Skyactiv Intake Valve carbon build up - Anyone taken a look at intake valves?

johnygfunk

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Car
I'm just curious as I only really started to look at carbon build up with GDI engines. My wife has a 2012 Kia Optima 2.4L and I have the 2.0L skyactiv. I'm concerned about intake valve carbon build up and am looking to see if anyone has taken a look at their valves and what mileage they have?

The last year my commute has shortened quite a bit (6 minutes with a short freeway stretch) and I'm concerned about the potential for carbon build up as a result.

Thanks
 
I was thinking about taking off the intake mani. But havent got around to it. Now that i got my last big install done I may.
 
Chris - not to derail my own thread but, I've followed both your builds here and on other sites - are you still running the SRI? Is it purely for sound? Also, have you gotten your tune from Orange Virus? Any changes you've noticed with the butt dyno?

Also have you looked at the jbr rear torque mounts? http://www.jamesbaroneracing.com/shop/index.php?main_page=product_info&products_id=813 Thoughts?


I would be very interested to see how the valves look? I can't find any pictures online.
 
I haven't looked at how the EGR is setup on the cx-5 but this would be one of the reasons why I want to block it . I figured if I keep it plugged in but just block the exhaust from recirculating in , I don't believe there are sensors that can detect that and trigger a CEL. At worst case scenario, the a/f ratio might change slightly when the EGR opens but then will correct with the o2 sensor signaling the ecu to correct again back to 14:1 a/f ratio. Assuming the fuel trim tables and corrections allow for it in the ecu .
 
Chris - not to derail my own thread but, I've followed both your builds here and on other sites - are you still running the SRI? Is it purely for sound? Also, have you gotten your tune from Orange Virus? Any changes you've noticed with the butt dyno?

Also have you looked at the jbr rear torque mounts? http://www.jamesbaroneracing.com/shop/index.php?main_page=product_info&products_id=813 Thoughts?


I would be very interested to see how the valves look? I can't find any pictures online.

Yes I am still using the sri, but I also have my engine tuned to best utilize it. Un-tuned it's mostly sound, in either case it's mainly for higher rpm performance (your intake temp will go up about 10 deg as well.) I am ovtuned, first 2.5 cx5 to be tuned by him (gave him the first ecu dump for that engine). Gains are worth it, and well documented on mazda6 forum with multiple real dynos. I actually have that mount, I couldn't get it on last time I was on a lift and haven't tried again since. I couldn't get the OEM mount out of it's bracket because the transfer case was in the way and I didn't want to lower the subframe. Oddly, another AWD owner was able to install it with ramps only so I'm guessing the way the suspension is loaded determines the clearance above that mount. there is also a rmm from corksport, and a softer looknig one from Hardrace
 
Yeah - I'm aware of what Mazda claims but I'd love to see what people are getting if any. The best thing I've seen recommended is to drive the cars zoom zoom but was wondering if anyone had taken a peak at the valves to see if they have any built up carbon.
 
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As long as I don't have to disassemble too much s*** I'll try to do it tomorrow. I'm just over 25k, running a tune since about 500miles
edit nevermind, dropping my car to have the wheels refurbished it will be later this week
 
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I'd be curious as well, but from everything I've read, Mazda designed on hell of a motor and got around most of the "issues".
 
I look forward to your post Chris_Top_Her. I did run my CX7 to over 80,000 miles and sold it running like new so I don't expect any issues with the New Mazda method of keeping intake valves cleaner. Ed
 
I haven't looked at how the EGR is setup on the cx-5 but this would be one of the reasons why I want to block it . I figured if I keep it plugged in but just block the exhaust from recirculating in , I don't believe there are sensors that can detect that and trigger a CEL. At worst case scenario, the a/f ratio might change slightly when the EGR opens but then will correct with the o2 sensor signaling the ecu to correct again back to 14:1 a/f ratio. Assuming the fuel trim tables and corrections allow for it in the ecu .

On the Mazdaspeed3, if you block off the EGR, the ECU will throw an engine code. I imagine the same thing is in place for the CX-5. There are also issues with failing safety inspections if you mess with the EGR, or any emissions device on the car for that matter. Regularly cleaning the intake valves, maybe every 30k miles should be done on DI engines.
 
Also something to consider is disconnecting the pcv from recirculating into the intake.

1. This will eliminate the blow bye oil vapors from the intake pipe and manifold. You can redirect the tube from pcv toward the ground or maybe put a catch can that vents not recirculates back into the intake.

2. Just want to point out you don't need vacuum to assist in relieving adequate pressure from the crank case with modern car motors. Just simply venting to atmosphere is enough. Only reason it's recirculating is for emissions .
 
Also something to consider is disconnecting the pcv from recirculating into the intake.

1. This will eliminate the blow bye oil vapors from the intake pipe and manifold. You can redirect the tube from pcv toward the ground or maybe put a catch can that vents not recirculates back into the intake.

2. Just want to point out you don't need vacuum to assist in relieving adequate pressure from the crank case with modern car motors. Just simply venting to atmosphere is enough. Only reason it's recirculating is for emissions .

The vacuum pulls the rings to the cylinders and helps with airflow management through the motor. It does indeed result in more efficiency and power.
 
The vacuum pulls the rings to the cylinders and helps with airflow management through the motor. It does indeed result in more efficiency and power.

Are you saying from personal experience or something you read some place?

I have to disagree because I have actually tested and dyno’d my car numerous times with vacuum and without. And these were back to back dyno’s not different days at different temperatures etc... This was not on the Mazda but previous Mitsubishi Evolution 9. Absolutely no difference with vacuum from intake pipe or vent to atmosphere. Now although it is not the same car, but both are modern engineered motors with tighter clearances and efficiently designed blocks compared to older vehicles. In addition, no difference in MPG.

Back in the old days hotroder’s with big blocks would have some gains due to multiple factors. Some examples would be due to engine build tolerances (loosely built resulting in more blowby) and crank case pressure created and not as well designed motors as today to relieve crank case pressures from the pcv etc.. just to name a few. What they would do is T into the exhaust pipe at an angle (forgot actual angle) that passing exhaust gas would create vacuum and draw out the crank pressure. This is called the Bernoulli principle.

I’ve been venting to atmosphere on all my cars I’ve owned such as 2003 Nissan Sentra SER Spec V, 2004 Dodge SRT-4, 2006 Mitsubishi Evolution 9 and 2013 VW GTI. Only thing that resulted was a bone dry intake piping, intercoolers and manifolds.
 
I'm just curious as I only really started to look at carbon build up with GDI engines. My wife has a 2012 Kia Optima 2.4L and I have the 2.0L skyactiv. I'm concerned about intake valve carbon build up and am looking to see if anyone has taken a look at their valves and what mileage they have?

I wouldn't be surprised if modified Skyactivs developed carbon issues on the valves but a well-running stock motor should not. At least there hasn't been a single documented case of it so I don't know why you would worry.

These are very sophisticated engines and are finely tuned and optimized. Of course if you start doing stupid things like plugging ERG valves, venting the crankcase to atmospheric pressure, etc, all bets are off. This old song is applicable here:

<dd>Toe bone connected to the foot bone</dd><dd>Foot bone connected to the heel bone</dd><dd>Heel bone connected to the ankle bone</dd><dd>Ankle bone connected to the shin bone</dd><dd>Shin bone connected to the knee bone</dd><dd>Knee bone connected to the thigh bone</dd><dd>Thigh bone connected to the hip bone</dd><dd>Hip bone connected to the back bone</dd><dd>Back bone connected to the shoulder bone</dd><dd>Shoulder bone connected to the neck bone</dd><dd>Neck bone connected to the head bone</dd>

Making these kind of changes, without extensive instrumentation and expensive testing, is simply stupid. Because of the interconnectedness of all engine functions, it would be rare that such changed would not "de-optimize" other functions. Modern engines have a certain amount of self-awareness and an ability to self-correct, but only to a degree. They are engineered and programmed to make certain assumptions that the hoses are all connected, the backpressure has certain characteristics at various rpm's and throttle openings, etc. They are not designed to compensate for changes to hardware, only for changes that might reasonably be expected, ie, barometric pressure, temperature, coolant temperature, etc.
 
I haven't looked at how the EGR is setup on the cx-5 but this would be one of the reasons why I want to block it . I figured if I keep it plugged in but just block the exhaust from recirculating in , I don't believe there are sensors that can detect that and trigger a CEL. At worst case scenario, the a/f ratio might change slightly when the EGR opens but then will correct with the o2 sensor signaling the ecu to correct again back to 14:1 a/f ratio. Assuming the fuel trim tables and corrections allow for it in the ecu .

Do these cars even have an external EGR system? I think the EGR might be done through clever valve overlap.
If they do have an EGR valve, blocking it would really be asking for knock.
 
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ok, just an FYI bought the car with 4 miles on it and right now there is about 100 miles on it. I just set it up to vent to atmosphere. My car will be the guinea pig for this.

I’m holding off on the EGR until I do a little more research and observation on how our system works. I mainly dont want the EGR to blow into the intake manifold if that is how its setup. If it is setup to go directly into the head then its not a big deal to me.
 
ok, just an FYI bought the car with 4 miles on it and right now there is about 100 miles on it. I just set it up to vent to atmosphere. My car will be the guinea pig for this.

I’m holding off on the EGR until I do a little more research and observation on how our system works. I mainly dont want the EGR to blow into the intake manifold if that is how its setup. If it is setup to go directly into the head then its not a big deal to me.

When you say "go directly into the head", do you mean the headers? If so, then that wouldn't make sense, as the gasses routed by the EGR system is supposed to go through the combustion process again.
 
When you say "go directly into the head", do you mean the headers? If so, then that wouldn't make sense, as the gasses routed by the EGR system is supposed to go through the combustion process again.

No not into the header on the exhaust side. I mean into the head form the intake side. I dont know the setup of the cx-5 2.5 motor’s EGR and I want to know where the exhaust released from the EGR is directed. Does it go into the exhaust manifold mix with the air and follow through ports to the head or is it routed straight to the intake ports in the head bypassing the intake manifold?
 
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