How do I correlate AFR to CO content...?? using a LM-2...
 

maybe I am mixing apples & oranges here, but, I am trying to set AFR on a 3.2L to 12-13...I understand that stociometric(sp) of 14.7 is perfect and it equals 1 per the instructions with my LM-2 unit...
I have read & been advised that at idle speed of 900-1k rpm's I want my AFR measurement to be around 12-13...
What does a CO reading of 2-2.5% equate to in terms of AFR...??
Thx, Bob

Co% 2 = 13.77 afr; co% 2.5 = 13.56 afr.

thx Mark...is there a conversion factor or a way I can convert afr to Co...??
What would the Co be for a 14.7 afr...??
Also, what is the afr for 1% Co; 1.5% Co and 3% Co...??
Thx Mark...these appear to not be linear...??
Bob

Bob, I have a CO% / AFR Table that I can e-mail to you. The CO for 14.72 AFR is 0.1 CO%. The AFR for 1% CO= 14.11; 1.5% CO= 13.94; 3% CO= 13.38

Thx Mark...please email me the table at bobf@design-associates-ne.com...

Basically, I am having trouble setting the mixture on a 1984 3.2L Carrera...my LM-02 initially had issues & was found to have a faulty cable for the o2 sensor...I found 1 vacuum leak & fuel pressure reg was bad...still experiencing a low idle speed & very lean mixture readings at a warmed up idle with mixture screw turned all the way in...when I drive car & put it under load = accelerate, the afr goes to 1 to 4 afr's...at idle or coasting it is 18-21 afr...

Any ideas on what to check...?? I have checked ALL vacuum hoses & ALL sensors on engine & all "seem" to be working w/in spec...

Thx, Bob

I copied this from BemariM3Ex: http://www.bemarim3ex.com/demos/repair-new-bemarim3ex-141/39-afr-vs-co-table.html

%CO AFR
0.1 14.72
0.2 14.54
0.3 14.42
0.4 14.34
0.5 14.28
0.6 14.23
0.7 14.21
0.8 14.17
0.9 14.15
1 14.11
1.1 14.09
1.2 14.04
1.3 14.01
1.4 13.98
1.5 13.94
1.6 13.89
1.7 13.86
1.8 13.82
1.9 13.8
2 13.77
2.1 13.73
2.2 13.69
2.3 13.63
2.4 13.59
2.5 13.56
2.6 13.54
2.7 13.49
2.8 13.45
2.9 13.41
3 13.38
3.1 13.34
3.2 13.31
3.3 13.27
3.4 13.24
3.5 13.2
3.6 13.15
3.7 13.12
3.8 13.08
3.9 13.03
4 13
4.1 12.96
4.2 12.93
4.3 12.9
4.4 12.86
4.5 12.83
4.6 12.8
4.7 12.75
4.8 12.7
4.9 12.66
5 12.64
5.1 12.59
5.2 12.54
5.3 12.51
5.4 12.46
5.5 12.43
5.6 12.4
5.7 12.37
5.8 12.3
5.9 12.25
6 12.25
6.1 12.22
6.2 12.18
6.3 12.13
6.4 12.1
6.5 12.09
6.6 12.03
6.7 12
6.8 11.96
6.9 11.93
7 11.89
7.1 11.86
7.2 11.82
7.3 11.79
7.4 11.76
7.5 11.72
7.6 11.69
7.7 11.65
7.8 11.61
7.9 11.58
8 11.54
8.1 11.5
8.2 11.46
8.3 11.43
8.4 11.4
8.5 11.36
8.6 11.32
8.7 11.28
8.8 11.25
8.9 11.21
9 11.16
9.1 11.12
9.2 11.08
9.3 11.05
9.4 11.01
9.5 10.97
9.6 10.94
9.7 10.9
9.8 10.86
9.9 10.82
10 10.79

Remember that the stochiometric mixture of E10 will be richer than pure gasoline.

304065...good point...how do I factor your input = E10 fuel these days into the tables here...??
Thx, Bob

Why not just change the mode of the LM-2 so that you can read AFR directly? Or am i missing something here?

regards,
al

...you are right Al...however, I am having trouble...STILL...with my brand new LM-2 unit & trying to figure it out...I am as certain as possible that the engine is sound but for the life of me I cannot adjust the fuel mixture then the idle...ARGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH...

I am about to run over the f'ng pos unit... :-) But I wont...it will probably turn out to be me not understanding something & I cannot figure this thing out...!!!

I think I need to find a local speed shop that has a known good exhaust reader so I can set mixture & then idle...

I found several cracked vacuum hoses...replaced them...fuel pressure reg was bad...replaced it... new spark plugs...I checked ALL sensors & w/in range per bently...just installed a cat bypass pipe as cat was plugged & still better but not correct mix & idle...

Anyone want to take a stab at this with me using my LM-2...I have the tail pipe clam that Al K. suggested to get & the rpm clamp...

Just when I thought it was going to get easy I am hitting my head against a wall...

911 tweaks:

I have had an LM-2 sorted out and running on my car continuously for over a year with the O2 sensor on my cat bypass. I would be happy to help you out. Email me or pm me.

pm sent to DrJ...thx

Thx again John...you were a great help...best of luck with your work in FL... Bob

My pleasure. Hope you get the rest sorted out and can enjoy the car.

...FINALLY found out what it was...it is going to sound quite obvious...intake runner seals dried out ~ cracked = leaking air...!!

I sprayed carb cleaner around the base gaskets & no idle spike...I initially sprayed a shot into the air box & the idle spiked so I knew the engine would spike "IF" a leak where sprayed...nope...

A buddy told me that carb cleaner is not as volatile as it used to be...try brake clean...so, we gave the intakes a shot with brake clean and WHAM...SPIKE...

Thought I would pass this along so others are not fooled when trying to perform a similar diagnosis...

Thx again everyone... Bob

Congrats!