1981 3.0 sc ROW CIS Low idle & dies off throttle

[boyt911sc]

Originally Posted by Vereeken

I think your WUR is fine. If the bimetal gets hot when connected to the plug all is well.
So why does your WCP not rise?

Is it the picture or does your wur inlet screen full of junk?

If the plug to bimetal connection would be broken you would not be reading 32 Ohms at teh plug.

Michel,

The yellowish disc you see in the inlet is the sintered filter media. A common replacement for the stainless mesh. Best way to test the WUR if it is clogged or restricted is to run fuel through with the PIN removed and monitor the flow pressure. Over 10 psi. (without pin) means flow restriction is occurring.

Tony

[Vereeken]

So were are we with this thing?

We established good CCP, good ohm, 12v, good AAR, good FP, a WUR inlet that is not clogged.

I have no idea where to go next. I never had an issue reaching WCP, maybe not the correct WCP but always going higher....usually it is CCP that is the issue.

[boyt911sc]

Michel,

We did FaceTime several times this week and confirmed the bimetallic spring was not deflecting at all. Brent tested a few bimetallic springs he had and found no suitable replacement.

Tony

[Vereeken]

Thanks Tony makes sense. So it is a simple case of the bimetalic gone bad?

Very strange I have old bimetals lying around and they continue to deflect.

[brentrussell]

Hi Michel,

It does seems that way…. I managed to borrow 3 bi-metal springs from a Mercedes repairer, plus one from a 072.
Purchased a dial gauge and tested numerous times to measure deflection.
Mine was the lowest of the 5. The best has a total deflection of around 0.7mm at 5mins.

I’m running short on time for a 5 day trip so have purchased another WUR from Tony and hopefully a 1mm deflecting bi-metal spring so I can get mine working later.
Tony is amazing! So knowledgeable and helpful with his time for all of us. In fact this Foroum is all about this… I would not have been able to get to this point without it…

Will report more when fitting replacement WUR and also swapping out my spring to resolve issue of WCP.

Brent

Originally Posted by Vereeken

Thanks Tony makes sense. So it is a simple case of the bimetalic gone bad?

Very strange I have old bimetals lying around and they continue to deflect.

[brentrussell]

Well had a break through on Sunday morning! Found the issue why my WCP was not rising.

Throughout the process I have been testing the power to WUR plug with Test light.., light works so all good.
When I have been bench testing my WUR Heater, bi-metal strip etc I've been using a spare battery and a Plug I wired up to it... test results other than pressures all seem to work.

It just wasn't making sense to me why it wasn't working on car when it was on the bench.. so I plugged the Test Battery and plug onto the WUR with the gauges connected and it straight away raised the WCP... YES!
Turns out I only have 10.3v at the WUR plug... and 13+ volts from battery on charge... So I obviously have a connection/break issue along there somewhere. Will investigate this more but may just tap into the rear fuse panel with a relay or another solution to get me running quickly and leave that for some spare time.
Again Tony has helped hugely with emails and Telephone discussions to get me testing and figuring out what is going on... I certainly know my WUR inside out!

Thanks Team.

[Vereeken]

This makes more sense to me.

Never use a test light, always a mult-imeter.

Look at the wiring diagram. You will notice that AAR, WUR, TTV share a common wiring with the FP relay upfront; and NO fuse in between.

It means that when you get a short circuit you get a burnt wiring from FP relay to the back.

Disaster electrics from Porsche.

[brentrussell]

Yes.
What would be the effect on the AAR & TTV at lower volts.. are they as sensitive to the voltage?
I need to work out how I repair the voltage to just the WUR or the whole system of these items.

Brent

Originally Posted by Vereeken

This makes more sense to me.

Never use a test light, always a mult-imeter.

Look at the wiring diagram. You will notice that AAR, WUR, TTV share a common wiring with the FP relay upfront; and NO fuse in between.

It means that when you get a short circuit you get a burnt wiring from FP relay to the back.

Disaster electrics from Porsche.

[timmy2]

Possibly the fuel pump is drawing down the voltage.
Look at the schematic and you can see the WUR, AAR and Vac switch are all coming from terminal 30 of the fuel pump, sharing the voltage to the fuel pump.
Connection T1d (single flat) at the front fuse panel could be poor, connection at 14 pin connector could be corroded as well. Also confirm the supply and ground on the fuel pump are good. Added resistance will drop the voltage.
Cleaning the fuse terminals for the FP relay would be a good thing as well.

[brentrussell]

Seems the piece of the engine loom with these 3 items has an issue effecting the current, have made a new temporary loom with Direct power through a relay when FP is running, this has now solved the operation of the WUR heater and all pressures are behaving as they should!

However, this has not solved the problem... again car started fine but as it warmed up began running rough and not idling... I'm now really getting frustrated with this car!

So, another email to Tony to get me back on track with some direction... he suggested testing AAV and AAR after I have smoke tested the system. Previously I had been using the soapy bubbles low pressure testing.... so I rigged up a Vape with tube into the side of airbox and up through sensor plate with the Air cleaner wrapped in a plastic bag... few puffs down the tube and I had smoke flowing out the edge of CIS Intake boot just above the clamp, closer inspection and it was torn.!


This would definitely give me some unmetered air!....


Will try and source a new Boot locally tomorrow, if not order from our Hosts...

Fingers crossed there is not another issue!

[Vereeken]

Well look no further

[jerrykrug]

brentrussell, can you share your smoke system details with us? what did you use to introduce /pressurize the air intake system

thanks Jerry

[jerrykrug]

brentrussell, can you share your smoke system details with us? what did you use to introduce /pressurize the air intake system

thanks Jerry

[brentrussell]

Hi Jerry,

I followed a You Tube video with a guy that did it with a cigar.

Firstly I wrapped the aircleaner in a Plastic bag and sealed that.


Next I poked a tube through inlet hole on right hand side of Airbox and sealed and poked tube gently up through sensor plate.

With the air cleaner re attached with rubber straps I then used a Vaping smoke to gently blow smoke through hose... smoke came out of CIS Boot split.

While waiting for a replacement Boot I bypassed this part of the system to check other Vacuum items around Airbox and hoses, by sealing off the two back hoses that go to boot, Throttle Plate and Sensor plate plus Pop Off valve and then introducing smoke to the Brake Booster Vacuum input I checked the rest of the system.... NO further smoke leaks.



Hope this helps others, I will definitely be using the Smoke/Vape test in future to make sure I find leaks.

Brent

Originally Posted by jerrykrug

brentrussell, can you share your smoke system details with us? what did you use to introduce /pressurize the air intake system

thanks Jerry