I know this issue has been discussed many times but what I am seeking is what the symptoms are of a stretched timing chain are, and I am not finding exactly what I am looking for.

The car is a 2008 Saturn Vue Redline with the GM 3.6 V6 engine. Approx. 130k miles.

What I am experiencing is a loss of one or two cylinders so it just chugs down the road with low power. This happened suddenly on the freeway when driving from Portland to Seattle a few months ago. Prior to that I had changed all the ignition coils and it was running great.

Since then, I have changed all the spark plugs which did not help at all. Four of the plugs looked fine but two showed signs of uneven firing. Wrong color and black and sooty. I also dumped some injector cleaner in the gas tank which had no effect.

I did and OBD II scan of the engine codes which was not very useful. I got code P0301 Cyl 1 Misfire without any other codes. If there is a timing chain issue shouldn't other codes should have been set?

It is still chugging around so I am at a loss to know what to do. How can I diagnose this problem? Would a car repair shop have diagnostic tools to pinpoint the problem? I am not sure how to proceed.



Thanks for any advice and suggestions.

Randy

 

I would check compression as the next step. The code indicates that cylinder number one is not contributing properly. The problem can actually be many things, but a compression test is a good next step. You indicated previous to the problem you had replaced the coils, why did you do that?

 

I replaced the coils as the engine would stutter and misfire at a specific RPM, usually between 1200 and 1800 RPM. If I accelerated beyond that RPM
zone it ran fine. After I replaced the coils it ran perfectly. The way it runs now is nothing like my previous problem. It just chugs around like an old
motor boat. I think that two cylinders are dead for whatever reason.

 

The car probably had a weak coil and by changing them all you found it. I would still check the compression, a timing chain problem will not make it miss on two cylinders. Three cylinders yes but two are unlikely.

 

Could it be a sudden fuel problem then such as clogged injector's from dirty fuel or similar? It happen gradually
while driving on the freeway at a steady speed and has gotten worse. If it were injectors or low fuel pressure wouldn't
a code be set indicating that? It will get up to freeway speed but it really chugs around at low speed. Sounds like
an old motorboat. Also, where is the Schrader valve located for testing fuel pressure? I can't seem to locate it.
Or is there another test port for testing fuel pressure?

Randy

 

Have you checked your catalytic converter to make sure it's not coming apart and clogging up the exhaust system?

 

Have you done any testing or are we throwing parts at it?