Afternoon folks,

We're talking about my 2006 MCS with 136,000+ miles. Recent work at the mechanic included the supercharger service and water pump replacement. Yesterday I replaced a really sorry wheel bearing and the car was running in tip-top shape for about an hour before the following occurred:

Was driving at highway speeds (south of Boston at the I-95/93 north exchange for those familiar) when the car went over a huge undulation in the road while coasting/decelerating for an off-ramp. Immediately after the ramp, the car was in limp-home mode, severely lacking power, and was throwing traction control/service engine soon/P0341 code.

Car limped home 2+ hours with no further issues, besides atrocious (13 mpg) fuel economy. The code (camshaft position sensor) does not reset. I checked all wiring harnesses for the easy fix: No obvious faults here.

I have had noisy rattling at startup for some time (years). My current diagnosis is a worn timing chain that jumped teeth at this random road dip. Sound right?

If I can get an "amen" in agreement, then my big question becomes: Should I tackle this myself? I've worked on my own vehicles for years and have done all the basic bolt-ons and not-so-basic suspension work on the Coop, but have never opened up the engine proper — it's still basically a black box to me. I have a workspace, all the non-special tools, and a Bentley manual. But the last time I tried to change a timing belt with a friend on a Subaru (an easier job than this, eying the manual), the car never ran again.

How difficult is the job, would I be able to visibly inspect and deduce what needs replacement (chain, tensioner, et al.), how likely am I to bork the job and drop something into the unreachable depths of the timing case?

The Bentley instructions do not fill me with confidence.

How many hours of work would this add up to at a mechanic?

Would this be a reasonable time to add a cam?

 

If you had the mechanic doing that other service you definitely want someone that knows what they're doing to do a timing chain service.

That being said I would be really surprised if your timing jumped from an undaltion in the road. Engines just dont lose timing from bumps in the road. If the chain was that lose and was jumping teeth the car would barely run.

You said it was in limp mode with no power. Did it idle ok?

Sounds like the car should go back to your mechanic :(

 

Car does not start or idle well: Very rough, lopey, stalls when coming to a stop.

Other possibilities with these symptoms if it's not timing?

 

Since you're getting the P0341 code for the camshaft position sensor, I'd look there, as either the wire for the sensor itself was jarred loose when your car passed over the undulation, or the sensor itself may have failed, either of which would cause the rough running symptoms you are having. Changing the sensor itself is a fairly easy task. I'd also replace the timing chain tensioner while you're at it.

 

Could be the cam sensor or it could be more. Check out this NAM thread here where the sensor didn't fix the issue for the OP, but was in fact a timing issue.

 

Initial diagnosis was correct, hopeful alternative scenarios were not. Car skipped two teeth and stopped starting a day or two after initial issues. At the shop now, due for a full service and camshaft switcharoo.

 

Sorry to hear, but glad you're getting things fixed up. Thanks for the update and be sure to let us know how it goes.

 

Ouch, let me know how it goes.

 

The timing chain was replaced on my 07 MCS. Not a simple "shade tree" project.