1982---911SC Targa CIS,frequency Valve chech

[vizail]

Need some info:

I'm having a hell of a Time trying to Diagnosticate an fine tune my 911SC.

I was cheking the Thermo Time Switch that actuates the Cold Start Vale and there is no constant voltage in the red wire.

I disconect the Frequency Valve Cable from the Frequency Valve and Nothing Happens.
The O2 Sensor has been disconected but no notisable difference.

Needles to say the cold start runing is nasty. Unpleasant Exaust Smell, shacky Idle speed...! But when it gets Hot it runs more or less ok
How can you Guys Help Me?
Vic

[fireant911]

My initial disclaimer... I am not an expert here but I will share what I think I know to be true and hopefully others will jump in (at least it will be a free bump!!!)

I am under the impression that if the car cranks then your cold start valve is working. My exhaust was terrible with gas fumes until I reconnected the Oxygen Sensor - which was grounding off to itself (coaxial wire). The CIS system runs in an open loop mode until the 15°C temperature switch (on the right timing chain cover) allows the Lambda system to take over control of the fuel mixture.

There could be several possible causes of the symptoms you are experiencing one of which is from clogged fuel injectors. My brother recommended to take an infrared thermometer to the underneath of the engine to see if there were any large disparities from one cylinder to the next (yes, 2 & 5 should normally be hotter since they are in the middle). Techron is highly recommended but I prefer concretrated doses of Berryman's B-12 Chemtool. Another possibly of your problems is from an incorrectly set basic fuel mixture - gain access to an exhaust gas analzyer or either have a knowlegdeable mechanic do this job. Has the car been tuned up recently - new plugs, rotor, fuel filter, air filter, etc...? Your Warm Up Regulaltor may not be set properly resulting in incorrect fuel pressures. Have you checked your ignition timing and verified that your distibutor is advancing properly and not stuck?

[john walker's workshop]

the frequency valve HAS to function before you bother with any tuning adjustments. it's computer is under the right seat. the computer is powered by a small relay which is also under there, toward the tunnel at the front of the seat. the relay is powered by the domelight fuse on the front fuse board. do the domelights work? the relay is the usual problem. if you unplug it and nothing changes, running wise, try a new relay. the computers don't usually fail unless they've been drowned.

[vizail]

fireant911

I also beleive that the Cold Start Valve is working.
The Oxigen sensor I beleive has to be changed " I beleive it has over 30,000 miles on it. Or at least since it was last changed.
Since I live in Puerto Rico the constant temperature here is around 78F to 90F , this means that de CIS is almost allways working in a closed loop.But anyway How can I check the 15C or 105c degree switch?
The Engine was rebuilt by a local Porsche BMW & Mercedes Specialist that has become a charlatan and I have lost my faith with him. Since I'm a retired Air Force Acft. Tech. I'm doing the rest of the repairs. One of the discrepancies that I found with this person is that he reinstal the engine back and did not install the buchings in the shift coupler.
In regards to the distributor timing I have timed it "Static at Z1" and then go on advancing up to 5 BTDC. .. Ah!! yes I beleive that the Ignition distributor advance plate or Ignition is damaged because I have to disconect the advance vacum line and leave the retard line in . If I don't do this it will not work properly or at least aceptable when warm up. It will advance too much.
The Warm up Regulator is New but according to my Voltimeter is not getting Voltage since is my understanding that during Warm Up, Voltage has to be present .

Vic

[vizail]

John

Thanks for the advice. You say the relay is located under the passager Seat beside the ECU?

Vic

[john walker's workshop]

yes. the warmup regulator also HAS to get voltage. you could always jump a wire to it for now, while you figure out the real problem. find a terminal on the rear fuse box that is only hot with the key on. find a wiring diagram too.

[vizail]

John
Thank's

Wath about the Ignition Distributor Vacum Advance?Very Clever to jump wire the Warm Up "Presure regulator"..!
In regards to Diagrams ,I have the Porsche 911 Service Manual for Coupe to Targa 1978 to 1982, The Solving BOSCH CIS Problems by Weber,The Bosch Handbook 5th Edition, 101 Proyect Book. And I have your expetice and camaradery.
I'm cheking for vacum leacks "while engine is runing" with Carburetor and Choke Cleaner and around the Air Box. So far no leaks have been found. Yes the guy use the old "Intake Manifolds to Air Box" rubber joinst, and Vacum lines. But apparently there are no leacks.

But needles to say when working with fuel and electricity..! I get a bit woried and Jumping a unit like the Warm Up Regulator!

Vic

[vizail]

How About some more imput..!
Vic

[john walker's workshop]

do the things i suggested first. did you? do the domelights work? yes/no? if not, check the domelight fuse, which also powers the oxygen sensor computer, which in turn powers the frequency valve. does the engine run rougher when you unplug the relay under the seat? yes/no? did you provide temporary power to the warmup regulator and did it run better after that? if the WUR doesn't warm up, the engine runs way too rich when it gets to operating temperature. you have to get these things working before you go any further.

[vizail]

john w

Thanks for the fast reply..!

The dome ligths ( The instruments ligths on the dashboard)Yes they light up..! I have to check that relay under the seat..!.It will be a surprice if I find it disconnected..!
I'm goin to get an old connector and hotwire the WUR
The time diference in your shop and mine is 4-hours, and rigth now is 10:00PM in Seattle WA. is 6:00PM
Thanks for the replys.. keep in touch..! I'll keep you updated..!
Vic

[emcon5]

Originally posted by vizail
john w

Thanks for the fast reply..!

The dome ligths ( The instruments ligths on the dashboard)

That would be the dash lights, not the dome lights. The dome lights are the car interior light.

[john walker's workshop]

the relay probably won't be disconnected. you need to personally disconnect it for a moment when the engine is hot and idling, to see if the idle gets rougher. i assume you're not a master of the language.

[vizail]

ecom5 and john

Thanks again!
Rigth now is 8:00am ,7:00am ET monday.
ecom5..The dome lights (Intirior ligths)are not working at all but all the fuses are there. I have to check the bulbs,door switches and the Voltage continuity.

john .. I say I have to check if the relay is connected because the person that worked in the engine left the O2 cable unpluged "among other thing's".
The way I see this proyect is that I'll have to check the entire cables harnnes ,one by one in this car.
Yes you assume rigth..., I'm not a master in the language.

Vic

[john walker's workshop]

fuses don't always burn out in the center. they may burn at one end, or simply be too corroded to make a good connection. put a fresh fuse in the dome light position if it doesn't look fresh and clean. if you have a test light, also check for power at the bottom of the fuse. you just have to get power through the fuse, regardless if the dome lights work or not. the fuse powers the relay under the right seat.

[vizail]

John
Thanks again
In the prosses of cheking the continuity on each one of the fuses.

Vic

[john walker's workshop]

the fuse box cover identifies each fuse. look for "total interior light". that's the only one you need to check right now.

[emcon5]

The O2 sensor uplugged in the engine compartment (assuming you mean the connection under the fuel accumulator & filter) doesn't hurt anything. If you unplug the O2 sensor on a 80-83 911, it will assume the sensor isn't up to operating temp, and default to open loop, which runs the frequency valve at a fixed duty cycle. It should run at 85% duty cycle for 1980, 65% for 81-83.

The engine will run just fine.

EDIT to Clarify: The Lamda system needs to be working properly for this to happen.

Tom

[Gunter]

Do as JW says. I have an '80 SC and the Ox sensor has been disconnected for years; it makes no difference on performance but the Frequency Valve has to run! Check and clean the electrical connections for the relay, and Ox sensor computer, under the seat. I use dielectric grease (or Vaseline) to prevent corrosion. Make sure that there is power to the dome light; test both sides of the fuse #18-5Amp.
With the engine hot and running, disconnect the relay for the OSU. There should be rougher idle, re-connect, idle should improve.
Thermo-time switch: power comes from starter (yellow wire) only for a few seconds while starter is running, just enough time to energize the Cold Start Valve.
Temperature Switch (15deg C) I am not sure: Is this switch normally open with engine cold? Closed when hot? Can someone confirm?
WUR: Voltage should be present to supply the heating element so that control pressure increases when engine heats up. Check both wires, one RD/WHT for Voltage, and one BRN for ground.
At least it is warm where you are, I am in the deep-freeze. Cheers.

[vizail]

To begin with I check all the fuses clean them and replaced a few ones for voltage continuity.
Now I have a 13.5 reading on the WUR as well as in the OXS relay with readings of 13.5 V between terminal30- and 85+ . also from 85 to 86 ,87 and 87B I also get the same readings.
I did not get or feel the Frequency Valve working and the only reading I get is between 1.2 to 1.5 volts at the quick disconect terminal. I disconnect and reconnect the Frequency Valve and nothing happened.
I also found a unit The Acceleration Enrichment Control Unit . This unit have a smal hole with treads on it apparently for some kind of adjustment .., Numbers fron 1 to 8 around a circle.
All this readings where taken after the engine got Hot .
Wath can you say about this findings?

Cordially
Vic

[john walker's workshop]

did you unplug the relay with the engine running? you don't have to unplug the frequency valve, just the relay. it's easier to get to. if you have power to the relay under the seat, then it's a good possibility that the relay is bad. could be the whole problem.