I finished up working on my intake manifold the other day. I decided to stick with a bead blasted finish instead of polishing it out. I took a portion of the top of the manifold out to 1500 grit and realized I wouldn't be happy with that unless the whole thing was polished. Since the VC and TB are bead blasted, I decided to blast the manifold. All the casting marks have been removed and the visible (and some not so visible) portions of the manifold have been smoothed out and rounded over.











I replaced all four injector bungs with new replacements. Some of the old ones were cracked.



First step in removing the manifold is to disconnect and remove the TB and throttle cable.







Upper coolant hose disconnected.



Expansion tank hose and FPR vacuum line removed.



Fuel rail and injectors removed. I will be cleaning and installing new o-rings and clips for all the injectors as well.





The upper o-rings for the injectors may stay lodged in the fuel rail, I pulled them out with some needle nose pliers.











Intake manifold removed.

 

Nasty disgusting breather original breather hose. The elbow was cracked and broke off the t-fitting when removing it.



Elbow cracked off.



Old junk removed!



New 034 breather kit.



Hard pipe and t-fitting out from the engine bay, ready to receive the 034 kit.





The turbo oil feed line was rubbing against the breather kit so I cut open a piece of vacuum tubing and slipped it over the feed line to help protect the breather line. Last thing I want is to have the metal rub open a hole on the breather line.



Attempting to secure the hose to the heat shield, haven't succeeded yet.

 

Those edges where the intake manifold is seated with the intake ports on the head are pretty chippy...

If your dressing everything up, why not go the whole 9 and do a top overhaul.

 

And from the pictures I do realize you took your head off and had it machined.

 

Your firewall got bent like that from a previous accident im assuming?

 

That chipping is just a rough edge from when it was cast and can't be seen with the intake manifold in place.

Nope, haven't removed the head.

Yes. The PO was in an accident bending the firewall. Car has been accident free since I've owned it.

 

Intake manifold gasket and new dipstick funnel in place.



Manifold installed!



034 breather attached.



Injectors reinstalled with new upper and lower o-rings and new clips.



Fuel rail bolted in.





The final product.

 

And now for the inevitable problem. The car isn't idling properly.

Before starting the car I made sure to do a throttle body adaptation since I'm using a new (used) TB. The adaptation was successful so I fired the car up.

The idle started out at 1500rpm. I let it sit there for awhile before tapping the gas. I brought the rpms up to 2k and released the pedal, the rpms dropped very slowly back down to 1500.

I let the car reach operating temperature and the idle was still high, averaging about 1250rpm (watching it via vag com.)

Tapping the throttle to bring the revs up to 2000 and then releasing it would bring it down to 1000, from there it would creep back up to 1300 or so.

I turned on the AC and the idle dropped to normal, 880rpm. I tapped the throttle, brought it up to 2k, released and it would return to 1000, not 880.

The only time the car would idle at 880 is after turning on the AC, but before touching the throttle. Once I hit the gas at all, the rpms wouldn't go back down to 880 unless I turned the AC on then off again.

I took it around the block and it drives great. It sounds better than ever. It just isn't idling properly.

I'm going to switch back to my old TB once the car cools down and see if that fixes the problem. Anyone else have any ideas?

 

Take a look at measuring blocks 003 and 005. You can see if your high idle is caused by the throttle staying open or a vacuum leak. I think there is another MB in the 60's that is for detecting vacuum leaks.

From the sounds of it, I don't think you have a vacuum leak since the engine speed drops to normal with the A/C on. It almost sounds like the weird idle behavior I'm dealing with on the V8. I'm hoping that my ECU switch clears it up because this is getting really old.

 

Yeah I was watching block 3 and block 98, the throttle is closed at idle. There might have been a difference in voltages at idle between the two throttle bodies, should've written the numbers down.

I swapped the old throttle body back in place and the idle went back to a normal 840-880.

Put the new one back in again and it went back up to 1100, so it's pretty clear something is up with the throttle body itself.