spark timing vs lambda

[veeefour]

Kooks with 1 7/8" primaries - some say they are more like mid length but IMO it doesn't matter. Stock shorty headers creates a lot of back pressure
as the stock cats are restrictive and AFR readout is just easier. Long tubes are 4 to 1 type vs 4-2-1 for stock so exhaust pulses are doubled plus cats are less
restrictive(or not there at all). They are passing the lambda sensor way faster and the ECU is "overshooting" the corrections.

Close to 40% in some areas. I also tried to multiply everything by 20-30% but this is not the correct way to do it - you may end with good results for
mid-range but it will not work for top end. The correction can't be "linear". You can observe this problem by comparing STFT between banks. VE rises
with RPM so theoretically you should not have more then couple of tenth's of % - the way I had it before was not acceptable(over 5% between banks).

I used Lambda percentage error and multiplied the Transport Delay by "half %" - as you can see it works like a charm.

[veeefour]

I may need bigger injectors - been hitting over 100% of duty cycle constantly - still works good but it's maxed out and this could also be an issue.
Time to swap to LU47

Max fuel flow for injector = injector high flow rate * number of cylinders
5,533827 g/s * 8 cylinders = 44,270616 g/s

Max supported airflow = Commanded lambda * stoich * max fuel flow for injector
0,82*14,08*44,270616 = 511 g/s
Corrected by stock fuel pressure drop and high flow * 0,95

485 g/s and this is what I'm seeing constantly at top end. That's why GT350 has LU47's stock.

[GSLSE20B]

I may need bigger injectors - been hitting over 100% of duty cycle constantly - still works good but it's maxed out and this could also be an issue.
Time to swap to LU47

Max fuel flow for injector = injector high flow rate * number of cylinders
5,533827 g/s * 8 cylinders = 44,270616 g/s

Max supported airflow = Commanded lambda * stoich * max fuel flow for injector
0,82*14,08*44,270616 = 511 g/s
Corrected by stock fuel pressure drop and high flow * 0,95

485 g/s and this is what I'm seeing constantly at top end. That's why GT350 has LU47's stock.

The gt350 uses the exact same injector as the GT

[veeefour]

The gt350 uses the exact same injector as the GT

The injector data in tune is completely different and the part number is different. Those are LU47's. Not the same.

[GSLSE20B]

The injector data in tune is completely different and the part number is different. Those are LU47's. Not the same.

Like I said exact same part and part number (9F593/cm5187). They are using a different fuel system and require a different calibration as would be expected between the gt and gt350 .

[veeefour]

You are right - I stand corrected. I just compared the data to LU47 sheet - not the same. I could swear I have a different part number in my car - need to check it out.

[GrannySShifting]

Nothing in that thread said what they were actually doing to prevent the WOT leanout/timing additions etc. I had just posted elsewhere about killing the ecus ability to ADD timing.

So does anyone know exactly what to change to keep this from happening or??? I moved the Timer up to 30 seconds from 10.

The Override Target Lambda, when WHAT overrides it? And why would it target 1.0, its always targeting 1.0 at part throttle conditions, if happens under WOT why would you ever want this set to 1.0?

Fuel Cyl Cutoff had 1.05 in most cells, but at high loads had 1.1. How do you have a target lambda when you are cutting fuel OFF? This is its target when rev limiting? Not really sure function is that clear here either

I see Fuel Imbalance Monitor Table being mentioned, but I cant find it in the 2015 Roush cal. Used the navigator feature no imbalance mentioned anywhere

[murfie]

If you are going lean at WOT and you're not hitting TC, TQ managment, IPC, and fuel trims are not way off, its most likely a hardware issue like fuel pump or injectors. large amounts of timing usually only gets added by the knock sensors. leave all their settings stock and they work fine. Correction for temps and lambda usually are not very large or changing quickly. The system is designed to work to the lowest values(based on minimum best torque) and the knock sensors are very sensitive, so you really need to try to get it to an unsafe value. So proper maintenance, a proper fuel system, Not raising MBT values or their lambda correction excessively or for no reason, and not disabling/ modifying the knock sensors filtering and all the tables that help set the knock sensors up to a better starting borderline should reduce the chance of any issues. The fuel imbalance and spark offset tables both work together and modifying one you should modify the other.

override target lambda is when something like an O2 sensor fails and true open loop is used. In closed loop its not targeting exactly lambda 1.0. It targets just rich of 1.0 then when O2s read rich it targets just lean of 1.0. It does this so there is a slight oscillation that can be used for better feedback error. If you are in this open loop condition and WOT PE is met the target lambda will be the WOT lambda values not lambda 1. If a fuel cut or temperature protection condition is met it will then be what those values are. It just will not have the feedback correction as it does in closed loop.

Lambda.PNG

Fuel cylinder cutoff is lambda for torque reduction. Going to a leaner lambda(enleanment) will reduce torque and that may be enough to satisfy the ECUs demand with out spark, ECT, or completely cutting fuel.

The fuel imbalance is under fuel> openloop/base> Fuel mass multipier. You will see the 8 tables that are "vs cyc. number"

[GrannySShifting]

The fuel imbalance is under fuel> openloop/base> Fuel mass multipier. You will see the 8 tables that are "vs cyc. number"

Ahhhhh. Why does every call it fuel imbalance moniter table, when its not labled that at all? That had me searching for another table I cant think of off top of my head for a while because the serach feature in navigator wouldnt pull it up by what everyone called it - was labled something else.

I can garuntee you those tables are a bit hokey. NO manifold is going to be 4-5% richer at 6900rpm moving .5 airload and at .75 airlob is going to be 3% lean, or likely going lean to rich to lean to rich again every 400 rpm even at lower loads. What are people doing with these in high load 4000-up? i would say set them at 1.00 and run few on individual widebands and apply a correction based on real data but I dont have a cross section for that. im also pretty certain the rear most cylinders would be the leanest in a roush supercharger or other PD type application, not the front couple like the tune is laid out (unless my thinking that 1.03 is adding 3% vs nominal is incorrect its actually leaning it out)

Does anyone have NA coyote, Boss manifold, or blower data on which holes are the leanest (assuming the injectors are set to 1.00 across the board and no cyl-cyl modifier is being applied)

[murfie]

In the non beta I think they are labeled as fuel imbalance monitor. I believe it was relabeled as this is a little confusing as it makes most people think of it as a bank to bank imbalance. Its an imbalance from cylinder to cylinder going through the firing order to help oscillate the measured lambda on a single bank. 1(rich)B1,5(lean)B2,4(rich)B1, 8(lean)B2,6(rich)B2,3(lean)B1,7(rich)B2,2(lean)B1. The imbalance is not bank to bank, but on one bank two cylinders will be rich and two will be lean. In the higher RPMs/ loads The lean cylinders will have spark pulled from them so that they are not more prone to knock. This is what the transport delay would be doing, but described in an open loop method. Depending on RPM and load it will fluctuate which cylinders are rich and which are lean.

[GrannySShifting]

What in the hell??? Eff oscillation at high load/rpm, I want the cyl cyl balance corrected! Thats an odd strategy that Ive never really seen employed in that manner

So when people were attributing lean #8 or 7 cylinders to this table among others, what were they doing with it? Im really tempted to make it 1.0 across everything into boost and put 5-7% in the back two like my gut tells me needs to happen LOL

[murfie]

You have seen this strategy before, you just don't realize it. It's exactly how narrow band sensors work. The same rich/lean/rich logic is applied to the wide band to achieve a Target lambda, the sensor can just has a wider range of targets.

[GrannySShifting]

I mean yes we have to mess with it on GM stuff because it will make it oscillate to strong sometimes, but its not a steady state variance via rpm cyl to cyl. That can make fueling issues under load???

This is one reason why I dont like WOT closed loop operation. Moniter, add if you have to, but never pull out and let me get the tune right. Just read the damn lambda and let me do my job! LOL

[murfie]

I've never understood the thinking the back cylinders would be leaner, especially with fuel injection. I was told this even in the early 2000s about the LS1's. We are not talking about a carburetor where fuel would need to travel further to get to them. If anything they would get less air than the front cylinders and be richer. With the large intake plenums and how much design goes into them, I don't think any cylinder is getting any more or less air than any other. If you are using a NO2 TB plate then thats a different story.

Open loop is simple, but extremely limited and doesnt utilize the ecu any better for fuel control than a carburetor does.
Closed loop requires feedback from a sensor so that the error can be measured and applied to fuel control.
What O2 sensors are reading is what happened, not what is happening or what needs to happen. So using a simple closed loop feedback wouldn't yield optimal results. Using a PID controller would yield better results, but it can be further refined, and is, by using a smith predictor. This is basically a closed loop PID controller that has an open loop predictor to make up for disturbances and the time delay on the O2 sensors that a tradition closed loop wouldn't be aware of until its too late.

Using steady state error to correct the models for torque, air, and fuel setup in the ECU, and then letting the ECU do its job will yield the best results, with the benefit of not having to constantly adjust things.The other benefit is knowing if there are any problems its not numbers in the ECU, but a physical problem.

I know it was blamed for it, but I highly doubt it was the direct cause of any engine failures. I see between 12-13 the borderline and cyl-cyl for number 4 has more spark pulled out of it. More likely out of control detonation form tunes that were getting too aggressive. The values in these fuel mass tables have only gotten more aggressive over time in OEM calibrations. a slight increase in transport delay 14-15 with a different exhaust and the introduction of DI in 18. I think these tables should be modified for LTs, but exactly how I am not sure. Roush and Whipple's calibration do not touch these tables, so leaving them alone is probably best.

[GrannySShifting]

They are because of air flow. Air is not evenly divided, this has been check with individual widebands and plug readings many times. Ive seen 10-13% leaner rear cylinder on magnacharged LS stuff