Nahpets

Hello everyone,

driving these cars are like a marriage. Sometimes you just love all the joy it brings, and sometimes you´re so sick of struggling with upcoming issues.

Earlier I had a post where my engine died erratically ( https://rennlist.com/forums/944-turbo-and-turbo-s-forum/446558-engine-dies-sporadically-why.html ) . Now this is fixed (bad ignition lead).
Now when everything is running well. But I have noticed my boost wont reach the same level as before!

I have some kind of tuning chip installed. Dont know what kind, but it let me boost up to at least 1 bar depending on the gear choice. (I have an externally mounted boost gauge to monitor the boost.) There are no other changes to the engine hardware, except for a simple manual boost "adjuster" in the engine compartment connected to the wastegate. You see it in the picture. Please dont be misled by the unconnected vacuum hose in red. It´s connected.

So now, the boost wont pass 0,75 bar no matter selection of gears. 0,75 bars is stock setting, right?
Howcome? Is it related to the earlier issue with the bad igintion lead, like the DME run into safe mode? I have deattached the battery for half a day so the DME should be reset, shouldnt it?
What could be the reasons?
Please advice.

Cheers
Stephan

special tool

Could someone have turned down the controller?

eniac

Are you still using the CV? If so the boost "adjuster" should be in between the IC pipe and CV, not the CV and WG.

Does the car cut fuel at .75 bar or run fine just boost won' t go any higher?

Nahpets

At the moment the controller is screwed maximum counter clockwise. With this setting the boost comes earlier compared to the maximum of the clockwise setting. But I dont see any noticeably difference in peak boost.
To be frank I dont understand what that controller does ... . An explanation would be nice .

Perhaps it could be clogged perhaps?

Hmm ... gotta get out trying adjust it again to be sure ...

Cheers
Stephan

Nahpets

I still got the CV (the three headed device under the intake manifold). It´s connected between the CV and as it looks the WG (Ive gotta double check...).
What IC pipe should it be connected with? Perhaps a picture to explain?

Everythings runs well! No cut of fuel. Boost just wont climb higher.

Thanks!

Cheers
Stephan

Keithr726

Removing the CV might solve the problem and it will help with future problems. Also Check the the IC pipe connections with the IC and TB. They can become loose and leak boost also causing a rich mixture.

eniac

The IC pipe running from the turbo the to IC has a banjo bolt fitting that runs to the hard line under the intake and into the CV. Your limiter valve would go on this line.

What type of valve do you have for controlling boost? If it's just a open/close valve that limits air then you will want to keep the CV. If you have a pressure regulator pop valve then you can remove the CV and be done with it.

Nahpets

Hello!

Wanted to follow up my own thread for other.

These are the connecting threads for my lost boost.
- https://rennlist.com/forums/944-turb...ve-faulty.html .
- https://rennlist.com/forums/944-turb...e-bov-bad.html .
- https://rennlist.com/forums/944-turb...necessary.html

I realised a couple of days ago that when I did my boost charging test disconnecting the wastegate acuator hose from the cycling valve/ timing valve, I blocked the wrong hose! . I did the actuator hose, but it should have been the hose connected to the valve!
Anyway I did this and went out for a spin.
With my MBGC fully open I didnt reach higher than 0,75 bar. So I suspect bad turbo or bad wastegate. Let´s hope for the later...
I´ll report.

Cheers
Stephan

blown 944

Have you really looked at the couplers for the IC??

They tear on the bottom side and may be your problem

Or the turbo outlet coupler

I doubt the turbo is bad. The KKK turbos are pretty well built.

Have you also put an accurate boost gauge on there??

Van

If you fully pinch off the actuation hose to the wastegate, and if your boost is still at "just" .75 bar, then you have one of 3 things happening:
-Wastegate spring is weak, or wastegate is otherwise not sealing
-Turbo isn't making full boost, likely due to exhaust restrictions or damage to impellers
-Boost pressure is leaking out of intake tract (from a torn boot, loose hose clamp, vacuum leak, etc.)

Nahpets

Yesterday I changed the WG!
The current one had a very weak spring.
Now I have installed a shimsed WG and it runs like a god!!

Thank you guys for all your input!

To summarize my issues. I have suffered from:
- bad BOV
- weak WG spring
- smaller leaks in the vacuum lines
- leaky venturi plastic part.

All these issues are now fixed. Venturi hose mess still remains though... this time not leaking .
The biggest contributing leakers were the BOV and weak WG.

I ask you all to check your intake system. You will probably be surprised of how many small leaks there are...

Cheers
Stephan