Vacuum Hose Connection

Hello

Does anyone advise me vacuum retard unit port (in Green circle in the attached pic) should be connected to ?
On the other hand, Vacuum advance unit port has been connected to the port on the throttle body which is before (upstream) butterfly valve.
Currently the retard port has been blocked by the plug, no connection anywhere.
(Please see the attached pic)

My car is VW Type4 with D jet 1.7L (Automatic model)

Back ground of this question is the following.
1) When Engine warmed up, idling speed is so high over 1500rpm. When cold, idling is about 1000-1200 rpm which is OK I guess.
I am wondering the above retard connection is the cause.

2) Also I always wonder why is  ignition timing setting.
I tried to set the timing at 10 deg BTDC at idling speed. However, if I did it Engine stall.
Eventually, I always had to set it at 27 deg BTDC. I know this is the defined ignition timing at 3500rom, not at idling speed.
But as mentioned, if I set the timing at 27 deg BTDC at idling speed, it run well at the idling with stable.
I don't know why 10 deg BTDC doesn't work...

Again, please let me know where the retard port should be connected to ?
If you could also advise me if the retard connection make some influence to the ignition timing, it would be highly appreciated.

Thank you in advance for your advice !!


JUN

Hi Jun,

please let us know which model year your car is and what is Bosch no of your ignition distributor.

Hello Dr D-Jet

Thank you for your reply.

My car is the following.
-VW412 
-1973 Model year 
-Automatic 
-1.7L with D-Jet

No. of Ignition distributor is 023 1172 019 (Bosch No.), 022 905 205P (VW No.)


Best Regards,

JUN

Hi Jun,

compare your connections with those on this scheme:

www.thesamba.com/vw/archives/manuals/elfrink_fi/83.jpg

Do you have the 2-way valve (#12) ?

And please let us know the solution.
The last request about the hoses was 10 months ago, what has been done since then?

Best Regards,

Marc
 

Hi Jun,
I dislike VW's system of just havin one mark at 3500/min . Other cars have a proper scale that you can read with strobe.

Now your distibutor should make 27 BTDC at 3500/min without any hose connected. At idle it should make 9° BTDC without hose and another 10° - meaning -1° at idle with retard connected. If you set it to 10° BTDC at 3500/min and you have no vacuum hose connected, it will have -8° BTDC which sound far too early to me.

You must have 2 connectors on throttle housing. One shows vacuum in idle - that one must go to connector of vacuum box toward distributor. The other will show vacuum when trottle is slightly opened - that one goes to outside connector.

Hello Marc,

Mine has no the 2-way valve..
I will check if the throttle body has 2 ports, one is for retard, the other on is for vacuum.

BTW, about my previous inquiry, at the time I had a starting problem with the Engine. 
Finally it was solved by doing the following.
-Changed wiring harness for the each injectors which was very hard, no flexibility.
-Changed cylinder head temp sensor

However, I still don't get why 27 deg BTDC at idling is OK for this Engine.
I will check it again.

Thank you for your usual help.

JUN 
 

Hello Dr-DJet,

Thank you for your advice.
I will check again if my throttle valve body has two ports for vacuum an retard.
Also I will check the ignition timing with following to your procedure.

Again thank you,

JUN 

Hello

I posted high idle and idle hunting at D rage (Not at N range) before.
I would like to share with you that they have gone by replacing Trigger contact.
The contact I removed from ignition distributor has certain bent of the contact plate caused by worn it out 

Since I replaced it there is no idling issue anymore.

Best Regards,

JUN

Hi Jun,

that looks very bad. Like somone broke off a part of trigger contact and fixed it provisionally. If TC signals too many contact closure on both sides, ECU will think of high rpm and increase fuel. However that should not increase real rpm.

Hi Dr-DJet,

Thank you for your comment !
Understood, again thank you for your usual excellent advice !


Best Regards,

JUN