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

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?

Bingo , finally we have a winning idea :astonished:

1 Like

Yes, closed loop.

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

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?

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

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

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.

Where can I buy a Cigar for my Smoke machine?

here is some idea for you:

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 :slight_smile:

I am thinking of this one - what do u think?

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

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

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.

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 (