Idling after rebuild FIP

[Pawel66]

Make sure the wrd filter is not blocked... It should be very easy to suck through.
I'd do cold start tests with it off completely.

That filter can be bought new from Mercedes if appears to be clogged.

[Rob12345]

Air filter is off. I started engine today with 2mm under BC. There was a lot od fluctuating... When I gave fuel everything was good. No fluctuaction, Stable RPM.
https://youtu.be/BB45Qgx3IXY
Now I think that the only way is turn full load screen ccw? I measure BC pin- 6,39

[Rob12345]

BC

[Rob12345]

WRD oval shim 0.6 and pin 0.77 mm. I also check for vacuum leakage. When I put finger instead air filter on FIP engine Die. Also the same situtation with screw on intake mainfold



Added: I change the mixture on full load screw 2 times ccv. The engine id working propertly on all RPMS. AFR is good on 750, 1500, 300 RPM. Now I have 2,1 mm shim under BC. And there is  posibility now to change mixture with shims for example on BC od WRD. Ealier my mechanic from workshop set the pump top lean. Now i must wait for cold engine and check cold RPM. Tank you for a link to FIP Simulator. IT was very helpful

[Rob12345]

So, I was waiting for cold engine. With 2 mm shim under BC engine is not starting. With 3,8 mm like ealier, engine is starting but there is a fluctuaction from 600-900 RPM. I dont know what to do now. When he is on operating temperaturę everything is ok, I can change the mixture... With cold i can do nothing even add few RPM more- because there is almost no reaction

[mrfatboy]

So just to clarify.

At operating temperature and 2mm BC shims the engine runs smooth and AFR is correct.

But when engine is cold, it won’t start. But if you change the BC shims to 3.8mm it will start?

Is this correct?

[Rob12345]

Yes

[mrfatboy]

That suggests that the mixture is too lean with cold engine and 2mm BC shims. Leave the BC shims at 2mm.

Now you need to adjust the WRD oval shims to make richer at cold start only. 

You will need to add shims to do this. For a temporary test you can loosen even both screws that bolt the WRD to the fip. This will act like adding shims and making richer.

Once you zero in on the engine starting add the actual shims. From there it will be a lot of fine tuning.

[Rob12345]

I did a test 2 hours ago. I gave 3,8 BC shim and add 1.6 mm WRD shim and I have only 900 RPM on cold engine. Maybe i must turn full load screw more-?

[mrfatboy]

It does sound like your full load screw is outside the normal adjustment. Did it come like that from the rebuilder or did you play with it early?

[Rob12345]

From rebuilder. I didn do nothing

[mrfatboy]

Make sure you write down all adjustments you make so you can always get back to where you were. This is tricky stuff 😀

[Rob12345]

I know. So What I can do.... I can turn ccw more- on full load screw and check and more- and check. This is not normal. When he is taking money IT should be done.

[mrfatboy]

Remember adjusting full rack screws changes mixture at all rpm ranges. You must be careful not to screw up mid and high ranges.

[Rob12345]

I will try turn screw full load only 1 or two clicks

[stickandrudderman]

Before doing anything with the BC you should confirm that it actually works.
Then, if the car runs fine when warm and you're getting around 4%Co, less than 500HC, 800-900 rpm all at idle and the engine picks up well without popping or misfiring, then and only then you should restrict your self to adjusting the cold start. Nothing else.
In all cases, you must ensure that the engine runs fine when warm before adjusting cold start.

[mrfatboy]

I was just in the middle of typing exact same thing 🤣

Check the pin length.  Directions here:

https://www.sl113.org/wiki/Engine/AltitudeCompensator

[Rob12345]

I found second BC in my second car. So I have two BC now. First and second looks that same. Lenght od pin the same. I AM sure now that the only way to eliminate idling on cold engine is turn back screws that holding WRD(I have second also- when I tryied nothing changed). I have there 4mm gap. Ten engine works good. So problem is on the pump I think

[mrfatboy]

Here is the info regarding how to know if BC is good. It is from the tech manual.  You will have to visit the link above to see the picture.

“ There are two styles of BCs. The first style pictured above has a brass collar at the top of the threaded section. The second style as shown below does not have the collar section. It is there fore important to measure the length of the BC pin from the base of the hex nut to the top of the pin. A good BC should measure approx 21mm from hex nut to the top of the pin. A bad BC will measure approx 25mm.”

[Rob12345]

I have 21mm

[Garry]

Rob,


All this information is all within the restricted area for Full Members.  Unfortunately Mrfatboy links wil not work for an Associate Member.


Membership is $30 pa and will save you that and more for the sake of a few coffees.


Garry
Membership Administrator

[Rob12345]

I solved the problem with idling on cold engine. The problem was with sucking air between shim and termostat like on a picture. I used loctite and now I have 1100 RPM on cold and 720 on hot engine. Should be a little more on hot but its working and A/F ratio is ok so I leave it. Thank you for your help.