Cps fail?
 

My 99 Boxes half of the time during either a a cold or warm start will require me to crank it several times before it fires up. Once fired up, it struggles (low RPM) for a moment or two. If I apply the gas, it will catch, but if it dies, it will fire up then idle normally. I've never had the P0335 CEL code, but my tach does not move at all during cranking. Is my CPS on the verge of failure or do I have a different problem.
-Plugs and coil were replaced <10K miles ago
Please advise before I start spending money on parts I don't need.

Just saw this. Sounds like:

CPS iffy but not sure if they go bad intermittently.

Fuel pump.

MAF

MAF appears to be working; when I disconnect the connector, the engine bogs down. The only other change I made recently is changing out the fuel filter since I thought that might be part of the problem. PO did not take care of the car.

In your other post you mentioned to check the fuel rail pressure. Will look that up to see how its done. What should the pressure be? Will low pressure indicate failing fuel pump?
Thanks

Yep. I don't recall pressure but if it ain't there with key turned over it's a bad FP. Mine had zero pressure. Fuel rail port is same as AC ports.

There is one definitive, simple electrical test for a suspect CPS given in full in the previous Thread.

You're wrong.

Did you install the fuel filter the right way round?

Please tell JFP directly that his CPS Test is "wrong" & why.We don't want incorrect info here.

Timco you are hilarious!

Nope. Still wrong.

Guess again.

YES! The hard start issue has been going on for several weeks. Ignored this problem until intermittent stalling at idle started. The stalling happened only on one drive. Another hidden gremlin. The hard start issue is hit and miss. Some days I can go out and it will fire right up, other days, it takes a few try's. On those days, it idles rough for a few moments, sounds/feels like it going to die until I apply the gas, then it settles out.

Sounds like a fuel pump issue to me.

I had the CPS fail on me one time, car shut off as I was driving and would not crank, but if I let it sit 20-30 minutes it would crank. Then it would shut off again 10-15 minutes later. Rinse and repeat.

If your car cranks up and runs rough and then smooths out, that doesn't sound like CPS to me, unless maybe it is doing some very rapid intermittent failure. Usually it just cuts off and then won't start until it cools down a little.

All,

Thanks for the responses. Will check fuel pressure this weekend. See if Advance Auto has a loaner rig. Now to figure out how to do it...
Of course all this will take place after I go to the 20th anniversary shin-dig at Amelia Island.

A FP relay is a common spare carried in older Porsches. They do not always completely fail and can cause intermittent issues such as yours. The problem is you can check fuel pressure and it works fine and can cause you to look elsewhere. If you haven't already I'd replace it with a new one, they're cheap <$20.

Thanks for the input. I will order the relay today. Will follow up after install to let you know if that fixed the problem.