I just got my LM-1 wideband a/f meter today but was wondering since it's got to be calibrated for the first time out in the air, will the cold temps (25-30F) affect my readings in the summertime or can I recalibrate it again when the temps come up?
Also, I have the exhaust bung to install, when I weld it in what should I disconnect electrical wise.

 

You can calibrate it as often as you like. I calibrate mine when I have not used it for a while just to be sure. I had my pipe off when it was welded so I did not have any electrical issues.

 

when welding, disconnect the battery

 

The Bosch LSU4 sensor that is used by the LM1 came as factory equipment in many cars including Cadillacs, Audis, VWs and Volvos. Those were all just calibrated once at the factory.

What I'm getting at is you can calibrate as many times as you want, but you don't have to re-calibrate just because the temperature is different.

It's also best to remove the sensor from the exhaust pipe before calibrating as it has to be in free air. If you leave it installed it will sense the lower oxygen air in the pipe and calibrate wrong.

 

Well, I got my LM-1 hooked up and running tonight. I still have to seal the bung a little better as I'm not that experienced at welding. I got it 98% sealed right now. It would have been easier to weld with the headers off even though I have sidepipes.
Anyway, I managed to make a run.......starting out at 1500 rpm in 3rd gear (TH350) I brought her up to 4500 at WOT. I didn't have the rpm converter connected at this point but looked at the tach for a reference. I coasted down for a few seconds before stopping the session just to be safe on the road. As you can see, I had a lean spot right where I went WOT, then it went rich when the accelerator pump squirted, then it was ok till I let off and coasted where it went rich for a couple seconds then it leveled off again. This lean condition was probably due to the welds not sealing properly and air got sucked in, but the rich condition when I let off is a little weird to me. Overall I think I'm in the ballpark. Here is the graph:


Then I hooked up the Rpm converter to test it and I first started out at idle which is about 1000 Rpm, then I went to 1500, then 2000. After that I blipped the throttle twice and held it around 3000. Again my crappy welds are showing extra air in the system by the way the afr increases when I did that. Here is the other graph:


So what do you guys think of the data I aquired? I know that to get an accurate reading for performance purposes I should be recording at WOT under a load in top gear, but I just wanted to get an idea of where I stood. Any info or comments would be great. I will be making a couple more runs tomorrow and will post the graphs as I get them.

 

air leak causes leaner reading. really needs to be tested again no leak

 

Your graphs look fine for a cruising engine but not for WOT.
At WOT you should drop into the mid 12.5 range or at least low low 13's to be safe.
At cruise 14 or 15 is fine. Your curves are remarkabley stable for a leaking weld.

If the car sits for a day you can recalibrate without pulling the sensor but I only recalibrate every month of two just to be sure.

 

The instructions say you can leave the sensor in for recalibration if you wait 6-8 hours to allow exhaust gasses to dissipate. Personally I don't see how the heck that could happen completely. I disable the EFI and crank the engine over for about 10 seconds while holding the throttle open to pump fresh air through the exhaust before recalibrating.

"The sensor MUST be operated in free air for calibration.

If the wide-band sensor is installed in a vehicle, wait 6-8 hours after running the engine so that all
exhaust gas is dissipated from the exhaust tract of the vehicle. Better yet, disengage the oxygen
sensor and expose the sensor to air (away from the exhaust) for calibration purposes..."

 

I know if I let the car sits for a day it will clear, but what about the lean spike at the point I hit the throttle? It looks like the accelerator pump does it's job when it dips into the low 13s and then stabilizes around the 14s when the main jets are in use. I will go with larger secondary jets next and see what happens. So the cruise signals are good......I'll leave the primaries where they are then.

Just as a side note, I shortened the secondary linkage a while ago to activate sooner, but I did that so that the secondaries would open up ALL the way at WOT. Could this be why it goes lean for a split sec when the secondary butterflies open before the jets catch up? I feel at WOT this mod works the best to acheive better power output near the topend so I left it like that, but if that lean spike isn't good I'll change it back.

 

A lean spike at tip-in is perfectly normal. I even see it on EFI cars. It doesn't hurt anything and I doubt you can get rid of it 100%.

Like Norval says: I'd be more concerned about your lean WOT readings. A small leak at the sensor will not affect WOT readings so I think what you see is real.

 

Ok, making jet changes as we speak. thanks for your input.

 

Keep us updated stroker-I think Santa may be bringing me an LM-1 for Christmas. So any info I can get ahead of time is very good for me.

ltlevil

 

Ignition misses also show up as spikes. If you have a miss you will see alot of lean spikes.
Again you seem to have a very stable graph and the odd spike is normal.
I wish I could post graphs but to post a real graph you need the program installed.

 

I agree you have some clean graphs going on there, the LM-1 is a great tool have fun

 

Ok here is a new graph I recorded after changing the secondary jets from 84 to 88. The primaries are 71. Also I should mention I have a 50cc accelerator pump for the secondaries. On this one I was cruising around 1500rpm and then went WOT up to about 4200. The lean spike is still there but if you guys are saying it's ok then I'll let that issue die. The WOT AFR is now down to the mid 12s.



Eureka! It even feels better now, but I still have the power tappering off near 5500 rpm. Could it just be the cam, because like I said, I am just going by what the seller had told me. He said I could shift at 7000 rpm all day long and it would be fine. He also said that he built another engine with the same specs for a 78 malibu that went 11:80s.

 

Just make sure you have the adobe reader as there is no paper manual, you have to read it on your pc. In fact just do a search on "LM-1 air fuel" and go to the Innovate site to view the online manual. I recommend getting the Rpm converter with it as the package, it's $20 cheaper. The converter has provisions for 4 more inputs that you may already have hooked up or planning to hook up.

 

Thanks for the info, it is much appreciated. Also glad to see you are making good progress quickly and efficiently Nice to know what the engine is doing all the time without relying on just a plug reading.

ltlevil

 

I made a 45 minute trip today to deliver a christmas gift to one of the CF members here and for the most part it was reading 14.7 at around 3000 rpm. If I let off or throttled it a bit the reading would vary but that is the engines nature. I left it hooked up just to see what the cruising AFR was and to show Jims79 what it looked like. Oh, and the 4 corner air mixture screws make a profound difference with the smallest amount of turning. Very cool! Watching a vacuum gauge is one thing, but having an AFR meter to see your changes is amazing! I think I'm all dialed in for now, that is until I get the No2 kit!