Intake Cam Timing advanced 20 Degrees at IDLE
 

Hey guys, as the title asks, how do I go about checking the AVCS timing? Can it be adjusted ?

My car has the intake cam advanced 20degrees at idle :-S

Would truly appreciate anyone helpglglglgl

How are you measuring that it's 20 degrees at idle? If it's via logging, what are you using? Which bank etc? Same on both? Does it noticeably feel different as it should? It would also likely throw a CEL.

Does it move around if you use the accelerator?

I'm doing a idling datalog through ECUTEK for my tuner.

When he go it the first thing he noticed was that the INTAKE cam is at advanced 20 degrees :-/

No engine light ever cam on, and that the weird part

it jumps around when u touch the throttle, but it stays in that particular region, while the others stick around -0 - 1

I think also it was on the left head, I'll have to back check if it's both headsgl

bump! need some help guys.


cant figure out what is causing this up to now. car wont idle on its own even.




it also sounds like a extreme unequal length header, meaning missing badly.

As Kodename47 said weird it not throwing and CEL codes and CEL light


AFAIK cams should all be at 0 at idle.


If just one is reading 20 then its possible that cam sensor is bad. but should throw code due correlation error.


If its now idling like crap mabe the cam actuator is stuck, but again you would expect cel codes/light.


mabe look through these TSB


11-130-13R : Difficulty Starting, Rough Idle, Cam Position, Misfire
http://www.ft86club.com/forums/attac...1&d=1375302652


02-132-12 : DTCs Relating to the AVCS (Active Valve Control System)
http://www.ft86club.com/forums/attac...0&d=1352490977

You have a JDL kit correct? I am running their kit and the downpipe touches my passenger side Cam Angle Sensor. Lots of others have had this issue, I've wrapped it in a loom and heat tape. Perhaps this could be a culprit?

I too thought it could be the cam solenoids, so I swapped the intake cam solenoids to see if it would move the problem over to the other head, but the issue is still on the left head. Same exact outcome


I will definitely read through the TSB's... I'm taking any advice that comes to me at this point

Yes I do have the JDL kit, I did notice that the down pipe runs rather close to that sensor so I did to a little Fab, but the issue is on the other head

Have you had the timing chain off of the car?


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What is the tune commanding?

Yes I just did a complete engine rebuild, changed rods, pistons, valves, springs and retainers

Not sure, I am doing F&G with delicious

haha, that changes things :-).


Still strange the ECU doesn't complain if its commanding zero and the sensor reads 20, that's assuming that's whats happening.

Yup! Same thing we all are thinking :-S

No codes makes it so much harder

If the ecutek logging for that cam and your ROM id is incorrect it could explain it.


but doesn't explain why engine runs like crap.

You should be able to log AVCS commanded, however at idle it should be 0 degrees.

Did the cams get timed correctly when it was put back together? That's the obvious issue and may need checking. If it's not that then I'd guess something is preventing oil flow to the solenoid to give it control. The fact the engine has been apart and is running poorly suggests it's going to be mechanical.

Thank you very much for your honest opinion. My mechanic has thought also it could be internal.

My mechanic took off the front cover and back checked the timing and said it is correct.

I will be speaking with my mechanic about looking into taking the engine back out and atleast check the internals and also make sure no oil ports are being blocked

Would be tuner be able to pick this up through the log I sent him?

I'd bet the chain is on wrong. It's also possible to install the cam sprockets incorrectly. They have a nipple on the back side to locate them properly but if you just run the bolts in anyway they bolt on.


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Calling my mechanic right now to mention this

As kodename47 said it's most likely mechanical issue. It's often difficult to detect from logs if it's mechanical issue. Best way would be to log a car with same calibration I'd ecu and confirm it logs ok

If you're logging using the supplied tune that is flashed to the car, this isn't the issue. As Steve said, it wouldn't tie in with the poor running anyway.

but what all mechanically could be related to this?


I have already got and replaced the cam sprocket :-S

any ideas as to what all mechanically I can look for?

all were installed correctly according to the Service Manual


anything else I can have a look at?

is it true that the cam sprockets advance timing with increased oil pressure?


so does this mean I dont have a oil pressure issue u think? or can lack of oil still cause this

Having a quick look at this: https://web.archive.org/web/20110820...hatsInside.htm

Having not looked into the system in detail I can't comment more, but there are only a few components that control the system. Is this the original cam systems? I'm sure I've read that some issues have occurred using older/newer components to the original ECU.

I'm going to have a read on this myself

Yes these are the same stock cams and cam sprockets that came on the motor that were reused, up until this past weekend when I got another sprocket from the U.S and changed it to see if anything changes, got the very same result

Hey Kris, yes those bad boys are controlled via oil pressure. Is this always stuck at a static 20 or do you see it swing occasionally negative or even zero at times?

When I was testing some bigger injectors that were leaking a little, my cams we're going crazy trying to compensate for the extra fuel. I was freaking out like something is physically wrong with the motor during the tune but after installing the original full-blown Motorsports injectors the cams corrected themselves after a few miles on the road.

Again this was a terrifying experience. I'm so happy I tried the original injectors that I know that work perfectly fine do something completely unrelated.

I see the cam timing jump up and down when I am applying throttle to ty and get it to idle, but always in the region of 20. Never as low as zero or near zero tho

We're u having a issue with all the cams acting up? Cause my situation is just one single cam :(

Mine was passenger side only, and I thought I lost a rocker or something. Did you install anything new like bigger injectors?

After programming Ecutek with the original injectors and driving it around for about five miles in first gear in the neighborhoods the cam came back online. The car did not want to idle either and would stall. I never once got a check engine light or a code

I was also 3 hours from home thinking my car is fucked and may need to be towed.

Never mind I see you purchased DW900cc in your build. Id really start with the old injectors and update your tune. Again It took a very nerve racking 5 miles to get it to come back online.

But yet again you may also be 1 tooth off.

Thank you very very much for this advice, I will definitely look into this

Could it be possible that something went wrong with my Ecu?

It's most likely mechanical. I've had these that have faults for AVCS but they run fine. Fuji bond stuck in an oil passage, timing chain off, cam sprockets not on right etc.


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I'm wondering if maybe some silicone is blocking the oil return passage and causing that particular sprocket to advance, not giving it a chance to relieve pressure

Sounds like a tooth off to me.

Ditto

When we back checked this, trying to adjust one tooth over in any direction, the cam sprockets timing marks would not be able to align

I notice this image here in the service manual with the section with timing the left head.

I see a mention with the sub image at the top it's showing something with a 25degree adjustment, could this be related ? :-S I'm not a mechanic so I'm just looking explanations, shouldn't it be that once the timing marks are pointing to eachother then it's correct? Or is there some kind of 25degree adjustment to be made. ( my left head Intake cam is advanced around 20 degrees at idle but jumps around to as high as 25 I think I've seen)