[CrewChief]

OOPS Check the frequency valve itself. It's simply a solenoid. Should measure 2 to 3 ohms.

Also, was it running previously? Or is this a restoration of a long idle car? If long idle perhaps a sharp rap or 2 to dislodge a mechanically frozen valve?

Gotta run. See if MY old CIS is running correctly!

No wait a minute.

"This checked out fine. We had 12v to the FV from the lambda relay side. When we tested the computer side, we read a constant +.5v. It could have been switching fast enough that the multimeter wasnt keeping up. "

This would indicate the FV is constantly ON. The .5V is reasonable for a solid state swtiching device (transistor). If the FV was switched OFF then there would be 12V on both sides as there would be no current flow. What does this mean? I really don't know. The resting state of the computer could be ON for all I know.

When I return this afternoon I will review the trouble shooting guide and share it also.

Look for the power and squarewave output on the computer test lead.

[Charlie Stylianos]

Check the frequency valve itself. It's simply a solenoid. Should measure 2 to 3 ohms

Measured 3.1 ohms

Also, was it running previously? Or is this a restoration of a long idle car? If long idle perhaps a sharp rap or 2 to dislodge a mechanically frozen valve?

Think this is a new car to Ken and never worked correctly while he owned it.

If long idle perhaps a sharp rap or 2 to dislodge a mechanically frozen valve?

Good thought

Look for the power and squarewave output on the computer test lead

How do we check for square wave output? Connect dwell to computer FV pin?

[Ken Robinson]

Quote:
Also, was it running previously? Or is this a restoration of a long idle car? If long idle perhaps a sharp rap or 2 to dislodge a mechanically frozen valve?


Think this is a new car to Ken and never worked correctly while he owned it.

Quote:
If long idle perhaps a sharp rap or 2 to dislodge a mechanically frozen valve?


Good thought

Although I bought the car last July, it was my understanding that the car didn't sit idle....however, two of the tires had some dry rot - first $400 out the door!

[CrewChief]

Checking the 'Squarewave'.

Yes. The drive if you will for the frequency valve is about a 70Hz sqaurewave in that the computer switches the frequency valve on and off at about that frequency. It the duration of the on portion that we want to read. Your previous post indicated to me that possibly the valve is actually in a constant on state (open) as you are measuring low (ground) voltage on one side of the valve. When the valve is off the voltage at both valve pins should be supply (12V).

The test lead is the pin in the round test connector provided that runs to the computer as identified previously. (The other 2 pins in the 3 pin connector simply provided power to the Porsche testing tool - I suppose). This test directly from the computer. I have never determined if the internal wiring is such that you are also testing the actual switching to the valve.

You can also (I have) test directly at the FV. Should get the same results as at the test connector.

I suggest, if you do not already have an dwell meter, and they are not entirely common anymore; then skip that tool and buy one of the many cheap mulitmeters that has a duty cycle function. Same difference except the new multimeter should be more versatile and higher impedance which is always a good thing.

Since you have checked power and grounds and the valve then all that is left is the computer but this should confirm.

Although, I must say that over the last 2 years screwing around with CIS I have come to the conclusion that the basic system evaluation is never done until you have put a fuel pressure guage on the distributor and at least test system pressure and control pressure. You can borrow mine if you like.

[CrewChief]

Ken:

Is it fixed?

[William Miller]

Ken reported to me yesterday that it was.
Before telling you the cause, the owner of a local P shop told ken to "stop torturing yourself trying to fix it............. (I am paraphrasing this because it's third hand-- Ken can confirm.)......... scrap the computer and retrofit it back to a K-basic system." ....... "By the way that will run 2-3 grand"

John, you are more knowledgable than I. How would that be done?
I ask because some brilliant P-car wrench did that to may car before I owned it. I had a K-lambda Fuel distributer on my euro k-basic car with a bolt plugging the hole where the fuel line from the frequency valve should go. Is this standard practice or was the PO's mechanic a real winner?

Back to Ken's car. I did in fact skim over most of the the back and fourth you had with Charlie. I didn't get that involved. Charlie and Ken seemed at their whit's end with this. It truely seemed like a wiring problem because no juice was getting to the frequency valve.

In pictures I had seen the harness connector for the K-lambda system (Near the left shock tower.) and saw the real thing in Charlie's car a few weeks ago.

This turned out to be the culpret. Ken said he cleaned up the connections the other day and now the frequency valve is buzzing away. He is running very rich and he is coming by tonight to see if I can lean it out.
(My guess is that with the frequency valve not working / I think closed the mixture adjustment was done and now with the valve working the pressure in the bottom half is lower and allowing more fuel to flow.

Anyway, I have done the mixture adjustment by ear on my car, and now that I have the A/F meter I use that. We don't have a gas meter. I'm not attempting to get him to pass emissions test but close enough to drive for a while. It looks like I can be aided by 2 things:
1. Unhook the O2 sensor from the computer and read the voltage and try and tune to try and acheive 450 mv from O2 sensor wire.
2. Leave the O2 sensor attached and tune till I acheve 55% duty cycle at the test connections.

I'll print and re-read the stuff above, but can you confirm this.
This is all of course while the engine is at temp.

BTW does anyone have an easy way to remove the tamper proof screw from the top of the mixture unit if it happens to still be there?

[CrewChief]

Ken came by the house. He fortuitously had received an email from someone pinpointing the location of the connector. Cause even though I was zero'd in on that; not being a 911 guy I had no idea where to locate the wiring. Anyway, yes, once the connector was cleaned the car would NOT start and run unless we disconnected the 'chatter valve'. Which was an excellent indication that we had fixed it. Left it disconnected and Ken went off. I just was wondering how it had gone from there and some confirmation of a complete fix.

My experience with the mixture adjustment is that if you disconnect the O2 sensor and just adjust the old fashioned way (by ear/rpm) you will be very very close. Otherwise known as close enough. Tuning by looking at the voltage output of the sensor would confirm and match. Keeping in mind that the narrow band sensor output is VERY peaky and will not be stable but will hunt. A lot. BTW, I think the sealing ball is gone. I did try to adjust the mixture but my tools were either too long or not long enough.

Your method 2 is in fact the factory procedure for adjusting the mixture. I still like by ear.

I am amazed at the conversion you describe. That is essentially what Ken's car was setup (as). My take is it would have required replacing the fuel distributor. My first guess is that a main difference between the distributors is the springs in the upper chamber on top of the diaphram. Perhaps changed them out. Or PFM. On the whole I vote for PFM.

[William Miller]

"PFM"?

Thanks for the background. Didn't know you were in there. I wouldn't have written a book.

I should have the right size (length) allen wrench. It works on my car anyway.

At one point I had 3 FD's in my posession. The 81+ US k-lambda (like ken's) 79US k-basic and finally I found the 81+ Euro that matched the rest of the system on my car.

I think the PO mechanic ordered the wrong part, put the bolt in it and let it go. This kind of treatment ultimately forced the PO to sell the car because it ran like $hit and he was tired of putting money into it.
I picked up the car for $4K (What the mercedes dealer offered him in a trade.) I spent about a year screwing with the CIS and during the process found learned enough to be dangerous. I found that many of the parts were swopped out with the wrong stuff. I got most of it back in order but couldn't locate the euro Fuel distributer. I got the next best thing which was at least K-basic. 79 US unit. After installing this and eventually rebuilding the engine I still had problems. I bought a narrow band A/F meter and finally discovered the problem. Even though you could tune the mixture and get it running good at idle It was very lean in mid-throttle/rpm conditions. It eventually richened up in higher RPM under load. This was because the FD didn't match the Mixture unit. Eventually I found a Euro Fuel distributer and that solved all of the problems. I still have some tweeking to do (I actually have the opposite problem to a much lesser extent.)

Anyway, I took a lot of pictures of the various Fuel distributers (Took the ones I'm not using apart.) The plungers in them are slightly different.
I think some of this is also controlled by how they are calibrated (Fuel flow by the adjustment screws on the top under the caps.)

I sorta stopped worrying about this since now I'm in the process of restoring the body.

I hope I can get things going for ken tonight.

[CrewChief]

I only just learned about the screws you mentioned. None I had apart had them. Apparently they can be used to move the mixture around. But CAREFULLY as I understand it.

Actually, if someone wanted to 'hotrod' around with the CIS the lambda unit lends itself. All ya gotta do is send different signals to the frequency valve and change the lower chamber pressure. It has significant control of the mixture. Not all that different than sending a signal to an electomechanical fuel injector.

FWIW. Ken told me the shop used a test light and determined that there was no power to the fv. Using a voltmeter I came up with almost the same thing. Only showed about 8 volts at the FV connector. Had a solid 12+ at the relay and the ground side of the FV checked good. I knew from the wiring diagram that the next step was to find that connector and while I'm just pondering how-n-hell I gonna find that; Ken just sorta outa the blue pulls out an message he picked up off the net with the connector location. BINGO! I love it when a plan comes together. Somebody tell Dave Riley he's full of it if he thinks these things are easier to get at than a 944! You too Tony. Anyway, sprayed some tv tuner cleaner nackumpucky on the connector. Hit it with a toothbush. Spread the fingers apart some. Voila! With the fv connected the car now won't run. Success.

The duty cycle actually measured something I did not expect. 65% I think. But hey. Lets don't get greedy right off the bat. I just sure hope this is it.

PS: Pure Magic. A technical term we use to describe how helicopters fly.

[Ken Robinson]

Bill, Charlie and John,

Thanks to all of you (and the poster from the Pelican Board) for your help! Last night at Bill's garage, Charlie, Bill and I were able to make all the adjustments to the CIS the old fashion way with a little help from Bill's new A/F and timing light toy. It was running so rich when I was driving to Bill's last night with the FV plugged in that if I came to a stop the engine would stall! I now idle at +/- 950 rpms and have the power and extra kick that I've been looking for since last July! Almost got caught in a speed trap on 270 last night as I was "flying" home!

The Fabspeed cat-by-pass and B&B tri-flow muffler really sound great! Not loud but throaty! 8)

There's a lot to learn about the CIS system.

Now we need to get Bill's 83 cab back together as it must be in a thousand parts!

Again, thanks Bill, Charlie and John!

Ken