P0016: chain stretch, cam sensor, crank sensor, OCV filters, OCV valve

Disclaimer: This is my first real post here besides in the introduction forum. I hope that I have put it in the right section. Feel free to offer some criticisms. I am still trying to learn the proper language and terms to discuss these things. If I've said something wrong please let me know so I can correct them. I often browse these types of posts to help me narrow down what might be causing my issue, so hopefully I can help others do the same.

I picked up an 05 Tacoma about 1 month ago now. The truck has 214 000 km or around 133 000 miles. It has developed a P0016 code and I've reset it several times. Each time it reappears after idling for a couple of minutes. The truck itself runs fantastic although it does have an issue starting when warm in that it won't start on the first attempt but always starts on the 2nd.

I spent time today hunting down the P0016 issue.

As you may know, the P0016 "Crankshaft Position Camshaft Position Correlation Bank 1 Sensor 'A'" code can be caused by a number of potential culprits including:
- Timing chain stretched or skipped a tooth
- Bad cam sensor
- Bad crank sensor

Some other anecdotal causes I've run across online include dirty oil, clogged OCV filters, and OCV valves which are not operating properly.

Since I have a leaking valve cover gasket and would be replacing it I figured that it would be interesting to look at the timing chain, whilst doing so, to narrow down my potential causes. I ran across this thread on FJ Cruiser Forums where an individual apparently did have a cam gear skip a tooth and kind of hoped I had skipped ahead a tooth and not just had stretch. I've got some photos of that part of the process in this post. For the other parts, I didn't take photos as it didn't seem worthwhile. I'll break down the process I went through into a list.

1. Camshaft position sensors
Tried: Switched their positions (ie bank 1 sensor to bank 2 and vice versa), erased the P0016, then started the truck to see if it threw a P0018 code (the same code as P0016 but for bank 2).

Result: The truck threw a handful of other codes and ran awful. None of the codes were P0018, but I only ran it for a very short while like this. I will definitely need to come back to this again. As I didn't have a new sensor on me I can not rule out a defective sensor (I assumed bank 1 and 2 cam sensors are interchangeable, is this correct?)

2. OCV filters
Tried: Removing the OCV filter on bank 1. It had a very few very small pieces of hard sludge in it but I'd have a hard time believing that would restrict any flow. I cleaned it off thoroughly in put it back in. The filter on bank 2 seemed to be behind the alternator and largely inaccessible. From the looks of the other filter, though, it didn't seem like a worthwhile endeavour anyways.

Result: No change

3. OCV valves
Tried: Removing both OCV valves, testing their function by running 12 volts across them, checking resistance across them.

Result: Both were fairly clean and did not look like cleaning would be worthwhile. Both seemed to operate fine. They fired briskly and there was no sticking. Both had around 7.3 ohms across them which I understand to be within the expected range. As there was nothing to do here, no change was noted in the operation of the truck.

4. Crank sensor
Was not able to access at this time due to it's position.

5. Timing chain
Tried: Comparing my timing chain to this guide from TOYO Headquarters. Note that my chain markings (the orange links) are not lined up in my photos. I assumed this wouldn't make a difference since I didn't need to line up to TDC, just to see if the markings themselves lines up.

Result: After the crank was lined up with it's 0 marking, I observed how things lined up up top with the VVTi camshaft gears... which is where I believe my problem lies. You'll notice that with the crank at 0, the VVTi camshaft sprockets on both bank 1 and 2 are ahead of their marks by about 1/3rd to 1/2 of a timing chain link each. I was not 100% sure that I had used the guide properly and as such need some confirmation to assure that I am looking at the right markings / places to line things up. I can add/edit photos if necessary.


Lined the crank up to 0




Bank 1: red line represents marking on VVTi housing and the cam gear (2nd photo) that is not lining up with the mark in the red circle.




Bank 2: Again, red line indicates the spot on the VVTi housing and cam gear we are trying to line up with the marking in the red circle



The piston which pushes on the guide rail is outlined by the red rectangle. There is no way that tensioner can extend any further, lending to the idea that this chain is in fact stretched too far. The red arrows are there to show the close proximity of the chain to itself as it goes around the idler sprocket.


Unlike the 1 GRFE on the FJ forum, my chain appears to simply be stretched and not have jumped a tooth. I believe this to be the issue since it is about the same amount out on both banks with the crank at 0. You've also likely noticed the accumulation of sludge which was probably a large contributor to the stretching. I guess the old owner didn't love the Tacoma enough to take good care of it. Since I will take the time to put on a new timing chain kit this winter, I'll run some Seafoam, Rislone, and ATF and do several oil changes to see if it makes a difference in the accumulation. It would be really nice to be able to take a valve cover off as part of the used car buying process!

 

The chain is stretched. It's not a bad job. Just lots of bolts. Can be done at home if you know what your doing or have the repair manual

 

I'm working on the same problem with a 2007 4Runner 1GR-FE I picked up as a project...P0016 and a "stretched" timing chain resulting from neglected oil changes by the original owner. Much worse condition than yours, but the #1 chain tensioner piston in your pics tells the story. I attached pics of the one I removed from my engine showing the tell-tale rings of sludge/discoloration where the plunger extended one ratchet step at a time as the chain elongated.

I took the same approach as you've done, and I replaced the #1 bank oil control valve and VVT actuator as well as the #1 chain tensioner. These have reduced the P0016 frequency significantly...only get it when the engine is not up to temp, occasionally, when driving in stop & go traffic conditions.

Mine looks much more sludgy than yours as shown in the other pics. Soot particles in over-used oil accelerate wear in the timing chain pins and bushings as I've found by research thus far. In my case this seems to account for my chain's condition...yours doesn't look neglected enough for this to have happened. And yet your #1 chain tensioner plunger is extended about as far as mine. Strange.

 

Did replacing this fix your P0016 code?

 

Do you have an update on if you got the P0016 code fixed?

 

No, as I said in the post I still get P0016 if I don't warm up the engine before driving off. The main chain is elongated, bank 1 intake cam has approximately 8 degrees retarded timing relative to the crank. Also, the main chain tensioner is over-extended as shown in the pics. The only fix will be to replace the timing chains, guides, and sprockets.

 

Update: I'm in progress replacing my timing chains, sprockets, guides, and tensioners. The attached pic shows the new Toyota chain next to the factory chain, both hanging from a level bar. This stretch was enough to cause approximately 8-10 degrees of retard between bank 1 intake cam and the crank.

 

Update: I finished reassembly and have just over 1800 miles on it, no issues and P0016 is gone. It's a very tedious job getting the timing cover back on given the 2 oil system o-rings, FIPG sealant bead, and oil pump drive. These require precision alignment and careful handling of the timing cover.

 

Nice job, looks like a PITA to fix. Here's a good video on what's involved:

https://www.youtube.com/watch?v=UR50da0sDOc

 

It's a terrific video, but omitted the really complicated part...reinstalling the timing cover as I described. The bottom o-ring for the oil pump pickup is an especially high risk piece, as there are no nubs molded into it to help hold it in place. I saw some people have used grease, I used Permatex aviation sealant and let it fully cure to lock that sucker into place before applying FIPG and installing the cover.

 

Jeez.. I thought I was handy. That’s some serious work getting in there!
I also have a 2007 4Runner and just got the P0016 code. My mechanic said my tensioner is very extended and I need a chain replacement. If I’m not have any driving issues at all, with sounds, acceleration, etc.. do you think I can put this off for a few months? I don’t have much time to deal with it right now because of work. Also, I got a $1,900 estimate.. looks like a ton of work that I can’t pull off. Does that price sound reasonable?

 

I ran mine for 12K miles from August to July w/ the stretched chain(s), resetting the CE light as needed. Didn't baby it, didn't flog it...just normal driving aside from a long morning warmup and bringing the engine to 2K RPMs for a second or two, returning to idle before dropping into gear and driving off.

Use oil with lots of moly to protect what's left of the link pins & bushings, e.g. Pennzoil High Mileage (regular or Platinum synthetic), or Quaker State Ultimate Durability. Change it at 5K mile intervals. I went this route, and the tensioner had not extended any further when I finally took it off the road.

$1900 is a great estimate, I would have gladly paid that rather than DIY. Local shops quoted average $3600 parts & labor. Good luck and keep us posted.

 

Wow, thanks for the quick reply! Awesome.. I was hoping I could make it to summer without some disaster.. broken chain, seize up, etc.. Mine runs great so hopefully it will just be a fuel efficiency hit.
My mechanic is terrific but really takes his time. I’ll need awhile to figure out some transportation arrangements for the week it will probably take him.

I came across other 2007’s with the chain issue. I wonder if Toyota got a bad batch of chains that year or something.. I only have 78,000 miles and I’m pretty good with oil changes so it’s a major bummer. The lock actuators just died and I can’t get the VSC warning to go away either. She’s getting old and falling apart even without the mileage, just like me!
Anyways, thanks again for the info. and advice!
Steve

 

I also observed 2007 (and early 2008 model year) 1GR-FE engines seem to account for the majority of P0016 errors due to elongated main chain. In many cases there was clear evidence of poor oil change maintenance, but not all cases. And I saw posts of earlier 1GR-FE engines with significant sludge, but the chain tensioner at normal extended length. Reasonable evidence that '07 chains were not of the same quality as the other years.

Not sure what's going on with your door locks, but the chain is a one-and-done repair if good parts (not chinese junk) are used. I went with Toyota parts (revised main chain part number), but it was $190 wholesale just for the chain. Cloyes and Melling sell complete kits, and both are reputable brands. Those three companies would be my only choices. I tried to negotiate with IWIS to manufacture a batch of their high performance chains for this engine, but they declined.

VSC light is part of the "Christmas Tree" error lights that come on with P0016 and many other error codes. It's a shame to lose VSC just for a minor valvetrain timing error. I bought an OBDLink-MX from scantool.net and just left it plugged into the diagnostic port, using my iPhone to clear the code as needed (pretty much every other day).

 

@Andrew83 Sorry for the very lengthy time period prior to my reply... I did in fact fix my code by doing a timing chain job. The code never came back. As mentioned by @craigs1 perhaps one of the most difficult parts is replacing the timing cover and trying to keep the oil pickup O-ring in position. I rehearsed the process with dry runs, prior to doing the real thing, several times and still managed to mess it up my first go at it. Sounds like we used similar methods in the end as I also used a bit of sealant to keep it in place during the procedure.

On my truck the A/C was shot and the system needed replacing. Given this, I actually had the refrigerant recovered and then removed the grill, A/C condenser, and the radiator. This gave fantastic access to all necessary parts during the timing chain job. If you do it yourself and just happen to need work on the A/C system, it's a really great way to do both jobs at the same time. Another suggestion would be to use an electric ratchet. Saved my hands and wrists a lot of grief.

 

Congrats, welcome to the club!