testing cold start valve

[Cdnone1]

Can I test the cold start valve on 82 SC while the engine is in the car. I can't even find the thing and the picture of it from the bentley is cropped too close to show where it is on the engine.
Thanks

[Scott R]

You can disconnect the CDI then use a test light on the thermo-time sensor located on the drivers side chain box cover. With the key cranking you will have +12v to the Yellow wire. Next crank and check it on the other terminal to make sure the thermo-time switch is closed.

Do this for very short intervals as you injecting fuel into the engine if the valve is working. You don't want to hydrolock.

After you confirm you have power you can move onto the next test. Sadly since this is an 83' you need to remove the valve to test for fuel. (if this was an earlier car you could just open the pop-off valve and watch it spray fuel) However the later cars use a metal vane to deliver the fuel from the CSV.

The valve is under the throttle body on the back side of the lower airbox. You need to do a partial drop, or if you're into masochism just remove the air boot from the top of the CIS system and go in from the top.

The valve is held in by two allen screws to the airbox. Pull these and pull the valve out. It will still be connected to the fuel supply line if you got your wrench around the line. You can now test it by placing it in a jar and cranking the engine.

[Cdnone1]

Thanks Scott
I just put my test light on the two leads to the thermo switch removed the CDI cranked and the test light did not come on?
Any ideas.
The problem I am having with the car is it will start right up and run fine for around 20- 45 seconds. I can rev it, it idles fine then the car starts to sputter, buck, ilde drops and eventually it will die.
I thought the cold start valve might be staying open and actually flooding the car as it warms up. Anyway the test light did not come on
Thanks

[Scott R]

The yellow wire to the thermotime switch comes right off the starter, I've seen a few that were cracked and broken above the starter near the heater box.

[47silver]

The csv gets 12+ from the same circuit that activates the starter solenoid.
The ground wire from the CSV goes to the thermal time switch. If the starter solenoid is engaged and if the engine temp is below the TTS setting then the CSV solenoid energizes.
You can have 3 problems:
1. the csv is bad.
2. the tts is bad.
3. the wiring is bad.
Test the wiring first: remove the plug to the csv. put a VOM meter in the positive side of the connector and to a good ground. Have someone crank the engine if you get 12vdc that means you have a good + circuit to the valve from the solenoid. If you dont then you have a wiring problem.
If you have 12+ then put the positive and negative probes of the vom into the connector. Crank the engine. If you have 12vdc then i would say that your TTS switch is ok.

If you have 12vdc to the plug that is on the CSV then i would guess that the CSV solenoid is bad. but if you want to test it:
the fuel pump has to be running, (jumper it out) crank the engine you should hear the CSV working and spraying.

[boyt911sc]

Originally Posted by Cdnone1

Thanks Scott
I just put my test light on the two leads to the thermo switch removed the CDI cranked and the test light did not come on?
Any ideas.
The problem I am having with the car is it will start right up and run fine for around 20- 45 seconds. I can rev it, it idles fine then the car starts to sputter, buck, ilde drops and eventually it will die.
I thought the cold start valve might be staying open and actually flooding the car as it warms up. Anyway the test light did not come on
Thanks

Steve,

The CSV is not your problem because the engine starts right away. CSV & TTS work only the first several seconds after engine starts running. The previous posters have given you ways to check the CSV & TTS. These are what I used for the test.



Getting to the CSV could be a problem to some people with big forearms because you have to reach at the back side of the engine just below the CIS air box where the CSV is mounted. I have no problem getting the CSV off the car but it is tedious. Engine partial drop is optional.

The translucent fuel line is used to test the injector spray pattern (FP running) when external 12-volt is supplied using the black connector. The blue connector is used to test the engine harness plug for CSV with a test light connected.

Tony

[89turbocabmike]

Originally Posted by Cdnone1

The problem I am having with the car is it will start right up and run fine for around 20- 45 seconds. I can rev it, it idles fine then the car starts to sputter, buck, ilde drops and eventually it will die.
I thought the cold start valve might be staying open and actually flooding the car as it warms up. Anyway the test light did not come on
Thanks

After the engine dies I'm guessing that it won't start up again for a bit?
Most of the bad cold start valves I've seen leak all the time even it you unplug the the electrical connector, they're stuck open and just begin to flood the intake as soon as the fuel pump turns on. If you check your fuel pressure you can see this from a quick loss of residual pressure.

[psalt]

The problem I am having with the car is it will start right up and run fine for around 20- 45 seconds. I can rev it, it idles fine then the car starts to sputter, buck, ilde drops and eventually it will die.
I thought the cold start valve might be staying open and actually flooding the car as it warms up. Anyway the test light did not come on


Cdnone1,

If your theory was correct, testing the electrical part of the CSV circuit will not tell you if the CSV is mechanically leaking. If it is stuck open, you have to remove it. The CSV does not work " only the first several seconds after engine starts running". Once the engine starts running and the key is in the "ON" position, the CSV circuit is off. Once the key is in the "ON" position, the CSV is irrelevent, and other devices create the rich mixture and higher idle needed to keep a cold engine running.

It is unlikely that your stumble and stalling on a cold engine is caused by too much fuel, it is much more likely that it is too lean. The 82SC is calibrated very lean for a cold start because of changes to the lambda default settings. A small vacuum leak, drop in compression or mixture and timing adjustment can cause a stumble and stall. The first thing to check is your cold control pressure and system pressure. If your pressures are good, try disconnecting and plugging the vacuum retard line, this will give you a much stronger cold idle. Once the engine is running , read the duty cycle of the FV from the test port with a dwell meter cold, open loop and hot, closed loop. It will tell you if the system is working correctly. An 82SC will not have good cold running performance if the lambda system is not working properly.