Robgrob

So recently Ive had some drivability problems, and from searching I was almost positive it had to be carbon build up in my intake. Seeing how "everyone" gets it, I was worried. I figured Id try a good old plug change first, knowing that I would need to remove the upper intake to do so, thus giving access to inspect the intake valves. To my suprise there was no carbon build up anywhere. Nothing. Dont get me wrong, this car has 160K miles on it, so there was some oil in the intake manifold, the swirlflaps, etc and a thin layer of minor oild residue that had dried up, but this could easily be removed with my finger. I used a can of brake cleaner to simply wash it off. It looked no worse than any other relatively high miliage car to me on the intake end, and the valves where actually perfectly clean. I mean perfect. No carbon buildup at all.


Im not going to conclude on anything as I dont know enough about what causes this problem, but I have read many claiming its due to poor fuel quality. Where I live the lowest grade fuel is 95 RON, same as US 91 premium fuel. There are strict laws requiring a very high amount of deteregents in the fuel here. The car has also, during my ownership that is, only been run on high quality, fully syntetic oil with frequent oil changes, and its redlined frequently. Old owner was a toyota mechanic, so it probably had the proper maintenance and lubricants with him as well (hard to believe when you read the rest!) No warranty work has been done to this engine, and it appers healthy in every way.


Oh back to my driveability problem... As this is my daily, and my other ride is a gtr, I dont pay to much attention to it really, I just need it to work to get the kids to school, for my wife to use it, etc. But lately I have used it every day and I just got the feeling somethings up. The engine was just not quite smooth, and I felt it getting worse. Well, it turns out, the previous owner who was kind enough to replace the spark plugs just before I bought the car 50K miles ago had forced the plugs in with the cardbord tip protectors still on!! I could not believe my own eyes! Note the soot on the seal indicating a leak, and all the cardbord on the threads - How is that even possible!! The car actually feels a lot better now, particularly at low and medium load.

Zmon

iTrader: (2)

Haha, oh boy, I can't believe it didn't act up sooner. I'm more impressed the cardboard didn't drop into the cylinder when he installed them. Glad to see you got it fixed though.

2013FSport

iTrader: (2)

You would have thought the CB would have kept the coil boots from seating if as it had to be push up and over the threads.

Is it indeed fixed?
160k, you might want to clean the MAF and that charcoal filter in the lid of the air box.

Robgrob

MAF is cleaned, but what is this charcoal filter?

Bempa

Wow, how on earth did he get the plugs in and engine actually running with cardboard still on the spark plugs? That itself is an achivement

timmy0tool

iTrader: (7)

wow now this is a first!
glad to see the intake was clean of carbon buildup, but do you suspect the mech did this job as well?

if he was a Toyota tech, he should be well aware of this problem hence did something about it (and probably had the means to do it well).
however if the same mech did the spark plug job...

the problem is fuel related yes but it's the lack of port injection that exacerbates the build up problem. i don't think running the right fuel alone will stop the build up of carbon.
EU markets might also have a difference in crankcase pressure or lack of a EGR valve for different smog restrictions, which may be why you don't see build up here, but this is just my theory.

Robgrob

Cant tell if he personally did it, but it was done just before he sold it.. Hopefully it was his GF or something

As for the carbon build up, I dont have the answer, its just an observation and a theory that perhaps the fuel quality and/or octane is a factor. I know Audi and BMW DI engines has carbon issues in europe, not sure about Lexus as they are not that common.. I cant see how we would have different crankcase pressures, the engines are as far as I know 100% the same, and neither EU or US models as an EGR valve as far as I know. My car has a near perfect service history and as far as I know nobody has ever cleaned the valves in it, but if they did it is at least 25.000 miles ago as thats when I got the car. Again, not trying to say I have the solution, its just an interesting observation..