Hi All. I know this is the "Z" forum, but figured I would ask you folks since you probably tinker with your engines probably more then the Quest folks, so please bare with me.

My wife drives a 2007 Quest that I had a friend, mechanic, replace the timing chain tensioner through the access cover. Reason being that the tensioner and chain rattled at startup when cold. He did one on a Maxima and was successful, so I figured I would let him fix mine. other than the rattle at startup, van ran perfectly.

When he returned the van, I noticed that the van felt like it was idling rough. you can feel the engine shaking in the steering wheel. you can also see the engine shaking under the hood. Idle is around 700-710 RPM's. The exhaust sounds great; no spitting, no missing or anything. has tons of power when you get on the gas. only issue is it seems to idle rough. He brought van to Infiniti, where he used to work, put on computer and it says one of the banks alpha reading is 100 and the other is 120. Not sure what this indicates.

He is where I'm at...... I'm convinced that the timing chain jumped a tooth when he replaced the tensioner. Not sure if there is that much slack in the chain to fall off the sprocket at the crank and then when he put the new tensioner on, it was off a tooth. Everyone I speak to tells me I'm crazy; that if it was off just one tooth, it would barely start and if it did, it would run really bad, regardless of the tooth off was retarded or advanced.

Does anyone have experience this to know for sure? back in the day, you could use a timing light to troubleshoot, but not sure if there is anyway to tell if timing is off without removing cover. If not timing, where would you recommend I check?

Hey Joe, you may want to download the FSM. You can find it here: http://www.nicoclub.com/archives/use-ni ... abase.html

In there you'll find the EC chapter. On Page 78 begins "Idle Speed and Ignition Timing Check".

Good news, you get to use your old timing light skills!

thanks for the information. I will give it a try.

wanted to follow up and ask for advice on next steps.

using the template found on this website http://www.jimwolftechnology.com/wolfpd ... mplate.pdf
, I was able to verify that the bank 1 cam is retarded 1 tooth..SIGH... reason for the rough idle. it seems to me that if removing the timing tensioner allowed the cam to slip off the chain a tooth, it would be possible to realign the timing without removing the entire timing cover. Does anyone have any experience with doing this?

I'd see if your mechanic friend would take responsibility for this and fix it. I don't know how much slack you'd need to jump a tooth, but it seems like it would have to be significant... more than a tensioner would allow/ disallow. If tensioners could allow that much slack, I suppose we'd hear about jumping teeth much more often. So, my guess is, you'd have to undo a bit more, including the cover, to get at this but alas, I'm just guessing. I haven't pulled on the chains for such engine. I doubt I'd be able to get that much slack on my 240sx engine chains, that's for sure. Do the teeth look worn, indicating a jumped chain? You could ask the guy that did it, maybe he knows if there would be enough slack.

i spoke to him and he says he will do whatever is needed to fix it, so we shall see. I will give him a hand. Will keep this group updated on what happens.