CIS with system and control pressures/need help

[Ron.G]

1980 SC euro 3.0 no CO sensor. Cold start problem.

I tested my WUR and system pressure as well as the Aux air valve and everything seems to be in spec. yet The car will fire, stumble and die when cold for about 5 tries more or less depending on the temperature.
When it finally catches It will run at 900 RPMS but does not fast idle like it should when cold. I checked the AAV and it was open when stone cold and closed after the engine ran for a while.

When the car is warm it runs absolutely great with know problems at all. starts very nicely.
Is there anything else I can check? Residual pressure is good also.........
here are the numbers.
System Pressure 71 in spec
Control pressure @ 3.3 celsius (38F) 1.3 bars in spec

[boyt911sc]

Originally Posted by Ron.G

1980 SC euro 3.0 no CO sensor. Cold start problem.

I tested my WUR and system pressure as well as the Aux air valve and everything seems to be in spec. yet The car will fire, stumble and die when cold for about 5 tries more or less depending on the temperature.
When it finally catches It will run at 900 RPMS but does not fast idle like it should when cold. I checked the AAV and it was open when stone cold and closed after the engine ran for a while.

When the car is warm it runs absolutely great with know problems at all. starts very nicely.
Is there anything else I can check? Residual pressure is good also.........
here are the numbers.
System Pressure 71 in spec
Control pressure @ 3.3 celsius (38F) 1.3 bars in spec

Ron,

Bosch calls it auxiliary air valve and you're correct but most people in this forum refer to it as auxiliary air regulator (AAR) and the supplementary air valve as auxiliary air valve. Let the engine run and when it gets to operating temperature (totally warm-up), remove the oil filler cap and closely observe the idle speed change. There should be a noticeable drop from 950 +/- rpm to 600-700 rpm range. Do this simple test and keep us posted. Thanks.

Tony

[Scott R]

What was the control pressure once it warmed up? And I'm leaning towards what Tony is thinking, this sounds like a vacuum leak somewhere.

[Ron.G]

I will try the oil cap tonight. The idle does drop off a bit but I don't think it was that drastic. Would a small vacuum leak mess with the warm up operation but let the car run great when warm?
I suppose it could if I tuned it (not knowingly) to compensate for the air leak????

Thanks for the help. I will check the control pressure when warmed up also.
Could be a air leak because I have had a few nice backfires while starting cold in the past.. I have checked that but have not found anything. (checked the air box and runners and all vacuum lines) I also have a pop off valve and have checked for leaks around the seal.

[al lkosmal]

+1 on the vacuum leak...and I do think that it has been tuned to compensate for the air leak.

regards,

Al

[RoninLB]

good luck on finding a small air leak in a CIS

[Ron.G]

I have another air box at the ready and the engine is coming out for another
repair shortly so I will install the new box and give that a try.

[Gunter]

Ron,

Does the Euro 3.0 have an adjustable Deceleration Valve?

AAR = The one with the electrical plug
AAV = Looking like a puck, close to the AAR
Decel. Valve = What kind do you have?
If it's the adjustable kind, it sits behind the TB with small vac. hoses going into it.

[Ron.G]

It may, I would have to check to see if it is adjustable. what are you thinking? take it out of the equation?

[Gunter]

No!
The adjustable type is preferrable.

Can you take pictures showing the left and right side of your engine?
I want to see how the WUR and Decel. Valve on the left, and the AAR and AAV on the right are hooked up.

It would really help to see your set-up to make recommendations.
Fixing the possible vac leak before the engine comes out will add to your experience; airbox may not be the problem.

BTW: Removing the oil cap usually only drops the RPM about 100 max.

[Ron.G]

Here is some pictures of the Decell valve. It hooks up to a tee .
it is connected to another valve with a electrical connection and also hook up to the AFM.
I checked the control pressure when fully warmed up and it did not change from when stone cold.

38F at 1.4 bar both cold and warm.
I also pulled off the oil cap and the RPM's dropped slightly. not enough to show on the tach.

[boyt911sc]

Ron,

Do you know how to test the fuel pump by jumpering 87a-30 (FP relay) with ignition switch @ON position? Hook up the CIS fuel pressure gauge and observe the control pressure change during prolong idle. If the cold control pressure is 1.4 bar, it should slowly increase up to 3+ bar (fully warm-up). If the WUR does not exhibit this change, there is something wrong with the WUR. Also check for the WUR's electrical plug. There should be power once the FP starts to run. Keep us posted.

Tony

[kodioneill]

It could be cold start system is not working causing the hard start cold symptom. CSV or the Thermo time switch or a power supply for said system.

[Ron.G]

The car starts instantly when the key is turned but runs rough with a low idle and dies repeatedly until it finally catches.
It runs @ 900 RPM's but the warm up cycle never happens. so I think the CSV is doing it's job but the rest is not.

Yes I know how to activate the fuel pump. I have been following the Bentley manual
step by step. I do have power at the WUR and AAV.

I let the car idle until in was warmed up (first white line on temp gauge) and the control pressure stayed @ 1.4 bar never moved.
Wouldn't the heat of the engine affect the bi metal strip in the WUR and change the control pressure?

I could check for voltage again at the thermal time switch, warm up regulator,
and aux air valve but I'm pretty sure I had power. Checked it awhile ago.

[ossiblue]

Originally Posted by Ron.G

The car starts instantly when the key is turned but runs rough with a low idle and dies repeatedly until it finally catches.
It runs @ 900 RPM's but the warm up cycle never happens. so I think the CSV is doing it's job but the rest is not.

Yes I know how to activate the fuel pump. I have been following the Bentley manual
step by step. I do have power at the WUR and AAV.

I let the car idle until in was warmed up (first white line on temp gauge) and the control pressure stayed @ 1.4 bar never moved.
Wouldn't the heat of the engine affect the bi metal strip in the WUR and change the control pressure?

I could check for voltage again at the thermal time switch, warm up regulator,
and aux air valve but I'm pretty sure I had power. Checked it awhile ago.

Okay, this is a bit confusing. Are you saying that even when the engine reached the warm running temperature that the control pressure was 1.4 bar? In other words, your warm control pressure is 1.4 bar?

[Gunter]

Looking at the pictures, the right side shows the AAR and AAV, alright.
The left side shows the adjustable Decel. Valve and a connection to the Thermo Time Switch (TTS) and WUR.
Looks like you have a TTS and Thermo Time Valve (TTV).
You desribe problems with cold-start.
AAR, AAV, WUR, TTV, TTS and CSV are all involved during cold-start.
Some have the TTV, some don't
You can see the vac line diagram in the Tech Section on Pelican.

How to find the culprit?

You could take the WUR apart, clean it and the tiny screen located in the top nipple.
Check the resistance for the small coil inside the WUR. How many Ohms?
Carefully reassemble with a small bit of grease on the pin.

[Scott R]

Before you crack open the WUR check the resistance mentioned above. It's almost always the heating element inside that's cracked and no longer working. Also check that you have 12v at the WUR plug when running.

[Ron.G]

Thanks guys I will do some more checking.
And yes the control pressure never changed from cold to warm,

[Paulporsche]

As others have stated, your warm cp should rise, and it isn't.

If you have power to the AAR, then you may have what I did, which is a non functioning bimetal arm within the AAR. This is very common. The plunger that the arm controls sometimes gets stuck, and the screen on the top of the AAR can get clogged as well.

I had to have a new bimetal arm swapped into mine, and then reset the control pressures to spec values. At the same time, I found and corrected a small hole about to break through the metal pipe that leads to the AAV near the engine oil cooler.

Once you have determined that there are no ignition system faults or air leaks, you should look closely @ your AAR.

[boyt911sc]

Originally Posted by Paulporsche

As others have stated, your warm cp should rise, and it isn't.

If you have power to the AAR, then you may have what I did, which is a non functioning bimetal arm within the AAR. This is very common. The plunger that the arm controls sometimes gets stuck, and the screen on the top of the AAR can get clogged as well.

I had to have a new bimetal arm swapped into mine, and then reset the control pressures to spec values. At the same time, I found and corrected a small hole about to break through the metal pipe that leads to the AAV near the engine oil cooler.

Once you have determined that there are no ignition system faults or air leaks, you should look closely @ your AAR.

Paul,

Glad to hear from you and spend some time with us in this forum. What have you been doing lately to keep you away from joining the fun? Don't work too hard!!!!

Tony