Civic VX Throttle Body trouble. Used replacement is also BAD. Any way to fix? - Page 2 - Fuelly Forums

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Old 09-08-2009, 05:35 PM   #11
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I have a 92 VX also. I took the throttle body off and cleaned it. Made a small but noticeable difference in how the car ran. I think about the only thing you can remove is the idle speed screw. Mine was full of black gunk after 200k miles. I would not recommend taking the throttle plate off the shaft because in the past I've had trouble getting it centered on the shaft on other cars.
I don't really see how a throttle body can go bad? As long as it's clean and the throttle shaft does not have alot of play in it.
Set the idle speed using the instructions in the Honda Service Manual. I did it by the book and the fluctuations went away.
And like the others have mentioned - chk the TPS position. It should be OK if set at the factory and the throttle plate has not been re-positioned. The screws holding the TPS had the snap off heads. I took a hacksaw blade and made slots for a screwdriver in the small nubby of a head that remained. Then I used regular screws to re-assemble.
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Old 09-14-2009, 11:39 AM   #12
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So I took the throttle body apart this weekend - there is an O-ring gasket on the idle valve and a seal for the throttle plate shaft - that one was very worn out.

It's not just a regular o-ring, but a complex seal and I don't think it's available from honda as a separate part, so if anybody knows of another source that has it let me know.

By the way, centering the throttle plate was not difficult, I just let it set itself before I screwed it in tight.

I also checked throttle position sensor resistance and it's fine. By the way - the car will run even if it's disconnected, so that's one quick way of checking it.
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Old 09-14-2009, 01:58 PM   #13
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I also checked throttle position sensor resistance and it's fine. By the way - the car will run even if it's disconnected, so that's one quick way of checking it.
So did the o-ring fix it? I'm going to guess not and instead tell you that it's the tps sensor. Resistance has nothing to do with the voltage signal it's returning, and disconnecting it and the engine still running doesn't mean anything either. There are two screws going through slots on tps sensor that screw into the throttle body. This allows the the sensor's position to be adjusted relative to the throttle shaft. It is actually quite sensitive to being calibrated/aligned properly, and unless you actually verify the signal voltage from the tps sensor with a multimeter while the engine is idling then you're ignoring a likely cause of your problems.

I apologize if I sound like a broken record, but i had this SAME EXACT problem on my crx vx swap, and I checked EVERYTHING ELSE before the tps because it sounded like a lot of work/technical. It's very easy, i assure you.

That being said, the only other thing i could think that it would be is a vacuum leak.
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Old 09-14-2009, 03:04 PM   #14
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So did the o-ring fix it?
For throttle plate shaft, it's not a simple o-ring, it's a composite pressed-in seal that looks kinda like a miniature crankshaft seal. It's very bad, as I can see a gap between this seal and the throttle plate shaft and I'm sure it's causing a vacuum leak, but don't know where to get a replacement.
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Old 10-18-2009, 02:54 PM   #15
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For throttle plate shaft, it's not a simple o-ring, it's a composite pressed-in seal that looks kinda like a miniature crankshaft seal. It's very bad, as I can see a gap between this seal and the throttle plate shaft and I'm sure it's causing a vacuum leak, but don't know where to get a replacement.
Finally got the leak via the shaft verified. Got another replacement throttle body - tested good, put it on.... But my saga was not over.

That good throttle body fixed majority of the idle hesitation, but I noticed that the car still had a small amount of vacuum leak as RPMS would occasionally go up and down at idle. This weekend I took the manifold apart and went over everything with a fine comb - comes out one of the studs that secures the manifold was missing. WTF.

Apparently the missing stud was letting just a little bit of unmetered air in to one of the cylinders. No idea why it was missing, this things don't just unbolt themselves.

So I got a spare engine and just took the stud off that engine and bolted it in and put the manifold back and now it is all good yea! But it took me like the whole weekend to figure it out, so I'm also MAD.

Now both of my VXes idle good. And they run good too. So for future reference, if anybody is seeking for a solution to an idle problem - it's a VAACUUM leak. In my case of 2 cars and three engines, it was: MAP sensor O ring, Throttle Body Shaft Seal, Manifold Gasket - all vacuum leaks.

I'm still not sure of a good way to find them though. I tried pressurizing the manifold and it did not show the leaks. May be $800 be smoke machine would work. If you got an idea on how to find a vaacuum leak - post it please!!!! As I still don't have a good way of finding vaacuum leaks. It basically took me 2 years and many many weekends of swapping parts back and forth to figure mine out, doesn't seem right, must be an easier way.
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