How to clean your throttle body

Discussion in '80-Series Tech' started by IdahoDoug, Apr 20, 2004.

  1. IdahoDoug

    IdahoDoug

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    8,782
    This was suggested as an FAQ by Jason/MoJ as a PM reply to him yesterday.


    Here's a synopsis - hope it's OK if I'm brief:
    Get fuel injection cleaner spray (not carb cleaner as it's too harsh), and have an old toothbrush (heat and bend brush part 30 degrees toward direction bristles point) and some clean rags on hand. Park truck on as steep an angle leaning to the right as possible (helps cleaner/crud run out of throttle body intake).  Removen rubber tube connecting throttle body to air cleaner (helps to remove air cleaner and go easy on this ribbed tube so you don't crack it in the ribbed area).
    Prop throttle valve fully open (I used a vise grip) and sparingly spray cleaner in and on the butterfly valve itself.  The objective is to clean the grundge you'll find all around the edges of the valve itself, AND where these edges seat when it's closed.  Those are the two most important surfaces and really the whole ball game.  Alternately wipe with the rags and brush as much of these surfaces as you can until you don't seem to be getting any more of these oily deposits out.  Forgot - put a rag where the cleaner fluid will drip onto the engine.  Once done, you'll find that the valve will close with a crisp metallic "clack" rather than silently onto the oily deposits.  If you feel you're getting a lot of the fluid deep into the intake, be mindful it's going into the cylinder and valves and thence a bit into the engine oil, so perhaps good to plan at the same time as an oil change afterward. Good luck!
    DougM
  2. CDN_Cruiser

    CDN_Cruiser

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    1,047
    Doug:

    What happens when you have a dirty throttle body :-[ Poor idle,...other symptoms?

    Cheers, Hugh
  3. Scamper

    Scamper

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    I don't think the TB is that hard to remove, and you can get much better access to the butterfly and back of the TB if it is removed. It's pretty hard to see the back side of the butterfly when it's installed, and that's where most of the crud seems to stick. If you have a S/C, then it's really impossible to see or reach anything in the TB when installed since it faces the back of the truck.

    I also pull the vac lines from the top of the TB (labeled as P, R, and E on a '97, as well as the PCV hose) and spray the cleaner down those ports to make sure they're cleaned out. You also want to make sure you get the butterfly shaft cleaned well so that there's no sticking going on and you have smooth operation. I also remove the IAC valve and clean all the ports and valve out--don't have to worry about where the carb cleaner or TB cleaner goes if you've done this since you can just let it run out onto a rag or can.

    Wish I had known you were doing a FAQ...I could have taken pics this past weekend when I did all this.

    Tom
  4. nakman

    nakman addict. Supporting Vendor

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    Yes, one symptom is the infamous high startup idle, and its subsequent valve clacking. Many have reported this going away after cleaning the throttle body, I'm hoping to do this in about 2 weeks, guess I'll see if it makes a difference. I'd love to see a fancy FAQ writeup though, anyone else have pics? -tim
  5. Scamper

    Scamper

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    In my experience, the biggest thing that happens is that the engine runs rough--especially at idle. But that's when it's just "mildly" dirty as opposed to all fouled up. I've never let mine get too dirty since it's so easy to clean.

    I'm only speculating here, but if you plugged up the R/P/E ports sufficiently, you'd probably get a CEL for the EGR (P0401 or the like) indicating an EGR malfunction. Those ports enter the TB right where the butterfly seats and are really tiny, so it wouldn't be too much of a stretch to see them gummed up by varnish.

    Tom
  6. semlin

    semlin rocker SILVER Star

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    I think Doug's method will work fine in most cases but
    I'm with Tom that it is easy to just remove the throttle body to clean it. 1.5 banana job. Don't be afraid of losing any coolant when you do this, it likely will not happen. By removing the throttle body you get a nice view of the intake chamber and also the EGR outlet and you will see any carbon buildup. I can also vouch for a plugged R port in the throttle body causing EGR malfunction. Very hard to clean these ports unless you have compressed air or tiny wires (I used a stripped twist tie from a loaf of bread!). If you don't have compressed air I recommend one of those aerosal spray air cans for cleaning computer keyboards. They are great for testing the ports and will clean up some gunk.
  7. DMX84

    DMX84

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  8. landtoy80

    landtoy80

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    I would say remove the intake chamber as you need one or more cans of carb cleaner to clean the EGR port. With that much crud and carb cleaner in your intake system, it can't be good for the motor when you start it.

    There are tiny holes in the throttle body that I don't think you can clean out with out removing it.

    If you are going to go through the work to clean it, do it right the first time. That way if you still have a problem you will know its not from carbon in the intake system.
  9. lagwagon

    lagwagon

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    I second removing the TB because the EGR port needs to be addressed as well. From the large opening to the EGR port is where I have seen the most clogging. This port was narrowed to about 3mm in the last 80 I worked on.
  10. landtoy80

    landtoy80

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    As seen in the pic, you would never be able to get it clean without removing it.
  11. ppc

    ppc M Go Blue

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    [quote author=nakman link=board=2;threadid=15114;start=msg142779#msg142779 date=1082555898]
    Yes, one symptom is the infamous high startup idle, and its subsequent valve clacking.
    [/quote]

    Not so, I had high cold start idle from the first day I bought it new. The high idle is by design to get the emissions systems functioning as fast as possible.

  12. MoJ

    MoJ Moderator

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    [quote author=ppc link=board=2;threadid=15114;start=msg143028#msg143028 date=1082583099]
    Not so, I had high cold start idle from the first day I bought it new. The high idle is by design to get the emissions systems functioning as fast as possible.
    [/quote]

    I'm thinking I only partially agree with this. I think high idle is by design but not as high as many folks are experiencing, i.e., dirty TB adds to it, making it even higher. This thought comes from reading many posts where folks have reported effectively reducing the high idle via cleaning the TB.

    In my case I'm hoping it fixes my intermittent LOW idle problem. I also plan on inspecting for cracks in the plastic intake piping as this seems to be another commonly reported cause of the low idle. Will tackle this weekend using IdahoDoug's procedure if my wife doesn't have me scheduled. :-\
  13. semlin

    semlin rocker SILVER Star

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    Phil, not sure what your cold start up idle is. After pulling my throttle body to get at my EGR and doing nothing to the throttle body/cables at all except removing and reinstalling my start up idle dropped from 1700 to 1400 rpm. After I removed it a second time and cleaned it, start up idle dropped to 1200 rpm and has stayed there for several weeks. Everything else seems perfectly normal. No adjustment was made to the cables and I didn't touch the sensors. I no longer believe it is a design feature and I suspect something hard to diagnose is wonky in the throttle body.
  14. Junk

    Junk

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    This thread could be a huge help to a lot of 80 owners, so can more folks post pics like Lagwagon. Labelling also is a huge help. Thanks.
  15. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator Supporting Vendor

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    [quote author=lagwagon link=board=2;threadid=15114;start=msg142968#msg142968 date=1082576220]
    I second removing the TB because the EGR port needs to be addressed as well. From the large opening to the EGR port is where I have seen the most clogging. This port was narrowed to about 3mm in the last 80 I worked on.
    [/quote]


    I'm not sure that's EGR. When you install a blower that gets blocked off and the EGR still appears to work. :-\
  16. Junk

    Junk

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    I'll go along with that Cdan. I'm still trying to figure out that if by adding the blower, it changes any of the flow of the EGR anywhere. I'm thinking it does.
  17. IdahoDoug

    IdahoDoug

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    I'll second Phil's experience with the high idle. Mine has done this since buying it new. Keep in mind Phil and I have the non OBD models (with the manly transmission and radiator) and the minor emission and engine electronics may create a difference vs the 95+ models.

    DougM
  18. Scamper

    Scamper

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    [quote author=cruiserdan link=board=2;threadid=15114;start=msg143205#msg143205 date=1082601645]
    I'm not sure that's EGR. When you install a blower that gets blocked off and the EGR still appears to work. :-\
    [/quote]

    Yeah, I've always wondered about where them gases are going. :rolleyes: I'll vouch for the fact that this port is definitely blocked off with the SC installed (the intake runner covers it right up and I remember a comment about this in the S/C install manual).

    I think I'll take a look at the plumbing again this weekend and if I pull anything apart, I'll take some pics.

    Tom

    Edit: I think the high idle problems (not startup idle) may simply be due to a sticky butterfly caused by all that gum, holding it open a bit. A thorough cleaning is probably the best medicine. When I pulled my IAC the first time about a year ago, there was a lot of carbon on the plunger gizmo and around the seat on the TB. Even though toyota says not to use solvent on this, I did and it cleaned right up with no damage as far as I can see. When I pulled it this time, it was nice and clean still--no carbon. I would hesitate to clean this by pouring in lots of carb/TB cleaner though...best to remove and go easy.
  19. NovaFZJ80

    NovaFZJ80

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    what do you guys consider low/high idle ??? my LC idles at 600rpms waiting at a red light.....only in the morning it idles high on cold start and after a min or so, you can hear it rev down..thats when i'll pull it out of the driveway
  20. landtoy80

    landtoy80

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    That hole is blocked on nonSC motors.
    I goes to the throttle body. The throttle body doesnt have a hole.
    It might have something to do with how they milled the intake chamber out???
    The hole does help in cleaning the port out.
    Under that hole is where it gets plugged up, thats the EGR port.
    [​IMG]

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