# Is this carbon buildup unusual?



## Takeeon (Mar 30, 2015)

It about 70k. Seems like an awful lot of crud in there. Usually run 93 and drive a ton on the highway. Any thoughts or ideas on how to help clean them out safely?


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## snowwy66 (Nov 5, 2017)

You're fighting a lost cause. You have no control over carbon buildup. 

As long as your CEL isn't on. You're running efficient. 

Try running a can of seafoam or ATF occasionally if it concerns you. 

The rest of us drive our entire lives without ever worrying about it.


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## Takeeon (Mar 30, 2015)

My own **** fault for sticking a camera in there


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## snowwy66 (Nov 5, 2017)

I like the pics you posted. That's pretty cool to see what the inside looks like. 

What did you use and where did you buy it from?


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## Takeeon (Mar 30, 2015)

I use mine through my phone. You can find them on Amazon by searching borecope or endoscope and your particular connection. Mine is USB c. You have to download a USB camera app of some sort. Useful as heck for about $20


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## Robby (Mar 1, 2013)

I only see normal carbon accumulation.....nothing of concern.

Rob


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## jblackburn (Apr 14, 2012)

Pistons aren't a concern; however, how do the backs of the intake valves look? That's the main concern with a direct-injection motor, but I haven't heard of carbon accumulation issues on the LE2 causing issues _yet_ (granted they are still fairly young). As you have a higher mileage one, I am curious.


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## Takeeon (Mar 30, 2015)

I made a post a while back where I took a photo of the valves with excessive buildup at like 18k. It started to run crummy recently, so I thought I may have piston damage. Upon further investigation, I've got a major spark advance retard accompanied by some hesitation. on acceleration at low rpm at -5 to -10 degrees and sometimes spiking to -20. I need to get in there and check the valves again. I have ran nothing but 93 from "top tier" stations since then. I'll jam the cam back in there soon and post those. I also have some new plugs arriving soon. The ones I have still look ok and the electrode isn't that worn, but I'm hoping it takes care of it.


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## snowwy66 (Nov 5, 2017)

Wondering why someone would waste time and money trying to fix something that's under manufacture warranty.


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## Takeeon (Mar 30, 2015)

Not sure what you're getting at, but maybe I was unclear. When I took the pictures of my valves, I was at about 18k. Now I'm at 75k


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## snowwy66 (Nov 5, 2017)

My bad. Just saw your last post mention 18k.

You might have a bad knock sensor or something causing the computer to run the wrong timing. I looked at mine coming home from work and the only time it was negative was throttle off. Coming to a stop.


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## Takeeon (Mar 30, 2015)

If I'm not mistaken, it looks like I'm leaning out.


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## eddiefromcali (Aug 21, 2017)

fuel trims are fine


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## Takeeon (Mar 30, 2015)

Right. The long term is fine, and it drives normally while cruising, but under load when the boost come on, the voltage on the 02 sensor tanks along with the timing.


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## snowwy66 (Nov 5, 2017)

Back in the old days of distributor. There were 2 forms of timing advance.
Vacuum advance run off port vacuum above carburetor throttle plate. The more air flow through the carb. More vacuum to distributor to advance timing.
Mechanical weights. Run off distributor rpm speed. The higher the revolutions. The farther out the weights swung to advance timing.

I could be wrong in today's world of ecm.
The ecm needs to know throttle position. TPS.
Airflow. MAF and MAP.
Engine speed.
Pre detonation or pinging. Knock sensor.

Everything else is probably tied in to the system in some manner as far as timing goes. Maybe.


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## eddiefromcali (Aug 21, 2017)

Takeeon said:


> Right. The long term is fine, and it drives normally while cruising, but under load when the boost come on, the voltage on the 02 sensor tanks along with the timing.


and I'm assuming you did a WOT or just gave it some gas between 9 to 5 on in those PIDs? Does look like your o2 sensor voltage drops (Lean) and it pulls back timing and boost decreases. Boost leak somewhere, maybe?


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## Takeeon (Mar 30, 2015)

I'll keep an eye on that throttle, too.

When it leans, it's usually on a partial throttle acceleration. Some WOT pulls, it'll hesitate at first, but usually comes out of it. Others it won't even go past 0 psi because it's pulling back so far. I'm gonna try to get in there tonight to check it the valves and throttle plate. Other than that, clean the MAF and replace the plugs are next on my list.


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## TDCruze (Sep 26, 2014)

That is not bad buildup at all. Looks pretty normal. 
Should have seen the insude of my F150 engine after it burnt an exhaust valve. Carbon was flaking off in chunks it was running so rich.


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## Takeeon (Mar 30, 2015)

It's really quite difficult to get that camera in there, so this is the best shot I could get. Looking pretty clumpy. I noticed the area around this valve is much dirtier than the other one I almost got to. I wonder if my valve isn't seating all the way.


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## jblackburn (Apr 14, 2012)

Takeeon said:


> It's really quite difficult to get that camera in there, so this is the best shot I could get. Looking pretty clumpy. I noticed the area around this valve is much dirtier than the other one I almost got to. I wonder if my valve isn't seating all the way.


I've seen much worse from DI engines, but a compression test will tell you if it's not sealing. If so that could be a cause of some of your issues. 

A boost leak might explain some of the issues too, make sure to tighten the hose at the throttle body well.


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## Takeeon (Mar 30, 2015)

jblackburn said:


> I've seen much worse from DI engines, but a compression test will tell you if it's not sealing. If so that could be a cause of some of your issues.
> 
> A boost leak might explain some of the issues too, make sure to tighten the hose at the throttle body well.


Luckily that hose is just held on my some funny clip. Got my new plugs in this morning. I'll see what it does in about 100 miles.


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## Takeeon (Mar 30, 2015)

Cripes. There was a leak in my clean air hose. Now, my issue is not leaning, it's going rich. Seems to go into open loop at almost any level of acceleration. I wish this **** thing would throw a code already. My only guess it's maybe a bad coil? No misfires tho


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## Fireworks234 (Jan 4, 2018)

Takeeon said:


> Cripes. There was a leak in my clean air hose. Now, my issue is not leaning, it's going rich. Seems to go into open loop at almost any level of acceleration. I wish this **** thing would throw a code already. My only guess it's maybe a bad coil? No misfires tho


From personal experience, these cars hate to throw codes. My last Gen 2 Cruze would misfire and even ended up getting replacement valve springs but never threw a code the whole time.


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## Takeeon (Mar 30, 2015)

I can't even get a pending code. Tests all pass. 

Today it drives perfect. I'm about to jump out the window. I think it's temperature related. It's almost as if it works well under 80 but at 81, everything goes to heck. That's why I'm thinking coils. I'm not sure what's an acceptable amount of resistance. I've got one that dances around 12, but the other 3 are at 11.85. I should buy the stupid repair manual


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