Glazedham42

Having a bit of a problem here in Indiana, and just wondered if any of you more knowledgeable people could help me out.

About a week ago I decided that I would clean out my throttle body, mainly because my throttle response had been terrible. Well I took the throttle body off and cleaned out both in front of the throttle plate and behind it. Well, before putting everything back together, I felt like being unneccessarily thorough. I got a little WD-40 and shot it where the throttle plate connects to the inside of the throttle body.

About a day later the Pro started idling different. When I first start the car it idles noticeabley higher than it did before. I can't tell you the exact revs, because I don't have a tach. Anyway, if I drive for a little bit, the revs will drop back down to where they used to always stay. Is the car just trying to warm up when I first start it or what???

Secondly, after the car gets warmed up the idle fluctuates. The idle goes higher than normal and then drops back down, then it will go up a little and drop back down. It keeps doing this as long as you sit there. I would just guess that it jumps up about 250-500 rpms. It is almost like the car is sitting there revving itself, and it is bugging the heck out of me!

I have three reasons to believe I started this problem when I took the throttle body apart:

1) The Haynes manual says to use a carburetor cleaner that is safe with catalytic converters, and oxygen sensors. Did I screw something up by shooting that WD-40 in there? (Oxygen sensor?)

2) My Haynes manual also says, "Do not remove the thin seal coating from the throttle valves or bore." What is that, and what is it talking about, and did I do that?

3) This problem didn't start until I started screwing with things!

Whew!! Please help! Any and all suggestions are greatly appreciated! I've got to get the Pro back to her glory days!

markv

The same thing happened to me after I put in a K&N filter. I also disconnected the hose that goes from the airbox to behind the radiator. My best guess was the extra air coming in was screwing up the idle. By cleaning out the throttle body, you probably increased air flow by a fair amount too. I got tired of the K&N (the engine ran better at high revs, but it felt like I lost some low-end torque) and after I took it out ant put the regular filter back in and replaced the hose that goes nowhere (?) the idle went back to normal.

Glazedham42

How can I tell if I have a vacuum leak or not? I didn't unhook any of the hoses that go to the throttle body, I just left them connected. Could one of the hoses be cracked or torn? Also, what is an unused nipple plug? I don't know what that is.

Kincaid

hehheh. I've got an idea about what this is. But somehow I doubt he meant what I'm thinking about

Glazedham42

Thanks for the help, I figured that much out myself... Anybody really know what this means? Hehehe

Sir Nuke

NIPPLE PLUG....if there is a small unused port on the intake, the throttle body...or any other apparatus on a car that is there for some feature that your particular car doesn't have...then they put a nipple plug on it....its a small rubber cap that goes over that port/tube to keep the system vaccum tight, thus keeping the system in balance. if you accidently knocked one off, it would act the same as if there were a leak in one of the hoses.

protejay

(because you don't know till you ask ):
Did you replace it with a NEW one???

Glazedham42

Is there supposed to be a gasket between the throttle body and the injection? There wasn't one in mine when I took it apart. Should there be?

Also, where are the common places that these nipple plugs would be placed, how big are they, what color, and how much are they going to cost me if I do need them?

protejay

well....i was thinking there was....but i guess i was wrong....my bad

Glazedham42

I don't know, maybe there is? All I know is my Pro didn't have a gasket. Which seemed sorta odd. But don't take my word for it. Hehe.

Anyone else know if there is supposed to be a gasket between the throttle body and the injection or at least something to keep air from leaking through the metal on metal surface??

protejay

http://www.miataforum.com/ubb/ultima...c;f=5;t=017926

may give you an idea of the problem....

Glazedham42

Okay, I replaced the gasket today between the throttle body and the intake manifold. It took me about an hour to scrape off the old gasket, which I thought was the source of my problems.
Unfortunately, after re-assembling everything, my idle is still fluctuating and driving me crazy.

Does anyone know if this problem could be linked to a bad alternator? Mine has been doing LOTS of clicking and clacking lately, and acts like its about to give out. Is it not sending a constant current anymore? Or could a bad bearing on the alt. be giving me problems? (as I'm not really sure what's wrong with the alt.)

I have checked every hose that connects to the throttle body and NONE of them are cracked or loose. This is about to drive me nuts, plus I think this fluctuating idle is KILLING my gas mileage...

protejay

did you also check the actual intake 'hose' for cracks??

Glazedham42

Yeah, I checked the intake hose too. Its perfectly fine. No cracks or leaks, and it's just as soft as a new hose.

There is, however, a small crack in the hose that goes from the intake into the valve cover. I tried to put some duct tape over it and fix it "Jesse" style, but I'm not sure it worked. Could this little S-shaped hose be the problem?

Davard

Yes. A vacuum leak is a vacuum leak. Where doesn't matter.

Duct tape has it's uses, but for vacuum leaks, I prefer to use electrical tape, but not the cheap stuff. Get the $3 3M stuff, as it is more flexible, doesn't harden, and the glue sticks to the tape, not everything else. Or just replace the hose.