1981 3.0 sc ROW CIS Low idle & dies off throttle

[brentrussell]

Well the car has been issue free for almost 4 years and then a few weeks ago i started having issues with the idle speed and dying when coming off the throttle at lights etc.

My CIS knowledge was pretty good 4 years ago when Tony helped me extensively to get the engine running after having numerous issues including the wrong WUR. I've combed back through my notes and some of the saved threads to put me close to the right track I hope

WUR 0438 140 089 31ohms at ambient
It first started with being a bit jerky cold and warm, occasional stalling but still easy to start... I resolved to there being a vacuum leak and hooked up my pump and various gloves to close off and found two smallish leaks around the POV. With some JB weld I blocked them off and re-check confirmed no further visible leaks. I thought this would solve the issue and be back to normal with nothing else changing.... wrong.

So now, cold start good but only rev's to 1100rpm at cold start, after 4.5mins starts dropping to 1050 and by 6mins its 800rpm for the next few minutes then at 9 mins its 600rpm and stalls.
Warm Restart is fine, but idle still too low and dies., can keep running with a little throttle.

I thought perhaps AAR, 0 280 140 201, ohms at ambient is 32.
10mins in the oven 85c and it's fully closed.

Left it in the freezer overnight and it's half open at best.


At Ambient its probably 90% closed.


I also borrowed a AAR off a friend, haven't tried in car yet but it's performed and looks exactly the same after freezer, oven and ohms test.

I've ordered S&G Fuel pressure gauges from USA but they 3-5 weeks away so me and you guys are flying blind for a bit which is not ideal.

Due to fixing the air leaks could it be as simple as now adjusting the idle/ bleed screw to increase idle? I'm not convinced on this as it had fine idle before.. it may fix it but think I have another issue.
Fuel Accumulator was brand new 4 years ago, 4500mile
Fuel pump new also
WUR was a recon/tested unit from Tony at same time.

Perhaps lean the mixture screw CCW to adjust after air leak fixed.. again was ok prior two weeks earlier.
Could double check sensor plate to make sure that is as per spec in Bosch manual?

Could try raising idle screw and take note of turns to prove the point..
Anything else I could check before my gauges arrive? 3-6 weeks without using my 911 is not ideal...

[Vereeken]

Not much you can do right now. You need the fuel pressures.

The 089 WUR is correct.

The 201 AAR is also correct. Although I must say that I prefer the 200, bigger hole faster closing....

The only thing you can check waiting for the gauges is the vac connections.
I am assuming you have a throttle body with 4 take off nipples for vac. 2 front 2 back?

With the 089 it is essential that they are correctly connected.

I think once you get the gauges for FP you will find FP above the graph.

When you measure FP it is important car sat for +10 hours and you note ambient temp.

[Vereeken]

Leave sensor plate and co screw alone for the moment.

You can always post a picture of sensor plate position on a cold engine with no fp.

[SkiVT]

I had similar symptoms develop about two years after wur rebuild. Turned out my wcp had slipped and was below spec. I also have an afr gauge so could see the engine running very rich at warm idle. Tony adjusted the wcp for me and all is good. Will be interesting to see what your pressure numbers are once the gauges arrive.

[boyt911sc]

Brent,

Sorry to hear about your troubles. How did you do the air leak test? If you had the CIS boot between throttle body and air flow meter installed during your leak test, you had not completely isolated the air box. This is a common mistake committed by many CIS troubleshooters.

Without knowing your control pressures, we will be doing a lot of guess work. Could you borrow a CIS gauge from the other Kiwi who got my name from you? The guy supposed to own a big Porsche shop in Christchurch. And I had rebuilt his FD that was picked up in California when he bought a car to ship back home.

Try to borrow one for your pressure test. Refrain from tinkering the mixture setting at this point. You will make a bad situation worse.

BTW, my wife and I visited New Zealand after the big earthquake in Christchurch. What year was the earthquake?

Keep us posted.

Tony

[brentrussell]

Hey Tony, so glad you responded

Do you recall getting me going 4 years ago? I had an incorrect WUR ex 964 Turbo? your wife took the correct rebuilt WUR 089 for my SC to Sydney with her the week we were discussing and I sent mine to Sydney for exchange
I've been all over your emails of that time to make sure I did it again correctly, accept the FP's...
Yes 100% removed the Rubber boot between Throttle body and meter. Put Glove over Throttle body and blocked rear hose ex AAR and plugged POV. Ran my little aqua pump and tested with water/detergent solution.
How's this look...


Ahhh, yeah that would probably by Glyn... he lent me the AAR to try, yeah, I'm sure he would lend them to me again... I just don't like borrowing tools like that.. I now have my kit on order so keen to use them when they arrive.

Now I have my wingman on board I will not tinker with mixtures

If I get impatient waiting for gauges I will ask our friend.

Earthquakes were 2011.

Brent

Originally Posted by boyt911sc

Brent,

Sorry to hear about your troubles. How did you do the air leak test? If you had the CIS boot between throttle body and air flow meter installed during your leak test, you had not completely isolated the air box. This is a common mistake committed by many CIS troubleshooters.

Without knowing your control pressures, we will be doing a lot of guess work. Could you borrow a CIS gauge from the other Kiwi who got my name from you? The guy supposed to own a big Porsche shop in Christchurch. And I had rebuilt his FD that was picked up in California when he bought a car to ship back home.

Try to borrow one for your pressure test. Refrain from tinkering the mixture setting at this point. You will make a bad situation worse.

BTW, my wife and I visited New Zealand after the big earthquake in Christchurch. What year was the earthquake?

Keep us posted.

Tony

[boyt911sc]

Originally Posted by brentrussell

Hey Tony, so glad you responded

Do you recall getting me going 4 years ago? I had an incorrect WUR ex 964 Turbo? your wife took the correct rebuilt WUR 089 for my SC to Sydney with her the week we were discussing and I sent mine to Sydney for exchange
I've been all over your emails of that time to make sure I did it again correctly, accept the FP's...
Yes 100% removed the Rubber boot between Throttle body and meter. Put Glove over Throttle body and blocked rear hose ex AAR and plugged POV. Ran my little aqua pump and tested with water/detergent solution.
How's this look...


Ahhh, yeah that would probably by Glyn... he lent me the AAR to try, yeah, I'm sure he would lend them to me again... I just don't like borrowing tools like that.. I now have my kit on order so keen to use them when they arrive.

Now I have my wingman on board I will not tinker with mixtures

If I get impatient waiting for gauges I will ask our friend.

Earthquakes were 2011.

Brent

Brent,

That is the right set-up for the air leak test plus plugging the two (2) vacuum hoses that connect to the CIS rubber boot. I remember his first name as Glyn and he contacted me before I mailed his FD to NZ to send it to California. Your set-up looks good except the POV. The POV should be opening toward the front of the car and not side ways. It is better than facing rearward. You will be fine.

When you get your CIS pressure gauge, do these pressure tests:

• Connect the CIS gauge accordingly and perform the test using the FP (engine off).
• The first data, WUR electrical plug should be disconnected.
• Connect the WUR plug back and take interval reading of the cold control pressures (1 min. or every 30 sec.)
• After several minutes, the CCP would stabilize and becomes WCP.
• There are two (2) values for WCP. Without vac and with vac applied (16” Hg).
• You need a hand held vac pump or run the engine to get the second value.

Post the above values and we will interpret your WUR’s data. Do not forget to record the ambient temp. when the test was done. If you have any question, let me know. Thanks.

Tony

[brentrussell]

Still waiting on my gauges... haven't left USA yet

Managed to also check the timing and that is correct.
In the last two days, at times the car has behaved normally, idling at 950rpm, no popping on deceleration.
This actually annoys me more , would rather it stay the same issue than an intermittent issue!

Can an Electrical issue cause the symptoms I've been having?

I also removed the vacuum from the Distributor and that had zero effect at idle, I assume no vacuum at idle.

Still planning to report Pressure tests when gauges do show up.

[Vereeken]

Hardly any vac at idle at the distributor.If connected correctly the vac for the dizzy is above the throttle plate at idle. It pulls vac when you open the throttle.

Did you check your throttle housing? Do you have the 4 nipples for Vac at the housing? 2 at the back 2 at the front?

[brentrussell]

Hey team,
So after 6 weeks the USA supplier hasn't sent gauges and can't advise when they will be available to send... so cancelled that order
So borrowed them off my Friend... finally have some results for solution.

1981
ROW engine
Bosch 0438 140 089
Ambient temp: 11 degrees Celsius
WUR resistance:31.5 ohms
System pressure: 4.7 bar
CCP: 0.8 Bar, 80kpa, 12PSI. Temp 10.5 Celsius
WCP: Same as above, did not move... waited for 10mins.

So my CCP seems low? and my WCP not raising when the WUR is connected and powered up.
I checked power to my WUR plug with a test light, has power when key on and FP running with switch as per above tests.

What's the plan from here? I'm thinking it involves opening up the WUR or if I can borrow from my friend to see if that is the issue...
I've triple checked my hose connections and plumbing, I did use the Hard line going between FD and WUR instead of directly into the FD... but I don't think that would cause an issue? Let me know if I should bypass this line.

Looking forward to your reply.

Brent

[SkiVT]

Did you use a vacuum pump when testing the ccp? The spec chart is with vacuum, which typically is .6 bar higher than w/o. Your ccp would be like 1.4 w/vac so might be ok. Based on the description of the way your engine is running, it seems impossible your wcp is the same as ccp. I would think the afr would be so rich the car would stall out every time. Maybe include a pic of the gauge setup and wait for others to chime in. Test the power level to wur and post the volts?

[T77911S]

connect test light to 12v and check the other pin to verify the ground is good,.

[Vereeken]

Numbers are OK if you did not connect a vac pump to WUR.
The vac nipple is on the left hand side of the 089. The nipple on top is only atmo.

Since you have 32 ohms at the plug it means your bimetal is OK.

Very strange that WCP does not come up. If you take a multimeter you should see 12 at the plug. The plug is 12v and ground; the ground does not come from the WUR.

If you get 12v this means that the pin fell off inside the WUR. But this is very rare.

michel

[brentrussell]

Hi Team,

Dropped past car to check further as per requests.

Checked Voltage at WUR plug is 0.1v, definitely not 12v. 100% have 11.5v at plug end when FP is running.

Ran tests again with Vacuum of 15Hg, Ambient 12.5 Deg Celsius
CCP 18.5 PSI/ 1.3 Bar
WCP Same as above, ran for 9mins no change.

When I turn fuel pump off gauge rises to 2.0Bar, don't think this means anything?

Attached a couple of images showing my system hook up and the gauge with Vacuum applied.

[Vereeken]

CCP is perfect. You can remove that from testing. The jump to 2 bar when you shut off does not mean anything. You can disregard that.

[Vereeken]

I do not understand what you are trying to say:

"Checked Voltage at WUR plug is 0.1v, definitely not 12v. 100% have 11.5v at plug end when FP is running."

If you disconnect the elec plug to the WUR what voltage do you see with a multimeter at the plug part of the wiring loom with the FP ON? This should be 10+Volt.

[brentrussell]

Hi Michel,

Yes I get 10+ volts on the plug end of the Wiring Loom when the FP is running.

On the below quote I was checking voltage on the actual WUR plug but that would make sense that it is 0.0 as there is no power too it..

Does that make sense?

Brent

Originally Posted by Vereeken

I do not understand what you are trying to say:

"Checked Voltage at WUR plug is 0.1v, definitely not 12v. 100% have 11.5v at plug end when FP is running."

If you disconnect the elec plug to the WUR what voltage do you see with a multimeter at the plug part of the wiring loom with the FP ON? This should be 10+Volt.

[Vereeken]

I think you set-up is OK but I do not see the connection in the back. The simplest way is to take off from the line at the fuel distributor to the wur.
The way you have it now I believe you could have hooked up to the return line and that would give you a false reading.

[Vereeken]

Originally Posted by brentrussell

Hi Michel,

Yes I get 10+ volts on the plug end of the Wiring Loom when the FP is running.

On the below quote I was checking voltage on the actual WUR plug but that would make sense that it is 0.0 as there is no power too it..

Does that make sense?

Brent

OK ! Yes at the wur itself you have 0 volt.

[Vereeken]

So you have good CCP, 12 Volt, good resistance and it holds vacuum. I say your WUR is almost perfect.

But you have no WCP.

1. you have the fuel line to test wired incorrectly.
2. the pin inside the WUR fell out. Not a big deal but it means opening up the WUR.

If you hook up the test kit as I described we will no soon enough.

Do that first.