Hello All,

I recently added to this post below when I discovered the dreaded P0021 code on my 2011 G37x with the VQ37VHR motor. My car only has 73,000 miles and 3k miles over the warranty so I was on my own to resolve this as I wasn't paying the cost to have the dealer fix this.

Oroginal post for Ref: https://g35driver.com/forums/g35-sed...ml#post7119608

Brief summary

The car pulled only 1 code, the P0021 which is bank 2 VVET system issues. I went ahead and diagnosed the following before digging in to the gasket repair.

1. Changed the oil and filter - Result, no change
2. Checked the Solenoid for sticking - No sticking and no debrees
3. Swapped the Bank 1 Sol with Bank 2 Sol expecting code to go over to bank 1 if it was the Sol and it stayed on Bank 2 - Conclusion, Bank Sol 2 good
4. Inspected Cam sensor - result good no change
5. Replaced 3 oil seals on Bank 2 cam cover - Result no change
6. Checked oil pressure - STRANGE that it seemed good at all RPMS of proceedure - Result - Since I thought that I never verified the oil temp at time of test (I let the car heat all the way up) that maybe it was still not at the high temp and the viscosity was not correct
7. I cleaned the bank 2 oil passage screen that was not clogged by any means but did have some metal particles on it. (this is where the oil come out of the galley from behind and feeds the Sol.

So After checking all this I said OK it's probably the Galley Gaskets so I tore the car down and did find that the gasket was torn in one area which was close to bank 1 and right at the top right side near bank 2 it was so stretched out of place that I suspect it had actually thinned the paper (I didn't measure this) but the last screw on the upper right was actually lose from the gap being smaller I suspect.

I bought new gaskets and installed them with red locktight as tight as humanly possible without stripping (since there is no torque spec for these).

Now 2 observations while doing my repair:

1. The timing chain primary tensioner seemed to be frozen or locked up at its current position. When I removed it it didn't fully extend. I was able to get it working again with a little help (aka, force) and a ton of black oil came out when I pressed the plunger all the way in. I stuck my wd40 tube in the tiny hole on the back and was able to clean the whole thing out until it moved freely. I also took some green scotchpad to the piston to clean it up. It seemed to be ok so I reinstalled it.

2. The Bank 1 Cam tensioner was extremely hard to depress and it almost seemed as the chain on that side had slack no matter how much I tried to extend the tensoner. My guess is that it had failed but at the time I looked and it seemed the only way to replace this tensioner is to remove the whole passenger side of the valve covers etc which I was not about to do at the time. I figured I had never heard any chain noise before and I was having trouble with Bank 2 not Bank 1 so it must be good enough as is.

So I put it all back together...

So, upon initial startup and clearing the codes before hand I almost immediately get the P0021 code again in the pending codes (F^%&!!!!)

I say to myself, maybe it just needs some time to warm up and get the oil all up in there at the top of the engine so I wait and keep revving the motor and clearing the code for about 10 minutes until it stops returning.... Great its fixed I think...

Test drive - I take it out and it seems to be working great, car pulling strong all the way to redline and clearly not going into limp mode and no codes being thrown. OK its fixed!

I park it and the next morning I go to Dunkin, half way down the street I hit the 3500RPM rev limiter and I say damn. P0021 is in the pending codes again.

So The car has been like this for a couple of days. It seems totally random, some times it will drive fine and sometimes it will throw the code and run in limp. I clear the code and then it will run fine again and pull hard.

Seems totally random to me and I'm a bit puzzled.

From here I'm going to order a new chain tensioner primary and new secondary and will swap those out to see if this is it.

Lastly I wanted to ask your thoughts. When going over everything and checking my plugs etc. I do notice that the Bank 2 cam sensor seems to move like 1/2 a millimeter in when I press on the connector. The Bank 1 sensor is solid in the Cam cover so I thought this strange. I'm going to buy a new cam sensor just for the hell of it.

Also lastly anyone trying to remove the harmonic balancer should just tie a strap around the pully and use the sway bar to hold the strap, worked well for me but I broke the first strap and bought a 8800lbs strap that worked well


Any thoughts?????


Mike

 

So, as I mentioned I still had the P0021 code after doing the gally replacement and I went ahead and ordered up a new primary, secondary tensioner and cam sensor to try and replace.

I took the small cover off the bank 1 side I was pretty pissed that I had to take off the pully bracket because 1 bolt is hidden behind that bracket. This involved taking the power steering pump cast iron bracket off so it was more time than expected just to swap the primary tensioner.

I went ahead and removed it and the damn guide shot over like a bullet (I hadn't bothered to put the motor at TDC prior to removal of the tensioner so apparently the chain was under a bit of load and I heard the chain skip a bunch of teeth behind the case (I couldn't tell from where (at the crank or at a cam))

I said oh well lets go ahead and take the whole damn thing apart again to reset the timing chain and hopefully I haven't destroyed any valves in the process.

I was able to get both banks to move without interfeerance back to their TDC position marks and then I rotated the Crank LAST to get it to TDC. Trying to move the crank first (very slow by hand) I was hitting the valves somewhere so I did the heads first then the crank last and it worked.

I lined the chin back up to all the points and installed the new tensioner. Got it all back together and started it up.........

The result???? No code.. I took it for a test drive, the result? no code and the car ran like it had a brand new engine!!! I couldn't believe the torque and respnsiveness. The car pulled so hard I couldn't believe it.

so my theory on what caused my problem is that although the galley gaskets were defective, I'm not convinced this was my problem. I believe because it ran low on oil the primary tensioner sludged up and failed causing it to seize and not extend as required. I then estimated that the Bank 2 drivers cam slipped only 1 tooth making it run but just run crappyier. Ultimately I suspect it slipped another tooth or more when I experienced the code on a daily basis from that point on.

So, my advice!!! if you have this problem and your oil pressure is appearing to be ok like mine was appearing to be and you see something strange with your primary tensioner, then check your timing chain marks!!!! I never checked when I did the gally gaskets and just assumed the engine wouldn't run if it was off.

That is all. Good night.

Mike

 

Really glad you got that all sorted out, logic seems sound, what an odd problem to have.

 

One last thing worth mentioning. I checked my fuel economy history today and noticed that on average at every reset interval I have been around 21.5 to 22 ish. The last record I had in there was at 17mpg. This definitely explains a condition of running out of peak performance and explains possibly one bank being slight off by 1 or more teeth.

Mike

 

Glad this was sorted.