Carbon build up on Valves? Prevention? Treatment? How often to change oil?

With Mobil1 Syn change every 5k, it drops from top mark to bottom mark on the dipstick, meaning I did not have to change oil but replace.

Last change, I did it at 4k mark - I do not know if this is going to continue with new injectors - I have to wait and see! If the color turns dark, I will change even at 3k! I heard color does not say oil is bad but I do not know enough to take risk having gone through difficulties recently.

@oilman - the only thing Royal Purple stands out seems increased MPG compared to M1.

What do u guys think of this:

This go via the throttle and therefore has a direct impact on Carbon of top of the piston? Its from CRC.

Ford does that as well on their Gen 3 Coyote 5.0 V8. Gen 1s were port injection, Gen 2s were direct injection only.

Well, I ended up in finding a video, turned out to be Scotty:

just know that CRC stuff will smoke the hell off from the muffler on the final stage, watch from 13:25

I used it on Mazda3 GDI and it smoked so bad that cars around me stopped on a 4-lane highway where I was “burning it out” after I thought I’m done with the initial “rev it up on a parking lot” stage… the CEL came on, car was barely responding to the throttle for a minute or so when trying to get it go for above 30 MPH, I was really scared from this “stuff”

after engine puked and sneezed all this crap out, it works find for ~25K miles now, but NO WAY I ever use this thing again, I better clean the valves up with manifold removal and mechanical/chemical method

One of the reasons I’ll never spray this stuff into the intake is the possibility of it pooling in the intake manifold.
Then it sits there and revving the engine with no load does not make enough flow to move that puddle.
Then you put it in gear and hit the road.
Now a lot more air flows and the liquid goes into the engine all at once.
Depending on the layout of the intake tract hydro-lock is a possibility

My car has GDI, but as long as it ain’t broke I won’t go fixing it.
If a driveability symptom crops up I’ll look at the valves and clean them with walnut blasting, or whatever.

Isn’t that like not going to the dentist until you have a cavity?

Some makes are more prone to intake fouling than others. I went for a “ride along” with a customer who was having a hard time explaining the hesitation and poor performance her car was having. After driving 5 blocks with her I asked if she had ever had an induction/fuel injection service, and that by 100,000 miles she should have had 3 of them. She said the dealer had been recommending one but they couldn’t seem to explain to her why it was needed. I told her that if she had done them every 30,000 miles the car would be running fine today. I ended up mostly “fixing” her problem with an induction service and a set of spark plugs.

My car with new injectors, what should I use to clean carbon from Valves?

The shop I took it to unfortunately does not use Smoke m/c. My car came out of the shop with a issue of LTFT maxing out on idle with Park or Neutral gear P0171 - when I drive steadily it clears the CEL. Well it did come out prob consuming more gas but it slowly healed giving me 105 miles for 5 gal - I do not know if 93 gas caused it - I supposed to use 87gas. Manual does have a comment about gas type.

Currently LTFT settles around 10. If I drive aggressively, it might go to 9. It uses MAP and I swapped it out too. When I took it to shop, LTFT was more like 4.

Today is the 1st time I heard of “Fuel Induction Cleaning Service” - I have used the red bottle injector cleaner.

One time it gave P0505 - cleaned IACV and it fixed it.
Fuel pressure & regulator are tested fine.

No. Maintenance is not the same as repairing what isn’t broken.

I figure a mechanic doing an induction service is safer than a DIYer spraying an aerosol can of stuff into a vacuum hose.

1 Like

This was my great fear too!
Fortunately, Mazda’s GDI engine gulped that with no long-term ill effects.

Did I get any improvements in drive-ability?

I would say “inconclusive”, as on one side it seem to get “peppier”, but since I was replacing spark plugs in the same time (75K miles where Mazda recommends platinum plugs for GDI), I’m not sure it’s purely from the valve cleaning only.

Maintenance is what keeps you from coming to me with a check engine light and misfires/poor performance. If “Bob” had done the induction service every 30,000 miles I wouldn’t have had to sublet his car to the shop I use to remove the intake and perform a walnut shell blast to clean his valves and manifold.

Valid comment.
The way people seems to overcome this is when having a steady flow is to rev up every 45secs. DIY way is to spray twice per minute without letting the car to stalll. Once the can is emptied, apply snap throttle a few times as instructed in the CRC bottle. Given CRC product is still successful, there appear to be no law suits. Should be safe if you take the precautions.

Thanks @circuitsmith for this valuable feedback.

Since it came out of the shop, filled the 2nd tank of gas yesterday (EVAP IM monitor was not ready for a while) - today it gave “P1457 Canister side” and surprisingly all the monitors are ready now (including the last one, EVAP). Just to be on cautious side, I removed the fuel cap and tightened it back. This is the first time I received the P1457 on this car.

There are two parts related to canister - one is mounted on the air intake called EVAP Purge Control Solenoid valve. Other is the actual Canister above the axle called EVAP Control Canister.

Tips are welcome - should I still explore smoke test?