07 QX timing chain slap noise - chain skip a tooth?

[jonnydclark1]

So I bought and fixed a wrecked QX last summer. It ran great except at high RPM (not sure what RPM because the tach doesn't work) I got a terrible marbles in the blender sound. I ignored it and figured I didn't need to drive it that hard. I've put about 5,000 miles on it and only occasionally have to let off the throttle when I hear that noise. Tonight I got on it hard leaving a stop light pulling an empty lawnmower trailer and definitely heard the noise. Immediately the truck started missing and shaking at idle and under normal throttle. I was able to drive home fine and no check engine lights have came on. Almost everything I read about for the QX timing chain is the 2011 version and the oiling issue. Does the earlier 5.6 have the same issue? Is it likely that I slipped a tooth on one side and the computer can't see the misfire?

I watched a timelapse video of someone changing the timing chain and it does not look pretty. I' put a new water pump and fan clutch forward on the truck as part of the repair and at the time didn't know that it could need a timing chain. Would have been nice to have fixed it then with easy access.

I see this timing chain kit on Amazon with guides and tensioners for $185 but it doesn't appear to have any oiler bolts / studs like I see them talking about on the 2011. Any DIY threads (I searched and didn't find any) on this or is it just too involved? I heard 4 hours for the guys that were doing them over and over as part of the recall so I'm guessing I could do it in a weekend but it wouldn't be fun.


Can I check to see if it skipped pretty easily or do I have to pull the entire cover off to see?

[jonnydclark1]

Fearing my check engine light may be just not working (instrument cluster in the QX is terrible about lights and gauges going out) I just connected my OBD2 reader but it shows nothing. Engine sounds fine under the hood but inside you can hear (and feel) the miss and shake at idle in park. Not sure where to start.

[marctronixx]

yes sounds like you skipped timing and exactly what happens when the timing is off.

[jonnydclark1]

Trying to eliminate other things before starting a 12 hr project.

I changed all the spark plugs and checked for compression. Each cylinder had only about 90 psi if I just started and let it idle. If I revved it up I got about 120 on each cylinder with one as high as 150. I would expect 150 but I didn't do anything to change VVT etc. I would expect that if I jumped a tooth I would have either a whole bank with different compression or damaged one valve and that would have different compression. Anyway, the previous plugs were probably original with 130k on it. They were slightly different from what Advance Auto sold me.

All the plugs looked great except for cylinder #8(?... back passenger). It was completely ashe fouled as seen in this pic.


Compression on that cylinder appeared to be the same as the others. I can't tell any difference now that I have new spark plugs in it. It runs ok driving around just less power and lots of shaking but somehow still getting the same gas mileage. No CEL yet. No smoke or rich smell coming out the back. I'm beginning to think it could be the computer limiting something after freaking out about cam or crnakshaft etc but would be weird without a CEL or code. I took out the VVT solenoid from passenger side and it opens and closes with 12V. I blew it out with carb cleaner and put back in. No change. Not sure where to go from here.

[retho78]

Could it be a throttle body issue or bad fuel, fuel filter?

[marctronixx]

good points retho,

petrol sender unit in tank, petrol rail, MAF....

im fascinated that you are skilled to take these things apart.

[jonnydclark1]

Well I'm a darn good shade tree mechanic but been spoiled as a Toyota owner for the last decade. I hope I don't regret not paying the extra $2k for a wrecked Sequoia instead I also have an mechanical engineering degree and I'm an optimist which makes me think I can fix anything. This sometimes gets me in trouble when I take things apart that I know nothing about but I'm a jack of all trades and master of none. In general, by the time I'm stumped the Stealership is normally no help. I did book with a local foreign car specialist for Thursday AM so if I don't get it fixed by then I'll be paying him for diagnosis.

I've been putting cheap gas in for a while. Today I put in 12 gallons of 93 octane (so 8 gallons of 87 still in there) and added an octane booster / fuel injector cleaner pint. Now i'm getting better gas mileage than I was previously even though it feels like I'm dragging a few cylinders behind the truck but I believe it is because of higher octane and I have a lighter foot due to the shaking.

I just found this thread at Titan talk and it sounds like bad fuel pump can cause the stumble at WOT but not sure why it would cause misfire. http://www.titantalk.com/forums/titan-g ... -what.html It does makes sense that it wouldn't throw a code though. My gas gauge is all over the place sometimes literally going from half tank to showing 30 miles left in a 10 mile stretch. I guess I could change the sending unit assembly and hopefully improve that as well as cross the fuel pump off the list.

[marctronixx]

there was a petrol pump sending unit tsb a few years ago on certain nissan armada/titan/qx (up to 2010 the qx was made on the same line ) since they were all born on the same line. may be worth a check.

well im impressed with your resume. ive been around armadas since 2006. i have a 2012 qx and i know that sucker inside and out. im not a mechanic at all, just an enthusiast.

this car is worth its weight, but if it was dogged out, then all bets are off. you have intel on foreign cars (toyota) so you will feel right at home here.

[jonnydclark1]

Well this is embarrassing.

I evidently have a great intuition but am just way too stubborn to actually listen to it. I've often thought that the front end noise at high RPM was fan or fan clutch related but only hear it when I'm in the truck going some place and forget to really check it out when I'm not busy. Finally I decided to test my theory and I removed the serpentine belt (which is a pain to do without removing fan shroud but possible if you have long skinny arms like mine.) Sure enough the truck purred perfectly without a shake or stumble and went to the rev limiter without emitting any nails on the chalk board combined with blending marbles. Everything seemed to spin freely so I put the belt back on. The shake came back and I lost my patience. Knowing it wasn't inside the engine I just revved it up to the rev limiter and crash splash splish. I turned it off and went out to find a fan blade was missing and pieces of it were lodged in one of my small coolant lines near the water pump. So while this isn't likely to help anyone since you probably wouldn't be driving around with a damaged fan blade like I evidently was, I wanted to close the loop and confirm that it was NOT the timing chain or the fuel pump. I've felt a lot of misfires and I can't believe that this is just a fan blade missing shaking the v8 engine and whole truck but evidently the tail wags this big dog.

What I'm not sure yet is whether the fan clutch is bad or just the blade. I replaced the fan clutch when I bought the truck and fixed the front end collision because the fan clutch was cocked from the radiator pushing on the fan. I'm guessing that the fan is the only culprit but will find out on Thursday night when Amazon delivers....

[marctronixx]

good news though! the fan clutch can cause some noise/groaning sounds at high rpms, so that is not too hard to understand.

strictly curious, do you have photos of the qx when you bought it? i ASsumed it was damaged when you purchased. do you know the history of the car? again this is all just curious side of me.

[jonnydclark1]

Changed it the shake went away. Still have a bad noise at high rpm when the serpentine belt is connected. I have to look to see if it is the fan shroud deflecting in with the wind or maybe the fan clutch....

[jonnydclark1]

strictly curious, do you have photos of the qx when you bought it? i ASsumed it was damaged when you purchased. do you know the history of the car? again this is all just curious side of me.

I created a new thread with some pics. Having trouble with Photobucket crashing and not sure where else to host them. Once I figure that out I can add some more....
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