Skipped timing questions - 2001 986 S 130k
 

Hi all,

Been struggling with an issue the last few months. The issue seemed to begin with a clogged eBay high flow catalytic converter. I had poor idle one day and gave the car some throttle a few times and part of the molten catalyst was ejected from the exhaust. I removed the cats and have race pipes.

Since then I've had a p0343 code(Porsche code 112), cam position 1 sensor above limit. Also some misfire codes.

I replaced the bank one sensor, replaced all plugs and coils. I also ran a cam deviation test and was slightly out of the "normal" range, but not by much. The biggest issue seems to be at idle, the idle is awful. Limited throttle response, backfires, etc. When the car will rev, it's sounds normal. I drive it around the block a few weeks back (gingerly) and while driving it sounded fine.

Questions:
Is there a way to rule out, or diagnose and true timing issue?
Does anyone know how to test the cam sensor wiring? I see a lot of comments to check that. I did not see any wiring issues with the cam sensor when replacing it.
I'm really trying to diagnose if the clogged cat and related back pressure caused the timing chain to skip.

Thanks!

The P0343 diagnostic trouble code on a 2001 Porsche Boxster (which corresponds to Porsche code 112) indicates a Camshaft Position Sensor "A" Circuit High Input on Bank 1. This means the engine control module (DME) is receiving an abnormally high voltage signal (typically above 4.5V) from the sensor.

Potential Causes
The issue is likely electrical, a sensor failure, or potentially a mechanical timing problem.
Faulty Camshaft Position (CMP) Sensor: Internal failure due to heat, age, or oil contamination is a common cause.
Wiring/Connector Issues:
Frayed, chafed, or damaged wiring in the harness.
A short circuit in the signal wire to a higher voltage source (like the 12V battery line, or B+).
Poor connections, corroded terminals, or loose pins at the sensor or DME connector.
DME (Engine Control Module) Failure: Though rare, an internal DME problem or outdated software could misinterpret the signal.

I'm 100% with you there. Do you, or anyone, know a way to diagnose? The code was not present prior to the cat failure. Common sense tells me it's likely timing, but I don't know how to confirm, or how to test an electrical issue. Is it as simple as putting a multimeter on the connectors? Are there any relays that could have failed? I don't know much about the cam timing.

I would start with a Porsche specific scan tool and see if the DME is actually seeing a signal from the sensor in question. If it is, check the cam deviation values vs spec, and check the cam positions with and without the Vario Cam activated for the expected values.

If the DME is not seeing the cam position values, I would back probe the harness connector for the sensor checking for the signal, if it is there, start tracing the harness from the sensor to the DME.

Thanks, that's a solid diagnostic path. I'll start with the scan tool and follow the signal from there.

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