Camshaft Position Sensor and No Start

[jpk]

Hi all, CEL came on a few months ago, and the code was P0340 (Camshaft Position Sensor). Although the CEL was on for months, I had not noticed any rough idle or loss of power as others usually see when they have a bad CPS. On the contrary, the engine was running as smooth as ever. But since I now need to pass smog, and an illuminated CEL is an automatic failure, the replacement has become necessary.

I read a few threads here and at other BMW forums, looked at the Bentley manual, and decided I could change the sensor myself. So I ordered a new OEM CPS sensor.

Now here's the strange thing that happened while I am waiting for the part to arrive. Yesterday morning, before I head out for work, I decide to pull the CPS sensor out of the engine just to have a look at it. (One or two forum members had suggested metal on the sensor head might cause malfunction.) I pulled out the sensor head, and it looked clean. So I re-inserted it, jumped in the car, and ... <click, click, click>. Nothing from the engine - just a quick series of loud clicks.

I had to get to work, so I tow-started. And strangely enough, the engine ran just as smoothly as before on the five mile drive to work. Workday done, I go back to the car (which I had parked facing downhill) and again, I only get clicks. So start rolling for a tow-start, but this time the engine won't stay running for more than a second or two!!!

I am completely confused by the combination of these symptoms. If it's all just a bad CPS, why the no start and the smooth running on the way to work? If it's more than the CPS, was it just the oddest of coincidences that it happened after a pulled the sensor? And why could I tow-start in the morning, but not later that day?

Any thoughts would be much appreciated!

[xxxJohnBoyxxx]

If the click noise is from the starter then the starter solenoid is bad. When you removed the CPS did you just remove the bolt and look at it or did you remove the intake manifold to unplug the sensor too?

[Sailfish]

Have 98 318ti,no compression!!! No oil or coolant in wrong spots!!! Any HELP!!!! Jim Sailfish

[xxxJohnBoyxxx]

Zero compression? You mean not even 1 psi on all cylinders? If that is the case compression gauge is broken or you have jumped cam timing and your valves are open during the compression stroke. This usually means bent valves since stock M44 motors are interference motors, valves should be bent.

Did you money shift it?
When you pulled the spark plugs how did they look? Clean or tips bent and metal all stuck on them.

The only thing I can think of that would cause zero (0) compression on all 4 cylinders is a jumped timing chain or the gauge is bad.

Do compression test will all plugs out and TB pinned wide open. Also pull the valve cover and see if all valves are on their rocker or are they stuck a little open by hitting a piston top.

Best of luck it could be real bad or just the way you took the test

[Sailfish]

Seems to be Head Gasket only...

[xxxJohnBoyxxx]

Originally Posted by Sailfish

Seems to be Head Gasket only...

A blown head gasket will not give you zero compression in all cylinders. Actually I have never seen a blown head gasket net zero compression and I've had lifted heads with the gasket completely blown out with water dumping out of the area but still had 10 psi or more compression. I've had a cracked pistons and broken sleeves at the same time from a NOS tuning error and the cylinder still had 20psi of compression with a completely melted piston.

I think you are going to find a problem that is not the head gasket if all cylinders have zero, "0", "Goose Egg", compression.

Just my internet guess which I'm wrong a lot of times...

Best of luck and please let me know what it is when you get it fixed and running. I'm interested

John S