am

Continuing putting back things around the engine i checked my cold start injector applying 12 volts to it , it's good.
I tried checking my auxiliary air regulator the same way to see if the passage of air inside the reg. will open but nothing moves , is it the right way to test it ?
I don't know if it could be related but before i take out everything for restoration the car had a cold start problem , it was too rich at cold start giving black exhaust smoke but i don't want to elaborate on that since i already posted for help at that time , i only wandered if the reg. could cause that problem .

Scott M.

AM;

There is a bimetallic spring inside the AAR that, once warmed will close off (nearly completely) the passage-way. When cold it should be fully open.
The FWSM has a resistance value, but I don't have it handy at the moment.
Is yours open, closed, or somewhere in between?

If open, apply 12v to it for about 3 minutes, see if it closes.

Scott

am

Scott , the resistance value is 21 ohms but, when cold it is around 85 % closed and i tried putting 12vdc 3 minutes and it closed approx 95% but cooling down it comes back closed 85% or opened 15%.
With what you said , and it makes sense ,one thing is shure it's that the part is no good and since i have nothing to loose with it, i'll open it to see what's inside but could it be the reason for black exhaust at cold start ?

jpitman2

The extra air valve is to allow more air to flow to lift the idle speed, so shouldnt give you rich mix - the opposite in fact. Ric sounds like cold start injector runs too long, or similar. Have you checked the thermotime switch? These on 928s are usually set for 8 seconds max due to the 12v supply heating a bimetallic strip. Try putting a meter on the thermotime, locate the supply lead to the cold start injector (continuous when cold), put 12V on the switch, check for circuit to cold start opening after ~ 8 secs. You should be able to read the stamps on the switch regarding the time and the temp at which it doesnt make circuit on a hot engine.
jp 83 Euro S AT 48k

User 4221

The AAR's function is to create a rich condition for easy start.

I assume this if for your '78. If so, I'm no K-jet pro so I can't help with the rich start (Black Exhaust) condition.

am

Thank's a lot Scott,

Jpitman2 , could you tell me where the thermotime switch is located or how it looks like or the location # on the PET exploded view ? just remember that my car is in pieces right now and the engine is out, Thank's

Dennis Wilson

The thermotime switch is brass, has a two pin Bosch type connector and is installed behind the thermostat housing. To check it first check for continuity between the two connections (not sure what the ohm reading should be), then check each connection for a circuit to ground. If either connection goes to ground or if there is no circuit between the two connections the switch is bad.

Dennis

am

Thank's Dennis , i'll try to find it !
Hey ,the way to check a thermotime switch is exactly the same than to check the magnetron of a microwave oven , maybe mine is cooked
Thank's

Sean79 5spd

AM, can you receive large e-mails - 22MB. I have a K-jetronic troubleshooting and test manual (given to me by another Rennelister).

Sean

am

Sean i'll try contacting you via pm.
Thank's

Randy V

Hey Sean - it would be swell if you could send me a copy of that test manual too!

My email address is randyv@rennlist.com

Thanks!