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

[sciconf]

@circuitsmith

Watch for change in fuel trims.

I tried it when the car is hot and its on Closed Loop.
No improvement on fuel trims - I am uncertain as to how much I pinched, so I repeated it - still no improvement on FT.

I might have to build a smoke machine or find another mechanic.

Am I correct that I should be doing these tests on Closed Loop? I also have a flowchart from the car manual - so wondering CL or not?

[VOLVO-V70]

@sciconf

find another mechanic.

Bingo , finally we have a winning idea

[circuitsmith]

@sciconf

so wondering CL or not?

Yes, closed loop.

[thegreendrag0n]

@sciconf

so wondering CL or not?

oh… my first impression reading this quote was if @sciconf is about to CraigList this beast

my mistake!

[sciconf]

@thegreendrag0n

@sciconf

so wondering CL or not?

oh… my first impression reading this quote was if @sciconf is about to CraigList this beast

my mistake!

Looks like I am getting ready for a ASE certification!
I had to tell this expert m/c to focus on injectors which he ruled out earlier based on his ohm test.
Where can I buy Cigars for my Smoke machine?

[thegreendrag0n]

@sciconf

I had to tell this expert m/c to focus on injectors which he ruled out earlier

Don’t go overboard on that or (as me) you can get labeled a troublemaker and banned from the shop

Still, I felt no guilt to point to blatant lie where the shop started to throw parts on the problem and when I asked if they made a smoke machine test, they said “yes, and everything was sound!” and yet I caught them on exhaust system having a hole big enough to fit a quarter

[sciconf]

@thegreendrag0n

Don’t go overboard on that or (as me) you can get labeled a troublemaker and banned from the shop

True, I told him a story as if someone was guiding me. It worked. I still have respect for him - he is very good and go slow and steady on the car. Next visit, he demoed me that the misfire followed with injector justifying the need for the new injectors.

[sciconf]

Where can I buy a Cigar for my Smoke machine?

[thegreendrag0n]

here is some idea for you:

DIY Smoke Machine For Vacuum or EVAP Leaks E46 P0171 P0174

you do not need to go overboard with a pressure regulator, just be careful how much pressure you create from your pressurized air source

ah… and the can’s lid works as a safety valve… just from experience

[sciconf]

I am thinking of this one - what do u think?
https://youtu.be/GOhl4r0GSiE

[sciconf]

Remove MAP sensor while smoking?
This means, another test is needed to ensure its not leaking where MAP is attached!

[thegreendrag0n]

from the amount of smoke it would produce… I would think it’s a joke…

if you had a hole the size of your finger… maybe you would see that, but I would not expect to find any smaller ones

[sciconf]

P0171 issue
– I had a used, but newer, MAP sensor – so I swapped it – seems a little better.
– The photo below is soon after changing the MAP – car was resting for just 1 hr. You can see the STFT slowly ramping (green) on closed loop. The red is the front O2 sensor. Gear is on Park.

– This issue started soon after vacuum leak on IACV was fixed with a new gasket. Wondering if I should loosen the IACV bolts and see if the issue goes away?

– I took it for a short ride and then put it on Park. When the car is idling (Closed loop) on Drive gear, MAP is giving higher reading of 5.36psi. If I shifted to Park, MAP gives lower value, 4.2psi and STFT increases, hence LTFT increases. I was moving Park to Drive (and back and forth - each time MAP value is affected). You can see it in the photo below.

– Does this have anything to do with Idle Air Control Valve? Faulty or Malfunctioning?

I call around shops and couple of them never answered my question as to if they have Smoke m/c. So its taking time to find good m/c with a Smoke m/c.

[MikeInNH]

@shadowfax

If you have a direct injection engine, just resign yourself to getting/performing an induction cleaning every once in awhile. Unlike older designs, fuel no longer washes over the valves in DI engines, which means whatever lands on the valve stays there instead of being flushed away.

Not ALL direct injection systems. Toyota has D4S system that is both Direct Injection and Port Injection that helps prevent carbon buildup on the valves.

Toyota Advances D4S With Self-Cleaning Feature on Tacoma (wardsauto.com)

[sciconf]

@shanonia

I used Marvel Mystery Oil in my gasoline after my 1984 Chevy 2.0 engine started some preignition knock when accelerating. I thought carbon buildup may have been the cause. The problem went away and I kept using the MMO. Somewhere under 200,000 miles I had the head off and the machine shop guy remarked on how clean the innards were compared to many he saw.

Once the Fuel trim issue is addressed, I will start using MMO. Thanks

[sciconf]

@thegreendrag0n

Don’t go overboard on that or (as me) you can get labeled a troublemaker and banned from the shop

Still, I felt no guilt to point to blatant lie where the shop started to throw parts on the problem and when I asked if they made a smoke machine test, they said “yes, and everything was sound!” and yet I caught them on exhaust system having a hole big enough to fit a quarter

Although my car passed SMOG now, the Fuel trim maxing out on idle is still there but lesser than before. I will be taking it to a shop shortly when I get time. There might be a leak on the EVAP - EVAP monitor is still not ready! Thanks everyone for the help.

[oilman]

put two changes of Royal Purple in the engine back to back and that should make things a lot cleaner. Royal purple has a lot of information on the net about cleaning the inside of the engine. Sorry, but it’s there. I love oil!!!

[sciconf]

@oilman

put two changes of Royal Purple in the engine back to back and that should make things a lot cleaner. Royal purple has a lot of information on the net about cleaning the inside of the engine. Sorry, but it’s there. I love oil!!!

Thank you @oilman - I will research move forward.

Update:
Could u share any tips and tricks? How often you would change, recommended oil filters?

[texases]

Oil will have no effect on carbon buildup, nor will it clean it out.

[thegreendrag0n]

@texases

Oil will have no effect on carbon buildup, nor will it clean it out.

if you added “substantial” to this statement, I would be 100% with you, so let me cover 1% where I do not agree

it is a test, which a number of oil manufacturers tend to hide on their published specs:

Noack volatility test

knowing this number, one can compare the expected difference in oil evaporation under high-temp conditions, so if one had two oils A and B on hands with all specs in complete match, but with Noack of A was higher than B, it is reasonable to expect that oil A will “burn” faster in the engine

having multiple Subarus in the past, which all used some oil between changes, selecting oil with lower Noack on the spec, it made a difference of having 0.5 quart down or 1-2 quarts down (and need to add) on 5000 miles interval

I can totally imagine that the oil evaporating is not getting teleported to the alien world, but ends up partially in the combustion chamber and partially in internals, where it get picked up by crankshaft ventilation system… eventually setting on the valves… bingo!

so, to some extent oil specs have a difference on carbon buildup… although it’s relatively minor factor to compare to the worn piston rings and old stuck PCV valves