1st gen carbon build up in intake, why and how to clean.

Hello, I have a 2003 3.4l 4x4 Tacoma that i needed to replace the knock sensors and tore every apart and found quite a bit of buildup. Im not professional mechanic so i don't know how bad this is, just wanted to know if this is common and how to clean it before putting it back together. And can i do it with minimal tools or need to be brought somewhere to be professionally cleaned. Also how to stop this from happening again as bad. Any information would be great thank you!

 

at the dealership we used to use a walnut shell blasting device. It worked very well. An oil catch can attached to the PVC system is usually the answer.

 

The crud is from PCV and EGR gasses going into the intake. It's normal for deposits like that to build up in any engine that has similar systems. Gasoline has detergents in it to break them up as you can see from the clean areas where the fuel sprays.

 

Yea i know they do the walnut blasting but obviously i don't have access to that lol, wish i did. Should i try to clean out as much as i can with some brake clean and a rag? Or will it be worse if i drop those deposits on top of the valve? Or just leave it

 

Leave it alone. It’s fine. Don’t try scraping it out. I attempted to clean similar deposits on a Chevy 2.8 and the loosened up crud plugged up the pickup screen on the oil pump. Leave it….. just leave it…..

 

You can use Marvel Mystery Oil if you want that breaks down the carbon and will clean it very well.
You would have to do one cylinder at a time when the valves are closed and let them soak and then
suck out the oil

 

Once you have it all back together you could do a water wash on the intake valves, or one of the commercially available intake valve cleaners
Basically, get the engine up to temperature, and feed water (SLOWLY!) into the intake via one of the vacuum hoses. The water droplets hit the hot intake valve and vaporize which knocks loose the carbon. Watch several youtube videos to get a better idea

 

That’s a lot of build up. These are mine after 200k+. What does your throttle body look like?

 

Leave it alone it has all most zero effect on any thing unless you are going racing, tinkering it can cause you grief. Early EGR systems cause issues but as time marched on it soon became no longer an issue. I would all most bet no one any more has a walnut blaster. Water was also a "fix" but hydro locking an engine is a really bad thing water does not compress.

 

That is a lot but I wouldn't mess with it unless you're taking the heads off. Just wipe a rag around to get some of the fresher oil out.
Catch can attached to both intake manifolds will help. One is PCV, the other is open.

 

Those are almost abnormally clean..

 

I honestly think it has a lot to do with how you drive the vehicle. Some engines you can’t get away from carbon build up. I had to walnut blast my gti (had a catch can) but never had an issue with carbon build up on a port injection motor. I recommend the OP put some Lucas in and drive it like it’s stolen for a little bit.

 

Bottom line I would call that normal. OP you might post the mileage. The water "might" help with carbon build up inside the engine but it's not going to do much for the gook in the intake that's where the walnuts come in.

 

Sorry for the late response everyone and thank you for all the replies. I went with the majority and left it alone, slapped it back together. The truck has 140k miles and it was my grandpas, meticulously maintained with a book full of every date he had a service. Thats why i was curious why its so bad. Throttle body is really not to dirty and also the upper intake manifold runners were pretty clean it was just in the heads that was the worst. Im going to throw in a Lucas fuel treatment for now.

 

If your truck were to ping at a later time it might be something to address later.
I would have cleaned it, my intake section

 

Okay so I have another problem I just finished the knock sensors and I replace the harness put everything back together and it is still throwing a code for the knock sensor bank 1. What could i have messed up? Brand new everything. Are the knock sensors 2 different could i have swapped there spots or swap the harness wire? I took pictures and video of everything and put it all back exactly the same. Spent the whole weekend and still didnt fix it fml

 

Where did you get the sensor from? And what did you pay for them?

Fake knock sensors in DENSO boxes are everywhere on eBay and Amazon.

Original ones if I remember actually have a date stamp on them

 

Just autozone, i got all the gaskets and harness from Toyota. Guess ill be ripping it apart again and just get oem from Toyota?

 

A friend just had the same problem with a faulty knock sensor fresh out of a box from NAPA. I have an oscilloscope so I tested all the knock sensors he had. One had gaps in the waveform, one was really low amplitude, one was good. Either you have a short/open in the wire or you installed a new bad knock sensor.

If you are concerned about the intake still, there are systems to clean intakes. You run the engine a little above idle and add a cleaner right into the throttle body. BG makes an expensive setup but I bet seafoam or someone makes a consumer level product.

Blow-by and oil brand have a big affect on intake manifold cleanliness. If the engine isn't run hard occasionally, you are likely to lose some sealing of the piston rings and cause more blow-by which will push more oil vapor into you intake through the PCV. Not all oils are created equal. An oil's Noack rating is important for intake cleanliness. Basically, it is a measurement of how much your oil evaporates during high temperature operation.

Okay, I'm done here.

 

If there is one section that you should stay OEM that’s the sensors with Toyota from the dealership
Probably get an OEM harness too=20.00.

I’ve learned the hard way trying to save a dollar And then have to replace it again , use OEM and from the dealership because of all the fake OEM type parts out there