Want better gas mileage? Clean your TB and Plenum
10-01-09, 09:27 AM
#1
Want better gas mileage? Clean your TB and Plenum
So my friend and I decided to change the spark plugs on my SC300. This is the first time I have ever replaced spark plugs, and spark plugs on a 2jz at that (I'm starting to do all of my own maitenence). Obviously I looked up how to do it and got it all done. When we took off my intake we looked in the intake manifold and saw that it was super dirty. The throttle body was nasty black, and it was a little thick. We decided to clean it all out with throttle body cleaner and got the intake cleaned up pretty nicely. All I have to say is that I am getting a lot better gas mileage. It has increased at LEAST by 50 miles a tank...which does add up... I used to get barely 300 miles to a tank (I dont really like to keep my foot out of it 
) Now I am getting pretty decent gas mileage. Before we did the plugs we also decided to seafoam it. Everything is running a lot better than it was before. Just thought I would throw out the idea if some of you have not thought about it. I also found out that I need some new valve cover gaskets....
but, it is what it is. I am going to replace those soon. Lots of oil where the old spark plugs were. I have 185K on my SC. Im sure any mileage SC would help. Let me know what you think...
) Now I am getting pretty decent gas mileage. Before we did the plugs we also decided to seafoam it. Everything is running a lot better than it was before. Just thought I would throw out the idea if some of you have not thought about it. I also found out that I need some new valve cover gaskets.... but, it is what it is. I am going to replace those soon. Lots of oil where the old spark plugs were. I have 185K on my SC. Im sure any mileage SC would help. Let me know what you think...
10-01-09, 11:18 AM
#2
Wouldn't be suprised if you noticed a little better throttle response as well as better gas mileage after all that. My old sc400 felt like it was hesitating, almost to the point of stalling until me and a friend cleaned out the throttle body. Ran as good as new after that!
10-01-09, 09:24 PM
#5
Lexus Test Driver
iTrader: (14)
Join Date: Jan 2003
Location: Charleston,SC
Posts: 855
Likes: 0
Received 0 Likes
on
0 Posts
You may need new gaskets however ive noticed the design of the valve covers is poor because if someone happens to spill oil when refilling during an oil change(pretty common) it tends to run under the plastic cover and head towards the plug galley which would cause oil to be down in there with nowhere to go until you change the plugs again.....
10-02-09, 06:31 AM
#7
Lexus Test Driver
Join Date: Jun 2008
Location: Minnesota
Posts: 869
Likes: 0
Received 0 Likes
on
0 Posts
Good post 
Are there any DIYs for installing plugs? From what I hear, it's a pretty good sized PITA on these engines and I've never done it before. Trying to decide if I want to have a go or if I want to just let the shop take care of it.
Are there any DIYs for installing plugs? From what I hear, it's a pretty good sized PITA on these engines and I've never done it before. Trying to decide if I want to have a go or if I want to just let the shop take care of it.
Trending Topics
10-02-09, 09:01 AM
#8
You are in the same place I was. Do I take it to a shop or not? Well, honestly im tired of taking my car to shops to get ripped off on the things that I can do, even though it might be a PITA. It took me a good while to do, but it really wasnt that hard. It was my first time doing it, and I think I could shave a good hour, or two off the second time, getting better each time. There really isnt much you can mess up here. The only thing that can be semi difficult is the throttle cable. It came off and went back on easily though. Honestly man, I would do it if I was you. Its really not that bad, and you know it will be done correctly. I know MANY people who have taken their MKIII supras and SC's with manifolds crossing over the top that have not gotten the two underneith the throttle body changed. At least you can know you did it. All I can say is make sure you have ALL sizes of metric sockets and open ended wreches, and a flat head. Also I HIGHLY reccomend buying a clamp that you screw for the coolant hose thats a main in the *** to get back on. and off for that fact. Needle nose pliars will help too. DO IT!!!!
What I did, was I got all the nesisary tools (I have a specific tool box filled with metrics), got a bucket for all the nuts and bolts that have to be taken off, needle nose pliars, lighting, plugs, and thats about it. Right now, I really wish I would have bought plug wires too, because one of them broke, but I managed to make it work. I also wish I had bought my valve cover gaskets at that time too. That would have been a perfect opertunity to change them. I am going to do them soon. Then I went crazy and started working on it. What I found out is, if it wont come off, there is another bolt/nut holding it on, if not two
. Also, as a word of advise, don't forget to put the freakin intake manifold gasket back on. I got it all back together and then I saw it laying in the bucket and I wanted to kill myself. Lol. After it was all done, I got some major black/blue smoke...it was dark... (refer to 1st post about oil in plugs) then I got some white smoke (it was kinda cold and I had seafoam still) and then I drove it. I definatly floored it up and down a main road up to 80, and turned around and did it again, and it ran GREAT. I could tell a major power increase and it felt like it was really smooth. Just gotta give it some time to burn off all the crap thats on it when you take them out. Let me know what you think. Im considering doing an official write up with tips and all. Let me know if that is something you would like me to do.
Last edited by Carfreak70; 10-02-09 at 09:07 AM.
10-02-09, 09:43 AM
#9
Driver
iTrader: (1)
Join Date: Oct 2008
Location: ca
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
theres a write up already. but i didnt clean my throttle body when i had the chance b/c i was lazy. but now i want to without having to go through all that mess again. can it be clean w/o taking the throttle body off?
10-02-09, 09:48 AM
#11
I know there is one already...but no offence to that poster or anything, I could do one a little better. And yes, I did use the one they made, but I feel like I can make a really good one (I have a creative side...lol). You can clean it without I guess. Take off your intake and see if you can get to it. You will need some type of cleaner and a rag. Its probably going to be caked on. Mine was. lol. The cleaner is the important part honestly. Get the good stuff.
10-02-09, 09:50 AM
#12
Yes, it is. I had a 400 too. I dont think I would even try that lol. I did have a shop do that. It was all expensive. I just got tired of it. Actually...I probably would try doing it myself. If someone else can do it, I can do it too.
10-02-09, 10:32 AM
#14
Lexus Test Driver
iTrader: (14)
Join Date: Jan 2003
Location: Charleston,SC
Posts: 855
Likes: 0
Received 0 Likes
on
0 Posts
I found it to be a lot easier than i thought when i did mine on a 2jz, with the right tools i could probably do mine in an hour or less now. it Looks a lot harder than it was all you need to take off is the throttle body. Basically you need to take off the intake tube going to the air box then remove the throttle cable,vacuum lines and electrical plugs. then its off with the 4 nuts/bolts and slide it off towards the pass side. then once its off you can take the plastic covers off and get to the plugs etc.. remember when putting it back together to make sure you seal it well because i had an air leak on mine and i had to take it apart again and use some silicone on the gasket to seal it up.
