Looking forward to hearing your results. I have been thinking about my "22" open loop number. Isn't that 50% duty cycle default?

If my 3mm screw is set in close to the right place and pressures are ok with the WUR, maybe 22-ish is normal?

I doubt it as there is so much extra fuel and extra air on cold start (even when 80F ambient) it cannot be rock solid.

There is a table that was posted in a Tim (Tirwin) thread last year that shows what the Lambda box tells the freq valve to do across all the operating ranges. I think it is broken down by year (edit: not 1980). Let me find that and report back.

Edit: See post #37. Explains why touching my throttle linkage sent my numbers higher. Phew.

http://forums.pelicanparts.com/porsche-911-technical-forum/787542-low-power-low-rpms-after-reconnecting-o2-sensor-2.html

Confirmed....my Fecklar FV es KAPUT! And the search goes on..................

Crap. That is a chunk of change. Keep searching. Any alternatives? I have never checked.

I know the Ferrari 512 Berlinetta Boxer had CIS. Any of those "Pull-a-Part" or "Pick a Part" yards in the foothills of CA? They have to be littered with tattered carcasses like the 512.

Found a used one at a Pcar place in the bay area. Buck and a quarter plus shipping. If this doesn't do it I'm selling the car in Ohio!

Yikes. Good luck with that. I wanted to do my test this evening but I got a huge electrical storm coming through the Atlanta area. Will try again tomorrow Bob.

I see that on weather.com. Ouch.

OK update: I tried when cold and got a goose egg! Then I found something. The switch on the Actron in the middle dwell position is a bit dicey with no real detent. When I played with it some the needle shot right up to 21 or so then dropped back to 7 quite quickly but the engine had got quite warm by the time I had figured out what was going on. I'll try again tonight once it cools down again.

On another note. I measured the resistance on my WUR when cold and it was only 10.1 ohms. Quite warm ambients in the 80's though. I think I'll pull it and send to Tony for a test after I measure some fuel pressures. Once warm the car runs like a champ though so I don't think there is really too much wrong with it.

The key is our friends at the EPA want our car to start in open loop with the 3MM screw set as close to 14.7:1 as possible but with the recognition that rich is required for cold engines.

If you set the 3mm screw to where it reads 50% duty cycle at warm idle and all of the cold start goodies are working right, the car will not blow out excess hydrocarbons while warming up. Lambda box should take care of the rest post the 90 seconds or so warm up.

My WUR resistance is in the higher twenties. But it's an 090.

Tony has the scoop on the 80 WUR. Sounds low but I am not into the full range of tech info as he is. Thy guy is amazing.

Just a side note. If you read that Tirwin had issues with the Mighty Actron not working properly, that is cool.

However, note that it is not to be used as an engine/car support when coupled with a 15" piece of wooden 4X4. It may "spread the load" as Tim says, but can perhaps impact functionality.

http://forums.pelicanparts.com/uploa...1437092403.jpg

Thanks very much for that Bob.

Ha yes I'll use it as a chock to stop the Mrs driving her car into the wall at the end of the garage. :).

Mine's an '82. I'm pretty sure that's the 090 WUR. It should be in the ~22 ohm range when it's "cold" like you said. I'll ask Tony if he'll check it for me once I can run a pressure test on it and check the timing. I verified it's got 12V+ at the plug.

The car's never had the elevated idle when it's cold. I can see that the AAV is open when it's cold so that's confusing. My injector seals are leaky so between that and the possible dodgy WUR I'd say that's at least part of the warm up issues. Once she's warm she flies so there's not too much wrong with it.

These are good little projects for a noob like me. I just need to find some time to myself to do them :).

Bob, what would happen to that meter/car stand if you set one of yer ham-hocks on it?!?!?

You have to put it face DOWN when using it to jack the car by the sump plate. :D

So, here's been my experience... I was having trouble with the Mighty Actron. Jim Williams said he tested a few of them against the Almighty Oscilloscope and there was a good deal of variation. Bob must've got the good one in the batch. Some guys have all the luck, you know?

The signal is a square wave. There are a few multimeters that have the ability to read the square wave. You have to know whether the reference for the meter is "on" or "off". 60% on and 60% off are different things.

I invested in a wideband O2 sensor gauge a while back. When I dropped the engine last year I finally got to take care of all the nagging vac leaks. When I started the car the first time I had AFR in the 10 range. Using the gauge and the AFR<->exhaust gas CO table I got it dialed in perfectly to what psalt recommends. I think I'm at 13.2-13.5 range at idle. The car has never run better since I've owned it. We also used it a couple of months ago to dial in garrett490's car after a fresh engine rebuild. He was set way lean before. Definitely more money than the Actron, but it is something worthwhile in the long run for CIS cars. The thing I like best is the data logging. If you pay attention it will tell you if something is starting to change over time.

I'm not going to be home for a couple of weeks, but when I get back I could try to hook up the Mighty Actron and the multimeter again for comparison against a known good baseline.

And it was JR (javadog) that posted the excellent reference for what the ECU does in various conditions, not me.

Thanks tirwin will be interesting to see what you get on the old Mighty Actron :). I've read all your threads on the subject. I've learned a tremendous amount. I'm over in Suwanee so we're not far from each other.

Just wanted to clarify something. You might have seen the old post where I tried the PLX gauge. I did not have good luck with it. For one, the gauge itself just quit working. I also learned (the hard way) that the narrowband output from the PLX was NOT compatible with the ECU. That was also another insight from Jim Williams. Failures are still learning experiences. :)

Right now I'm using the LC-2 from Innovate Motorsports with a gauge. I haven't done a permanent install yet. One day I will take my test pipe to a muffler shop and have them weld in another bung so I can run the narrowband and wideband in parallel. The narrowband still feeds the ECU and the wideband is for the gauge and data logging.

Jason,

The voltage on the O2 sensor goes from .1 - 1V. Since it's a narrowband sensor, you can think of it's output as either lean, stoichiometric, or rich. It can't really tell you how lean or how rich. If you really want to dial in the ideal idle AFR you need either an exhaust gas analyzer or a wideband O2 sensor.

The surging could be because the ECU is trying to find a happy place and can't. It might be detecting rich, then leaning, going too lean, then richening the mixture, going too rich... rinse and repeat.

I think ossiblue, psalt and javadog have all noted that this is why some people have disconnected their O2 sensors -- they were trying to solve a surging idle. The disadvantage is poor fuel economy and it's not really necessary.

Assuming your fuel pressures are good, no vacuum leaks, idle and timing are set correctly and the O2 sensor is good, you should be able to dial in a good idle mixture and not have surging.

Has anyone tweaked the 3mm screw to see if the dwell changes away from the low readings?

WUR tests and evaluation.......
 

gazzerr,

Do you know the number on the WUR? Your USA model '82 SC should have the -090. And don't expect to get a good and nice cold idle with an out of spec. WUR. When it is warm that would not be a problem. Your erratic cold idle will not go away unless you solve your cold fuel pressure. If you want the WUR tested and evaluated, send it ASAP because I will be going to Europe mid August and won't be available till first week of September. Or I could lend you a WUR to use or test on your car and see if it solves your problem. PM me if you need help.

Tony

Hi

Hi Tony,

In post #50 gazzerr mentions he thinks he has an -090.

Hi Guys,

Thanks so much for the info. I still haven't plugged the Mighty Actron back in. Work's been conspiring against me. Thankfully it's Friday :).

Tirwin I think I did read that post! Jim did quite a science experiment on that one from what I can remember from it. Thanks for the warning appreciate it. Once I get everything sorted nagging vac leak wise I'll find a shop that will stick a gas analyzer up it's rear and have them sort the CO for me.
I might be able to borrow one too. See how I go.

Tony & Bob -> I do have the -090. No worries I can wait until September, there's no rush. I'd love you to check the WUR out for me when you get back and settled from your trip! I'll send you a PM when the time comes. Thanks so much.

Bob, I haven't tried to play with the 3mm screw. I don't actually have a 3mm allen key that will fit. Keeps me from temptation :).

Once I get a day to myself I'm going to check those fuel pressures and post here.

Maybe for the best.

I do have a pic of a 3MM tool I made that helps with the metal lines. I may wait for Tony to let me know when it's ok to post. :D

Efffff the Mighty Actron - wut youse need is something like this . . . mounts between the seats (to a rod on the parking brake lever), or pick it up and move it to the dash mount for better visibility while boosting. Getcha summmmm! :D

http://forums.pelicanparts.com/uploa...1437195105.jpg
http://forums.pelicanparts.com/uploa...1437195137.jpg
http://forums.pelicanparts.com/uploa...1437195160.jpg
http://forums.pelicanparts.com/uploa...1437195179.jpg

Ronnie what kind of cash have you got sunk into that bad boy?

If it weren't for the inductive voltage 'ringing', i.e. the multiple high voltage spikes,
when the frequency valve is switched off, any voltmeter would provide good
voltage readings to calculate the actual duty cycle. Any device used to determine
the duty cycle needs to 'ignore' the voltage spikes in its measurement. Obviously
when using an o-scope, one can just measure the on/off times of the frequency
valve and calculate the duty cycle.

Update on this. I bought Louie's male OXS connector plug and installed it, since mine had disintegrated. I cleaned up the wire connection, but left a little unshielded wire since I figured it made no sense to shorten the wire any more than I had to; any interference from a length of unshielded wire was going to be similar to the interference from the unshielded connection between the wire and Louie's connector (which is nicely made, IMO).

Car is idling differently. Not better or worse, just differently. So I think I was having a connection issue on the OXS. Also, the smell of gas in the exhaust is stronger than I remember it, so I'm thinking we're running a little rich now.

Going to check fuel pressure, then vacuum leaks (again), then set timing, then check duty cycle. Will let everyone know what I find. Suggestions welcome.

Good idea to replace the connector. Louie85 makes a great product.

Hi Jason, I seem to remember a thread that described the method for installing the new connector. As I recall you had to be quite careful with how you install the shielding (needed ground?) around the coax. It should be pretty easy to test if the OXS box is getting input from the sensor.

You've probably already read this but will place here for convenience:

http://forums.pelicanparts.com/porsche-911-technical-forum/497025-o2-sensor-connector.html

My OXS was kaput and it turned out to be just the sensor itself. My car smelled very rich at idle too. Once I replaced the sensor it smelt much better. I believe the system just turns full rich with O2 connected but non functioning. This is different to just having the sensor disconnected all together. I'm probably just telling you stuff you already know.

mysocal911 -> thanks for the input! I guess the most accurate way is to use the o-scope and calculate it.

Perhaps trying the 3MM screw is an option rather than pounding on the dwell meter as a POS. I don't need to defend it but it has not been given a chance.

See setup for metal line 3mm screw below.

Do you guys know which way to turn it for lean? Whatever you do, do it in 1/16 turn increments followed by a slight clockwise turn to set the threads.

http://forums.pelicanparts.com/uploa...1437602423.jpg

Using the "tennis ball and shop vac and soapy water" test, I found no vacuum leaks. That doesn't mean there aren't any...just that I didn't find any. Next up is to look at fuel pressure, but I need a fitting for my FD that I don't have. Does anyone know offhand what the right size fitting is for the connection to the FD? M7 female?

PS gonna try to compare my MM dwell reading with the MA (Mighty Actron). I'll report back or post pics of the smashed MA.

If you put a hammer through yours I can send you mine to see if you get a better result.

I just tried my MA finally and I can't get it read above 7 on a stone cold engine. It is high 80's ambient here in Atlanta though.

gazzerr testing the MA using the balloon theory.

http://forums.pelicanparts.com/uploa...1437606874.jpg

Fuel pressure test.........
 

Jason,

The fittings for the FD head are 8 mm x 1.0. I would recommend that you do the installation of the pressure gauge kit at the WUR side instead of the FD side. At the WUR side, you would need a 12 mm x 1.5 fitting which are very common. Second, it is more convenient to do the installation at this end than at the FD end. And when you remove the WUR in some cases, it is easy to break the fuel lines for removal.

You could do it at either end. There is no right or wrong side. It is a choice and since you are having problem finding the correct fitting for the FD side, using 12-mm x 1.5 should be easy to find. This is the same size fitting for CIS injectors. So you should have plenty of fitting in your kit. Have you tried the WUR side before? Keep us posted.

Tony

Will instruct shortly as to dwell.

L(eft)=lean. R(ight)=Rich

Thank you, Rich.

When you get in there every three years and fiddle, one forgets.

I hope to make a video tonight of richening my CIS. I want to see if I can replicate the sub 10 on the 8 cyl scale.

That may lend some hope.

Bob - HA - very good.

Can there be any correlation between a bad WUR and low readings on the MA?

I can't claim that perm though :).

I would think yes.

We don't know if your screw has been jacked with for various reasons.

All I want to do is see if I can replicate your symptoms with my 3mm screw. It is not the answer. It may be, but you don't yet have the pieces of the puzzle confirmed (i.e., fuel pressure)

Edit: and with experience, you will see it is a relatively simple puzzle.

Hey Bob,

Yes definitely - Tony's gonna test my WUR also given the low resistance. Given my air leaks I have been chasing and fixing I would be willing to bet a full .25c that the 3mm screw has definitely been jacked with. The plug has been drilled out on the top of the FD. :)

Thanks very much for trying on your car. I'm excited to see what you get.

I'm going to test fuel pressures as soon as I can and I will post here.

FYI - All I did on the screw was cut off a piece of 3MM allen wrench stock. Drilled a hole in the end of a chubby allen head screw (cap screw?) and JB Weld epoxied it in. So much easier to navigate around the metal lines.

Back to basic........
 

Gazzerr,

The first thing you have to confirm or verify is the absence of a significant source of unmetered air going into the system. That fuel mixture screw should never be touched or adjusted in the first place. Once it has been tinkered from factory setting, you lost it calibration already. This is the main reason people are having so much problem with CIS troubleshooting. Someone posted a thread on how to adjust fuel mixture with gauges and it is a good procedure. But the author failed to mention that unmetered air should first and foremost eliminated or corrected before attempting to make such adjustment. The post was so old that the author could not edit any longer and became a standard procedure for other troubleshooters.

I have a pretty good success in CIS troubleshooting and the last thing I would do is tinker the mixture screw without testing and verifying the absence of unmetered air going into the system. No gas analyzer nor dwell meter could fix the erratic performance of your CIS engine if you have a significant amount of unmetered air.

Not being able to locate the source of a vacuum leak does not mean you don't have any. So test and confirm. What good would a good working WUR could do if you have vacuum leak. BTW, anyone suggesting to use starting fluid or carb cleaner to locate this illusive air leak is not a CIS guy. And most of the time, you would fail to locate this leak using the volatile liquid. There is an efficient and better method to locate this hard to find air leak/s in CIS engines.......pressure test.

Tony