My Last Vacuum Leak?, Throttle Body butterfly shaft -VIDEO Options

[ctc911ctc]

914-2L, '74 all original

While I was working on an injector problem, I installed a professionally rebuilt distributor and set the dwell angle right on the numbers: 48 degrees. After correcting the injector trouble I moved on to setting the timing. With the 27Deg RED mark only on the rear side of the flywheel I had to draw a mark on the _other_ side so I could get this done with the timing light, etc. Why do they think of a million other things and not think about marking the fly wheel on both sides?

I believe that I was about 20+ degrees off, after getting it correct, all of the engine missing just went away. I may be at the end of this journey with this car, drove all day, not a flinch, just worked properly. Like my 2 year old 1.7 in 1973.......ahhhh.... (IMG:style_emoticons/default/driving.gif) (IMG:style_emoticons/default/cool.gif)

HOWEVER

I then noticed that the idle was too high, around 1800. I set the idle screw and it is in all of the way - still around 1800. VACUUM LEAK!?! (IMG:style_emoticons/default/mad.gif)

On this car I have had perhaps a dozen different vacuum leaks, manifold gasket (did not seat right), Plenum (needed a complete re-weld), Manifold tube cloth connectors to the plenum (too lose, needed to be snugged a bit closer to the plenum). So, where is this leak?

I recently purchased a smoke machine and was using it incorrectly - I thought that I would see the smoke being SUCKED into the vacuum leak.......well, that did not work, then I wanted a few videos and put the smoke in the throttle body and This is what happened:

https://youtube.com/shorts/rAf5c66Zow4?si=y3TRgC0EJgBFMfmX

Apologies for the bad video, but it seems that the throttle plate shaft in the throttle body is very leaky, any ideas if this is something that could keep the idle high?
Also, note that in the video you can see that I plugged (blue plug) the vacuum valve with the heater in it. does not change the idle very much when plugged - perhaps 200 rpm reduction.

Any ideas as to the shaft leaks and how tight that part of the vacuum circuit it should be?

thank you teeners

[rfinegan]

can you feel the play in the throttle shaft? Are the plates sticking or staying open? this was the symptoms of my shaft before adding bushings to it. Mine did not change the idea speed that much. but smooth and did not stick
Timing adds to the faster RPMS
Idle mixture on ECU adds faster RPS
Aux Auxiliary Air Regulator valve AAR ( this is its job)
Vacuum leaks

ALSO: be sure the decal valve is not staying open and keeping the idle high ( a simply unplug and cap the hose test will let you know)

[ctc911ctc]

can you feel the play in the throttle shaft? Are the plates sticking or staying open? this was the symptoms of my shaft before adding bushings to it. Mine did not change the idea speed that much. but smooth and did not stick
Timing adds to the faster RPMS
Idle mixture on ECU adds faster RPS
Aux Auxiliary Air Regulator valve AAR ( this is its job)
Vacuum leaks

ALSO: be sure the decal valve is not staying open and keeping the idle high ( a simply unplug and cap the hose test will let you know)

Thank you for the thoughts, I have not touched the ECU, will do that next, also I do not remember any play, though there was a great deal of smoke coming through, will check.

I have plugged the AAR hose with little change (once it is warmed)

Will take a look at the shaft play and the ECU,

(IMG:style_emoticons/default/smile.gif)

[rjames]

That's a lot of smoke... Hard to tell everywhere it's coming from, but it's more than just the throttle body. I wouldn't worry about the ECU. Your high idle is most definitely from the vacuum leaks.

For starters... I see smoke coming from the intake runner gaskets (replace the gaskets) and where the throttle body sits on top of the plenum (replace the gasket that sits between).
Also likely there's a leak where the rod for that the butterfly is fastened to goes through the throttle body. Adding a bushing there to fix that.

Are you sealing off the top of the throttle body while testing? If not, you should. And make sure your PSI isn't high enough during your test to cause a leak where there wasn't one before.

[emerygt350]

That's way too much added rpm for the tb bushings. although it is pouring out the TPS side.

Have you put a thumb over the idle screw inlet inside the throttle bore. Sometimes the screw just doesn't seal anymore and that can add a couple hundred rpm. Even with that plus the throttle bushing issue you are too high by a long shot. Remember, a hole the size of the aar inner bore gets you 500 rpm. That's about an 8mm hole.

First, disconnect each vacuum hose from the plenum and plug the port. Same with the retard port on the carb. Then go one by one reattaching them and see what effect it has.

Also, if you are timing it correctly with the hose plugged to the dizzy and then attaching your retard line to the advance side of the dizzy you will be immediately adding 10 degrees to your timing and that will definitely get you a very high idle.

With an idle that high, if it is a leak, you will hear it. I can hear my aar sucking when it is open. Unless it's death by a thousand pin pricks, which is possible. You may want to grab a bottle of carb cleaner and shoot some spots since the smoke looks like a little bit of a disaster.


And now that I think about it... What kind of PCv do you have? If it's the active one make sure you plug it, that is a huge vacuum leak if the valve isn't original or working correctly.

[VaccaRabite]

That's a lot of smoke, and the video does not show where its coming out of.
Almost makes it look like its coming out of the TPS. That much smoke could be your 1800 rpm idle.


https://www.youtube.com/watch?v=1BbU4JeyzMo
this is what a leaking throttle shaft looks like.

If it is your throttle plate, you need to either replace the throttle body or have it rebushed. And the replacement may be worn out as well, since all of them are OLD. Rebushing will require the services of a machinist to make bushings and fit them. The TB was not really serviceable as designed.

For my car I went with the 53mm throttle body replacement for a Vanagon and adapted it to work on my 2056. On a Djet 914 this may not be possible, but with modern EFI not only did it work, but it opened up more fueling bins at the top end of the rev range.

[ctc911ctc]

That's a lot of smoke, and the video does not show where its coming out of.
Almost makes it look like its coming out of the TPS. That much smoke could be your 1800 rpm idle.


https://www.youtube.com/watch?v=1BbU4JeyzMo
this is what a leaking throttle shaft looks like.

If it is your throttle plate, you need to either replace the throttle body or have it rebushed. And the replacement may be worn out as well, since all of them are OLD. Rebushing will require the services of a machinist to make bushings and fit them. The TB was not really serviceable as designed.

For my car I went with the 53mm throttle body replacement for a Vanagon and adapted it to work on my 2056. On a Djet 914 this may not be possible, but with modern EFI not only did it work, but it opened up more fueling bins at the top end of the rev range.

Good to know someone else has traveled this path, I was thinking that I would source a cylindrical shim kit and start there (IMG:style_emoticons/default/shocked[1].gif) or something equally stupid - a new throttle body is interesting.........I believe I probably killed this one when I rebuilt it (IMG:style_emoticons/default/huh.gif)

Here is the rebuild:

http://www.914world.com/bbs2/index.php?sho...=337051&hl=

[FlacaProductions]

Also, if you are timing it correctly with the hose plugged to the dizzy and then attaching your retard line to the advance side of the dizzy you will be immediately adding 10 degrees to your timing and that will definitely get you a very high idle.

I'm leaning toward something like this - timing can add to/affect idle.
I can see this by adjusting advance at idle rpm via my 123 distributor. that's one fun thing with the 123, you can mess around with specific rpm bands