The AVO CEL Saga

[AVOturboworld]

The AVO Cel Saga

Sounds like a bad novella... but our Saga started around the 2700 mile mark. Subiefest and 86fest in California had come up, so I drove down from Seattle, Washington to L.A. when the car was at the 1500 mile mark. Up till that point, there were no issues with the car. However, once I arrived in L.A., the CEL/idle issue that had affected others suddenly appeared. Even though it had shown up, it was intermittent, and when it did happen was always after it warmed up completely.

Now, while I fully intend to take it into the dealer for warranty, I put it off after the trip to California for two reasons. No.1, I needed to test fit our new turbo kit to the car, and No.2, I wasn't sure that Subaru/Toyota was entirely clear upon the situation, or any fix for the situation.

The next part in the story came when the turbo kit went on. That, of course, is a separate story all in it's own. But once the turbo kit was on, up to bat was Ross from our Japan office, who has been the master tuner for these turbo kits. He flew over the morning after the turbo kit install, we went straight to the dyno, and he sat down and tuned through the entire day. More importantly, he logged everything as we went. During the tune, the issue cropped up intermittently - made things interesting. It's easy enough to just turn off the CEL's via ecutek, but there would also be a corresponding loss in power when it did happen.

We were still in a bit of a rush to get on the road to SEMA, since we had to cover 1400 odd miles in the next two days, so we didn't go into it much while on the dyno. However, Ross continued to tune, and log, for the two days down to SEMA and two days back. And it's during that time that we narrowed down the issue.



What was/is happening to our car is relatively simple. Looking at the photo above says it all. Ok, ok, to actually explain what's happening, VVT Exhaust Angle #1 is getting stuck open at idle, instead of going to zero properly. The interesting thing is that, after you get some rev's into it, it'll "unstick" and start working properly. We suspect that this is an oil pressure related issue.

Now, we still don't know precisely the issue, but we have a fair idea what it is, in that it's mechanical. Here's a quick rundown of what we've noted.

1. In our case, it only will happen when the engine is fully up to temperature. In fact, it happens most often when the car has been on the freeway, cruising along.

2. Once you let it cool down fully, it goes back to normal at the restart. If you don't let it cool down fully, or at least past a certain point, the issue remains.

3. If you reflash the ECU via ecutek while it's still hot, the cam position resets and it goes back to normal. This is where the "mostly" mechanical part comes in. If it was only mechanical, why would it go back to the normal position? Note that unplugging the battery and doing an ecu reset would probably accomplish the same thing.

4. We had a wideband a/f monitor hooked up, and when the cam issue came up at idle, it would start going from 14.7 a/f and creep to 10 a/f. That's the main reason for the idle/stall. The ecu is trying to compensate for the rich a/f at idle, and causing the idle compensation to go to crap.

We experimented with "tuning" the issue out with limited success. Ross couldn't eliminate it fully, but could minimize the effects and make the "intermittent" part of it more "intermittent". I went a step further after the trip, acting on a theory of mine, and changed to a Redline 10-40 weight oil. I was only comfortable doing this because of the turbo kit, it's not something I would recommend doing if it was purely n/a. We've seen that take up to 10hp off an n/a car on the dyno.

But... With the oil weight change, the idle issue is mostly gone. It's not that the issue has gone away, but between Ross's tuning experiment and the heavier weight oil, it is very rare for the idle issue to come up. The one time it did, I simply held rev's above 2000rpm for 10 seconds, and it settled back down to a normal idle. So I think we are fairly right about it being oil pressure on the cam solenoid (re: cam sprocket replacements).

Please keep in mind, though, that this is just our car, and may not be the same issue others are having. I also don't suggest trying to compensate for the idle issue like we are - just bring it into the dealer and have them do their job. This is just a FYI to let you all know our experience and our feedback on it.

[GeeTee86]

Thanks for the share. What is the stock weight of the oil the cars are shipped with? For our climate we use a heavier weight because of the heat.

[AVOturboworld]

0-20 weight is what they come with from the dealer.

[GeeTee86]

Yeah thats way to light for ZA.
Will change to 0W40 when run in is over.

[Lonewolf]

Hope someone with a brain at Toyota/Subaru is considering this...

[czar07]

interesting..

[Sportsguy83]

Is the cam solenoid only controlled by oil pressure or is it electrical?

[nix]

Nice work boys. I'm waiting on delivery of your kit from lee, my car had it happen today after 4 or so hours of 80-150kph then peeling off into a servo.

[gmookher]

as far as turbos go, yours is the go to kit imho over the other piece meal thats out there.

I run an oil cooler and am weary of the engine, and yes, its cam solenoids 'liking' hot oil, especially the type of heat from a turbo.

perhaps your kit would benefit cooler, thicker oil? 0-20 turns to water when hot!

[2forme]

Originally Posted by gmookher

as far as turbos go, yours is the go to kit imho over the other piece meal thats out there.

I run an oil cooler and am weary of the engine, and yes, its cam solenoids 'liking' hot oil, especially the type of heat from a turbo.

perhaps your kit would benefit cooler, thicker oil? 0-20 turns to water when hot!

I've always thought this motor needed an oil cooler anyway. Would that negate the need for thicker oil, even with a turbo kit?

[gmookher]

Originally Posted by 2forme

I've always thought this motor needed an oil cooler anyway. Would that negate the need for thicker oil, even with a turbo kit?

well, imho, thats why they are seeing better results with the thicker oil, I own turbo cars. oil gets hot proportional to right foot usage!

[2forme]

Originally Posted by gmookher

well, imho, thats why they are seeing better results with the thicker oil, I own turbo cars. oil gets hot proportional to right foot usage!

I own a turbo car as well. I know this, but my turbo car has an oil cooler on it. I've never boosted a car designed for NA, though.

[gmookher]

see,I could never run or drive a turbo without a oil cooler
my pumped up z car sees 250F oil often, but I run much thicker oil there too
SC wont direct heat oil like a turbo since different oil is used to cool the sc bearings/drive system, but turbo has its place and benefits when executed right, too
turbos used engine oil to cool the bearings, since turbos are driven by hot exhaust gas, much heat transfer occurs to the engine's oil
I'd say buyers of turbo kits need to factor in the added cost of adding oil coolers..but thats me
SC buyers benefit too, but perhaps since youre not using engine oil in another system, you may not 'need' it. but most anybody in warmer climates benefits cooler oil
thicker oil has its downsides, rod bearing clearances, cam oiling channels, all were designed to flow 0w-20(cst 6.x to 9.x), even hydraulics of the cam timing system

I dont think the cst of 10-40 is good for this motor longer term, machining tolerances are way different for oil thats so much thicker:

here is redlines 0w-20:API Service Class SN/SM/SL/SG/CF
Viscosity Grade SAE 0W20
Vis @ 100°C, cSt 8.2
Vis @ 40°C, cSt 43

now look at their 10w-40
API Service Class SN/SM/SL/SG/CF
Viscosity Grade SAE 10W40
Vis @ 100°C, cSt 14.6
Vis @ 40°C, cSt 93

I simply can not pretend the two fluids are at all interchangable. It may feel like a bandaid, but likely isnt very good for the motor's health. one is almost twice <eek!> as thick as the other whilst running at 100c.
the start up figure @40c suggests its twice as thick when cold, too. anyone who knows oil knows, that is a NO NO. not smart engineering in my book.
most your damage to the internals will occur then, despite the higher HTHS of the thicker oil
must be my genetic deformity, elephantitis of my right foot!

[AVOturboworld]

I'm not actually recommending anybody change to 10-40, it's a band-aid and an experiment on our car only. But sometimes, when you are trying to find a cure, you throw different medicines at a patient till one sticks. Then you can track back from there to find out what the cause was.

Now, the thing about this issue is that it doesn't show up in proportion to the amount of beating the engine gets. When we drive it hard and vigorously, the issue doesn't come up as often. No, when it comes up the most repeatedly is under light throttle freeway cruising at 2,500-3,000 rpm for some time.

And I know you haven't seen our turbo kit in operation (the mechanicals), but the amount of oil running through it is negligible compared to the rest of the engine. Oil is pulled off the top of the engine, and runs slowly through the turbo, into a reservoir tank, and then through 2-3 feet of oil line. By the time it's pulled back into the engine block, the temperatures are not that high, nor is it a high percentage of the oil running through the rest of the engine. We logged oil temperatures and water temperatures throughout the entire trip, and even in the desert, they never got high.

I'm not saying oil coolers would not be useful in general. But I am saying that a lot of people are making assumptions about the car based on, say, past Subaru engines or other setups. This engine isn't related to any past Subaru motor in any way besides the boxer configuration. The only way to know what's going on is to do what we and others are doing - log it in operation, analyze it, tear it apart, and learn.