thermo-time switch.

[Benny771]

Hi again:

I read somewhere that the "thermo-time switch" (Or other name) also controls the idle when the engine is cold. Am i correct in my thinking? Car takes 10 min to idle correctly, Cold pressure and fuel volume are now in spec, but it still has a cold idle issue it never had before.

I have a 1987 930 and wondering where it is and what resistance (or how to test it) i should be getting if it is working right?

If anyone knows ( i cant find it in the shop manual) it would be a great help for me. I don't believe my wur is the issue,but still may be.

It looks like this: Pelican Parts - Product Information: 930-617-118-00-OEM


Or possibly this: Pelican Parts - Product Information: 930-606-117-00-M100

[Ronnie's.930]

This thread explains the placement, workings and testing of the thermo time switch:

930-78-3,3 thermo time switch ??

[Benny771]

Thanks, ive read that one.
Im looking for the switch that controls the idle somehow untill it engine reaches norm temps
?? Temperature Sensor??? Possibly ??
The post i read , the guy had the same idle issue as me and he thought it was the WUR as well. but it wasnt, he used a ohm meter on it and it was out of spec, changed it, problem solved. 10 min time frame to idle right.
Now i cant find that post . If it rings a bell to anyone he had a picture of the sensor/switch on the last post.

[cole930]

Ben:

You'll find it to the left of the distributor and down on the upper left side of the chain cover with two wires connected to it.

Cole

[Benny771]

There is no electronic connector's on the left side. There is one on the right but only one wire.
It is closed when cold. And appears to be 0 res.

1989 930.

[mark houghton]

Benny, the TTS does not control your cold idle...or any idle for that matter. All it does is work in conjunction with an injector to inject fuel direct into the intake manifold for a short period of time, dependent upon engine and sensor temperture, to richen the mixture and facilitate starting. After a few seconds the TTS become inoperative.

If your control pressures at in spec, then look to a malfunctioning AAR. It it isn't opening, or not enough, then you will see a low idle until the engine is warmed up.

[Benny771]

Ya, did the control pressures, and tested the AAR. I thought the AAR was only used for 1min or so at cold start-up? Mine is like 10min of bad idle.
Going to swap a WUR out to test mine tomorrow. 2hr drive. Is there no other tempature sensor that could do this? Like the two listed in my first post?

[JFairman]

there is a small vacuum switch that blocks vacuum retard going to the distributor to raise idle about 200rpms for about a minute after a cold start in your '87 but there is no switch that raises idle for 10 minutes.

there is an aluminum valve sometimes called the auxilairy air valve to the right of the WUR that bypasses air from the intercooler around the throttle body into the intake manifold to raise idle around 800rpms relatively when it's cold. It slowly closes and idle speed gradually lowers over a mantter of minutes depending on ambient temperature.
i'd guess this device is stuck closed and may be your car's problem.

when it's very cold out the thermal time switch in the left side chain case cover opens the cold start injector under the throttle body while the starter motor is cranking. dwell time for that injector depends on how cold it is and how long and how often the starter motor has been cranking.
it has nothing to do with idle speed.

the other sensor you mentioned is in the right side chain case cover and it disables the lambda emissions system while the motor is cold so it will run stronger and smoother but it doesn't make it idle higher.

[cole930]

Ben:

Sorry !!!!!! I have one of those 1980 antique, hexed, euro 930's.

Cole

[Benny771]

Originally Posted by cole930

Ben:

Sorry !!!!!! I have one of those 1980 antique, hexed, euro 930's.

Cole

Not old, beautiful !!

[Benny771]

Originally Posted by JFairman

there is a small vacuum switch that blocks vacuum retard going to the distributor to raise idle about 200rpms for about a minute after a cold start in your '87 but there is no switch that raises idle for 10 minutes.

there is an aluminum valve sometimes called the auxilairy air valve to the right of the WUR that bypasses air from the intercooler around the throttle body into the intake manifold to raise idle around 800rpms relatively when it's cold. It slowly closes and idle speed gradually lowers over a mantter of minutes depending on ambient temperature.
i'd guess this device is stuck closed and may be your car's problem.

when it's very cold out the thermal time switch in the left side chain case cover opens the cold start injector under the throttle body while the starter motor is cranking. dwell time for that injector depends on how cold it is and how long and how often the starter motor has been cranking.
it has nothing to do with idle speed.

the other sensor you mentioned is in the right side chain case cover and it disables the lambda emissions system while the motor is cold so it will run stronger and smoother but it doesn't make it idle higher.

Well, lets hope its the WUr then.... I will keep you posted . Im swaping out with an 82 930. That wont be a problem R-I-g-h-t ???

[mark houghton]

Originally Posted by Benny771

Well, lets hope its the WUr then.... I will keep you posted . Im swaping out with an 82 930. That wont be a problem R-I-g-h-t ???

Let's hope it's NOT the WUR. You said that your control pressures checked out ok, so the WUR is the last place I would look. Look at the AAR (or AAV, interchangable nomenclature). Do this: Start your car, see the low idle, pinch the hose going to the AAR. If the idle does not drop, then the AAR is not letting enough air into the intake. The reverse would be true if you had too high of an idle....pinching the hose would restrict the air and lower the idle.

Do you have both the cold and warm control pressures documented?

[Benny771]

NO, just the cold. It runs great when its warm. I guess i should test that as well.
I will try that test when i get back home

[Benny771]

Well,

It does not seem to be the WUR. It ran great on his car. I will recheck the AAR and let you know Mark.: )

[930Penny]

Originally Posted by mark houghton

Benny, the TTS does not control your cold idle...or any idle for that matter. All it does is work in conjunction with an injector to inject fuel direct into the intake manifold for a short period of time, dependent upon engine and sensor temperture, to richen the mixture and facilitate starting. After a few seconds the TTS become inoperative.

If your control pressures at in spec, then look to a malfunctioning AAR. It it isn't opening, or not enough, then you will see a low idle until the engine is warmed up.

Hello all if you would answer my question
Is it possible for the thermo switch to allowed the 7 fuel injector to stay open?
My 76 930 was running great up a till last weekend it took too long to start and when it did was miss firing then I notice fuel coming out or dripping from the exhaust pipes right where the right n left side come together

Any help would be greatly appreciated

[gorskined]

Originally Posted by 930Penny

Hello all if you would answer my question
Is it possible for the thermo switch to allowed the 7 fuel injector to stay open?
My 76 930 was running great up a till last weekend it took too long to start and when it did was miss firing then I notice fuel coming out or dripping from the exhaust pipes right where the right n left side come together

Any help would be greatly appreciated

The easiest wat to test to see if your colsd start injector is flooding you out is to reach around and unplug your cold start injector. i know my thermo switch is next to impossible to access but im running an ic on my 76.
.. The car will run and start just fine without the injector unless its really cold then it will take a minute or two to idle good once warm .. doing this is easy as long as you don't have the factory air box on
.. 75 up untill mid late 76 had a solenoid going into the right side of the main cis just below the fuel distributor . This solenoid has a single yellow wire. i believe, The solenoid advances the air fuel plate adding extra fuel i could never get a straight answer about how it worked . . 76 didn't have an aar . Most early turbos unless a concours car have long since abandoned that solenoid. you may want to unplug the yellow wire if you have it to test. to see if that corrects your fuel issue .

[gorskined]

Originally Posted by 930Penny

Hello all if you would answer my question
Is it possible for the thermo switch to allowed the 7 fuel injector to stay open?
My 76 930 was running great up a till last weekend it took too long to start and when it did was miss firing then I notice fuel coming out or dripping from the exhaust pipes right where the right n left side come together

Any help would be greatly appreciated

I believe the cold start injector is only energized while you are cranking over the starter but i could be wrong . The only thing the thermo switch does is it will complete the circuit to ground and allow the 7th injector to spray fuel if the engine is below 95 deg while starting. This is what i was lead to believe but im not an expert . The easiest way to test is to reach around and unplug your cold start injector. i know my thermo switch is next to impossible to access but im running an ic on my 76. The switch is not a in and an out. One side is 12 v for a heater and the other is the ground for the 7th injector so dont try and jump it out.
.. The car will run and start just fine without the injector plugged in unless its really cold then it will take a minute or two to idle good once warm .. unplugging the injector is easy ( just grab and pull the electrical socket off the injector ) as long as you don't have the factory air box on.
.. 75 up until mid 76 had a solenoid going into the right side of the main cis just below the fuel distributor . This solenoid has a single yellow wire. i believe, The solenoid advances the air fuel plate adding extra fuel during start up . i could never get a straight answer about how it worked . . 76 didn't have an aar . Most early turbos unless a concours car have long since abandoned that solenoid. You may want to unplug the yellow wire if you have it . to see if that corrects your fuel issue .

[mark houghton]

Yep, as mentioned, unplug it and see what happens. The TTS should only function when it sees power from the starter circuit, and then completes the ground to the injector (not sure if it's a frequency valve or a solenoid in the fuel distributor). I would have to pull out my circuit diagrams to see where that injector/solenoid is getting it's power from but my gut says a faulty TTS would not cause the injector to stay on...rather the opposite.

[Alan L]

If the TTS sw is 'faulty' the best it could do is stay in circuit (cold) mode, or stay stuck in no circuit mode. The latter means the CSV won't work at all. The former means the CSV will work all the time - WHEN and only when the starter is cranked - ie hot or cold.
If it appears the CSV is working all the time, the only possibility is the CSV is stuck open. Not impossible. It is a simple solenoid valve. They are prone to seizing with rust when not used regularly.
So, as others have said - the way to eliminate that option is to pull the plug - rear base of the pancake inlet manifold. Not the easiest thng to get to, but welcome to the 930,
Alan

[930Penny]

Thank you everyone for taking time to help I did the sugested unplugging the 7th injector and i am still getting too much fuel. I am going to start removing the injectors i believe they are originals
any tips as to how to test them at home ?