The saga continues with what appears to be my cursed FC. After performing the throttle body mod and removing a bunch of the unnecessary (IMO) cold start thermowax etc, I have encountered yet another issue. I set the TPS as best I could and put the throttle body and intake manifold back on. Started the car and it died after a couple of seconds. Started it again and gave it some gas and it went straight up to 3,000rpm and just held there with a bit of a misfire. Gave it a few seconds and then turned the engine off.

Took the intercooler off and had a look & play with the throttle body and butterflies. When I open the throttle and then let the butterfly go back slowly and gently it will stick open, as you can see in the pic below and the video further down. When I just let the butterfly go back quickly it will shut fine but it when I let it go slowly I had to apply pressure on the other side of the butterfly to get it to close.

[youtube]Unv-FqqAH_Q[/youtube]


I've tried spraying the hell out of the throttle body with WD-40 but it didn't seem to have any effect. The throttle body is clean of gunk as I gave it a good clean after doing the throttle body mod. Can't seem to get it to move freely though at the end of its travel. Any ideas how I can get it moving smoothly back to its closed point?

An unrelated point, the butterfly has a fair amount of free play in it before it actually starts opening up the throttle plates. Is there any way to decrease that and tighten it up?

 

OMP rod adjusted correctly?

 

look at the alternator plug and 2 TPS' in the VID. It's an S5.
maybe pb blaster? maybe something int he linkage is bent?

the freeplay in the linkage should tighten up with the tention of the throttle cable.

 

Yeah it's an 1991 JDM S5 FC.

Will try spraying the whole area with PB blaster and seeing if it has any effect. Saw someone else has put the whole throttle body in oil for a day or so; think that might be worth a try?

 

Naw. The springs on the shaft should be the ones holding the throttle linkage full closed. The cable should have zip to do with it. I'd suggest, seeing as how you say the butterflys have play, that the springs on the shaft are installed wrong. You take 'em off at some time?

*****An unrelated point, the butterfly has a fair amount of free play in it before it actually starts opening up the throttle plates. Is there any way to decrease that and tighten it up?**********

In my mind the butterflys ARE the throttle plates.........so I don't understand the above.

 

I think what he was talking about is the free motion of the plate that the throttle attactes too. We all know it feels kinda sloppy and loose with out the cable on there, and i was refering to the sloppiness going away with the cable adjusted properly.

 

oh

 

penetrate the hell out of it and keep moving it.. probably got corroded, mine did the same when i did the same mods as you.. took a while but eventually i no longer have any problems.

 

You sound just like my ex-girlfriend...

My explanation of the free play was bloody awful. I'm gonna take the intake manifold off tonight again so I'll try and make another movie to show you what I mean. If it's normal then that's fine; I'm just trying to find out what should and shouldn't be the case.

 

mine did that for a bit, just keep sparing it and driving it

i used cable lube on my throttle cable too

 

might be carbon build up around the outside of the throttle plates

thats happen to me before, just have to take off the throttle body, and take a fine grained sand paper to it, then clean it meticulously!

IF thats the problem anyway

EDIT: went back and reread, since its a mod, i imagine that u would have seen the build up
sorry never mind

 

Yeah I gave it a hella-clean after doing the throttle body mod.

 

Here's a video of that butterfly free play:
[youtube]nOT1BlKtroc[/youtube]

Well, the cursed FC continues to not want to be fixed. Tonight I was playing around a little and the throttle stop screw has stripped the threads in the throttle body that it went into. So I'll have to get that retapped and a different bolt put in. A guy on a forum here in Japan who's used to working with FC's thinks it's probably a bearing that's in the throttle body that has rusted or just gone bad, and probably needs replacing. Might be a job for my regular tuning shop if so. They're pretty used to my mechanical incompetence by now.

Another question that someone will be able to answer very quickly for me. Should this part of the throttle body (not sure the exact name) be bending inwards towards the throttle in the area I've highlighted below?

 

ya that outside one WILL have free play, they all do.
honestly, and i bet u dont wanna hear this, but u might wanna just get another.
i know u just modded it, but its causing u too many problems and from the pics ive seen, the Japanese air has rusted it pretty good
and may continue to be a problem

just post up on the parts for sell a WANT TO BUY modded throttle body, blablabla
thats what i did, and got a modded, polished uim and throttle body!

btw checked out the webpage, very cool

 

Terminology is a SOn of a bitch. and in this case, your getting all confused.
That end plate that you KEEP calling a butterfly, ain't no stinkin butterfly, it's the throttle cable attachment plate. like HAILERS said, the butterfly are the plates or "valves" inside the throttle body. There is absolutely nothing wrong with that. as soon as you put the cable on, that freeplay goes away!

and that TPS plate is bent as much as the stock s5 wastegate. LIKE it's supposed to be. go drive your car, i wouldnt be surprised if all these problems with it sticking went away after a little driving.

 

Well I'm trying to get the car on the road and in a position to pass it's Japanese inspection. Unfortunately, a 3,000rpm idle isn't really going to allow it to pass.

 

Isolate the problem. Seperate the linkage b/t the primary and secondary throttle shafts.

From looking from the side of the throttle body that has the mating places for the throttle cables...........look at that side and find the SECONDARY throttle SHAFT. Now slowly move the linkage by hand, from where the throttle cable attaches.

As you slowly move the linkage to open, you'll see the secondary throttle shaft does not move til you reach a certain point. Now look and you'll see a flat plate that ties the primary linkage to the secondary linkage. It's a flat plate with holes on each end. One end tied to the primary linkage and the other to the secondary throttle shaft linkage.

Disconnect that plate at the end that is connected to the primary linkage. It's just a small circular clip that holds the flat plate in place.

Now with primary sepearted from the secondary throttle shaft.........repeat what you did in the YouTube video. If the primary closes each and every time, then the problem lies in the secondary linkage/shaft. And vice versa if it still won't close all the way.

I'll post a jpg of a series five throttle body LATER.

The two TPS plungers ride on cam shaped pieces of metal as shown in one of your jpgs above. The cam shape lets off the plungers as you go to open with the throttle. IF with the throttle in the closed position, you can move the plungers a tad with the tip of your fingers.........then the TPS plungers are not holding the throttle linkage open.

 

While the throttle body shown in this jpg is filthy and grimy...........it snaps shut each and every time you open/shut it.

 

just leave it alone.. just chill in the car and throw like a hundred pedal pumps on it.. should clear up.