I thought I've already made this clear, but I'll try again.

Lean burn isn't "hotter" overall. There is indeed less overall heat. Hence less power.

Lets look at this one way:
The more fuel you burn, the more energy (HEAT!) you release.
The heat is a direct result of the flame temperature.

Flame temperature vs equivalence ratio (equivalence = 1/lambda, so numbers <1 are lean >1 are rich

As you can see, going lean does indeed drop off in temperature quick. We get more power being rich because even though flame temperature lessens slightly, we burn more fuel, getting more overall heat.

Now if we assume a cylinder has an adiabatic process, that means all of this heat goes into pressure (because the volume of the cylinder is fixed). The problem is NOTHING is a perfect adiabatic process, so the heat has to go somewhere.

So now we look at what's left to heat:
- Gases in the chamber
- Cylinder head/wall

Heat will start to TRANSFER via the normal routes (convection, radiation). Heat transfer is determined by two things: How much heat, and how long.

From the Wikipedia article on Lean Burn:

A "top" speed cut-off point is required since leaner gasoline fuel mixtures burn slower and for power to be produced combustion must be "complete" by the time the exhaust valve opens.

AKA Lean burn takes longer. This is hugely important.

So we know Lean takes a longer time, so there's more time for heat to transfer, despite less heat.

Now we need to look at where the heat is transferring.
In a simplified manner:

Lean:
- Nitrogen (from air)
- CO2 (from complete combustion)
- H2O (from complete combustion)
- Oxygen (we had more oxygen than fuel!)

Stoich:
- Nitrogen (from air)
- CO2 (from complete combustion)
- H2O (from complete combustion)

Rich:
- Nitrogen (from air)
- CO2 (from complete combustion)
- H2O (from complete combustion)
- CO (from incomplete combustion)
- Hydrocarbons (from incomplete combustion)

Now from that "Ask a scientist" you directly posted:

Now you have to look at what is being heated in the combustion process. If the fuel / oxygen mix is "lean" (excess oxygen), the heat capacity of the gas in the cylinder consists mostly of nitrogen and CO2 -- all the hydrocarbon is already burned. This mixture of gases has a comparatively low heat capacity. As a result the temperature skyrockets (you are heating less gas and those gases have relatively low heat capacity (e.g.) nitrogen.

So we have a couple problems:
A) Lean burns longer
B) The left over heat transfers into low heat capacity gases and cylinder

So the overall temperature GOES UP.
At stoich we have less time with the same gasses.
When rich we have little time, with HYDROCARBONS. Hydrocarbons heat capacity is high (its what we abuse to release the power in a way), so it sucks up the heat and you send it out through the exhaust.

Even though the temperatures are lower for lean, the time is longer, the heat capacity of whats left in the cylinder is incredibly low, so it does indeed get HOT.
This heat, which was less to start with (less fuel), didn't go into pressure expansion either. It simply burned too slowly for that to happen, so we lost torque in the process.

I don't know how much more or better I can explain this, but I promise, I'm not trying to mislead or make stuff up.
Leaner in general will increase cylinder temperatures. The whole fact that NOx emissions goes up is indicative of that. It's evidence for the crime of raised temperatures in the gases in the first place. The energy goes into the nitrogen and oxygen, to the point that they start to react with each other!

Leaner is HOTTER from the reference of your engine block, as it will see more heat. Richer is COOLER because that heat never makes it far enough to hit the cylinder, it gets absorbed by the gases.

Vince Calder in Ghost's link says that as well, as would many other people familiar with combustion engines. Notice Bob Wilson in the link was talking about the temperature of the BURN, not the temperature of everything else. That's the key part he's missing. His model is over simplified.

If after all this, you still don't buy what I have to say, here's an experiment for you to try if you really stand behind your logic:
At WOT, we run rich, which is cooler. By your logic, running stoich is the hottest we can get, and then after stoich it gets cooler again.
So, logically speaking, there is a lean point beyond stoich which is cooler, that you could run at WOT.

If you're guys' theories are right, you should be able to run WOT lean of stoich, without an issue.
By all means, go ahead. Target 1.1 or 1.2 at WOT. I mean after all I'm just a guy on the internet

(But really don't do that, or we'll see you in the Blown Motor resource thread after your engine suffers a glorious HEAT death from heat-induced knock.)

But hey, don't listen to me, I'm just a guy on the internet

 

I dont disagree with anything you're saying there. I grasp it. I'm not disagreeing that a higher percentage of the heat created during lean combustion events gets transferred to the cylinder and head instead of being absorbed by unburned fuel and spent out of the exhaust.

What I am saying is that I believe there is a huge difference between WOT operation and low-load cruise. The variable is fuel mass.

Without knowing the exact numbers, I'm going to try to make up an example that tries to exhibit what I'm thinking. Excuse my inability to produce accurate temperature data, because I don't feel I have everything I need, and honestly I don't know how to properly calculate it.


Example: ~2300RPM cruise vs ~2300rpm WOT (with Idle as a reference point)
(Idle logs show 0.37 lb/min airflow mass, we'll calculate for 14.7 AFR)

6th gear, at 62mph, cruise control set, level ground. (according to a datalog I did of this exact scenario)
Manifold Vacuum: -6psi (12inHg) steady
RPM: ~2350
Load Actual: ~0.360
Airflow Mass: ~2.3 lb/min
AFR: 15.73:1

3rd Gear, WOT (Also from a datalog I took)
RPM: ~2350
Boost/Vac: ~14psi
Load Actual: ~1.600
Airflow Mass: ~10 lb/min
AFR: 11.91:1


Let's look at the different scenarios. The only real values we're concerned with here is Airflow Mass and AFR.

First, I want to convert lb/min of air to grams per second for some extra resolution.
.37lb/min = 2.79g/s @ Idle
2.3lb/min = 17.39g/s @ Cruise
10lb/min = 75.60g/s @ WOT

Now, I wanna figure out how much fuel I'm burning for one second of time at the respective AFRs. I know this isn't entirely realistic for the WOT pull because the car wouldn't maintain that load/rpm/airflow for a full second, but it could on a load-bearing dyno, so I'll deem it a valid test.

Idle: 2.79g of air at 14.7 AFR means 0.18 grams of fuel over one second of time.
62mph (2350rpm) Cruise, for 1 second: 17.39g of air at 15.73:1 AFR means I should be burning 1.10 grams of fuel over one second.
2350rpm WOT, for 1 second: 75.6g of air at 11.91:1 AFR means I should be burning 6.34 grams of fuel over one second.

What we all know to be true becomes very clear here that at WOT we are burning significantly more fuel than we are at cruise, RPM's being equal.

Now this is where it gets difficult because I couldn't find how much energy a gram of gasoline has in BTU. What I did find is that 1 kilogram of gasoline has 46.9 megajoules of energy. So I did some conversions.

1 kilogram is 2.2lbs. Using Google's conversion calculators, I found that 2.2lbs is about 998 grams. and 46.9MJ is about 44,453BTU. Diving BTU by 998 grams gives us (I think) what we need here...

1 gram of gasoline has about 44.54BTU, therefore;

Idle: 0.18/s of fuel = 8.01 BTU per second
Cruise: 1.10g/s of fuel = 48.99 BTU per second
WOT: 6.34g/s of fuel = 282.38 BTU per second

So here's the tricky part. I have tried to estimate here how much heat in BTU is being created for 1 second of time under each circumstance, but what I now need and do not have is the percentage of heat being absorbed by the engine in each scenario. We already know that less heat is transferred to the engine components in a rich condition, but we don't know exactly how much as a percentage. So I'm going to make a wild scenario that is probably much more dramatic that what is really happening but will still highlight me entire point, hopefully.

Let's say during the lean burn that 100% of the BTU is absorbed into the head and block, and that during the rich burn, only 50% is absorbed, and that stoich splits the difference. Obviously, 100% of the heat can't possibly be absorbed by the engine under any condition, but I feel this example no matter how exaggerated only magnifies the idea that lean burn causes more heat to transfer to the engine than rich burn.

Applying that ridiculous scenario, we see:

Idle 8.01 BTU, 75% gets transferred to engine... 6BTU absorbed by engine
Cruise 48.99 BTU, 100% gets transferred to engine... 48.99BTU absorbed by engine
WOT 282.38 BTU, 50% gets transferred to engine... 141.19BTU absorbed by engine

This is my entire point. The fuel mass being burned at cruise is SO LOW that it's just not producing enough total heat to make a significant difference. Even if 100% of the heat energy that the burn created were transferred to the block, it would still be nothing but a fraction of what the cooling system is designed to deal with. I feel the coolant easily could, and almost certainly does, pull every bit of that extra heat from the head and block and throws it right out the radiator with zero problem.

So, yes, lean cruise allows a higher percentage of its heat to be transferred to the cylinder head, cylinder walls, piston heads, valves etc. BUT, the total amount of heat created (and therefore absorbed) is still so low that it doesn't matter. A higher percentage of heat absorbed means nothing if the total heat available to be absorbed is practically zero. I feel like that's the part that we're not paying attention to. Sure, at WOT, you don't want to absorb that extra percentage of heat, because theres a lot of total heat there that could damage parts, but at cruise, total heat is so low that it's not making a significant difference.

EDIT: I'm not trying to argue, I don't feel we are arguing. I just want to point out that WOT and Cruise are two completely different scenarios and that the difference between total amount of heat being generated is so great that 100% of one is still much less than even 50% of the other. If we know the cooling system is able to handle 50% of WOT heat without blowing up or overheating, it should and probably does handle 100% of cruise heat because total heat at cruise is just so much less.

And no, I'm not gonna run my car leaner than stoich at WOT. LOL

 

Okay, so now I think I've got the heat point across, lets concentrate on the other part, cooling.

First, 1kg to 2.2lbs to 998 grams is a silly conversion 1kg is by definition 1000g.

Second, the other important factor is COOLING the engine from that heat.
We have to also think about how many MJs of heat we can pull out of the engine block during these various conditions.

There are various cooling factors in place. From inside the cylinder, and in particular this car, we have several cooling areas:
- Coolant: Cools the walls, heads, and exhaust headifold.
- Oil: Cools the walls, valvetrain, and pistons (there's also piston oil squirters in this engine supposedly)
- Fuel: In our engine, cools cylinder wall, piston, and exhaust valves.
- Air: This does lots of duties actually It keeps the radiator cool so it comes back to temp, it keeps our charge temps cool so the air in the cylinder is cooler, and it helps cool the oil when flowing over different components. Its component cooling is minor, but the radiator one is HUGE.

At a lower RPM, both Coolant and Oil flows slower, which lessens their cooling values. As RPM raises, Oil moves quicker, Coolant moves quicker, and fuel is injected more often. All of these raise our cooling capacity.

When we run lean, we take out a very important one: Fuel. The unburnt fuel (hydrocarbons) have a HUGE heat capacity.
Your equations for BTUs released doesn't take in to account that when running at WOT nice and rich, not all of it burns. And the stuff that doesn't burn can soak up A LOT of that heat that was released.

Even with that though. WOT at steady state cannot almost never be done on even a load bearing dyno. The engine still gets too hot and the dyno fans cant push air over the radiator fast enough. WOT on an engine dyno like an OEM does has special cooling setups. Intake Air is chilled, the coolant usually goes through essentially a big air conditioner, and still some engines can run too hot for WOT steady state.

So lets play with your numbers here (not going to vouch for their validity, but they'll be close enough )
Idle = 8BTUs
Cruise = 50BTUs
WOT = 280 BTUs - Unburned adjustment: (11.9 = 0.8 lambda. Theoretically speaking we'll graciously burn 90% of it, which is probably an over-exageration) and get 250BTUs.

Now, we need to look at cooling contribution:
Idle cools pretty well assuming your coolant fan and water pump are working, but on the other hand,Sports bikes for example, have idle overheating issues. They get WAY too hot at idle, despite the minor BTUs. The main reason is just getting airflow over the radiator. We're operating at stoich with just enough torque to overcome losses, so all component temperatures usually remain fine. At stoich, fuel only contributes minor cooling, as most of it burns.

WOT. We're generating the hypothetical 250BTU. Our RPMs steadily rise, increasing coolant and oil flow, keeping our valvetrain and cylinder walls mostly in check. The oil squirters help keep the bottom of the piston cool. We run RICH, which helps our power improve, but probably even more importantly, it absorbs a ton of heat. The piston's crown and exhaust valves stay cool. We probably have a cooling capacity while moving through the air of 230ish BTUs, leaving only 20BTUs into the engine. But even at a track, we don't run WOT continually, and as soon as we lift off, we have more cooling capacity than generation, especially with RPMs staying high, so around the track we can hopefully stay cool enough to keep going for the day. But maybe we don't. Some people on this forum have had some overheating issues where the engine starts to cut boost because of temperature limits. (There's also one thing we're leaving out, but running too rich can start to raise exhaust gas temperatures and manifolds will start to glow, as combustion starts to happen slightly in the exhaust and all the heat the fuel absorbed gets transferred into the exhaust.)

Lean Cruising, we have airflow and plenty of coolant circulation. Oil circulation is also fine. But we're missing one important thing. Fuel cooling. It all burns away (at least until we start misfiring), leaving very little fuel behind. Remember heat and temperature are two different things. We might have less heat, but where it goes and gets absorbed raises the temperatures. The piston crown gets hot. The spark plug gets hot. The exhaust valve gets hot. We might only have our theoretical 50BTU going through, and our coolant stays nice and cool, but parts not touched by coolant, that are cooled and protected by fuel, are no longer protected.

That's where the issue arises.

Also just as a point of contention:
Lets flow 20lbs/min of air (about mid RPM), but run at that 1.1 lambda and 0.8 lambda:
1.1 lambda: 9.35049206 g / s = 416BTU
0.8 lambda: 12.8569266 g / s = 572BTU (lets do the 90% thing again here) = 514BTU

Rich is making more heat (MOAR POWAH!), but the cooling caused by fuel negates a lot of it, and we don't blow up.
Lean is making less heat, but will easily put a hole in your piston.
Of course using your 50% vs 100% we'll quickly see lean takes in more heat overall, but it would while cruising as well.
While your argument about total heat works in general, it's missing the time aspect.
I can boil water on medium heat or high heat. High heat takes less time, but both eventually raise the temperature.

In this case our medium "lean" heat will last much longer (the whole time your cruising!) then the high "rich" heat (WOT), and that time could eventually do damage.

That should make it clear that while rich may make more heat, lean's heat is more dangerous, because the heat it makes is absorbed into components you don't want.
Also remember heat transfer takes time, we might have less heat to transfer, but you spend more time cruising than you do going WOT, and you have less cooling capacity on components in the cylinder.

Every production lean burn engine I know of to date does something to address these issues. (And has fancy catalysts for the NOx, which we're ignoring as you don't have a catalyst anyhow )

First, all of the lean burn engines built to date have used a high compression ratio (at least for their time period), increasing the efficiency of the combustion process (converting more the energy acrobatically into pressure, and not waste heat).
Chrysler had a trick timing system (one of the first mass production electronic spark control systems by the way), which worked quite well for the time. It modified timing to increase efficiency. It had careful temperature monitoring that would disable the system and retard timing to lower temperatures. (Though we don't want to retard too much, as suddenly a lot of the heat will be wasted and cause the same issue!). It wouldn't pass modern emissions (NOx wasn't a deal at the time), and it suffered reliability issues mostly related to the computer.

Cummins achieves their system for gasoline by using a double injection system. A very lean initial setup (Like 28:1) is placed in, and then a rich mixture is put in quickly (about 7-9:1). The rich mixture ignites quickly, and expands out, which both helps prevent misfire, and raises the flame speed (and thus the time it takes to burn), which increases the engine efficiency, keeping waste heat down. Regardless, Cummins engines are heavy-duty, and have extensive cooling to deal with the extra waste heat.

Honda does a similar process, but via different means. By using stratified injection, where the AFR next to the spark plug is rich, but the overall mixture is lean (basically its non-uniform, but the average is lean), so we save fuel, but we can start the combustion as it's rich there, and the initial flame propagation is like-wise fast, helping prevent waste heat.

The Focus has none of those things. It has no way of keeping waste heat down by having a stratified injection, it's not a high compression engine. It's just not made for it, so you'll suffer the normal consequences of excess heat and wear for no reason.

I'm not saying you in particular will blow up, but keep this in mind moving forward. Lean cruise adds heat to important combustion components far more than the standard stoich would. More heat is more wear on the components even if you don't push them far enough to wreck your combustion chamber.

Is it worth the 2-3mpg?

 

I don't think 2-3 mpg would generate enough monetary savings to offset the lost revenue of time spent thinking about this instead of being at work making money. LOL

I see what you're saying... I'm just wondering what the actual values are. It would be a much easier question to answer if we knew the percentage of heat that gets absorbed in rich vs lean situations. I'd also like to know how much heat the cooling system and oil could remove at cruise RPM. That would make a lot of this less hypothetical.

I would think that running something near 15.25AFR (1.03 lambda) at cruise is probably not lean enough to cause much temperature change. Maybe the 1.08+ range might? I don't know. These are all questions that we cannot answer because we just don't know what the temperature is of these things inside the engine.

It seems like the fluid temperatures (oil and coolant both) should be higher than normal during an extended lean burn cruise. But I guess that's hard to say or test because unless you're doing 40-50 miles on a completely flat road (damn near impossible anywhere) you're never going to be running lean for long stretches. It's almost always a little bit uphill then a little bit downhill then a little bit flat then repeat.

Taking that into consideration... I'd like to point out that my Closed Loop fuel targets are only lean for a very thin window of load ranges. If the car starts to go uphill, load increases and it richens up, and when load decreases going downhill, it richens up as well (as the computer blends cell values to the idle load AFR target). Also, the fuel injector cutoff on full deceleration is still there as well, so when I'm completely off the pedal, it just pumping air which is doing its cooling job too. So it's constantly going back and forth, only during actual steady-state flat road cruise is it lean. I wonder about in that real world scenario if staying lean for such short periods of time is long enough to make everything get that hot, do the periods of enrichment due to load fluctuations keep part temps in check? Who knows!?!?!?

Either way, all of this does make sense to me. I think engine part temperatures probably do rise, but I still have my doubts about how much they do in the real world being that my AFR isn't lean for long stretches of time. I suppose I may richen it back up to maybe 15.1 - 15.25 range (which should be safe?) until I can figure out how to determine exactly how to see how hot things are getting in there.

EDIT:... yeah... I don't know what I was thinking when I did the 1kg to lbs and back to grams thing... This is what happens when you're on FST at work and you're not fully paying attention to EITHER OF THEM! haha

 

Getting real numbers on that kind of thing is hard and requires some expensive equipment unfortunately

I understand the desire for cold hard numbers. Honestly 1.03 isn't going to be that bad (direct injection does have its benefits!). I thought we were talking going like 1.1 or more.
The heat difference between 1.00 and 1.03 is probably only a few degrees C. even to the parts.

You're probably fine, but if you do ever manage to get a temperature probe in there, I'd love to see the data


To prevent myself from making unit conversion mistakes, I make way too much use of Google
For example: 20lbs/min to g/s at 0.8 lambda

 

Yeah I wasn't ever considering trying to run it at 1.1 or more. The most I've tested was 1.08 (15.85:1) with idle staying close to 1. I figure anything under 1.1 is probably safe, but will create some small amount of extra heat.

If I ever win the lottery, I'm buying all sorts of wild equipment and I'm going on a science binge IN the name of high performance automobiles that still can get decent mpg haha

 

ANYWAY... Back to regular tuning tomfoolery with ATR..

I was looking in the Advanced Parameters (Toggles) list and I have some questions. Maybe you all know...

There are 4 fuel responses to overtemp conditions... Catalyst, Exhuast Flange, Exhaust Valve, and O2 Sensor. All of them are unchecked on an OTS Stage 3 map. Why? I can understand unchecking the catalyst one if you don't have a cat anymore (like myself) or unchecking the O2 sensor one if you've removed your rear O2 sensor even... But why disable the high temp response for Exhaust flange and Exhaust Valve temps? Are the thresholds so low as to always be hit? There seems to be no explanation about the operation methods and parameters of these other than giving you the option to turn them on or off.

It seems to me like in my case, I should have them all on except for catalyst. I can't see what harm they would do to have on, but I can imagine what harm they would do to have off in the event you were to need them.

@COBB?

Also, since we're talking about this screen of options, I see there is a check box for enabling/disabling the compressor bypass valve. When I get around to swapping the turbo out, I know I'm going to have to install a BOV in the charge piping. When I do, do I just un-check that box and then run the BOV vacuum line from a manifold vacuum source to allow it to function directly off of throttle closures? Seems like the easiest way to do it, if that's the case... @matt@pandamotorworks?

 

ANYWAY... Back to regular tuning tomfoolery with ATR..

I was looking in the Advanced Parameters (Toggles) list and I have some questions. Maybe you all know...

View attachment 59035

There are 4 fuel responses to overtemp conditions... Catalyst, Exhuast Flange, Exhaust Valve, and O2 Sensor. All of them are unchecked on an OTS Stage 3 map. Why? I can understand unchecking the catalyst one if you don't have a cat anymore (like myself) or unchecking the O2 sensor one if you've removed your rear O2 sensor even... But why disable the high temp response for Exhaust flange and Exhaust Valve temps? Are the thresholds so low as to always be hit? There seems to be no explanation about the operation methods and parameters of these other than giving you the option to turn them on or off.

It seems to me like in my case, I should have them all on except for catalyst. I can't see what harm they would do to have on, but I can imagine what harm they would do to have off in the event you were to need them.

@COBB?

Also, since we're talking about this screen of options, I see there is a check box for enabling/disabling the compressor bypass valve. When I get around to swapping the turbo out, I know I'm going to have to install a BOV in the charge piping. When I do, do I just un-check that box and then run the BOV vacuum line from a manifold vacuum source to allow it to function directly off of throttle closures? Seems like the easiest way to do it, if that's the case... @matt@pandamotorworks?

If you're going to run the external BOV from the intake manifold vac source, then yes, uncheck that box. If you don't have a vac source or want ECU tunability of the valve, then leave it checked and connect the valve to the factory solenoid. That's how mine is set up. Can't say it's better one way or the other. I have the stock intake mani and didn't want to drill and tap for a port, so I used the stock solenoid.

 

My girlfriend was watching me look at logs while I was tuning VE for light/medium throttle drivability and noticed that they all come from excel spreadsheets. I was explaining that I have to make adjustments so that the end goal is to have the total of LTFT and STFT be within 5% for every single situation...

She called me silly... and then took the keyboard click click clickity click click and BAM... new row of data for which each cell is the sum of LTFT and STFT for its respective row.... I loaded it into datazap, so much easier to look at.

HDFX Driving Check

Whyyyyy has no one mentioned such amazing things before? I did a search of the forum and couldn't find anything about anyone doing this for themselves to ease data analysis....

 

Any of you guys have a look at the update for ATR and the v2.04 maps? My self tune is based on a v2.03 map, but I understand there are some significant changes in 2.04.

I'm wondering if it's worth just copy/pasting my VE table's over to v2.04 and starting a new self tune from there? Any of you have insight on this?

 

I don't see why not. The BP change is nice. I had a lot of fluttering before that is now gone.

 

Is the boost target about the same? I didn't change my target from the factory cobb stage 3 map. I also don't see myself using the map switching.

What I may do is just load up the 2.04 file and turn off map switching, swap out VE tables with my current file, swap my power demand and closed loop fuel targets over, and then flash that to the car to start logging and adjusting spark from scratch

 

they're set to 1 so nothing changes

 

Swapped over my VE values to the 2.04 base map, also swapped the spark tables and scaling and LTFT breakpoints and such. Everything seems good. Smooth. Switching is cool (never used it before)

I mentioned in the Cobb Alpha firmware thread that my OAR isn't moving from 0.0 though... Couldn't get it to learn at all last night or on my way to work this morning. Don't know what's going on with that yet.

 

OAR has moved from zero to -1.0 as it should. Took a lot more miles of driving for it to budge at all initially.

I guess some people are seeing less boost on 91oct 2.04 tunes? I haven't paid much attention to mine, but I'll try tomorrow and see if the 93octane 2.04 tune has the same issue for me.

 

Car seems to be running really well across the board. Trims are good. I'm going to start tweaking WOT for power when I get back from this work trip that I'm on. Got a dog last weekend so I've been a bit busy and unable to do pulls for logs.

 

Well, I've gone and broken my clutch foot. Gonna be out of commission for a while during the healing process. In the interim, I'm going to try to do some reading and sharpen my understanding of the systems we have here on our cars. If any of you have any suggested reading, please send it my way. Thanks.

 

Ouch. That's one of my big fears with driving stick. Especially since the wife doesn't want to learn lol.

Get well soon!

 

@BoostedSTIG

Starting to mess with VE corrections as some of my LTFT are 9% and have some STFT on top of that. Starting with idle as that seems the easiest and then perhaps some steady state and then WOT. From the tuning guide, looks like we just identify which HDFX table is being used an apply STFT+LTFT at a given RPM to correct the VE? How are you handling situations where you have multiple HDFX tables being used in terms of applying correction based on percentage of weight?

 

What I've done is started at certain points where two or more tables are at near even weights.

For example, if WOT at 4500rpm tables 7 and 8 are both at 50% and combined trims are +9... I start at tables 7 and 8 at 4500 and make even adjustments of about half that. Tapering in both directions.

I don't do the mathematical calculations and weigh the adjustments, I make even adjustments to all of the active tables. Small ones. Then reflash and retest.

I'm not home at the moment, but once I get home I'll pull up a datalog and make some example points for you.

The easiest ones are where there's two or less active HDFX tables.

I started at the higher RPMs WOT and went downward because there are less tables active there.

as far as cruising situations, I make logs of using cruise control and adjust from there. Usually steady state cruise is only using a blend of two tables at any time.

Remember that LTFT is associated with the Learnjng breakpoints scaled in CFM, so at low load cruise at almost any speed, LTFT will be similar because airflow will be similar. You won't ever get it perfect, but I've gotten mine to stay within 4-5% in almost every situation I've logged (WOT, Cruise, medium throttle, heavy throttle, light throttle) it took a long time, but it's close.

 

Cool, I think I'm getting the hang of it. The 4500+ part of WOT tuning seems pretty easy as it appears to favor HDFX 7 the most. Idle is another easy one...HDFX 1.

Going back to the days of HP Tuners, maybe we should be doing STFT corrections only and just disable LTFT while doing this. It seems like LTFT is applying such a broad correction that isn't exactly specific to what is happening at the time we are logging.

 

You could disable LTFT. I wouldn't sweat it too much though as long as you can get the sum of the two trims to be at 5 or less when you turn it back on.

I left mine on because I wanted to be able to see the adjusted values when I loaded it and be able to log again on the new flash without having to re-flash to disable LTFT again.

 

I've honestly had to make zero changes to VE with my modifications so far, and I'm still just a downpipe short of 'Stage 3'.

I've never had LTFT issues, and the normal STFT we see (on tip-in as we boost, and at 4500RPM+) I corrected purely with transient tuning.
I'm pretty sure none of the standard modifications would cause significant VE changes, except for an intake manifold. VE is like "how much air does this MAP pressure cause to go into the cylinder".

That means everything pre-map should already be fairly well accounted for, because they really don't significantly effect the airflow. After air has gone through an intercooler, through the long piping we have, its pretty solid by the time it reaches the MAP sensor. I'd only expect post MAP (like intake manifold and actual head changes) to really affect VE. Everything pre-MAP honestly should have almost zilch effect on your VE. Air should be laminar by the time it hits the throttle body (else throttle position wouldn't be consistent in controlling air flow). So it should really only be items directly connected to the heads that will affect VE much. Intake Manifold and turbo.
I wouldn't even expect the downpipe to make too much of a difference on VE to be honest, at least on this car.

Tuning VE is something a lot of people jump to very quickly, but tuning VE correctly means removing transients from the calculation, which for a WOT pull just won't happen.
So be careful!

 

I've never tuned a car that had perfect MAF calibration or VE tables 100% accurate. Outside of idle, my fuel LTFT is generally 5%. Idle has been fixed though where it was running 12% at most times and my car has stopped smoking like....a smoke stack....on startup.

 

Are you still running an E30 blend? Your Stoich Scalar may not match your fuel. I noticed with my blends my match was not perfect, and that caused me to be off until I zero'd in on it.
MAF transfer and VE tables from the factory should match your car fairly close, enough to where the KAM adjustments can hone in on the last bits in my experience.

Perhaps I've just been lucky in that my Focus hasn't required any changes. I can't speak to any previous cars I messed with, as I usually had swapped heads and cams, which has a dramatic effect on VE.

 

Sorry I've been off the radar lately. Broke my foot a month ago and haven't been able to do much with the car and have been busy trying to keep an income rolling in for myself until I can go back to my day job.

I'm still around though.

 

It's been very eye-opening reading through this thread and should hopefully give me some good points to work from when I begin self-tuning mine within a month or so!

 

Lots of good info floating around here and on the rest of the forum too.

Also, I just got my cast off my foot. Going back to work feels good. Hopefully I'll be able to get a few more good revisions of the tune in before winter hits.

 

Well now that in back to work and healed from my injury I've been able to be mobile enough to start fooling with the car again...

I fire up ATR today and get an update, plug in my AP and get an update... Looks like it's time to rebuild my tune based on 3.00 so I can use these new features.

By the time I got the first new file flashed, it was too chilly out for any logs, kept ripping the tires loose in 3rd gear and wasn't about to attempt a 4th gear pull anywhere near this area.

What I'm trying to do is go to the drag strip this weekend with a few buddies in Sunday, assuming the forecast doesn't get worse. I'd like to use the track as a place to get some logs while going at it hard.

I'm also interest in attempting to tune boost by gear and this would be a great way to test that out.

 

I'm going to be in Chicago to see Ace Frehley in November

 

Yeah!!!! I'm trying to go to that too but i haven't gotten my tickets yet because i just got back to working and money is extremely tight right now until i start getting some checks. But for sure I'm gonna try to go. Ace is my dude!

 

Sounds good!

Should have my AP and ATR very soon, so I should be starting self tuning mine soon