308 GTSi Cold Running Behaviour

Hi,
i have a minor problem (but a difficult question) about a 308 GTSi US 1981:

Car starts perfectly in first second 1200 rpm. But after a few seconds rpm drops to 700. Then go up to 1000. When driving in the first 2 minutes sometimes again down to 700..800. But no hunting. Then all ok.

Image Unavailable, Please Login
(You can buy my pictures like this one)

My conclusions, maybe to be corrected:

• cold start fuel valve is working (also tested a few years ago)
• I dont think less fuel or less air
• Wrong ignition advance when cold (I have to prepare a picture of Pin 6 on ECU) ?

History:

• I had some problems with the car and some guys did help me in the past (incl. Michael me308) and now the car runs really good when it is warm.
• Fast Idle is not mounted anymore (maybe this will be another thing later)
• The thermoswitch is a closer (cold=open and warm=closed). It is shortened, so system thinks always it is warm.

I didn´t tell everything, because some strange things would confuse you.

Regards
Paul

 

Hi,

i have measured "Pin 6" to "Vehicle Ground" and it is not "open circuit" (infinitive resitance).

Then disconnected the white connector (blue cross) and disconnected the thermoswitch (73, red cross) and i am worried: not "open circuit".

Image Unavailable, Please Login
(Source: WSM in extracts)

I understand it like this:

If Thermoswitch is closed the "Vehicle Ground" is on "Pin 6".

While measurement both ECUs were connected. So "Vehicle Ground" was on "Pin 9" . Maybe internal thing of the ECU. My question:

What is the expection for the resistance "Vehicle Ground" to "Pin 6" if:
Disconnected the white connector (blue cross) and disconnected the thermoswitch (73, red cross) ?

Paul

 

Hi,
i forgot to mention the reason for "Wrong ignition advance when cold (I have to prepare a picture of Pin 6 on ECU) ?"

Image Unavailable, Please Login
(Source: WSM in extracts)

But if that is the problem, many of you would have this behaviour.

Paul

 

Hi,

can anybody confirm that the thermoswitch influences the ignition advance when cold ?

My opinion about "Fast Idle" was in the past:

Thermoswitch is open when cold -> No "Vehicle Ground" on air bypass valve -> air bypass open -> more air -> more fuel only due to K-Jetronic -> higher rpm

And more or less influence to the ECUs because:
more air -> less vacuum (higher absolute pressure) -> MAP sensor in the ECUs, independent of "Pin 6"

But now maybe there is a second thing with "Pin 6".

Paul

 

Hi,
ok, there are open questions but i go on with a try.

I put back the electrovalve #119 and did only electric connection, no vacuum connection:

Image Unavailable, Please Login
(Source: WSM in extracts)

Before i put it out many month ago, i did some drives with complete disconected electrovalve #119. There was no difference as expected. The only thing is that the "I am cold" light on dashboard is always off. Even if the thermoswitch is open.

So there should be no difference when electrovalve #119 is connected. We will see.
Paul

 

Hi,
i didn´t drive with electrovalve #119 connected so far. But another test for the question "..thermoswitch influences the ignition advance when cold ?"

I used a manual switch inside instead of the thermoswich and instead of short circuit the thermoswich directly.

Started with manual switch with short circuit -> Warm mode as in the past.
While driving a few hundret meters (cold engine) and the rpm is low i used the manual switch to open the connection -> Cold mode
The rpm drops additionally. More than one time used, same result.
When engine is warm i feel no differences.

I don´t know why rpm drops instead of raising or not changing. But there is no bypass for the air in my car. If it is a change in ignition advance the result is for me:
short circuit of the thermoswitch is the wrong way to disable the fast idle system. And the better way is to block the bypass permanatly.

Mabe there is another error. The try of the last post will be done soon.
Paul

 

Hi,
yes, not easy thing.
"runs very good" -> yes when warm.

Cold: Drops from 1000. Reason ? Maybe the ignition advance.

"drops from 800 to 700RPM" -> System reacts to short circuit the thermoswitch, although the "Fast idle" is not mounted.
So is there another possibllity instead of ignition advance ?

Paul