986 Boxster S cranks but no start

[JFP in PA]

I think you are in the market for a new sensor.

[BoxSinit]

Yes! Thanks for helping me out! It's nice to go through the steps of testing instead of throwing parts for a fix. I will be ordering the part. Torque setting for the CPS bolt?

 

I just have a couple of questions to get an understanding. After I got a low-voltage drop at the fuel pump, I turned it over and the tach didn't move much, does this indicate the CPS may be faulty? Also, can CPS just go bad from sitting or could this be more of a coincidence?

Edited February 11 by BoxSinit

[JFP in PA]

Torque is 8 ft lbs.

 

Lack of tach movement is a common indicator of a failing CPS.  The CPS is a simple Hall effect sensor, it has an infinite shelf life.

[BoxSinit]

Got it. Thanks!

[BoxSinit]

Hello JFP,

 

Well, I finally got a chance to install the CPS. It didn't start. Of course, I am disappointed, I really want to get this car going. This car always ran like a champ, but after sitting for over a year, it just won't start. What are the usual suspects in a car sitting? I'm just a bit frustrated 😤. Can I be missing a fuse or something? I did change the ignition and fuel pump relays. Is it back to a fuel delivery issue? What's my next step?  I know I can get this done.

 

[JFP in PA]

At this juncture, I would be looking at the immobilizer, pull it and open the case looking for signs of corrosion or moisture damage.  It also has its own small fuse in it, check that as well.  It is under the driver's seat.

[BoxSinit]

Will do. Is the immobilizer easily accessed for removal? I'm just curious, would this be inspected first before fuel delivery troubleshooting, based on its more susceptible to corrosion damage by sitting?

[JFP in PA]

The immobilizer is not susceptible to sitting, but it is dangerously susceptible to moisture intrusion, which is a common problem with these cars.  Here is a video about the problem and how to remove and examine the unit.

https://www.youtube.com/watch?v=x9rpTYXSdYc

 

And this is what the internals' look like if they have been wet:

 

 

[BoxSinit]

I hope it isn't that. That looks like an expensive fix.  I'm not sure if I mentioned it but the car does turn over strong but won't start. Could it be the starter as well? I took a look under the seat and it's not wet at all. 

Edited Saturday at 06:36 PM by BoxSinit

[JFP in PA]

If the immobilizer is dead, the car will aimlessly turn over and never start; it is your anti theft system.  The most common reason these things fail is moisture, but we have seen them with burnt circuit boards as well.

 

Take the box out, open it and look, only then you will know if it can be excluded.  And yes, it would be expensive as the part is pricey to begin with and you need access to a PIWIS system to code it to the car.

[BoxSinit]

The car did fire up then died when I used starter fluid. Doesn't this suggest it's a fuel delivery issue?

[JFP in PA]

Have you tested the car for fuel pressure and delivery using the test port on the fuel rail?  If it has full pressure and delivery rates, the answer would be "no".

 

And, as noted from your first post, you got an "immobilizer not ready" warning..............

[BoxSinit]

On 1/16/2025 at 11:53 AM, JFP in PA said:

Whirring.

 

You need to check for fuel pressure and delivery rates; otherwise, you are groping in the dark..................

 

 

I think I know what happened here! I piggybacked the original poster, Andrew Howell, and he was getting the "immobilizer not ready" warning! I think we are back on track here! As in the quote that I have attached reads, you initially suggested that I check the fuel pressure and delivery rates. It went a different direction when you thought there was something in the tachometer being off and that's where the CPS fix came into to play. I understand your mixup because your tending to a lot of different threads.

 

Moving forward.   I did purchase a fuel pressure kit. Where is the fuel pressure rail? What readings should I be getting for the fuel pressure and delivery rates? I have never performed this test before. All new stuff for me, but rewarding and going through the steps.

 

By the way, I just donated again. I do appreciate you, JFP and this site!

[JFP in PA]

For a 2002 Porsche Boxster S, the fuel pressure at the rail should be around 3.3 to 3.8 bar (47.9 to 55.1 PSI), and the fuel delivery rate should be around 850 cubic centimeters (cc) in 30 seconds. 

 

The test port is on the passenger side fuel rail, under cap #7 you will find a Schrader valve :

[BoxSinit]

Ok, I am going to look into it. Thanks!