Timing chain nightmare

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wbailey

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See if you can crack this:

About a month ago I got a code p0012 bank 1 overly retarded timing. Swapped OCV valves and it the code jumped sides so I replaced it but still had the code...weird. Opened the valve cover and found a loose cam chain where the tensioner had failed. The primary tensioner was extended (but not by a lot) and at TDC the cam marks were off by 1/2 a tooth.

Ordered a chain set and replaced everything but couldn't get the marks to line up, they were off 1/2 tooth with the painted links right where they should be on the sprockets. I don't know if this is NORMAL but with the gears lined up I would install the chain and have a little slack between the bank 2 cam and crank, if I rotate the crank to move the slack into the tensioner side, the crank advances ahead of the cams and I'm back where I started 1/2 a tooth off. Heres a drawing of how I set it, I did not skip a tooth.
PT7XWhC.jpg


I figured maybe the VVTi makes micro adjustments to the cams to accommodate a few degrees and sealed it back up. Cranked it. Drove it. Still had retarded timing.

opened it back up and redid the ENTIRE process, I even held the crank in place and cranked the cams back by hand to get the chain TIGHT and it still wouldn't line up. there is no way to take the extra slack out without retarding the position. Was I sold a used/stretched chain? The tensioner isn't wayyy out like it would be on a stretched chain. How can an unstretched chain be off by 1/2 tooth?!!


Pics showing the out of time gears
1gr fe - Album on Imgur
 
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Your drawing is wrong. Bank 1 intake cam sprocket does not align w/ the raised timing mark on the bearing cap at 12 o'clock. It aligns with the indented timing mark located to the right of the raised timing mark. If you aligned the intake cam timing mark wrong, there's your 1/2 tooth error on the exhaust cam.

See pic below from mine:
 

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I found the easiest way to get everything lined up was to remove the camshafts and re-set all the chains/camshafts at the same time. It's more work, but it made more sense to me that way.

The FSM has a section for measuring the chains to see if they are stretched. You could do that if you think your chain is too long.

How do the rest of the tensioners look? Are any of the guides worn down?
 
OK, this is a good troubleshoot so let's dig in starting from the original problem:

"About a month ago I got a code p0012 bank 1 overly retarded timing. Swapped OCV valves and it the code jumped sides so I replaced it but still had the code"​

1.) The initial symptom was P0012 with factory components. How many miles on the engine at that point?

2.) The OCV experiment: they are not readily interchangeable between banks given the mounting bracket angles, so explain the "swapped OCV valves" process. New OCV installed on bank 1?

3.) The result of the OCV experiment: explain the "code jumped sides" outcome in more detail. What error code was set?
 
waypoint said:
OK, this is a good troubleshoot so let's dig in starting from the original problem:

"About a month ago I got a code p0012 bank 1 overly retarded timing. Swapped OCV valves and it the code jumped sides so I replaced it but still had the code"​

1.) The initial symptom was P0012 with factory components. How many miles on the engine at that point?

2.) The OCV experiment: they are not readily interchangeable between banks given the mounting bracket angles, so explain the "swapped OCV valves" process. New OCV installed on bank 1?

3.) The result of the OCV experiment: explain the "code jumped sides" outcome in more detail. What error code was set?
Click to expand...

1. 185k miles
2. I swapped the valves after seeing it on another troubleshoot post, they fit real snug but I had them twisted because of the brackets and not bolted in.
3. code p0012 timing retard bank 1 became a p0022 timing retard bank 2.

Since it will come up here's a pic of the original tensioner before I replaced anything.
p0012 - Album on Imgur
 
wbailey said:
1. 185k miles
2. I swapped the valves after seeing it on another troubleshoot post, they fit real snug but I had them twisted because of the brackets and not bolted in.
3. code p0012 timing retard bank 1 became a p0022 timing retard bank 2.

Since it will come up here's a pic of the original tensioner before I replaced anything.
p0012 - Album on Imgur
Click to expand...

Thanks for the tensioner pic, looks like it was extended by 1-2 ratchet clicks but not likely enough to account for the original problem.

Your other pics showing timing marks do not indicate a stretched chain...this failure shows more timing retard on bank 1 than on bank 2 relative to the crank position, as there are more (worn) links acting on bank 1 given the longer distance from the crank. Let's take the chain and your installation off the table for now and assume they are correct, and that the static chain slack accounts for the retard you are seeing at the intake cams.

Swapping the OCVs was a good experiment and would seem to have indicated the OCV was the problem. But P0012 is still happening with the new replacement OCV, correct? And other than the check engine light, does the truck run well?

If P0012 is your only current symptom, here's what I'd do:

1.) Remove and clean or replace the OCV filter on bank 1 if you haven't already. Get a new crush washer from the dealer to ensure good sealing during reinstallation of the filter and plug. Report your findings when you remove the current filter.

2.) If the OCV filter doesn't correct the problem, I'd remove the intake cam actuator/sprocket and replace it. Not cheap for a Toyota part at $170 or so, but it can be done without removing the main timing cover (again). I did mine early in my project, had to buy a 17mm offset box wrench at Sears and a 24mm long open-end wrench to hold the cam without slipping off as the crescent wrench did.
 
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I checked the filter and it wasn't clogged, really the whole engine is rather clean for the miles.

It runs, but not well, poor mpg, the idle is a little rough and sounds like a tractor, I thought about the intake cam gear because of the sound. Like if the hydraulic pressure wasn't building and the lobes were just rattling inside the gear housing. But the way the gear is assembled it doesn't seem like it would cause minute slack in the primary chain, am I over thinking?

EDIT: regarding other DTCs I have a p0420 but that's been happening for 2 years and it drives ok, sometimes it would clear on it's own.
 
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I'm really questioning your OCV swap. The OCV has holes and passages down the sides that match up with holes/passages in the bore where it is mounted. That allows the proper pressure/bleed down of the VVT system for that bank. If you just swapped one side for the other and 'twisted' them, I can't help but think those grooves and holes are misaligned. You really ought to buy two new ones.

LH Dorman: 917-231

RH Dorman: 917-238

I've been running these for about 2 years with no problems.

RWGa8t1.jpg
 
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I agree, the OCV swap was not a good test, I just did it because it was easy and recommended on another forum. I replaced the bank 1 sensor and still get the code so it's on to the timing gear.

is there a way to test the gear without removing it? I just tried unplugging the ocv to see if it made a difference in sound as seen in this video
YouTube
but it stayed the same.
 
Is it possible everything is working fine except you have a bad cam position sensor? If the chains line up as you've said, the OCV's and filters are known to be good - what else could it be? Scratching my head.

Also, how did you determine the screens weren't clogged? They may not have trash in them, but a scaly substance that is not real apparent unless you spray one section of the screen and hold it up to the light.
 
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wbailey said:
I checked the filter and it wasn't clogged, really the whole engine is rather clean for the miles.

It runs, but not well, poor mpg, the idle is a little rough and sounds like a tractor, I thought about the intake cam gear because of the sound. Like if the hydraulic pressure wasn't building and the lobes were just rattling inside the gear housing. But the way the gear is assembled it doesn't seem like it would cause minute slack in the primary chain, am I over thinking?

EDIT: regarding other DTCs I have a p0420 but that's been happening for 2 years and it drives ok, sometimes it would clear on it's own.
Click to expand...

The actuator/sprocket assembly has a lock pin which is unlocked by oil pressure when the OCV first opens. With the engine off, the pin should extend under spring pressure and mechanically lock the VVT actuator vane to the sprocket base.

You should be able to test the lock function by rotating the intake cam (wrench on locator flats) back and forth a small amount while observing the sprocket. If the cam moves independently of the sprocket, the lock is not set and is suspect.
 
weather is looking bad for today so I'll open it up tomorrow and rotate the cam to check. It was mentioned that the gear can be changed without opening the timing cover, is there a secret to this? Do I lift the cam bearings? There's very little room between the intake gear bolt and the timing cover.
 
wbailey said:
weather is looking bad for today so I'll open it up tomorrow and rotate the cam to check. It was mentioned that the gear can be changed without opening the timing cover, is there a secret to this? Do I lift the cam bearings? There's very little room between the intake gear bolt and the timing cover.
Click to expand...

I did mine during the initial diagnosis without removing the timing cover by following the shop manual procedure, links are below. I did have to unbolt the cam bearing caps and lift the cam in order to remove the VVT actuator/sprocket and install the new one. Good opportunity to inspect the VVT oil passages in the camshaft are clear...carefully so as not to nick the bearing surface. I used a can of compressed air and plastic straw, gunk came out.

NOTE: I did not remove the exhaust cam, and I don't recall removing the exhaust sprocket but I may have needed to in order to get the side chain off and free up the intake cam lift height. Tie off the main chain to prevent it from falling into the timing cover...I used a large zip tie to secure it to the engine somewhere.

Removal:

http://www.customtacos.com/tech.old.../06toyrm/06toypdf/06rmsrc/rm2006ta/007004.pdf

And here is the installation section:

http://www.customtacos.com/tech.old.../06toyrm/06toypdf/06rmsrc/rm2006ta/007005.pdf
 
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If you're curious about the internals of the intake cam VVT actuator/sprocket, here are pics of the one I swapped out on mine. My engine was much sludgier than yours due to original owner neglect, but this one was working correctly despite the sludge buildup outside the vane path. Note the big lock pin on the vane hub, and the corresponding hole in the housing...there's a small oil passage at the base of the hole where the OCV sends pressurized oil to unlock the pin.
 

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Hey thanks for all the info Waypoint, I never would have found these shop manuals.

NOW, this is the part where I lose my mind:

I took the cam bearings out along with the B1 timing and exhaust gears, put air through the oil slots and no gunk came out, just nice pretty oil. The lock pin seemed to function fine so I decided to reassemble the cam and check B2, then I dropped the No. 1 tensioner pin down the timing cover and had to rip it all apart. A 3rd time.

When I inspected the timing marks they are all now PERFECTLY LINED UP. Rotated the crank twice and it's still good. I hate it when I fix something by accident. I have no idea why it's good now but I really would like to know. If this isn't a sign of another problem I'm sealing it up and calling it a day.

EDIT: Nevermind, I rotated it a few times and it's off again.
 
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I decide to measure everything from the kit that I installed, the chain is ok. But there's a difference in the idler and crankshaft sprocket diameters. Idler is 2.5 in. crank is 2.4, the manual says a minimum spec of 2.4 in. but no max. Are they supposed to be the same? Also the chain snugs around the Crank better than the idler. Change in circumference is 1/3 in. which is about how far I'm off the timing marks so...

Could the slightly larger idler be the source of the extra slack in the primary chain?

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