dr bob

Stan, check your meter or your keyboard. The numbers you report are off of your target by a factor of 10. Look for open-circuit oxy sensor voltage in the 0.5V range rather than the 0.05V range you report. I usually set the meter manually to read millivolts, and look for 500.


Ken, does the MAF adjustment screw set CO for much beyond idle speeds? My impression has been that it's pretty much out of the picture by 1500 RPM's or so. Don't know where that impression came from though.

Mrmerlin

Dr Bob the digital meter was set to a range of 2 volts.
next range was 20 volts then 100 then 200 What range should i have been using??
There is also a Millivolt section 200 MV
The MAF is set to 375 OHMs and the car seems to run well and the exhaust smells different than before i started.
The MAF was set to 497 prior to any adjustments.
AQhh just reread your post, i will go and try the millivolts section and look for 500

Mrmerlin

OK I went and drove the car to warm it up then with 2 different meters connected to the O2
I am getting
50.2 or so with the scale on the 200 millivolts scale the readings are fluctuating between about 48.2 to 51.2
The grey meter seems to move slower then the yellow meter What are you seeing??
I added 2 more pictures with the range selected at 2V and after the engines warmed up its shows between .045 to .053 v

PorKen

JS has posted about the CO adjustment before, IIRC saying the percentage is reduced as rpm/load climbs.

I can look at the code, but the assembly language math still escapes me. AFAICT, the injector supply voltage is also used as a variable in the CO plus or minus calculation.

I'm planning on adding a relay at the battery to supply the fuel pump to take the load off of the injectors to see if it makes for more consistency at high rpm (the LH relay supplies the fuel pump, O2 sensor heater, and injectors).

Mrmerlin

do these reading look correct for the range selected on the meters .
I should be looking for a a point 5 volt reading ( .5V )
first 2 pictures show the meters on the millivolt scale second 2 pictures show the scale to 2 volts

John Speake

Your meters will be trying to average any reading that is fluctuating and that could explain the difference, due to different filtering and processing in thre meters.

But your readings are crazy low, as Dr Bob says. Readings should averag around 0.5v.

Effect of CO pot dimishes with rpm on a square law basis IIRC.

Mrmerlin

well i went and checked my S4 O2 sensor its brand new and the numbers are .562V so my sensor in the 86 car is bad.
Thanks for all of your assistance.

Landseer

Another great thread for subscription!

Mrmerlin

Ok update. I put in a new O2 sensor regapped the plugs to .032 and fixed the aircleaner housing and adjusted the MAF to give a hover of .5 volts it is actually jumping around from ,2 to ,8 volts .
From my research if the O2 is giving lower than .5 volts then the fueling system will add more fuel to compensate thus making the mixture richer if its over .5 v then it will tend to make the mixture leaner.
I had better luck back probing the O2 than just reading wire from the sensor then adjusting the MAF to get it so the numbers were averaging at about .5 volt my
MAF is now set to a 520 OHM this is after adjusting the idle, with the MAF set at 380 the O2 was giving .1 to .3 Volts so the fuel system was adding fuel thus making the mixture richer
My passing reading was 17.1 and max is 20.0 this was for CO. Thanks for everyones assistance

Mrmerlin

this needs to be in this thread so i linked it

https://rennlist.com/forums/928-foru...maf+adjustment

LH 2.2 pin layout diagrams

https://rennlist.com/forums/928-foru...2-pinouts.html