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P0012? vVTI control actuator assembly

75K views 45 replies 14 participants last post by  maroonxbox2005 
#1 ·
Just bought this XB 3 weeks ago (used, 70k miles). So I love this car and just want this ordeal to get fixed and be over with it. I bought it as a family vehicle for my wife and 1 year old. Couple days after I bought it, I got the three stooges light. I figured it was a loose gas cap, reset it by disconnecting the battery and it did nothing. The lights would appear and disappear on their own every day. I finally went to Aamco today (free check engine light scans) and the code P0012 showed up (cam over-retard). From there I went to the dealership and they diagnosed the car for about 5 hours. They called me back and said it was pin pointed to the VVTI control actuator assembly (+$500!!). Now, I bought this vehicle from a dealership and it comes with a 90 day, 3000 mile limited powertrain warranty (i am still within the parameters). The dealership is now saying that my issue is an electrical one and not covered under that limited warranty. Does anyone know if this is bull? Can anyone show me a link or something in writing that clearly states that this problem is something that can be covered under that warranty? And finally, how the heck does this sort of thing happen? Thanks in advance for reading and any help.
 
#6 · (Edited)
Hey pch I would like to try that fix from the link you sent but no idea where those parts are. Do you have a picture or diagram.

As far as the 90 day 3000 mile powertrain, here is what it says : engine- all internally lubricated parts including crankshaft, main bearings, rods, pistons, rings, camshaft, timing gears, belt, valves, lifters, pushrods, springs, oil pump, heads, block.

Transmission- torque converter, vacuum modulator, internal electric control units, over drive units, shift forks and cases only if damaged by the failure of an internally lubricated part listed above.
 
#7 · (Edited)
Camshaft actuator should fall under "timing gears".

The part that dealeship says needs to be replaced is attached to the intake camshaft. On the pic it's the one of two top chain driven gears (the one on the right and has 4 bolts in it)



Other parts that may be affecting the operation of the actuator are the solenoid valve and the filter behind it. They are located near the alternator and can be accesed without taking the the side engine cover off.

 
#13 ·
My background is push rods and carburetors. Can someone explain how this variable cam timing component works? I understand it adjusts the length of time the intakes are open. My question is HOW does it do it?
I mean that timing chain is locked to the crank and exhaust cam. How can the intake spin at a different speed?
What actual adjusts this change in speed?
 
#14 ·
The lenght of time and speed are not changed. VVT changes when the intake valves start to open by advancing the intake camshaft. Kind of like spark advance in the distributor. It's done by regulation how much oil pressure is allowed inside the actuator. At high engine speed the intake cam is advanced and at idle it's not. So you can have more valve overlap at high RPM and still have good idle and low emissions.
 
#15 ·
^yup, it's the same way a vtec honda motor works... But doesn't VVT-i isn't a performance upgrade with the stock configuration. It's more of a gas saver. Now with a camcon you can adjust the vvti settings and gain i think 5-10hp just from that alone. Then if you alter fuel curve and tune and such, probably if done right, 10-15hp, 20hp at the very most.
 
#16 ·
So it is like a torque converter in an automatic transmission?
At idle the adjuster/camshaft has some slip, so doesn't open right away.
then when you rev up the oil pressure is increased and this locks the adjuster tighter to the actual cam shaft which caused the valves to open sooner?
But wouldn't this also cause the intake valves to stay open later?
 
#17 ·
It's more like an adjustable camshaft gear. The simple mechanical one looks like this:



And VVT actuator is controlled by how much oil is pumped inside:



So the slip is there only for a very limited angle during adjustment. Otherwise it's basically always locked and even if there is no oil pressure it will simply be fixed at the most "retarded" (zero advance) position. More oil expands the inner chambers and camshaft advances relative to the chain or a belt sprocket. Computer continiously looks at how much advance there is and regulates the oil flow with the Oil control valve.
This system is very sensitive to oil contamination. So clean good quality oil with right viscosity is very important. The contriller has wearable parts and seals inside that will fail at some point. All you can do is to make them last longer.
 
#18 ·
Old thread, but I'll give it a shot--
My 05 xB falls within the TSB & way beyond 60K, P0012 appearing regularly since 35K....I'm a very conservative driver, get excellent mileage, so no drivability problems for me. Always a problem getting yearly inspection, as it won't pass with MIL on, so must wait for MIL to go out, then wait for "Ready" on ScanGuage, and quickly get inspected before MIL comes on again.
Is there a way to shunt the signal to the ECM which tells it the camshaft is over-retarded? What type of logic is involved here? Can it be as simple as grounding or opening a circuit so the P0012 is never indicated?
 
#20 ·
Thanks, PCH, for your response. What I was hoping to shunt was the signal that was generated that would place the P0012 code into memory, and light the MIL. That would involve a "switch" ie., "off" meaning "no P0012 code into memory" and "on" meaning "put code P0012 into memory". I have a feeling this logic takes place within the heart of a particular i/c chip within the ECU itself and so an intimate knowledge of the actual chip involved would be necessary.....inasmuch as I would not want to disable any other codes from being generated, it sounds high near impossible to isolate this one code for elimination.
 
#21 ·
That would require some serious ECU software change. Not possible.
There are OBD2 simulators out there that generate "everything is OK" signal to any code/memory reader hooked up to the test plug. Illegal for the purpose of passing an inspection but still available on the internet.
 
#22 ·
the guy I bought mine for said the three stooges lights had been one for a long time and he had takin it to Toyota 3 different times with no luck. So I got the car alot cheaper than he was asking. when I checked it it was throwing the P0012 code but it wound go off every once in a while. and I noticed that if I ran no ethanol gas it would not come on. then I changed the spark plugs and it has not been on since so if your havin this trouble I would try changing the plugs first. O I also run two bottles of seafoam thought it. good luck and hope this helps save you some money from the stealership
 
#23 ·
Thanks, Coffeybean, but my box has over 100K miles on it now, been thru first set of plugs, had all kinds of gas, and since it does fall within the affected VIN# range for the TSB, I'm reasonably sure an actuator change is my only hope. Even tho I drive conservatively, still I wonder if I'd get a bit better mileage @65MPH on hiway, if the camshaft would advance properly...
but not convinced that the potential savings would justify the expense.
 
#24 ·
The wifes xb started throwing this code a couple of months ago. reset the lights with obII reader and it did not return for 800 miles. then threw it again.now it's throwing it about every 200 miles. replaced cam position sensor last month (yeah I know, a waste of $85). no change.
pulled the oil actuator valve and it was clean and free. Also the mesh filter was clean as well. Oil has always been changed at 5-6k miles with castrol 5w30 syntech. All miles are highway as work is a 45 mile drive everyday for her (one way). No short 2 mile trips at all. Ever. She drives like the typical little old lady. Gets 75 k out of a set of tires where I get 30 k. Anyway it looks like a cam gear change is in order but I can't get to it for at least 5 weeks. I was thinking maybe thicker (heavier ) weight oil would help delay this until I have time to get to it. She has logged when it occurs and conditions seem to be engine under little or no load (read lower oil pressure). Just throwing this out there.
Chad
(long time lurker, first time poster)
great forum!!!
 
#25 ·
If the actuator wore out to the point where it internally bypasses too much oil then heavier grade may help. But if you don't have any driveability issues why don't you just wait for the new camgear? It would be cool to find out if switching to 20w50, for example, helps just for the purpose of passing smog check though.
 
#26 ·
Well I have to admit, in the ship industry the knee jerk reaction is thicker oil to solve problems. That being said it usually creates new problems as well.
20w50 may bbe a bit extreme, however I was thinking about 3-4 ounces of STP just to see what happens. Overall she has been quite pleased with this car and aside from this (knock on wood) no other problems in 85k miles.
Fantastic mileage too.
Chad
 
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