Base setting of mixture for CIS 1980SC?

[scottsc]

Originally Posted by boyt911sc

Scott,

Leaking fuel injector/s would have a dramatic effect for starting and depends how much fuel was dumped into the cylinder. Once you are able to start the engine, the excess fuel would eventually be consumed by the subsequent combustion in the cylinders. How easy could you get the engine to start (cold)? Have you checked the spray patterns of the six (6) injectors?

You have to determined if the smoke generated was produced due to excess fuel (mixture) or engine oil being burned.? Drive the car for 20 - 30 mins. a couple of times and observed if the smoke has changed.

I had experienced a severe smoking from a newly rebuilt engine that was discouraging to see. My garage was covered with white smoke and was worried my neighbor would call the fire department. I was doing an engine start-up with the engine installed in my engine test stand and took me a lot of start-ups (running) to eliminate the smoke.

BTW, if you were closed to the optimum fuel mixture setting, it would need very small amount of adjustment. This is a very sensitive adjustment and requires very small movement of the screw. I always discouraged or warned people not tinker the fuel mixture setting. That would the last thing I do and I'm pretty much happy with my work.

Keep us posted.

Tony

Tony,

As you would have now read the smoke has cleared completely and i am relieved. I am not surprised now as I couldn't believe the difference in fuel delivery out of the injectors before and after FD repair. There was about 1 litre in less than a minute coming from the six injectors and it didn't matter where the metering rod was, as opposed to 100mls or so when fixed. The poor engine and exhaust system had copped so much fuel it took time to burn off.
I have checked the spray pattern before i refitted the injectors and one is not so good the other 5 seem to be spraying a cone shaped pattern though. Also as I said there was a drip from injectors just before they fired. But it is running OK. It probably could be better, which I will work on. At-least it's running now so I can tinker, but still drive her! I will have it tested on a CO meter once I am happy everything else is working fine. For the moment is is most likely running a bit rich.

Regards
Scott

[boyt911sc]

Originally Posted by scottsc

Tony,

As you would have now read the smoke has cleared completely and i am relieved. I am not surprised now as I couldn't believe the difference in fuel delivery out of the injectors before and after FD repair. There was about 1 litre in less than a minute coming from the six injectors and it didn't matter where the metering rod was, as opposed to 100mls or so when fixed. The poor engine and exhaust system had copped so much fuel it took time to burn off.
I have checked the spray pattern before i refitted the injectors and one is not so good the other 5 seem to be spraying a cone shaped pattern though. Also as I said there was a drip from injectors just before they fired. But it is running OK. It probably could be better, which I will work on. At-least it's running now so I can tinker, but still drive her! I will have it tested on a CO meter once I am happy everything else is working fine. For the moment is is most likely running a bit rich.

Regards
Scott

Scott,

Try to source a single fuel injector locally (Australia). Replace the leaking injector. If you are not having any starting problem, then the leaking injector is dripping insignificant amount of fuel in the manifold. Re-check that the engine has no air leak (unmetered air) and have the exhaust checked using a gas analyzer with the engine totally warmed up.

I missed meeting you but will be there next summer (your winter). Keep us posted.

Tony

[scottsc]

Hi all,

I have my car running OK now. All smoke has cleared to zero as it was before the FD went faulty. The reco FD has a slight fuel weep between the two halves which has been a disappointment however I have been offered a refund and info on how to reseal it myself, not sure about that though. (I have installed a fire extinguisher).

I have found cold starts are now taking too long compared to before. The WUR is working correctly 28psi cold 45psi warm, so I may have a cold start injector problem. I will have to check this if someone has the procedure? I know one of the injectors does not have the desired conical spray pattern even after cleaning so I will be changing that.

I have been enjoying the lovely Aussie spring weather in the 911!

Scott

[scottsc]

Originally Posted by boyt911sc

Scott,

Try to source a single fuel injector locally (Australia). Replace the leaking injector. If you are not having any starting problem, then the leaking injector is dripping insignificant amount of fuel in the manifold. Re-check that the engine has no air leak (unmetered air) and have the exhaust checked using a gas analyzer with the engine totally warmed up.

I missed meeting you but will be there next summer (your winter). Keep us posted.

Tony

OK Tony, we will get together then for a drive. I'm sure I will have plenty of projects left on my car for you to suggest!

Scott

[boyt911sc]

Originally Posted by scottsc

Hi all,

I have my car running OK now. All smoke has cleared to zero as it was before the FD went faulty. The reco FD has a slight fuel weep between the two halves which has been a disappointment however I have been offered a refund and info on how to reseal it myself, not sure about that though. (I have installed a fire extinguisher).

I have found cold starts are now taking too long compared to before. The WUR is working correctly 28psi cold 45psi warm, so I may have a cold start injector problem. I will have to check this if someone has the procedure? I know one of the injectors does not have the desired conical spray pattern even after cleaning so I will be changing that.

I have been enjoying the lovely Aussie spring weather in the 911!

Scott

Scott,

I realize that you can't wait to test drive the car and enjoy the coming springtime. But if your FD has a sign of fuel leak, you are taking too much risk driving it!!!! This is like playing a game of Russian roulette (familiar with this game)? I would consider fixing it first to stop the leak before it is too late. Keep us posted.

Tony

[scottsc]

Originally Posted by boyt911sc

Scott,

I realize that you can't wait to test drive the car and enjoy the coming springtime. But if your FD has a sign of fuel leak, you are taking too much risk driving it!!!! This is like playing a game of Russian roulette (familiar with this game)? I would consider fixing it first to stop the leak before it is too late. Keep us posted.

Tony

Yes I agree with you Tony.

I was given a refund off rebuilt systems for the leaking FD. They are sending me O-rings and instructions on how to reseal it myself. I was a bit reluctant but then I thought I might give it a go and if it doesn't work out I can send it back to them.
They said they may not have sanded the two halves enough for a good seal.

I an having some trouble with cold starts and think the cold start injector may not be working, as that is the symptom. WUR is working good as I have checked pressures and AAR is opening and closing.

Scott

[ago85carrera]

Originally Posted by timmy2

I am going to type this out for you as I can't get a good picture from my Service Manual. Not word for word and you don't need to bleed your lines.....
From:
Basic Adjustment of Mixture Control Screw after Replacement of Operating Lever

1. Pull injectors with lines attached and place in clear jars to see fuel flow.

2. turn mixture screw 1-2 full turns counter-clockwise

3.Turn on ignition and pull the safety switch or jumper the fuel pump relay socket to force pump to run.

4. Turn the mixture screw clockwise until the injectors just begin to eject fuel, then turn screw back 1/2 turn counter clockwise.

5. Run engine to full operating temperature and adjust idle speed and CO level to their specified values.

That is all they give.

Hope it helps.

Hi all,

I'm fresh off this process after a complete CIS rebuild and have attached pics of Larry Fletcher's tech post on his CIS Flowtech website as well as the Porsche manual page Timmy2 references above. The Porsche manual method defines the target point pretty vaguely so I combined Larry's and Porsche's methods to narrow my search for combustion. Step 5 in the Porsche manual says to find the point at which the injectors start to eject fuel. I wasn't sure if that meant when the injectors form a drip or form a weak spray and that difference was at least a couple turns of the mixture screw. So, I focused my search between the point that Larry's protocol defines and the mixture screw point that creates a weak spray (as possibly meant by Porsche). It's a trial and error process no matter how you go about it to find a combustible A/F ratio and tiny turns of the screw make a big difference so the ability to narrow the search area helps immensely.

As unsolicited advice, buy a remote starter from any auto parts store so you can crank the engine from behind the car (make sure it's not in reverse ). You'll need to manipulate the airflow meter by hand the moment you get some stumbling combustion until you find the mix that creates a decent idle with the airflow plate in its resting position. That process took me dozens of failed starts and small turns of the screw before I found combustion leading to idle and that process would have been a giant hassle relying on a partner to turn the key.

[Schulisco]

Originally Posted by ago85carrera

Hi all,

I'm fresh off this process after a complete CIS rebuild and have attached pics of Larry Fletcher's tech post on his CIS Flowtech website as well as the Porsche manual page Timmy2 references above. The Porsche manual method defines the target point pretty vaguely so I combined Larry's and Porsche's methods to narrow my search for combustion. Step 5 in the Porsche manual says to find the point at which the injectors start to eject fuel. I wasn't sure if that meant when the injectors form a drip or form a weak spray and that difference was at least a couple turns of the mixture screw. So, I focused my search between the point that Larry's protocol defines and the mixture screw point that creates a weak spray (as possibly meant by Porsche). It's a trial and error process no matter how you go about it to find a combustible A/F ratio and tiny turns of the screw make a big difference so the ability to narrow the search area helps immensely.

As unsolicited advice, buy a remote starter from any auto parts store so you can crank the engine from behind the car (make sure it's not in reverse ). You'll need to manipulate the airflow meter by hand the moment you get some stumbling combustion until you find the mix that creates a decent idle with the airflow plate in its resting position. That process took me dozens of failed starts and small turns of the screw before I found combustion leading to idle and that process would have been a giant hassle relying on a partner to turn the key.

Oh, my goodness, way too complicate!

You can exactly follow as the Porsche manual says. On #5 they write "when the injectors barely eject": The injectors give a squealing noise when they inject fuel. This noise is loud enough to be also heared when they are mounted in the intake runners. The manual also does not advises to take out the mounted injection valves from the intake runners. So you can only hear them when they spray and not see them. So you must listen the injectors only when turning the mixture screw (with bridged and running fuel pump of course and sitting engine). You'll hear the sqealing noise of them for sure.
Then turn the mixture screw half a turn back quickly after the injectors have been started spraying, exactly as the manual says, to not to flood the engine. There's no starting of the engine necessary while this procedure!!!

That setting is precise enough to start the engine rightaway without stepping on the throttle. Of course only then, when all the rest CIS components are in shape and working in spec.
If the engine still won't start with this setting, you still have another issues to be sorted out before!

Thomas