P0012 Saga

Quick and Dirty explanation/diagnosis (1GR-FE '15 113k miles)

Two weeks ago, the engine light came on. P0012 DTC code

What I've done so far with no effect on the DTC code:

-New OCV (bench tested before installation)
-NEW camshaft position sensor (checked ohms before installation)
-I checked the VVTi Filter (it looks new)
-I had the electricity checked from the ECU to the connections to the OCV and cam sensor, all is good
-I brought it to a dealership and got a full diagnostic, but nothing to explain the code. The mechanic ran the Live Data while I drove it. They also checked all the electrical, OCVs, and CAM sensors. Everything checked out.
-Checked timing chain tensioner. It's not extended further than it should be so not a stretched chain

I will look into the valve case tomorrow, but expect nothing out of the ordinary.

I am looking for advice on whether I should tackle this job myself or pay a mechanic. The best instructions on how to do this seem to suggest that it is not so involved; from what I've seen, you can get the camshafts out without removing the timing cover.

I use my truck for work and need it ASAP. I am also looking for a ballpark cost associated with the cam gear replacement, both from a dealership and a shop. Would love some part numbers if possible.

Thanks Yall

 

Did you replace the correct oil control valve? (Bank 1 is passenger side)

I would really want to verify what part is bad before tearing an engine down as a guess but that's just me. The phasers themselves rarely fail, you can check if they are operating with a bi-direction scan tool. You command the VVT to move and see if the engine starts chugging, if it does then the phaser is most likely fine.

The only way to check actual cam timing is checking cam/crank correlation with an oscilloscope.


This a known good from my truck.

 

It's guessing without an oscilloscope, but its likely a chain at this point.

Also just to appease us, you're replacing and checking the parts on the correct side of the engine? No offense but its good to clear the air with this.

The tensioner isnt a sure fire way to be sure. Also there is a secondary chain tensioner. Wouldnt hurt to remove the valve cover and see how everything looks, maybe the secondary tensioner has collapsed.

 

Secondary (exhaust cam) chain jumping/stretching wouldn't throw a timing code though I wouldn't think because the exhaust cam doesn't have a cam sensor.

 

Fair point, only dual VVTI has it. 1GR is such a dinosaur haha.

Valve cover off would show the primary chain though and if it has slack, doesn't hurt.

We see the secondary's fail on the 5.7 along with its primary's often.

 

113k is really low miles for a 4.0 to have timing chain issues if it's been well maintained though, the OCVs seem to be the most common cause of the P0011, P0012, P0021, & P0022 codes on the 2nd gen Tacomas. Stretched/jumped chain typically sets P0016 and/or P0018 codes.

 

We usually see P0011 p0012 for chains here, I've actually never changed an OCV on a 4.0, the 2GR transversed was known for them.

I've only seen debris/filter issues on a 3GR oddly.

We actually have a burnt valve 1GR waiting to be fixed, propane truck haha.

Again, just sharing, doesn't mean anything.

 

Interesting I'm just going by what I see on here, it seems almost ever time someone pops up with a P0011, P0012, P0021, &/or P0022 an OCV fixes it.
I actually very rarely get Tacoma's in the shop and when I do it's typically minor stuff. Don't get many Toyota's in the shop in general, manly see Ford, Gm, & Chrysler/Dodge/Jeep stuff in the shop.

 

The OCVs have both been replaced with new OEM units. The dealership performed the VVTi system test, as did I. Bank 2 bogs as it should, but you get no response from Bank 1 when actuated. I guess I'll buy an oscilloscope and see what I get. The three mechanics I've talked to all say the same thing about the phasers never being the issue, but it's looking like my Bank 1 is the issue.

 

Bank 1 is the issue, verified by the scan tool VVTi actuation test. Bank 1 VVTi gear does not actuate when told to by the scan tool. Bank 2 works fine and bogs when actuated.

 

@Dm93 I've never used an oscilloscope before for this. Is there a video you'd be able to point me toward that would walk me through the steps of checking the cam/crank correlation? Also, just for note, the camshaft position sensor has been replaced, too.

 

Ah so scoping the cam crank signals probably won't help us then.
If the valve is working, it's getting the right signal to it, and the VVT screens are clear but the phaser isn't moving it can't really be anything else but the phaser that I can think of.
Kinda crazy for one to fail especially at just over 100k.

 

@Dm93 I am seeking advice on whether to tackle this job myself or pay a mechanic. The best instructions on how to do this suggest that it is not so involved; from what I've seen, you can get the camshafts out without removing the timing cover.

 

As far as changing the phaser without removing the timing cover I do not know, if there's physically enough room to get it out I guess you could but the problem is gona be getting everything back in time correctly without taking the cover off.

 

https://www.tacomaworld.com/attachments/06-4-0-left-cam-removal-pdf.4649704/

According to this, it can be done. Removing the timing chain tensioner gives enough slack in the chain to remove the intake and exhaust camshafts/gears. Obviously, if the chain drops off the drive shaft, you have big issues.