I've got an 09 MCS that has started a slight shutter when it's cold at idle. It will be normal then shutter then be normal again, it's intermittent. Doesn't feel like it wants to die, I don't have to Rev or anything, it's this the beginning of the tensioner letting go? If not what else should I look at? I've got the valve cover gasket and oil lines on my list to replace in the next week or so.

 

By cold do you mean outside? Or that the engine is cold (starting after it sat for a few hours)?

 

Cold engine

 

Could be several things. Your carbon build up could be rather excessive if you haven't had the valves blasted. You could also have carbon build up in the combustion chambers (this was my case). Poor fuel can cause this as well. High pressure fuel pump may be on its way out. Tensioner is not out of the question, but unlikely. Do you get any warning lights at all?

 

No warning lights, and once the engine warms up it goes away completely.

 

Haven't noticed a decline in fuel mileage or anything like that either

 

Might try some seafoam this weekend, didn't even think about carbon buildup.

 

Could also have a very small vacuum leak that goes away once warm due to heat expansion. Basically, there a lot of things that could cause this. Will be very difficult to tell without codes or guess and check.

 

Gotcha. Well I know I'm doing the valve cover gasket and oil turbo lines next weekend and I'll try the seafoam this weekend..... So maybe one of those will fix it lol

 

Seafoam will be good for a fuel tank additive to get to the combustion chamber. It will do very little for the intake valves (it may help a little, but doesn't fix the issue, if thats the issue)

 

So use it as an additive instead of directly into the PCV? Everything I was reading was saying the opposite, or did I read wrong?

 

No, you didn't read wrong, but it has shown mostly ineffective for the overall issue at hand. It'll help a little, but will not get the large pieces off the valves, if any at all.

 

Okay that's what I thought. The walnut blast being the best way I assume?

 

Absolutely. No known better way. Plus, if your going to be working on it anyway, that'll be a good time, as long as you have the proper equipment. You can use chemicals if you dont have a media blaster, but it'll take a lot more time to do so. There is a good write up on the process somewhere in the forums.

 

Awesome, I'll see if I can find it after work tonight.

 

I found a thread with a similar problem. It doesn't have a resolution, but it was from 6 months ago, so perhaps the member fixed the issue and nver updated the thread. You may want to pm the OP on that thread and see if they fixed it.

https://www.northamericanmotoring.co...-problems.html

 

awesome, thanks!!!