Lexus IS250 4GR-FSE Engine Carbon Build-up (merged threads)
07-07-12, 08:36 PM
#1051
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I've experienced the carbon built up symptoms at 40k twice when the car almost stalled on me. Solved by driving aggressively (red lining when entering the freeway).
Last edited by rookieIS; 07-07-12 at 08:39 PM.
07-09-12, 07:52 AM
#1052
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This past 4th of July I manually cleaned my valves. I don't know how bad carbon buildup is on your vehicles, but some VW/Audi engines are plagued with this.
Before:
After:
Here's a quick clip of the actual cleaning process:
http://www.youtube.com/watch?v=3R1FmTKjAEU
Before:
After:
Here's a quick clip of the actual cleaning process:
http://www.youtube.com/watch?v=3R1FmTKjAEU
This was at 74K, different car, yes.
07-09-12, 12:41 PM
#1053
Driver School Candidate
For those that have followed this entire thread, i've posted my belief as to what is the simple solution in these cars since they do have a 7th injector, and my belief that there is a correlation between carbon build up and average temperature - in colder weather the 7th injector runs and cleans the valves.
My original solution was a signal intercept that would run the 7th injector on start up for 30 seconds or possibly something like a turbo timer that would run the 7th injector before shutting down. It was complicated due to the requirement that you'd need to also intercept the signal to the cyl. injectors to shorten duration slightly so that it wouldn't have an error read by the o2 sensor.
In retrospect the solution is much simpler. We simply need to trick the car into thinking it's cold when it starts. Whatever temperature sensor that reads initial start-up temp should be intercepted and tricked into telling the car it's cold for the first 30 seconds or so, and program in an override so that the system shuts off if the engine temp is over say 150* at start up. We don't want to overheat it. I think that could be an even simpler fix. I'm sure I could build a plug and play black box solution for under $200. (Possibly more like $50 depending on how much the plug ends cost to intercept the signal and where they would be located to know where the box could mount etc.) If such a device existed and were shown to be effective, would you try it? In the alternative if I wrote up exactly how to build it including part numbers and explained the code necessary for the chip - would anyone build one on their own? I don't much care about the $, I just think they will cost that much to build and a lot of folks don't have the skills or EE background to do it themselves.
Does anyone have a good argument for why this won't work? I'm not an expert on this engine. It's my wife's car and I have enough warranty to outlast how long we'll own the car. I'm just interested as a tinkerer and it's a fun "problem" that should have a very easy cheap solution.
My original solution was a signal intercept that would run the 7th injector on start up for 30 seconds or possibly something like a turbo timer that would run the 7th injector before shutting down. It was complicated due to the requirement that you'd need to also intercept the signal to the cyl. injectors to shorten duration slightly so that it wouldn't have an error read by the o2 sensor.
In retrospect the solution is much simpler. We simply need to trick the car into thinking it's cold when it starts. Whatever temperature sensor that reads initial start-up temp should be intercepted and tricked into telling the car it's cold for the first 30 seconds or so, and program in an override so that the system shuts off if the engine temp is over say 150* at start up. We don't want to overheat it. I think that could be an even simpler fix. I'm sure I could build a plug and play black box solution for under $200. (Possibly more like $50 depending on how much the plug ends cost to intercept the signal and where they would be located to know where the box could mount etc.) If such a device existed and were shown to be effective, would you try it? In the alternative if I wrote up exactly how to build it including part numbers and explained the code necessary for the chip - would anyone build one on their own? I don't much care about the $, I just think they will cost that much to build and a lot of folks don't have the skills or EE background to do it themselves.
Does anyone have a good argument for why this won't work? I'm not an expert on this engine. It's my wife's car and I have enough warranty to outlast how long we'll own the car. I'm just interested as a tinkerer and it's a fun "problem" that should have a very easy cheap solution.
07-12-12, 06:00 PM
#1054
For those that have followed this entire thread, i've posted my belief as to what is the simple solution in these cars since they do have a 7th injector, and my belief that there is a correlation between carbon build up and average temperature - in colder weather the 7th injector runs and cleans the valves.
My original solution was a signal intercept that would run the 7th injector on start up for 30 seconds or possibly something like a turbo timer that would run the 7th injector before shutting down. It was complicated due to the requirement that you'd need to also intercept the signal to the cyl. injectors to shorten duration slightly so that it wouldn't have an error read by the o2 sensor.
In retrospect the solution is much simpler. We simply need to trick the car into thinking it's cold when it starts. Whatever temperature sensor that reads initial start-up temp should be intercepted and tricked into telling the car it's cold for the first 30 seconds or so, and program in an override so that the system shuts off if the engine temp is over say 150* at start up. We don't want to overheat it. I think that could be an even simpler fix. I'm sure I could build a plug and play black box solution for under $200. (Possibly more like $50 depending on how much the plug ends cost to intercept the signal and where they would be located to know where the box could mount etc.) If such a device existed and were shown to be effective, would you try it? In the alternative if I wrote up exactly how to build it including part numbers and explained the code necessary for the chip - would anyone build one on their own? I don't much care about the $, I just think they will cost that much to build and a lot of folks don't have the skills or EE background to do it themselves.
Does anyone have a good argument for why this won't work? I'm not an expert on this engine. It's my wife's car and I have enough warranty to outlast how long we'll own the car. I'm just interested as a tinkerer and it's a fun "problem" that should have a very easy cheap solution.
My original solution was a signal intercept that would run the 7th injector on start up for 30 seconds or possibly something like a turbo timer that would run the 7th injector before shutting down. It was complicated due to the requirement that you'd need to also intercept the signal to the cyl. injectors to shorten duration slightly so that it wouldn't have an error read by the o2 sensor.
In retrospect the solution is much simpler. We simply need to trick the car into thinking it's cold when it starts. Whatever temperature sensor that reads initial start-up temp should be intercepted and tricked into telling the car it's cold for the first 30 seconds or so, and program in an override so that the system shuts off if the engine temp is over say 150* at start up. We don't want to overheat it. I think that could be an even simpler fix. I'm sure I could build a plug and play black box solution for under $200. (Possibly more like $50 depending on how much the plug ends cost to intercept the signal and where they would be located to know where the box could mount etc.) If such a device existed and were shown to be effective, would you try it? In the alternative if I wrote up exactly how to build it including part numbers and explained the code necessary for the chip - would anyone build one on their own? I don't much care about the $, I just think they will cost that much to build and a lot of folks don't have the skills or EE background to do it themselves.
Does anyone have a good argument for why this won't work? I'm not an expert on this engine. It's my wife's car and I have enough warranty to outlast how long we'll own the car. I'm just interested as a tinkerer and it's a fun "problem" that should have a very easy cheap solution.
It may help, but the root cause may be fuel getting into the oil and then travel through PCV in addition to the valve overlap that pump some of the air fuel mixture back into the intake side.
07-16-12, 07:04 AM
#1055
Driver School Candidate
The reason I don't think it will always work, is that the Toyota fix include replacing piston and ring. So I think there might be ring tension and piston wear that may have caused this (like Saturn oil burn).
It may help, but the root cause may be fuel getting into the oil and then travel through PCV in addition to the valve overlap that pump some of the air fuel mixture back into the intake side.
It may help, but the root cause may be fuel getting into the oil and then travel through PCV in addition to the valve overlap that pump some of the air fuel mixture back into the intake side.
Has anyone with this issue sent their oil into a lab for analysis? If mine does ever have the problem I will, but as of now no issues.
FWIW I also suspect that Lexus doesn't have a ****ing clue as to how to fix it without adding fuel flow over the valves so they're throwing darts at a solution. And they probably aren't allowed to re-program the computer to run the 7th injector because it may slightly increase emissions and the EPA would throw a fit about it.
07-20-12, 11:13 AM
#1062
Lexus Test Driver
07-20-12, 10:48 PM
#1064
Just took mine back for another non-related issue, but since i'm still having the carbon build up shake, i'm having them check it too. After this i'll be in contact with Lexus corporate to see what can be done. I don't expect them to have a fix for it this time, especially since the pistons and all have already been done.
