jcorenman

Agreed, I think your NBO2 sensor is broken somehow. This is not typical or expected.


It is shown as a pair of values on the Fuel-Mon page, but not logged. I am not clear on what the two values represent. I generally leave O2-adaptation disabled and ignore this.

Correct, this is the "O2 sensor adjust" that you see on the Fuel-mon page, and is also available for logging. This is also what gets turned off in "open-loop" mode, either disabled by coding plug, disabled in ST's Fuel-param page (both of which also change fuel maps), or by a disfunctional or disconnected NBO2 sensor.

Hint: Add a SPST switch to the NBO2 sensor wire to force open-loop without changing maps.

Important: Forcing open-loop (by any method) does NOT disable or reset the "Adaptation" values. This can seriously confuse things.

ptuomov

The adaptation being applied also in open-loop mode is a revelation to me, and indeed important.

Does adaptation then apply to high-load, high-rpm cells as well? If it does, and if adaptation seeks to bring AFRs to 14.7, then if the car ever operates in a closed loop mode in a high-load, high-rpm cell then doesn't the adaptation value for that cell lean the cell seriously under WOT operation?

Also, since you're in the know, I'll repeat one of my above questions: Does the "O2 adjustment value" in the data logs include both the adaptation value and the high-frequency O2 correction or just the high-frequency O2 correction?

AO

Quote]Does the ST2 O2 sensor adjustment value (as displayed on the screen and the data logs) only include the fast-moving correction? You seem to indicate that it's just that. If adaptation is enabled, I would suspect that the value displayed is the sum of the slow-moving average correction and the fast-moving correction, but this seems to be inconsistent with what you wrote above.[/quote] I can't say for sure, but I think the value in the O2 Adj is only the fast moving O2 Adj and does not display the Adaptation values. My guess is that it opperates similar to how the WOT, Warmup Enrichment, etc. maps work in that it's an additive value to some base number.

Don't know for sure, but the O2 Adj value is bound to +/- 20%. When the cummulative adjutment is bound to the same amount or not is unclear (at least to me). My beliefe is that it does not take into account the Adaptation value. Furthermore, I don't know what the Adaptation value is bound to, if any.

Again... what does this all matter? What is your goal? Start with the goal in mind. How you achieve it is not important. Personally, I think you're digging into too many aspects of the LH to be of value.

jcorenman

Yes.

The O2-adaptation is the short-term correction computed by the LH based on the NBO2 indication, which in turn is determined by the base fuel map, acceleration enrichments, any warm-up or WOT map additions, the O2-adaptation values (if not disabled/reset), and any previous O2-adjust values.

The characteristic of O2-adjust is that it "hunts" over a 8-10% range as it seeks a stoichiometric mixture. The 3-way cats like the alternate rich/lean character of this, without cats we don't care.

O2-adjust is bounded by +/- 20%.
O2-adaptation is also bounded, I believe by +/- 25% but I am not sure of that. Disable it, reset it, and ignore it.

Going back to a previous question: Set the light-load areas of the map up for stoich, or close to it. Then consider setting up the moderate-load areas up slightly rich, as you suggested. The LH will generally operated is closed-loop here, and will drive these cells back to stoich. Then set up the higher-load areas up to be however rich you want them for WOT, the LH should be open-loop here.

You will need to do some testing to see where, exactly, the LH switches to open loop: WOT certainly, but also higher RPM and/or load. Log O2-adjust, and Sharkplotter will show you where it is open-loop (larger data-dots), and will also show you where you have knock-retards going on.

Always log the knock-retard (KR) numbers, when plotted against RPM & load they tell you a lot about what is going on.

Remember that both EZk and LH have WOT maps: The EZK's WOT map replaces the RPM/Load map with a simple RPM-based map, and should be disabled-- do all of your tuning in the main map.

The LH's WOT map adds fuel to the base RPM/load map, and should be zero'ed unless you want to replace the WOT switch with a pressure switch and make it a high-boost enrichment.

A lot of stuff in the LH and EZK mapping is there to keep the engine "safe" with aging MAF's (which trend lean with age), sensors that may be out of cal, etc. So the separate WOT maps can be disabled or hijacked for other purposes such as high-boost enrichment, O2-adaptation can be disabled, etc.

Cheers, Jim

ptuomov

My goal is to build and tune a car that
- gets produces a reliable 600-800 hp at the crank
- gets over 20 mpg on highway cruise
- runs with cats and the cats last
- idles like a clock
- transitions between high-load and low-load states like a turbo car that came out of the factory

I believe that if I start randomly disabling features from the stock ECUs without really understanding what these features do, I will probably not achieve my goal.

John Speake

If you stay in closed loop, then you won't achieve your goal of wanting steady state non-WOT throttle settings to give you richer than Stoich A/F ratio.

You will be able to adjust the transient enrichements when you apply a little more throttle (below WOT)

As you haven't yet put a WBO2 on the car, what is your perception of a problem with the car as John tuned it ?

In what way doesn't it meet your targets above ?

ptuomov

I basically went to get the car from John before he had finished tuning, so that I could learn how to do this on my own before I drop in the new engine (featured in my current avatar). When that one goes in, the ECUs need to be remapped, since the head CFM changes, cams change, and static compression changes. I want to be able to do that big project on my own, so it seems logical to me to start tinkering with this engine.

The car drives really well. I drove it 910 or so miles to Boston, and have been playing and commuting with it. From the objective perspective, there's no problem. If I had bought a car in this tune from a dealer, I wouldn't complain.

But this is a hobby and therefore there's always something to tinker with. And me trying to understand how LH and EZ-K work is part of the hobby. Even if the tune would be guaranteed to be perfect, I'd still want to understand how the ECUs work.

That all said, there are some perceived "problems":
- Idle hunting when A/C, which I was able to cure. It was as simple as aligning the steep part of the slope in the EZ-K idle table with the LH idle rpm set point.
- There is a slight hesitation or jerk sometimes when lifting the throttle after acceleration.
- Most importantly, I don't know how much power is still left on the table before hitting the knock limit. It's really interesting to me how far one could push the stock long block. John thinks there's 50-100 safe hp still left on the table. I don't know, but I want to find out.

It's just a hobby, I guess it all boils down to that.

Bill Ball

1. Does putting a switch in the O2 sensor wire really cause the LH to go open loop or does it just set the O2 at zero voltage, i.e, a false somewhat lean? My impression would be that w/o changing to coding plug, the LH would continue to read the O2 but as zero voltage (lean). With narrowband, it's only slightly lean, and the LH only has limited range for responding to this, so it's not like it would then force the fuel to super rich, but I don't see how effectively cutting the O2 wire is the same as open loop.

2. Disabling O2 adaptation confuses me too. If you are forced open loop via coding plug, the O2 sensor should be ignored, so how could the adaptation setting of the O2 sensor have any effect?

The "force non-cat" or "ignore coding plug" and "disable O2 adaptation" in ST are only active during tuning, right? So, you would physically have to alter the coding plug to force non-cat/open loop after tuning, right? I've read whatever versions I have of the ST manuals and can't find this spelled out.

John Speake

The jerk may be the injectors switching back on after the rpms drop below about 2k rpm on decelaration ?

Do a data log at WOT in a low gear and monitor EZK load, rpm , knock and Kr1-8. You will also hear an audible squark for each knock count.

A run through a gear at WOT may give 1 or 2 knocks, I would say that was safe on a lower spec engine, but I would retard igntion slightly to give no knocks in your case.

But before you do that, get the WBO2 on there and check the mixture is safe at the top end (12.5:1 or richer at your level of boost) before you play with igntion.

I have the answer on what igntion advance is measuring.... the answer is the advance on whatever cylinder is active at the time of the data sample. If no retard is being applied, then you get a correct answer. If retard is being used then you will get a random value each smaple.

John Speake

Hello Bill
1)Swicthing out the O2 sensor will force the LH ECU to go to mid range O2 loop value. You are still working on the cat maps.

We should really be more exact with "open loop" and "closed loop ", maybe use "cat mode" and "non cat mode"... and "cat mode with O2 sensor disconnect".

2) If you change the coding plug to go to non-cat mode, adaptation of O2 loop clearly is not effected, but idle adaptation still is.

3) "Force cat mode" or "ignore coding plug" are effective when tuning and also when not. BUT note that this ONLY affects the LH ECU maps in use, the EZK will still obey the coding plug.

"Disable O2 adaptation" is also effective in both tuning and non-tuning modes.

Hope this helps...

Bill Ball

Did John perhaps disable the fuel cut-off on decel/closed throttle? Some racers do that, but the fuel cut should be left on for a street car.

ptuomov

Thanks a ton for that answer!

More generally, thanks again for the wonderful ST2 device and the help in understanding how the ECUs and the ST2 device works!

jcorenman

That's an option on the ST's Fuel-param page. I disabled fuel-cuttoff on decel for our GT, makes a nice little burble on deceleration. It also seems smoother on and off the gas at light throttle, but that may just be my imagination.

Toumo, I doubt if this is the cause of the hesitation you are seeing, but you might give it a try. The fuel map should also be quite lean in this area or it may backfire. (Louie's formula for a "nice show" was quite rich and very little advance, as I recall).

Cheers, Jim

John Speake

Thanks - you're welcome !

hans14914

OK, now I am confused/curious. What is the optimal setup between coding plugs, internal ST2 "coding" parameters (ignore coding plug, ignore 02... ) for a boosted car. I am not sure I would want much if any O2 adaptation after getting a map dialed in. Also, does O2 adaptation skew SharkPlotter results, or does SP extrapolate the O2 enrichment map into the standard fueling map?

Is there a way to lock cells so they cant be re-written by the LH dynamically? I can see how having the O2 adaptation could be useful in the lower RPM/load range where its just slightly off idle, like neighborhood/parking lot driving speeds, but anything above that, I am not sure I want the LH messing with a good SharkPlotted tune.

Sorry if these are total newbie questions, we are getting our local ST2 next week.