different rough running problem

[Cdnone1]

I have searched and read a lot on this subject (maybe too much ) so I need a fresh perspective.
I have a 82 SC
It has been running great. I gave it a tune up, new plugs, filters, rotor, cap, fluids and it ran great.
I was running the car without an O2 sensor and decided to hook up a new one about a week after the tune up. At first the car ran great though it seemed to search for idle and a very light stumble or hesitation at times. Last week it started to stumble when started cold (OK cold for LA 60 degrees) like it was running with a couple of plug wires unplugged, backfired a couple of times, but ran fine when warmed up.
A few days a go it started rough and stayed that way. Like it was running on 4 or 5 cylinders. I can not see anything amiss and the car ran great when I parked it.
It starts fine but runs like crap, like it had a cracked air box. There is a pop off value on the air box and it is well seated. I have looked at the rotor, cap and looked for obvious air leaks, including looking for a crack in the air box. I can't see anything wrong
I was worried after years of running without a O2 that might be it. I unplugged the O2 FV relay and it made no difference whether it was plugged in or not. I replaced the FV O2 relay, still runs like crap. I disconnected the O2, still runs like crap.
Any idea's at this point? Maybe Lambda. It was running to well when I parked it for a major vacuum leak to develop just sitting in my driveway for 2 days
I can't keep it running to check for leaks with carb cleaner by myself.
What do you think happened and where would you point me next?
Anyone in LA like to come by and look listen and give me some idea's?
I would appreciate a specific thread if anyone knows of any
Thanks
Steve

[longhornchris04]

When you say you were "without O2" did you still have the lambda system installed and active - i.e. just disconnected the O2 sensor - or did you disconnect the power supply for the lambda system.

If its the former then I'm stumped. You will need to provide more info.

If its the latter, remember that the lambda system always runs the frequency valve to reduce the control pressure, even in open-loop. As such, if your system was tuned w/o the lambda functional at all then the lamba in open-loop is is running way-rich, probably beyond the capability of the system to correct in closed loop.

If you can get a CO meter, I'd adjust your CIS via the bently instructions. Another option is to wire a multi-meter up to the O2 sensor and use its readings in place of a CO meter in the tail pipe.

As an aside, I had to adjust my CIS (no lambda), as it was running rich. While futzing with it, I got my directions backward and too rich resulted in the following:
- hunting for idle
- stumbling on initial acceleration
- failure to "capture" idle when coming off gear. Basically if I went to shift my engine idle fell like a rock. If I popped the clutch at ~4000, the engine would nearly stall.

Just once, I stalled the engine out by adjusting way-rich (slowly) and right before it quit it sounded like a cylinder or two weren't firing.

If these sound like your symptoms, then you are probably running rich. Re-tuning per the manual (which tunes with the lamba in open-loop) is your best bet.

[kodioneill]

Sounds like a vacuum leak has developed. Use a can of brake clean a give a small spurt on the right and left side of the engine while running. Make sure it's not hot. You will hear a marked difference if you hit the leak. At that point you can narrow it down. I saw a post by John Walker where he found a obscure vac. leak at the brake booster hose.

[Cdnone1]

Thanks
I had just disconnected the O2 sensor by cutting and taping the wire. I did not touch the Lambda or do anything other than cut and tape the O2 wire. It ran great like that for years.
What more info would you like or need?
Steve

[Cdnone1]

Soooooooo
I reconnected the O2 sensor and put in a new FV relay.
Car starts no problem still runs very rough.
Checked for vacuum leaks and there are none. Pop off value is tight and you can't lift it while car is running.
So I figure something electrical or fuel metering.
I haven't touched the mixture since the car went from running great to crap.
Any ideas?!
Steve

[longhornchris04]

Best guess is still vacuum leak, probably a loose hose. It could also be behind the rubber boot from the air metering venturi to the throttle body.

The other option is electrical. Whats the condition of your plug wires, coil, CDI box, etc.

Electrical problems can look like fuel problems. A weak spark could cause these problems.

[Cdnone1]

Plug wires are relatively new. Coil, CD box I have no idea.
I'm thinking electrical because it went from running fine when I shut it off to like a dog when I started it
Anyone in LA have an O2 meter and a set of CIS pressure gauges I could borrow?
Steve