need help accessing gas analyser results

[jumpinjimmy]

Hi, I'm trying out running my 1983 SC in open loop and would really like input on the readings I had prior to disconnecting the o2 sensor and afterwards. It seems everything stays pretty much the same after disconnecting the sensor expect for the leap in HC, which according to my gas analyser instructions, indicates a lean condition and a slight decrease in lambda. If I increase the richness, the lambda goes up to around 1.07 and the HC is still in the 400ppm range which is too high. Not sure about what sort of settings I should be opting for in the CO, HC and lambda range for running in open loop and I don't want to bugger up anything by running too rich or too lean. Any help or opinions would be appreciated.

Photo one are the readings prior to the o2 disconnect. Photo two is afterwards. I have a catalytic converter but the probe hole just in front of the CAT is too small for my probe so I can only read direct from the tailpipe.




ooopps. ASSESSING, not accessing.

[scarceller]

If the HC increase in open loop then you most likely may be to lean resulting in lean mis-fires.
If read what you wrote you indicate that HC is good in closed-loop (o2 connected) but HC goes very high >900ppm when you disconnect the O2, correct?
If this is the case then with the O2 disconnected slightly richen the mixture via the Air Fuel mixture screw, does the HC go down?

[jumpinjimmy]

Yes, if I richen the mixture via the air fuel screw, the HC goes down, but what's an acceptable level of HC for normal use. I won't be able to get to the same level as with the o2 sensor connected.

I JUST REALISED THAT THIS DIDN'T PROPERLY DOWNLOAD THE SECOND PHOTO THAT SHOWS RESULTS WITH THE O2 SENSOR DISCONNECTED. HERE IT IS:

[scarceller]

Try to get the CO set first at 0.6 - 0.8% that's about 14.0-14.2AFR, then we'll see what the HC is at. Normally we'd like HC at less than 200ppm but if the engine burns some oil that may not be possible.

[timmy2]

Interesting, my '78 without any Lambda has a spec for CO of 3-4. I would think running in open loop you would want to set your CO to the euro values for your year.
I believe they are very similar to mine.

[scarceller]

My books show Euro CIS cars are speced at 2-3% CO my earlier numbers are for the 84-89 Carrera, sorry for any confusion.

Originally Posted by timmy2

Interesting, my '78 without any Lambda has a spec for CO of 3-4. I would think running in open loop you would want to set your CO to the euro values for your year.
I believe they are very similar to mine.

[scarceller]

Originally Posted by jumpinjimmy

Yes, if I richen the mixture via the air fuel screw, the HC goes down, but what's an acceptable level of HC for normal use.

This indicates a lean mis-fire condition, keep richening till the HC drops below 200ppm and target the CO at 2-3% see if you can hit that CO level.

[jumpinjimmy]

Mine is actually a US import. Euro models in 83 didn't have lambda or Cat converters. I've been thinking of getting rid of both but not 100% sure yet.