[can]

The front lower control arms were replaced last fall.

Replacement of the LCA has certainly improved suspension feel, but driving over some cracks (not all of them, probably depends on direction) I still hear clunking. Have a feeling that the diagonal cracks are causing that more than perpendicular.

Are those strut mounts going?
Or should I look at the sway bar bushings first (does Quest even have a sway bar)?

 

[plplplpl]

I can't speak to a Nissan Quest, but for the Pilot sway bar bushings are an inexpensive, easy and effective fix in many cases.

http://www.piloteers.org/forums/69-2003-2008-pilot/98762-2004-pilot-front-stabilizer-links-bushings.html#post1017114

 

[mclasser]

Motor mounts are a common source of clunking in Nissan's. I'd look at those before spending money on suspension components.

 

[can]

Possible, but mine sounds as an instant metallic click when the front wheels go over a crack, so I doubt it's the motor mounts. I would expect that motor mounts would make a low pitch boom when going over the larger potholes or bumps. Just speaking from experience with the other cars - the Quest is relatively new to me (bought it 3 year old in 2008 and drove ~80k miles).

From your experience, folks, what do the worn strut mounts sound like and in what circumstances do they make clicking or clunking noise?

 

[Rocky]

You can also tell motor mount failure by excessive movement of the engine when revved.
Does sound suspension related. Start by making sure ever is bolted together properly. Especially since you had recent work done.

 

[can]

I was going to go back and ask mechanic to double check everything, as it was still pulling slightly left when accelerating and slightly to the right when decelerating.

 

[can]

Figured out the issue was the stabilizer links. Not going to do anything about them for another year or two.

 

[can]

Some time ago the Quest stalled, stranding my parents. They called me and I told them to turn off the ignition, wait a minute and start it again.
It did start and they made it home, even though the engine ran poorly.

At that time I waiting for the OBDII readers and once they arrived, read the codes. There was a pending code for the throttle pedal position sensor. Fortunately, I first posted on the Quest forum and was told to replace the camshaft position sensor instead. I ordered both and was lucky to replace the front bank CPS first, as that fixed the code and the engine ran fine since.

Then I got the dreadful P1273 code for air/fuel mixture and read about it. Some said that a learning procedure should be followed. I followed it twice and first time waited more than 10 seconds to shut off the engine, so the code came back in the next about 10-15 miles. I repeated the procedure and timed exactly 10 seconds. Then I drove about 70 miles to work and back and the code came back only after about 50 miles.

I repeated the procedure and drove to work the day after. On my way to work the light did not come on, but I heard a pop and the exhaust broke. It turned out that the O2 sensor bung popped out. My mechanic welded it back in, but ever since I picked up the van it backfires 3-4 times when I start and shut off the engine. What could possibly cause that? Does it mean that the O2 sensor was damaged when it popped? And also, has it popped because there was already incorrect air/fuel mixture and once it backfired it popped the bung?
It happened on a highway at very moderate speed, perhaps when I was very mildly accelerating from 30 to 40 miles an hour.

I am assuming that once popped, the O2 sensor just hung there, could it possibly break from dangling?

 

[can]

The problem solved itself.
After driving a bit more backfiring stopped and there are no further codes. The engine runs well, knock on wood.

 

[can]

I hate "drive by wire"!

Last Friday my family got stranded in the Quest with all their groceries. They lost power, the engine would only rev to 900 RPM in neutral.
I left work early to give them a ride home in the Pilot and stayed with the Quest to try figure it out.

After I un-plugged the throttle pedal position sensor and plugged it back in, everything worked as usual. Damn Nissan for their random electric failures!

This whole ordeal would not have occurred, if there was a regular cable from the pedal to the throttle. Drive by wire is a scam.