Blueelectron,

First thing is to check the lambda system as already recommended.

That WUR looks pristine.

I think the lambda system is working. The shop told me that they checked the O2 sensor and it was not working. They wanted $350 to replace it and I said thanks but no thanks. I replaced it myself last week for a fraction of the cost. After that my idle would fluctuate and hunt up and down. Disconnecting the O2 sensor would stop the hunting. I think because of the very low cold control pressure, the shop had adjusted the mixture too rich and now the O2 system was trying to correct the rich condition. The pulsing idle went away when I turned the mixture down by an 1/8 turn.

Boxster GT can probably help you with the line you broke.

Since the hot pressures are within spec, I am dubious that you have any obstructions in the return line. Those would raise hot pressure, and yours is within range. Plus it runs fine when warmed up and driven.

Since you report hard cold starting, and have a quite low cold control pressure, why not adjust that? A C clamp might allow you to give it a small nudge. Up-Fixin long ago had an article on how to make the cold pressure adjustable externally. I prefer a different method: drill and tap the iron slug which holds the post. Screw a nut on a bolt (an Allen/inhex is the most convenient)to fit the thread you made. Place a washer over the hole and screw the bolt in until it bottoms. Use an Allen wrench to hold the bolt in place, and a wrench on the nut to pull the slug up. If you do this with the WUR disconnected, but fuel pump connected and your gauge in place, you can see when to stop. If you overshoot, loosen the nut just a bit, and knock the plug down. Because the slug sits below the surface of the housing, you can use the washer trick to raise it. This is a lot easier than trying to drill a hole half into the iron, and half into the aluminum to prevent rotation of the slug (which you can see you don't want, as it will dislodge the stuff inside). You can't do this adjustment hundreds of times, or the friction between the slug and the aluminum housing may eventually get too low to hold the slug. But it isn't a problem if it is only done the few times one needs.

An alternative for lowering the CCP still more is to shim the end of the post internally - less convenient, but same result. But you need to go the other way.

Or you can guess at how much to raise the post with the C clamp or otherwise, and then watch the pressures after everything is back in the car as you try tapping the slug down.

Did you ask the shop if they shimmed the system pressure regulator?

But the WUR looks like a pretty likely suspect for your cold start issues - mixture too rich. The ratio adjustment screw can make mixtures too rich or too lean over the entire RPM/heat range, but don't affect the control pressures.

Your residual pressures look fine, so that's not your hot start problem. So that one is a bit of a mystery, though the fact that the WUR system makes the cold start too rich may make warm starts (the WUR hasn't cooled all the way back down to ambient)iffy.

Others (Tony, for example)who have seen the insides of lots and lots of WURs may have a different view, but the upper compartment is basically sealed against the outside world, so it should look pristine.

And maybe Tony will chime in on what your now measured pressures show.

WUR calibration.......
 

The cold control fuel pressure is already out of spec at this point. Cleaning the screen is good but will only bring the CCP down. You need to get the CCP up. This too RICH or too low CCP to begin with.

Since you have the WUR out, could you post a picture of the top? What is the resistance (Ohms) value of the heater? Keep us posted. Thanks.

Tony

I have attached a photo of the WUR. The resistance across the terminals is 26.2 ohm. I suspect the shop tried to adjust the cold pressure when the lines were clogged. I can see indentations on the adjustment pin.

Cold start valve leaking?
 

I used 1/8" ID fuel hose to temporarily fix the broken WUR return line and adjusted the cold control pressures. Even now the car takes several seconds to start and is very rich right after starting. The exhaust is extremely smoky and the car doesn't idle without throttle input.

I have bought a wide band O2 sensor to check for lear or rich and waiting for it to arrive.

Is it possible that cold start valve is leaking all the time and flooding. I understand that the Cold Start Valve is hard to reach but can it be tested.

Loose electrical connection
 

I was trying to find where the cold start valve is and found this loose electrical connection. Any idea where this is from. http://forums.pelicanparts.com/uploa...1572196202.jpg

Backside of the engine. There are 2. One is supposed to be blue, the other green. Problem is when the blue one gets old it turns green. That being said, yours looks pretty green.

One is the air plate safety switch (blue one IIRC). I think the other is the cold start injector.

Anyway, use your left arm and feel around on the backside behind the pope’s hat area and you should find the other end of the connector.

Here’s a pic:

http://forums.pelicanparts.com/uploa...1426352215.jpg

Tim
Is this the air flow switch connection.
http://forums.pelicanparts.com/uploa...1572200008.jpg

I don’t think so. You have the pope’s hat off. Feel around directly behind the opening on the right in your picture. That is the plunger side that is connected to the fuel distributor.

I took another look. The cold start valve is blue and has a blue connection to it. I tried to take a picture with a mirror but wasn’t very successful. The air flow switch is the one that is not connected. Could this cause the rich start condition ?

It shouldn’t. The airflow switch is designed to cut off the fuel pump in the event of an accident where the engine is no longer running. If no air is moving through the air plate, then a ground shows up on pin 85 of the FP relay and the FP turns off.

Oh, that makes sense why the car still runs even with that disconnected. I will proceed with the daunting task of removing the Cold Start Valve/Injector. I can't think of any other reason why the car is flooded during a cold start. The fuel injectors shouldn't be leaking because they are new.

You said the injectors are new...

Have you done the “baby bottle test” where you pull the injectors and stick them in bottles to make sure they are at the correct opening pressure? Meaning no dripping, relatively even flow from all injectors, etc?

If you bought them from one of the CIS shops (or Tony) they likely did it for you.

I have not tested the injectors. I assumed they would be fine because they were new. IIRC I bought them from our sponsors. The bottle test seems to be less involved than trying to remove the CSV.

Blue,

The black plastic box shown in the picture is not the AFS (air flow sensor) switch. That is the lambda enrichment switch. The throttle body is at left side and AFS or metering unit is at the right side in the picture. Right behind the AFS or metering plate is the switch. Refer to Tim’s picture.

Tony

Fuel injectors leak?
 

I pulled all six injectors out and while doing this I disconnected the fuel line at the injectors of cylinders 5 and 6. I was expecting some fuel leak but nothing came out.

When I ran the fuel pump by jumping the relay none of the injectors dripped. The spray pattern was also good when I lifted the plate through the air-box. I let the pump run for some more time and dripping was not obvious.

However, no fuel coming from undoing the fuel line seems suspicious. Is it possible that the fuel lines are fully sealed at the fuel-distribution and that is why they didn't drip. Similar to using your finger to close the top of a straw.

Fuel delivery........
 

That is NORMAL. A good and properly calibrated FD will not have fuel delivery as long as the plunger is down at rest and the FP running.

Tony

Fingers crossed - started finally
 

My AEM AFR gauge came in today, so I thought I will give it a shot. Had bought a PLX one but the phone app just keep crashing. I re-connected the air-flow sensor switch, installed the AEM wide-band O2 sensor and gave it a shot. As a surprise the car started right away and wasn't smelling as rich as before, still rich though. I could slowly see the O2 climb to around 12 as the car warmed up. I waited for it to warm up and adjusted the mixture to about 14.5 O2. It would fluctuate between 14.5-14.7 at idle, over the next 15 mins even with several engine revs. I was surprised to learn how little (1/16th turn or less) you have to turn the mixture screw to make it rich or lean.

Here is my theory of what was wrong. I don't know if the Cold Start Valve is somehow logically connected to the air-flow sensor switch. With the AFS disconnected, the fuel pump would run without starting the car and along with this so would the Cold start valve (theorizing here). My car has numeric ignition lock and so it takes time between turning the ingition on and actually starting the car. With the weather being cold here most of the time, the CSV sprays because the thermo switch is closed, and floods the engine without cranking. Me blindly playing with the mixture wasn't helping either.

The high temperature is going to be -7C tomorrow so will have to wait for a couple of days for another cold start and hopefully a drive. If it starts first attempt on Wednesday I am buying this theory because the only that changed between yesterday and today is the AFS. Just a theory here, feel free to poo poo all over it.

There shouldn’t be any correlation between the AFS and the CSV.

I am spitballing here so bear with me. Is it possible the wires for the CSV and the AFS are switched?
I’m trying to think if that is even possible. And if so, what would be the effect? I’m just wondering since you found one wire disconnected... did someone play around with the wiring?

The CSV is controlled by the thermotime switch located on the left cam housing cover. The logic is basically, if the engine is cold, it fires. If not, it doesn’t.

I’d have to look at the wiring diagrams again but off hand I don’t think there should be any correlation between the two.

By the way... the idea of disconnecting the AFS seems to be a “trick” that some ill-informed mechanics seem to do on these cars. They somehow think it’s a shortcut to fixing CIS problems by having the FP run as soon as the key is turned and before cranking. When I bought my car I took it to a shop because of all the CIS issues I was having. That mechanic disconnected the AFS and told me he had done something else to fix it. That was the first and last time I used that shop. Been wrenching on my car ever since.

CIS Troubleshooting.........
 

Tim,

Some CIS mechanics or troubleshooters found out that disconnecting the AFS plug helps start a stubborn engine. And became a common procedure without really understanding the real culprit/s. What a disconnected AFS plug does is make the FP run before turning the ignition to START position.

Inspect the electrical plugs for the CSV & AFS by checking the wire color for the AFS. The AFS plug has two (2) brown wires (one with a red stripe). Confirming the right plug at the AFS, will also do the same for the CSV.

Tony

Providing starter is being cranked.

From the wiring diagram looks like the CSV is only energized when the starter is engaged.
http://forums.pelicanparts.com/porsche-911-technical-forum/205716-911sc-wiring-diagrams.html

I am not sure what fixed the cold start. I am not even sure if it is fixed because I started it only one. Maybe adjusting the cold control pressure along with the mixture setting did it. Will try to start again in a couple of days, when I can open the garage comfortably.

Tony, I will also check the wires going to the air-flow switch. But my guess it is hooked correctly and cross connected with the cold start valve.

Test and confirm........
 

Blue,

Test and confirm. You are doing too many guess-work troubleshooting. Stop guessing and inspect the CSV, AFS, and TTS. For starter, test terminal #85 (FP relay socket) for ground. Use a test light or continuity tester to confirm that the switch is working when you lift up the air sensor plate.

The electrical plugs for the CSV and AFS could be installed incorrectly (interchanged). Keep us posted. Thanks.

Tony

Yep. Just a point of clarity. Nothing more.

FWIW I know that on the mid 70's D-Jet based Jag XJ's the cold start injectors would ramp down the spray duration based on the valve's internal heat build up - just from cranking a stone cold engine. First start attempt, say seven seconds. Second attempt, five seconds. Etc

I don't think ours do that. They just spray when the starter is engaged until the cut off temp is reached from a warm engine.

Recently my friend called me to talk about a problem with he was having with his '94 Mustang. He rebuilt the engine and it was dumping tons of fuel into the cylinders. He was racking his brain and needed to talk it through with someone. We checked the fuel pressure regulator. We tried to see if something was causing the computer to think it was lean and over-compensating on fuel delivery. After 2 days of fighting, he finally tried something remarkably simple. Turned out he had bought new fuel injectors for the rebuilt motor and every one of them was bad. He put the originals back in and it fired right up and ran like a champ.

The lesson here is sometimes it's best to not overthink a problem. It's easy to overlook the obvious. Verify the basics. You verified the injectors. Good. Now double check that the AFS and CSV aren't incorrectly wired.

End of story........
 

Blue,

What is the conclusion at the end. Did you finally able to find the culprit/s and solved the problem/s? Keep us posted. Thanks.

Tony

Tony
From what I can tell the car running too rich was the problem. Adjusting the CO seems to have fixed the problem. Started without any problems from dead cold 3 to 5 times after the adjustment. But do not know have a long term test. Essentially after all this work I had to store the car for winter. Hoping it will start right back up.

My cold start issue was relatively easy. Check valve in the neck of the fuel pump failed.

Good luck.

Mine was pretty easy too. I mistakenly disconnected my cold start valve by accident when I installed my engine doh! (happened when I pulled my air hose, on the air boot, out of a pinch with the front of the engine bay (another doh!)). After a few tries to install the connector in situ I finally got it. Thank goodness for my necked inspection camera on wifi.