AFR values all over the place.. Lamb DUH Connector???
 

Can this Lambda connector be the source of all my agony?

http://forums.pelicanparts.com/uploa...1563934922.jpg

I'm having a hell of a time getting my CIS running smoothly and after tonight I have one more anomaly..

I have a 1981 911SC 3.0 with Lambda.

I have an AFR fuel gauge with the o2 sensor unplugged

Timing is dead on at 5 degrees

System pressure is 4.8

WUR - 090 - has 10 ohms (out of spec)
Cold Control Pressure 2.8 (in spec)
Warm Control Pressure 4.1 (out of spec)

Car runs and idles fantastic at certain times and is a complete DOG (wont start wont idle at other times) I have adjusted idle mixture and idle bypass to get the car running smoothly several times over the last few months and then the next day (next week) it is WAY out of spec - idle and AFR measurements will change and are never consistent for very long.

I had it running fine with AFR at 13-13.5 at idle and 4th gear 3K RPMS and about 12.1 - 12.4 .. Drove the car 500 or so miles over a period of a few weeks.

A few days later it wouldn't run (too lean) had to turn the idle mixture screw a good half turn clockwise to get the car running - then adjust idle bypass again to 950 RPMs to idle smoothly.. The AFR gauge then read 13.8 - 14.1 at idle and 16 in 4th gear 3K RPMS - and the car had NO POWER.. WOT the AFR went higher to 17 even 18??

Tonight when starting- Car would not idle at all (hunting severely) AFR stated 10... I turned the mixture screw counter clockwise and reset idle - dialed it in - AFR around 11.2 - drove it and all the POWER returned (it loves to be rich)..

Now the story takes an interesting turn - grabbed my wife to go get ice cream and I turned on my lights and the car started to idle rough - shut lights off -car ran smoothly.. it wasnt just the lights - if I turned the fan on - car runs rough - turn off fan - car returns to smooth idle.. Thought good lord - why me? This gremlin has never happened.. SO...

Shut the car off - let it sit for 30 minutes while I did some other work - then got curious on the electrical crap - started car up and of course it now has a low bumpy idle - however I turned on lights and fan and no change (still rough low idle) - AFR however was now at 13.. (not 11 .2 as I left it).. OK just what I want is more data..

Then I thought Id wiggle some wires to see if I could get the headlight issue to reoccur... This is what all good mechanics do right? Wiggled the above Lambda box and Idle smoothed out and rose to 950 and AFR gauge dropped to 10..

I don't understand this - besides the connector possibly being corroded not connecting etc.. but what does this suggest the ECU is wack? Why would it cause an immediate change in my idle? AFR? Is it adding fuel through the "frequency valve"?

I believe my WUR is out of spec and may need to replace but now I thinking I discovered another Dr. Jekyll.. What about the turning on fan or light causing an idle issue - is it all tied? anyone have this issue before?

Bad ground at engine mount (coming from harness as it reaches the engine) is one thing I’d check. Also clean and use some deoxit on the male and female terminals in the 6 pin connector.

I'll look for the ground..

Is this a 6 pin connector (the lambda plug)?

How the heck do you get it unplugged? I don't recognize how it separates..

1/2 the height is where it separates. Just like the 14 pin connector on the back of the fuse panel.
There is a Lid and main body on top and bottom of the connector.
Grip the top 1/2 and gently wiggle /pull it off.
‘81? Maybe a 12 pin connector.

Looks like some custom wiring was made to that harness from that TS in your previous thread.
Perhaps, that's the source of your woes.

http://forums.pelicanparts.com/uploa...1563942653.jpg

I'm not familiar with the set up on the 81, but that doesn't look like a lambda connection to me. Have you check the voltage of the system?

I had some running issues with my 84, and installed an inexpensive cigarette lighter charger with voltage meter (this one as some are not long enough). I noticed that i had an erratic alternator, that would charge most of the time but would occasionally drop off. Watching the voltage I could reliably see that performance would fall off as the voltage got close to 11V.

I know you are seeing lean indications, but an O2 sensor doesn't actually measure fuel, it measures remaining oxygen in the exhaust, so if you have a misfire due to low voltage to the ignition system you will not get e complete burn and therefore will have unconsumed oxygen and raw fuel in the exhaust stream giving you a lean indication on the wide band.

I think it's the Lambda system we are talking about. I know for certain the voltage for the frequency valve travels from the Lambda box through this connector and probably the O2 sensor wire as well - downstream two feet or so from the O2 sensor connection.