# Induction Service



## BDCCruze (Jul 12, 2017)

I've been reading a lot lately about GDI engines and the issues they have with carbon buildup. It reminded me of a trip to a local GM dealer where they offered to perform a diesel induction cleaning service. I declined at that time but am now having second thoughts on if I should have this performed knowing how bad DI engines get. Obviously this is the type of thing where it's easier to prevent the issue than it is to try and fix it after the fact, ie preventative maintenance.

I know there's going to be those here who say "I've put 200k miles on mine and never did that". That's great, but has anyone else done an induction cleaner on their CTD that is known to be safe to the DPF and turbo? If someone knows of any GM documentation that says not to do induction service on it, I'm happy to follow that recommendation as well.


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## Snipesy (Dec 7, 2015)

I know what they are talking about. GM does have their own 'injector cleaning' kit, but this is an aftermarket device judging by them calling it "Induction Service".

Is it snake oil? Not really. It's more like taking advil when you have cancer....

That is all.


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## IndyDiesel (May 24, 2015)

I am not sure about the induction service. I don’t plan on doing that. If the intake gets plugged, will just remove it and clean it. I had a 95mercdes Diesel and I did that and it had over 250k miles.


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## snowwy66 (Nov 5, 2017)

Semi's have never heard of this induction services. They'll go a million miles. 

Carbon buildup in gasoline engines. Hasn't been an issue since leaded gasoline disappeared back in the early 90's. 

My motorcycle had to have the head removed and cleaned in 1985. Dealer told me to use unleaded gas to clean up the rest of the carbon. Preignition problem disappeared in 1000 miles. No one is getting that procedure done anymore.


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## Robby (Mar 1, 2013)

Diesel, by virtue of the crankcase venting system (non-pcv) and the fuel itself, do not exhibit enough intake system buildup to ever need a formal cleaning.
Port fuel injection gasoline engines (as well as carbureted), by virtue of the fuel being introduced ahead of the intake valves, tend to wash off accumulated debris stuck to the backs of the intake valves.
This debris is a result of blow by gasses condensing on the cool(ish) intake valve stem.....it is carbon and it disrupts airflow into the cylinder.

DI gasoline engines are very prone to this buildup because the fuel is directly injected into the cylinder (same as a diesel) but the intake air is carrying blow-by gasses from the crankcase as well as clean air.
Since the gasoline is not mixed with the intake charge, there is a tendency for the blow-by gasses to condense on the back of the intake valves with nothing in the airflow to wash the debris off.
Some engines are more prone to this than others.....the jury is still out as to why, but it seems related to short trip usage and the operating temperature of the intake valve itself.....a cooler valve tends to show the buildup sooner.

To combat this, carmakers (Toyota for example) are introducing a 'dual injection' type setup.
The engine is DI but it also has injectors upstream (port) of the intake valves.
This design operates off the upstream injectors at idle, which tends to wash the valve and port with gasoline......the DI injectors are shut off.
Upon throttle apply, the port injectors are disabled and the DI function resumes.

I imagine this method will become the norm.....it has proven very effective.

Rob


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## BDCCruze (Jul 12, 2017)

snowwy66 said:


> Carbon buildup in gasoline engines. Hasn't been an issue since leaded gasoline disappeared back in the early 90's.


Modern Gasoline Direct Injection engines are well known to have significant carbon buildup on the intake valve due to not being washed by fuel. GDI was not used by US manufacturers until recently but its been a big problem with European cars for a while. Ford has a big problem with it right now on their GDI (EcoBoost). Type in GDI Carbon or EcoBoost Carbon on Google and you'll not run out of enough to read about.


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## MP81 (Jul 20, 2015)

Robby said:


> Diesel, by virtue of the crankcase venting system (non-pcv) and the fuel itself, do not exhibit enough intake system buildup to ever need a formal cleaning.


I'm not sure you've looked inside the intact tract of a CTD, haha. That **** gets nasssssty (mainly due to the EGR).


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## BDCCruze (Jul 12, 2017)

MP81 said:


> I'm not sure you've looked inside the intact tract of a CTD, haha. That **** gets nasssssty (mainly due to the EGR).


Yeah, if you're pulling crankcase fumes and pushing it back into the intake there's going to be some buildup. I'm just wondering about if it's enough to cause problems if left unserviced. Seems the guys at TDI club can't agree either Why don't TDIs accumulate carbon on intake valves/head like Gasoline DI engines? - TDIClub Forums


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## MP81 (Jul 20, 2015)

It does if too much gets on the EGR valve. I'm waiting to see how it affects the intake runners, since those move.


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## snowwy66 (Nov 5, 2017)

BDCCruze said:


> Modern Gasoline Direct Injection engines are well known to have significant carbon buildup on the intake valve due to not being washed by fuel. GDI was not used by US manufacturers until recently but its been a big problem with European cars for a while. Ford has a big problem with it right now on their GDI (EcoBoost). Type in GDI Carbon or EcoBoost Carbon on Google and you'll not run out of enough to read about.



It was explained pretty clearly in this thread.  The whole valve wash never donned on me.


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## oreo382 (Sep 17, 2014)

My diesel is in getting the head pulled as I type this due to carbon build up on the back of the intake valves.The comment that this doesn't happen to diesels is not correct.A lot of owners are experiencing morning start missing/stumbling that clears up when the engine is warmed up,no codes.That is the indication of carbon build up,worse if you do a lot of city driving.I suspect there are a lot of diesels out there with this problem.


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## MP81 (Jul 20, 2015)

oreo382 said:


> A lot of owners are experiencing morning start missing/stumbling that clears up when the engine is warmed up,no codes.That is the indication of carbon build up,worse if you do a lot of city driving.I suspect there are a lot of diesels out there with this problem.


Thus far, we have determined this to be carbon/oil gunk built up on the EGR valve, causing it to be sticky. If it sticks open, the vehicle will not start.

Ours was having the typical starting issues/cold-start running issues until I pulled out the EGR, which was disgusting, and cleaned it. Then it was great. Seems like it is due for another cleaning here soon, given the car has occasional times where it requires a good few engine rotations before it actually starts.


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