While logging with my LM-1 (VE table is relatively smooth in low rpm, light load including in gear to 1600rpm) the car idles and runs smooth, and while watching on the LM-1 it will idle around 14.7 +/- 1 or so for the most part. First question, what error should I have (in terms of VE) for a given A/F Ratio vs stoich. I wasn't sure if there was a constant proportional relationship there or not (ex, 14.7/15.2 = 0.967, so add another ~4% to current VE). I know that the BLMs can be used to estimate in this manner, and my BLMs are currently locked at 128. This isn't that important, and not the main point of my post though, but something I thought of while writing this. The second question is, should I see random spikes up to 19.x, 20.x and above in WB readings, for one, two, three samples (LM-1 programmed to average samples for frequency of 6/s). What would cause this? I was suspecting a leak at the headers/head, but would it be random and not a consistent lean condition? I haven't noticed any symptoms of this like blackness around the flange or noise. Do the sensors ever become flaky and if so could it cause this symptom? It's been a little while since I've looked at an actual log file but I think the spikes show in the log also. Thanks Ben

That VE table looks like the high MAP settings have been jacked up from around the 60 or 70 kPa region almost to the levels at 100kPa. IMO that's enough to drive the wide fluctuations in AFR you're seeing. I'd expect the 60 or 70 kPa VE's to be about 10 units lower than the 100 kPa (give or take).

The method you're describing works for me.

Yes in some WBs (although I'm not familiar with yours). An AFR of 20 is "free air" on my WB, and as an example, I get that every time I back off and trigger DFCO.

John

Well the thing is I get these spikes while idling and idling in gear, which is the closest thing I've gotten to actually driving the car.

Also, from the VE table, I have not been able to tune above about 50-60kpa as of yet, hence the drop at ~70kpa, the table should continue to rise (when tuned).Although it does seem maybe high VE for 1600rpm/60kpa, at almost 70%. Is this too high? Injector constant is 24 which I thought is what the Ramjet comes with. Is there another constant I'm not aware of that may be over-rating my VE table here?

The lean spikes you're seeing are probably just the sensor or box (or software) blinking out randomly. I have about 6 working LM1s at work, and have seen this problem very very often (but not all the time). It's annoying. I attribute it to either the sensor flaking out, or the cheap price of the pcb components. I also often lose connection to the software at the end of a DFCO for some reason (and I don't think it's from shaking, I think it's a software issue).

I also often see problems with LM1 stuff, but it's still good enough and cheap enough, and portable enough. I've returned several for free overhauls, though (but have another completely blanked out one waiting to go back as well).

One thing to be careful of, with those lean blips, is that they could be a misfire. But, a single cylinder misfire will not typically reach so lean. I usually see misfires as pretty small spikes of maybe 1.5 to 2 AFRs lean.

Also, does your logworks record at half the time rate of reality?

I've gotten lean spikes using my ZT-2 WB. The muffler bracket on my passenger side MagnaFlow muffler broke recently resulting in a hanging muffler. What I found is that the band clamps I was using were allowing
air to enter the exhaust at the muffler/rear Y pipe junction. This was enough to throw off the tune in low rpm region with high VAC/low MAP. I had experienced an exhaust popping whenever I went to decel. I never thought that fresh air at the muffler would make its way all the way back throught the cat and at the collector where both the NB and WB are located. But it did. Once I used new stainless steel band clamps, the EBL Learn VE started taking fuel out where it had been consistently been adding fuel. The BLMs and INT are much more stable now than ever before. The Magnaflows are pretty much straight through pipes, so I still get a bit of exhaust popping when I back off from a hard accel. Didn't have that issue with Flowmasters, but I dom like the Magnaflow with the 2.5" muffler inlets and 3" rear Y-pipe.