BLMs say rich, but WBO2 and NBO2 and surging all say lean - what gives?

[myburb]

I am not trying to be a smart ass but I don’t understand. Above there was a line in the post.

Even at idle and cruise the WB is around 14.7, but the ECU keeps pulling fuel. I set the BLM limit to 120, becase it would go 108 and run super lean.

Which is it, 14.7 or lean? It can’t be both. If the WB stays at 14.7 the ecm is doing what it has been ask no matter the blm say. It would only look like the ve table wasn’t very good.

[SkinnyG]

Ah, yes, that is unclear. My bad.

I can fatten the VE table until I get 14.7, but the BLMs see "rich" and pull fuel. If I set the VE to what the BLMs want (I lean out the VE), the BLMs still see rich and pull still more fuel to the point of surging and lean misfire. The engine just doesn't want to run where the BLMs want to take it. The ECU wants it leaner, but the engine isn't liking it. Idle, cruise, doesn't matter, the ECU wants leaner. When I look at O2 Averages in the History Table, the -average- voltage is already reading lean where the ECU want to pull still more fuel. The voltages are making sense to what the engine is doing - when it "feels" and "acts" lean, the O2 is telling me "it's lean" and the BLMs are saying "it's rich; pull fuel."

I've limited how far the BLMs can go (120 instead of 108), which has (for the most part) kept me out of lean surging (usually 14.7 at that point), but the BLMS will go right down to 120 trying to pull more fuel.

I'm having a thought that the ECU might be seeing a high IAT sensor and mathematically pulls fuel, despite the existing VE and O2 saying "we're good." Just a thought....

Does that make more sense??

[SkinnyG]

I guess I should clarify: this wasn't a "known good" setup to start with. The factory tune "worked" (more or less) with the unmolested LO3 305 V8, but I've put a very different engine in and I'm sorting it out and trying to make it work.

[SkinnyG]

Humble pie.

I max'd the Open Loop temperature, and set min and max BLM to 128, and went for a drive. OMG. Rich. Ok. So I will do a bunch of datalogging and mapping and get back to you all.

[SkinnyG]

Mind you, it did throw a High-MAP, Rich-O2, and EST codes. I'll check those out first. Maybe make sure the chip was fully seated....

[SkinnyG]

OK,

With BLM restrained to 128, and Closed Loop turned off, I went and did some driving for about 40 minutes. Strangely, the ECU still went into open loop (gasp!). I could -see- "Open Loop" enabled on the TunerPro dashboard. Hmmm....

Nevertheless, with the BLM restricted from going anywhere, it was just me, the VE table, and the O2 Voltage levels. It drove quite nice, with the NB and WB showing me just a few more slight rich and lean spots. I tweaked the VE based on the Average O2 Voltages per cell, then went for another drive with with BLMs now allowed to go as far as 122 (5%).

Almost right away, the BLMs went 122 (my set minimum), ECU was pulling fuel, and I was getting into a lean surge. If, at 5% leaner, I'm getting into lean surge, I must have my VE table pretty close, no? Anyway - here is a screen shot showing the BLM Averages with BLM set to 122 minimum.

18-07-21.jpg

Makes me wonder, since it is STILL going into closed loop despite the Closed Loop Min Coolant Temp set to MAX, there has to be something else going on that I'm missing.

While EGR temp was maxed to prevent it from operating (it is removed and blocked off), I went into both EGR Spark Advance and EGR Fuel Multiplier and set everything to 0 (it wasn't before) just in case it's being enabled despite my temp setting. I haven't tested this yet, but it's the tree I'm barking up right now.

[dave w]

Each ECM might work slightly differently. Sometimes it might be necessary to use a "belt & suspenders" approach to disabling a routine like "closed loop". For example, setting EGR on at 255 MPH should disable the EGR (belt only). Disabling EGR on at 255 MPH and disabling EGR on at 151 Celsius is "belt & suspenders" approach to disabling a routine.

Usually changing the fewest possible parameters is a good strategy for disabling a routine. Maybe setting min/max BLM's at 128 is, or is not helping with disabling closed loop? Some definitions lock the BLM's at 128 when in open loop.

Some definitions like $4D are not as thoroughly "Hacked" like one of the more popular definitions, for example $42. It's possible $4D has parameters that are still undefined? Maybe there is a $4D undefined parameter that would prevent "open loop"?

dave w