reasons for replacement: (1) Preventive maintenance - Crankshaft Position Sensor is 12 years & 129,000 miles (2) Engine has been getting harder to start during the last six months. Hard starting only occurs during the initial start of the day (cold engine). Engine cranks a little longer than usual before starting, then runs rough for about 20 seconds. Check Engine Light appears on dash - code reader usually indicate "Misfire Cylinder 6" but sometimes other cylinders will appear. This problem used to occur about once a month but has gradually gotten worse and now occurs about twice a week. If replacement of the Crankshaft Position Sensor does not resolve the problem then I will look elsewhere. Is it located below the A/C compressor? If so, is it accessible from below the car once the belly pan is removed?

 

Sounds to me like you need some new coils. As previously stated CPS is likely not your problem.

 

Thanks for the suggestion about replacing the coils. I should have mentioned in my original posting that I've already taken several steps to resolve the cold hard starting problem. During the last several months, I've replaced all six spark plugs (no change), replaced the fuel rail sensor (no change) and replaced all six coils (again no change - in fact, the problem is getting worse because it's happening more frequently). I figured replacing the Crankshaft Position Sensor was the next logical step. I appreciate the assistance in trying to diagnose the problem but no one has yet answered my original question of where the CPS is located and how it can be accessed. Has anyone ever done this?

 

I think you were on the right track with the fuel pressure sensor as cold starting issues can also be caused by fuel pressure issues. (ie if some of the pressure bleeds off, it will tank the pump a few cranks to build up pressure). Similarly this can lead to misfire codes. Only way to know is to measure the pressure. You could have a weak pump, a leaky injector etc.

As to the location, I don't have any experience with the 3.2 directly but its likely to be same as the I5s where the sensor plugs into the top of the transmission where it can read the flywheel's rotation. Should be a single 10mm bolt holding it in. you'd need to pull out the intake air box and related tubing etc to get at it. RobertDIY has a Youtube vid showing its removal.

 

Thanks for the quick reply, mt6127. I've seen the RobertDIY video but didn't find it too helpful since my engine looks different. I've already removed the airbox & tubing and the battery & battery box to get a better view of the top of the transmission but still couldn't see the CPS or its electrical connector. It might be hidden under the A/C compressor but I'm hesitant to disturb that unless I'm sure. I appreciate your comments about the possibility of a weak pump and/or a leaky fuel injector but if I had either of those conditions would'nt the car run crappy all the time? After the initial 20 seconds of rough running after a cold start, it runs fine all day (no misfiring, no hesitation).

 

I've been a dealer tech since before that engine came out. I've never had to replace one. Save your money. But if you really want to replace it, then yes, it is between the engine and transmission basically below the compressor.

You need a new fuel pump, by the way.

 

Can you advise why you suspect the fuel pump when the car runs fine except on the initial cold start and only on certain days? I would think that a faulty fuel pump would cause more problems than I'm currently experiencing.

 

I've seen it a few times. The internal check valve fails, causing fuel to drain back to the tank when shut off. This lack of fuel pressure on startup causes a longer crank. Cylinder 6 is furthest from where fuel comes into the rail, so usually sets misfire codes.

 

That makes sense. I'll check the fuel pump. Thank you!

 

No problem, good luck!

 

Just wanted to post an update on my progress in resolving the cold start problem on my 2008 V70. Many thanks to ES6T for his diagnosis of a faulty fuel pump. I dropped the tank (major pia job!) and replaced the fuel pump about a week ago. The engine now starts immediately, even on the first try in the morning. ES6T was correct in that fuel pressure was being lost as the car sat overnight and fuel was apparently not reaching Cylinder #6 on the initial start. Thanks ES6T!