# Intake valve Carbon build-up



## Robby (Mar 1, 2013)

Specific to intake valves.....this is something that comes up from time to time on DFI (direct fuel injection) setups. The Cruze is port injected so the intake valves are washed with gasoline with each intake charge......hence, no concern.

Throttle bodies will collect debris regardless of injection type since that occurs downstream from the throttle body.
The debris that does collect is condensed blow-by gasses from the crankcase breather system.
Remove the throttle body, saturate a rag with the cleaner and wipe off any debris you can reach. DO NOT SPRAY anything into the throttle body!

There are bearings at the ends of the throttle shaft.....they are not sealed on the plate side (not needed, filtered air). Any cleaning spray fired into the throttle body can and will migrate into the bearing cavities and, over time, the throttle shaft can begin to bind.......you will end up replacing a throttle body that you caused the failure.

Rob


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## Lazer (Feb 14, 2016)

Thanks for impute, others have mentioned adding a catch can to collect the vapors.


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## jblackburn (Apr 14, 2012)

Lazer said:


> Thanks for impute, others have mentioned adding a catch can to collect the vapors.


Totally unnecessary in the Gen1. The PCV system recirculates oil vapor right back into the crankcase (when properly working).


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## cruzemuse (Nov 18, 2018)

I thought that the 1.4L turbocharged engine was direct injection. Was I wrong?


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## Robby (Mar 1, 2013)

cruzemuse said:


> I thought that the 1.4L turbocharged engine was direct injection. Was I wrong?


Generation I........1.4t MY 2011/2015......Port injected.

Generation II......1.4t MY 2016/present...D.I.

Same engine displacement......entirely different engines.

Rob


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## jblackburn (Apr 14, 2012)

Robby said:


> Generation I........1.4t MY 2011/2015......Port injected.
> 
> Generation II......1.4t MY 2016/present...D.I.
> 
> ...


2016 Limited (Gen 1 body style) uses the old port-injected motor as well.

Because GM likes to make model years complicated. Owning the '16.5' has gotten in the way for me a couple times already.


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## cruzemuse (Nov 18, 2018)

Thanks. I just realized this is the Gen 1 section of the forum. Still getting used to the forum.


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## RaysnCayne (Dec 11, 2018)

The 1.4 is port-injected, for real?! Oh happy day! 
I just bought a 2013 LT with 80k a couple days ago. I was going through some of the papers the previous owner left in the glovebox yesterday and I came across a local mechanic's checklist. At the end of the check list, it said "GDI service recommended". Upon googling the "GDI service" I fell into a world of fear and worry about this whole carbon build-up issue on early-gen DI engines and how much of a pain and expense it is to have it serviced or try to spray it with the CRC solvent (and hope you don't ruin your cat or turbo afterwards). So, yay for port-injection! Now all I have to worry about is the PCV labyrinth and LSPI and I'm sure something else I've yet to discover.


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## Robby (Mar 1, 2013)

GenI unaffected by low speed spark knock......

Although the pcv system problems crop up, try to remember that there are millions of these things that never experience a failure.

Rob


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