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Hey guys. Just looking to make sure this tune is "safe". This is what I've come up with after a couple days of trying to tune my first car. Its a TB2541 Turbo, EV14 injectors (630cc), 1.8 2000. Car drives fantastic and feels fast as ****. I know that's a butt dyno but this is exactly what I wanted when I was 17. 10 years later and its exactly what I wanted haha. AFR cruising is whats scaring me though. When I'm in vacuum, I'm at 16-not even showing. Once I give it any amount of gas though, it goes to 15 and then when I'm in boost it always hits the target afr's. How lean is TOO lean for just highway cruising? Say you are going 65 with cruise control in 6th gear, what is safe?
Targets look okay, when you can hit them. Not leaner than 16.5, better target 15-15.5 in cruise. Just richen up the 45kpa >3k rpm cells a bit.
I hope you are running E85, because thats a shitload of timing in boost for pump gas. No wonder it feels fast as hell You can scale your spark table bigger and use all of the cells for more resolution.
AE needs some tweeking, but that's not going to blow it up instantly
Targets look okay, when you can hit them. Not leaner than 16.5, better target 15-15.5 in cruise. Just richen up the 45kpa >3k rpm cells a bit.
I hope you are running E85, because thats a shitload of timing in boost for pump gas. No wonder it feels fast as hell You can scale your spark table bigger and use all of the cells for more resolution.
AE needs some tweeking, but that's not going to blow it up instantly
Thanks for taking a look man! Here is the MSQ. This is actually on 91 pump gas, how bad is the timing? You're basically saying I should retard it a bit at IN boost? Feel free to make changes to the MSQ, like I said, I'm a total noobie and this is my first attempt to any help is very much appreciated. I've done a lot of research but I even had trouble getting this sucker to idle, even after watching video after video for hours on end
In the 101 row, take out 3 degrees accross the board, then take 2 degrees off for every 2 psi after that. 2psi is about 14kpa, so I would also set your rows to that. Looks like you roughly have 4 psi rows, goal is be around 10 degrees at 18psi, not 22. You can taper these max figures to reasonable numbers to avoid zero or negative numbers in low rpm/high boost cells, not that you'll hit those anyways.
In the 101 row, take out 3 degrees accross the board, then take 2 degrees off for every 2 psi after that. 2psi is about 14kpa, so I would also set your rows to that. Looks like you roughly have 4 psi rows, goal is be around 10 degrees at 18psi, not 22. You can taper these max figures to reasonable numbers to avoid zero or negative numbers in low rpm/high boost cells, not that you'll hit those anyways.
Sir, how does this look? Apparently I posted my first attempt, this is the actual table on my current tune!
New AFR table, let me know what you guys think! Tried to richen up cruising and lean getting into boost a bit.
One thing that sucks is I'm getting TERRRRIIBBBLEE gas milage. Seems to be bad even when I'm not just staying in boost. Went through a quarter tank in 50-60 miles while doing some spirited boost pulls. Roughly 24-25 MPG when not sitting in boost.
Targets look okay, when you can hit them. Not leaner than 16.5, better target 15-15.5 in cruise. Just richen up the 45kpa >3k rpm cells a bit.
I hope you are running E85, because thats a shitload of timing in boost for pump gas. No wonder it feels fast as hell You can scale your spark table bigger and use all of the cells for more resolution.
AE needs some tweeking, but that's not going to blow it up instantly
Just realized I posted screenshots from the first save of that tune, it didnt run right on that spark advance table. I updated the first post with the CURRENT spark table, its not nearly as hot!
One thing that sucks is I'm getting TERRRRIIBBBLEE gas milage. Seems to be bad even when I'm not just staying in boost. Went through a quarter tank in 50-60 miles while doing some spirited boost pulls. Roughly 24-25 MPG when not sitting in boost.
Well you really don't have too many ***** to turn for this.
I really wouldn't go leaner than about 15.5:1 AFR for multiple reasons. The only thing you could check was your VE table accuracy and that O2 correction is enabled. Ignition is going to have a very small impact on BSFC, like tenths of a MPG per RON number in cruise conditions. And from the photo you don't have adjustable cam timing. I can't remember if MS has an injection timing table, but that's also going to be small potatoes and not so easy to calibration outside of idle w/o a steady state dyno.
And it would seem you don't have an electronic wastegate, so you're going to be limited on your boost control. Ideally you would try to run below N/A WOT with the wastegate open for best cruise BSFC.
So unless your VE map is considerably off, it's a combination of the turbo and your right foot. I don't know what your drive mode is, but highway FE will be slightly lower due to pumping losses given that you've added a substantial exhaust restriction. No, turbos don't run off of free energy, especially considering without an EWG you are always pushing exhaust gas through the turbine. And anything above N/A WOT (low boost accels) is going to consume considerably more fuel than the engine ever could naturally aspirated.
Well you really don't have too many ***** to turn for this.
I really wouldn't go leaner than about 15.5:1 AFR for multiple reasons. The only thing you could check was your VE table accuracy and that O2 correction is enabled. Ignition is going to have a very small impact on BSFC, like tenths of a MPG per RON number in cruise conditions. And from the photo you don't have adjustable cam timing. I can't remember if MS has an injection timing table, but that's also going to be small potatoes and not so easy to calibration outside of idle w/o a steady state dyno.
And it would seem you don't have an electronic wastegate, so you're going to be limited on your boost control. Ideally you would try to run below N/A WOT with the wastegate open for best cruise BSFC.
So unless your VE map is considerably off, it's a combination of the turbo and your right foot. I don't know what your drive mode is, but highway FE will be slightly lower due to pumping losses given that you've added a substantial exhaust restriction. No, turbos don't run off of free energy, especially considering without an EWG you are always pushing exhaust gas through the turbine. And anything above N/A WOT (low boost accels) is going to consume considerably more fuel than the engine ever could naturally aspirated.
You're likely right, its probably just that I'm having so much fun in boost. I used to just use cruise control.. Now that's pretty boring. That being said, is this the correction you're talking about? Mine is currently set to disabled.. Should it be set to simple?
Timing map looks pretty sloppy and dangerous IMO, your running a fair bit of timing in mid-range RPM high boost which is where your going to be making most torque and most likely to bend rods/detonate.
I would pull timing out of the 100 to 157 kpa rows, at least at the 3-6k rpm regions, you want your timing to slowly increase as RPM raises, .
For perspective, this is what my rough map looked like for a built 1.6 running 21 PSI, looks a lot different now ended up adding a fair bit more timing recently using knock earmuffs in the 200-240 rows.
Don't use this whatsoever but hopefully it shows the trend of increasing spark timing as you go higher in RPM and pulling timing as you go into more boost.
I'm pretty aggressive in low load areas but it makes for nice torque.
Accel enrichment we can't really comment on as it is pretty setup dependent, when it comes to accel enrichment I would not focus on AFR whatsoever purely focus on throttle response feeling.
When I tune accel I focus purely on how it low medium and fast tip-in feels, you just want to tune for no bogging/bucking on tip-in. Start with low roll on, then medium, then really fast tipping in (like flooring it from nothing).
However you should only tune that once the rest of your VE Table is tuned in well.
In terms of your AFR table, I would probably run a little leaner in the 150 and 175 region, more around 12-12.5 IMO, your not in that range for long
I would set your 175 region to 12 and interpolate between the 100 and 175 region.
For cruise I run around 15:1 sometimes leaner around 15.5:1, it's also a bit dependent how lean you can go and still have it feel drivable, , it is also very unlikely to damage anything even running VERY lean at cruise on a flat road because your load is quite low.
Really it doesn't make a huge difference in fuel economy, and if you run quite lean it can make your accel enrichment harder to tune.
Rough AFR table for reference, I run something around this at 21 PSI.
When I get home I'll compare to my actual current tune at 21PSI, this is just all I have on hand atm.
Post your .msq file and we can properly inspect it.
Also rescale your RPM axis' to something like what I have, makes it much much nicer to tune.
Timing map looks pretty sloppy and dangerous IMO, your running a fair bit of timing in mid-range RPM high boost which is where your going to be making most torque and most likely to bend rods/detonate.
I would pull timing out of the 100 to 157 kpa rows, at least at the 3-6k rpm regions, you want your timing to slowly increase as RPM raises, .
For perspective, this is what my rough map looked like for a built 1.6 running 21 PSI, looks a lot different now ended up adding a fair bit more timing recently using knock earmuffs in the 200-240 rows.
Don't use this whatsoever but hopefully it shows the trend of increasing spark timing as you go higher in RPM and pulling timing as you go into more boost.
I'm pretty aggressive in low load areas but it makes for nice torque.
Accel enrichment we can't really comment on as it is pretty setup dependent, when it comes to accel enrichment I would not focus on AFR whatsoever purely focus on throttle response feeling.
When I tune accel I focus purely on how it low medium and fast tip-in feels, you just want to tune for no bogging/bucking on tip-in. Start with low roll on, then medium, then really fast tipping in (like flooring it from nothing).
However you should only tune that once the rest of your VE Table is tuned in well.
In terms of your AFR table, I would probably run a little leaner in the 150 and 175 region, more around 12-12.5 IMO, your not in that range for long
I would set your 175 region to 12 and interpolate between the 100 and 175 region.
For cruise I run around 15:1 sometimes leaner around 15.5:1, it's also a bit dependent how lean you can go and still have it feel drivable, , it is also very unlikely to damage anything even running VERY lean at cruise on a flat road because your load is quite low.
Really it doesn't make a huge difference in fuel economy, and if you run quite lean it can make your accel enrichment harder to tune.
Rough AFR table for reference, I run something around this at 21 PSI.
When I get home I'll compare to my actual current tune at 21PSI, this is just all I have on hand atm.
Post your .msq file and we can properly inspect it.
Also rescale your RPM axis' to something like what I have, makes it much much nicer to tune.
Edited a bit based on your suggestions. I actually am gonna just try out your timing chart because it looks less aggressive than what I was running anyway... I'm gonna attach my MSQ now if you'd like to take a look! Definitely feel free to make any changes you see fit. I'm gonna tune it tomorrow before I head to work and see how it drives. I'm running around 13 PSI right now, car feels great! The fact that you said the AFR is less important at cruising is a weight off my shoulders. I actually just found an exhaust leak today that I fixed. Also, turns out that some metal shard STILL ended up in my oil even with a flush after tapping. It was in my oil feed line. Its a good thing I had the urge to add coolant lines to the turbo today or I wouldnt have caught it. Flushed oil, hoping to not see any more metal from tapping the oil pan! I also did negative on the AE, it seems to pull out some fuel so I don't run super rich for a blip during decel. Doesnt jerk in on throttle either, very smooth. This is all after turning on the 02/ego control to PID. I left the settings default except the ign events to 32. That smoothed out my AFR's a LOT. Thanks for the help man! Definitely post your current afr table if you get a chance. I'm still learning so that would definitely give me a good reference where mine sits.
Just had a quick look at that tune, will have a deeper look when I'm home from work.
I would highly recommend disabling all O2/EGO Correction and getting the VE Table tune sorted, as it is really rough still.
For comparison, below is your VE Table then below that is an old copy of my VE Table.
Obviously our cars are running much different boost so expect them to look different, and my one I'm posting is pretty rough but has the rough trend of VE raising with load/rpm and then plateauing and dropping once past peak torque, but a lot of your VE table is really high, you can see where AutoTune has been working by the lighter blue areas which is good.
I would recommend disable all O2 correction, disable Accel Enrichment and drive around for about 20 mins with autotune on, and try do as much varied loading as you can, i.e. up hill 3rd gear roll on, 4th gear roll on 5th gear roll on, down hill, coasting etc etc.
That should cover a much larger range of load vs rpm, from there you can fill in the gaps by looking at the trend.
Basically your most important things are, start with a very safe timing table, tune VE table until it everywhere you drive it is meeting your target AFR, from there you can start tuning your accel enrichment, and other modifiers, then you can tune your cold starts, then start working on timing.
Only then should you enable O2 corrections/etc. Otherwise they are always working extremely hard to account for the tune being wrong, it also stops you from ever getting your tune bang on if you tune with it enabled.
Some notes, your VE should typically never go above 100 and at a rough estimate an engine is about 50% ve at idle and about 100 at full throttle N/A, based on turbo efficiency it will either be at or below 100 depending on where in your compressor efficiency map you are.
With a speed density system it is not feasible to have a VE fueling table that will match the actual volumetric efficiency of the engine. The required fuel can be adjusted to scale the table to have any range. Ultimately the difference from the lower to higher cells will be similar if the AFR is similar. All FI and high-performance NA engines have a volumetric efficiency over 100%.
With a speed density system it is not feasible to have a VE fueling table that will match the actual volumetric efficiency of the engine. The required fuel can be adjusted to scale the table to have any range. Ultimately the difference from the lower to higher cells will be similar if the AFR is similar. All FI and high-performance NA engines have a volumetric efficiency over 100%.
Yeah I was driving around trying to get the auto tune to fix my VE table like the other guys was, but even that did over 100 in spots. Ultimately, I just restarted on a base file. Here is my current MSQ, I'm gonna test it on my drive home in an hour. I think it'll drive better. My car HATED the less advanced timing. It was bucking all over and just wouldnt drive right. It might be because I changed spark gap to .025? I have no idea.. But for now, I'm gonna try trubokitties base tune ignition table, my old AFR table, most of my old settings (save a couple I figured the previous owner hadnt tuned correctly) and give her a whirly on the way home! Wish me luck ya'll!
Just had a quick look at that tune, will have a deeper look when I'm home from work.
I would highly recommend disabling all O2/EGO Correction and getting the VE Table tune sorted, as it is really rough still.
For comparison, below is your VE Table then below that is an old copy of my VE Table.
Obviously our cars are running much different boost so expect them to look different, and my one I'm posting is pretty rough but has the rough trend of VE raising with load/rpm and then plateauing and dropping once past peak torque, but a lot of your VE table is really high, you can see where AutoTune has been working by the lighter blue areas which is good.
I would recommend disable all O2 correction, disable Accel Enrichment and drive around for about 20 mins with autotune on, and try do as much varied loading as you can, i.e. up hill 3rd gear roll on, 4th gear roll on 5th gear roll on, down hill, coasting etc etc.
That should cover a much larger range of load vs rpm, from there you can fill in the gaps by looking at the trend.
Basically your most important things are, start with a very safe timing table, tune VE table until it everywhere you drive it is meeting your target AFR, from there you can start tuning your accel enrichment, and other modifiers, then you can tune your cold starts, then start working on timing.
Only then should you enable O2 corrections/etc. Otherwise they are always working extremely hard to account for the tune being wrong, it also stops you from ever getting your tune bang on if you tune with it enabled.
Some notes, your VE should typically never go above 100 and at a rough estimate an engine is about 50% ve at idle and about 100 at full throttle N/A, based on turbo efficiency it will either be at or below 100 depending on where in your compressor efficiency map you are.
Sorry Morrob got busy last night and this totally lapsed my mind.
Your AFR table is fine, I would start by just tuning AS-IS with lots of time using auto-tune and then manually tweaking after.
I would recommend going and watching carpassionchannels videos on tuning they are pretty good, also DCWerks has some good videos explaining how to get started tuning (on Speeduino not Megasquirt but same tuning software and same process).
If you want I can adjust your timing table to be something relatively safe for your boost level assuming high octane pump fuel (98 here in NZ, I think 91 over in states for u peeps cos of weird RON vs MON), and set the AFR table to be what I would want for the setup you've got, from there you can get the car running better by going round for a few hours with auto-tune, then send the new tune and I'll take a look and do some manual interpolation. Just a note on you mention that you are seeing values over 100, you should not be. This means your fuel injector size, fuel injector dead times, or some other parameter is wrong. Ideally you should be ensuring all of these are accurate (including the battery voltage read by ECU is the same as what the injectors see) but for now lets just get you a relatively safe running engine.
Honestly loading the trubokitty base timing map will be more than adequate for now, also have you set your base timing with a timing light?
If not I would not go into boost until you do or your risking melting your pistons, if it is bucking from pulling timing I would be worried either your base timing is REALLY far out, or you were already way past MBT (minimum best timing or basically minimum amount of timing needed for most engine torque) and now are gaining cylinder pressure by coming back to MBT and ignition system can't keep up.
Below is a big rant unrelated to your topic, sorry... I just HATE when people post misleading information like this that just serves to confuse people.
It might also give you a bit of an understanding of how the "VE" number goes into the ECU's decision making process for how much fuel to inject and why you have to tune it.
Originally Posted by LeoNA
With a speed density system it is not feasible to have a VE fueling table that will match the actual volumetric efficiency of the engine. The required fuel can be adjusted to scale the table to have any range. Ultimately the difference from the lower to higher cells will be similar if the AFR is similar. All FI and high-performance NA engines have a volumetric efficiency over 100%.
This just flat out wrong, and also completely unrelated to this topic.
This stuff isn't magic; its math and physics.
Yes required fuel can be adjusted to scale the table to have any range, and yes some guys who know what they are doing and WHY will do it intentionally in order to gain higher resolution on their fuel table, but this is something for people that know what they are doing, for general tuning you should not be seeing values over 100 and should not be trying to do this, don't go telling noobs that won't even know why this provides more table resolution that their tune should see numbers it shouldn't, this is how we end up with people blowing engines up for avoidable reasons.
But that's besides the point, the fact is that it is not possible to have a volumetric efficiency over 100%, literally by definition, so idk WTF you got that idea from.
Volumetric efficiency is a ratio of the volume of fluid that is actually delivered to a pump (in this case air to the engine) versus it's theoretical limit which is its displacement.
A 1.8L engine cannot displace more than 1.8L of air, when you add boost you are simply consuming a higher density of air but not a higher volume of air.
The speed density algorithm does a pretty good job of modelling the real world volumetric efficiency of an engine.
If your engine parameters are correct and your ECU is seeing correct values, you should not see anything over 100, sometimes you will see something a tick over.
You will very very commonly see values over 100% if you do not use the functionality to incorporate your target AFR into the algorithm as opposed to what the algorithm assumes which is a target AFR of lambda 1.0 and by targeting a real AFR richer than that, you are making the ECU think it needs more fuel.
By using incorporate AFR the ecu instead modifies the AFR value used in the algorithm to be what you are targeting and so can more accurately determine your volumetric efficiency.
Here is some math:
You have a 1.8L engine, you are at sea level and have a barometric pressure of 100KPa, an air temperature of 21 degrees Celsius, relative humidity of 50% and 230cc injectors.
Your air density is 1.17876kg/m^3 or 0.00117876g/cm^3.
You have a 1.8L engine so you have a volume of guess 1800cm^3, lets assume you have a really nicely built engine and are hitting 98% volumetric efficiency at peak torque RPM and 100KPa load.
That means you have 1800*0.00117876*0.98 grams of air in the engine every time it does 1 revolution which is 2.121768 grams of air.
Roughly 21 percent of our atmospheric air is oxygen so we can say we have about 0.44557128 grams of raw oxygen entering the cylinder.
Now what about when we are running 100KPa of boost so a total pressure of 200KPa, and are intercooled so maybe at 25 degrees celcius.
We now have an air density of 0.00232987, so we now have 4.10989068 grams of air in the cylinder engine, the volume of air did not change, the volumetric efficiency did not change, and yet the ECU can know it needs more fuel.
This is why you have a MAP sensor, IAT sensor, etc, and why they need to be reading consistently and accurately.
Nothing changes this fact, if you are using auto-tune or tuning in a typical manner using the actual sensor and actuator data for your engine (i.e. injector size etc) then you are modelling the actual volumetric efficiency of your engine.
In some extremely well designed engines with well tuned cams, cam timing, intake runners, etc, you might see it tick over 100, because of resonance/etc sometimes the flow of air at high rpm can give an extra push into the cylinder slightly raising the pressure of air actually entering your engine, so the engine gets more air mass than the ECU sees, it still only gets 1.8L and the engine is still not more than 100% Volumetrically Efficient, the ECU just is missing part of the picture in those cases as since we are measuring MAP,IAT,ETC before the cylinder we can't get a perfect model, however in all the engines I have tuned.
I have not seen a VE number over 100 that wasn't due to something being wrong such as low fuel pressure at high rpm, wrong injector dead times, etc etc, or being intentionally setup in order to gain higher resolution on low resolution ECU's such as Speeduino/etc.
The bases of your argument is that because the density of the incoming air has increased, the volume has not. In ICE engineering the efficiency is based on the quantity not the condition, double the moles of o2 and you have doubled the volume of the oxidizer. You may have heard of a term called scavenging in discussions about the pumping efficiency of an IC engine. The velocity of the air has momentum, and it will continue to fill the engine as the piston is traveling up. When an engines valves are in overlap the velocity of the exhaust gases can draw out left over residual gases that are left behind in the unswep volumes, combustion chamber etc. This is a change out of non-burnable residual gases with incoming mixture that will support combustion. At high velocities it will also generate a low-pressure situation in the cylinder which will further increase the volume of the incoming charge. These are volumes that are not calculated in the displacement of the engine. There are many production engines that exceed 100% VE. Most modern performance motorcycle and car engines are 100%+. The last NA F1 engines were achieving 120-125% volumetric efficiency. With forced induction the increased pressure will increase the volume of oxygen in the cylinder and also increase the scavenging by blow down which empties the unswept volumes.
Originally Posted by venetox
Sorry Morrob got busy last night and this totally lapsed my mind.
Your AFR table is fine, I would start by just tuning AS-IS with lots of time using auto-tune and then manually tweaking after.
I would recommend going and watching carpassionchannels videos on tuning they are pretty good, also DCWerks has some good videos explaining how to get started tuning (on Speeduino not Megasquirt but same tuning software and same process).
If you want I can adjust your timing table to be something relatively safe for your boost level assuming high octane pump fuel (98 here in NZ, I think 91 over in states for u peeps cos of weird RON vs MON), and set the AFR table to be what I would want for the setup you've got, from there you can get the car running better by going round for a few hours with auto-tune, then send the new tune and I'll take a look and do some manual interpolation. Just a note on you mention that you are seeing values over 100, you should not be. This means your fuel injector size, fuel injector dead times, or some other parameter is wrong. Ideally you should be ensuring all of these are accurate (including the battery voltage read by ECU is the same as what the injectors see) but for now lets just get you a relatively safe running engine.
Below is a big rant unrelated to your topic, sorry... I just HATE when people post misleading information like this that just serves to confuse people.
It might also give you a bit of an understanding of how the "VE" number goes into the ECU's decision making process for how much fuel to inject and why you have to tune it.
This just flat out wrong, and also completely unrelated to this topic.
This stuff isn't magic; its math and physics.
Yes required fuel can be adjusted to scale the table to have any range, and yes some guys who know what they are doing and WHY will do it intentionally in order to gain higher resolution on their fuel table, but this is something for people that know what they are doing, for general tuning you should not be seeing values over 100 and should not be trying to do this, don't go telling noobs that won't even know why this provides more table resolution that their tune should see numbers it shouldn't, this is how we end up with people blowing engines up for avoidable reasons.
But that's besides the point, the fact is that it is not possible to have a volumetric efficiency over 100%, literally by definition, so idk WTF you got that idea from.
Volumetric efficiency is a ratio of the volume of fluid that is actually delivered to a pump (in this case air to the engine) versus it's theoretical limit which is its displacement.
A 1.8L engine cannot displace more than 1.8L of air, when you add boost you are simply consuming a higher density of air but not a higher volume of air.
The speed density algorithm does a pretty good job of modelling the real world volumetric efficiency of an engine.
If your engine parameters are correct and your ECU is seeing correct values, you should not see anything over 100, sometimes you will see something a tick over.
You will very very commonly see values over 100% if you do not use the functionality to incorporate your target AFR into the algorithm as opposed to what the algorithm assumes which is a target AFR of lambda 1.0 and by targeting a real AFR richer than that, you are making the ECU think it needs more fuel.
By using incorporate AFR the ecu instead modifies the AFR value used in the algorithm to be what you are targeting and so can more accurately determine your volumetric efficiency.
Here is some math:
You have a 1.8L engine, you are at sea level and have a barometric pressure of 100KPa, an air temperature of 21 degrees Celsius, relative humidity of 50% and 230cc injectors.
Your air density is 1.17876kg/m^3 or 0.00117876g/cm^3.
You have a 1.8L engine so you have a volume of guess 1800cm^3, lets assume you have a really nicely built engine and are hitting 98% volumetric efficiency at peak torque RPM and 100KPa load.
That means you have 1800*0.00117876*0.98 grams of air in the engine every time it does 1 revolution which is 2.121768 grams of air.
Roughly 21 percent of our atmospheric air is oxygen so we can say we have about 0.44557128 grams of raw oxygen entering the cylinder.
Now what about when we are running 100KPa of boost so a total pressure of 200KPa, and are intercooled so maybe at 25 degrees celcius.
We now have an air density of 0.00232987, so we now have 4.10989068 grams of air in the cylinder engine, the volume of air did not change, the volumetric efficiency did not change, and yet the ECU can know it needs more fuel.
This is why you have a MAP sensor, IAT sensor, etc, and why they need to be reading consistently and accurately.
Nothing changes this fact, if you are using auto-tune or tuning in a typical manner using the actual sensor and actuator data for your engine (i.e. injector size etc) then you are modelling the actual volumetric efficiency of your engine.
In some extremely well designed engines with well tuned cams, cam timing, intake runners, etc, you might see it tick over 100, because of resonance/etc sometimes the flow of air at high rpm can give an extra push into the cylinder slightly raising the pressure of air actually entering your engine, so the engine gets more air mass than the ECU sees, it still only gets 1.8L and the engine is still not more than 100% Volumetrically Efficient, the ECU just is missing part of the picture in those cases as since we are measuring MAP,IAT,ETC before the cylinder we can't get a perfect model, however in all the engines I have tuned.
I have not seen a VE number over 100 that wasn't due to something being wrong such as low fuel pressure at high rpm, wrong injector dead times, etc etc, or being intentionally setup in order to gain higher resolution on low resolution ECU's such as Speeduino/etc.
The bases of your argument is that because the density of the incoming air has increased, the volume has not. In ICE engineering the efficiency is based on the quantity not the condition, double the moles of o2 and you have doubled the volume of the oxidizer. You may have heard of a term called scavenging in discussions about the pumping efficiency of an IC engine. The velocity of the air has momentum, and it will continue to fill the engine as the piston is traveling up. When an engines valves are in overlap the velocity of the exhaust gases can draw out left over residual gases that are left behind in the unswep volumes, combustion chamber etc. This is a change out of non-burnable residual gases with incoming mixture that will support combustion. At high velocities it will also generate a low-pressure situation in the cylinder which will further increase the volume of the incoming charge. These are volumes that are not calculated in the displacement of the engine. There are many production engines that exceed 100% VE. Most modern performance motorcycle and car engines are 100%+. The last NA F1 engines were achieving 120-125% volumetric efficiency. With forced induction the increased pressure will increase the volume of oxygen in the cylinder and also increase the scavenging by blow down which empties the unswept volumes.
Good point and yeah from the ICE engineering definition, engine efficiency over 100% is possible, think I was a severely off the mark there with my rant, I'd like to blame me just waking up but don't think that works..., my main argument is that for the purposes of tuning speed density you shouldn't be seeing VE over 100 in most typical cars, since at least as I understand it is using VE from the perspective of percentage of theoretical maximum filling of cylinder.
Perhaps my understanding of VE is flawed or perhaps its a definition thing, my understanding is when we're talking VE in the speed density world its purely how full is the cylinder is from its theoretical max (total displacement), this matches up with discussions I've had with ECU engineers which is where my hubris comes from on this.
Where I assume when ICE-engineers are talking VE they are talking volume of atmospheric air/fuel to volume of cylinder.
Certainly then it is easy to see it is possible to get more than 1.8L of air into the engine, my main problem is that I see this come up a lot, and gets mentioned in a weakly defined way and I see noobs ending up with badly setup ECU's because they get told over 100% VE is expected when in reality their injector dead times, required fuel and a whole bunch of parameters are wrong making the rest of the ECU's calculations respond badly to changes in just about everything.
Good point and yeah from the ICE engineering definition, engine efficiency over 100% is possible, think I was a severely off the mark there with my rant, I'd like to blame me just waking up but don't think that works..., my main argument is that for the purposes of tuning speed density you shouldn't be seeing VE over 100 in most typical cars, since at least as I understand it is using VE from the perspective of percentage of theoretical maximum filling of cylinder.
Perhaps my understanding of VE is flawed or perhaps its a definition thing, my understanding is when we're talking VE in the speed density world its purely how full is the cylinder is from its theoretical max (total displacement), this matches up with discussions I've had with ECU engineers which is where my hubris comes from on this.
Where I assume when ICE-engineers are talking VE they are talking volume of atmospheric air/fuel to volume of cylinder.
Certainly then it is easy to see it is possible to get more than 1.8L of air into the engine, my main problem is that I see this come up a lot, and gets mentioned in a weakly defined way and I see noobs ending up with badly setup ECU's because they get told over 100% VE is expected when in reality their injector dead times, required fuel and a whole bunch of parameters are wrong making the rest of the ECU's calculations respond badly to changes in just about everything.
Hey brother, I found THREE exhaust leaks today! My turbo bolts to the manifold came loose... OH and my vBand clamp on my downpipe needed to be tighter. Funny because I used locktight and tightened the **** out of them... And one of my bolts on my exhaust manifold came out! So I put that all back in, used copper gasket seal as an added bonus and took it for a spin. Made tons of boost I didnt know I could make and the little bucking stopped. I did pull a lot of timing since I'm now running the trubokitty base ignition table! I also changed to two squirt alternating injector staging and it smoothed out a TON. But really, I'm just kind of going off what other people are doing and what I've seen in videos. If you dont mind, definitely take a look at my latest tune and make any adjustments you see fit! I'll throw it on and test it out. I'd really appreciate someone taking some time and going in to double check and make sure its all safe. I'm tempted to take it to a tuner and have them do a final once over. Thing is, everytime I have anyone else work on any of my cars, its always a mistake because they always do shittier work than I would have done. Maybe I have a knack of choosing crappy mechanics! Anyways. Here is my latest tune. Would you mind taking a look at my idle? That is the one thing that occasionally bogs down with the AC. I did adjust the duty cycle in the ac idle up section. Seemed to help a bit but every ONCE in a while, not often at all and only when the engine isnt completely warmed up, it seems like it wants to die when the AC comes on. Definitely need ac, its 100 degrees out haha. Also, I'm pushing about 12 PSI. Today, I hooked up the coolant lines for my turbo and it is DEFINITELY keeping the turbo a bit cooler. Anyway, definitely a work in progress. I greatly appreciate the help and time you've spent responding the past couple days!
Hey brother, I found THREE exhaust leaks today! My turbo bolts to the manifold came loose... OH and my vBand clamp on my downpipe needed to be tighter. Funny because I used locktight and tightened the **** out of them... And one of my bolts on my exhaust manifold came out! So I put that all back in, used copper gasket seal as an added bonus and took it for a spin. Made tons of boost I didnt know I could make and the little bucking stopped. I did pull a lot of timing since I'm now running the trubokitty base ignition table! I also changed to two squirt alternating injector staging and it smoothed out a TON. But really, I'm just kind of going off what other people are doing and what I've seen in videos. If you dont mind, definitely take a look at my latest tune and make any adjustments you see fit! I'll throw it on and test it out. I'd really appreciate someone taking some time and going in to double check and make sure its all safe. I'm tempted to take it to a tuner and have them do a final once over. Thing is, everytime I have anyone else work on any of my cars, its always a mistake because they always do shittier work than I would have done. Maybe I have a knack of choosing crappy mechanics! Anyways. Here is my latest tune. Would you mind taking a look at my idle? That is the one thing that occasionally bogs down with the AC. I did adjust the duty cycle in the ac idle up section. Seemed to help a bit but every ONCE in a while, not often at all and only when the engine isnt completely warmed up, it seems like it wants to die when the AC comes on. Definitely need ac, its 100 degrees out haha. Also, I'm pushing about 12 PSI. Today, I hooked up the coolant lines for my turbo and it is DEFINITELY keeping the turbo a bit cooler. Anyway, definitely a work in progress. I greatly appreciate the help and time you've spent responding the past couple days!
That VE table looks a lot better by my eye, still needs work but looks like you got a lot more RPM/LOAD regions covered.
Just a note, are you intending to have Table Switching enabled (Table Choices tab)? I would probably not enable it yet unless you are intending to, Tune just Ign Table 1 and VE Table 1, when tune is better then copy them over and make adjustments for the table switch.
Table 1 feels a bit hot on the timing, Table 3 feels better, not sure which is TruboKitty basemap.
Idk where you are located and whether our timezones would line up (I'm NZ so GMT+12) but if you have a laptop, can hotspot it and setup remote access software like teamviewer, I can give you a quick remote tune.
That VE table looks a lot better by my eye, still needs work but looks like you got a lot more RPM/LOAD regions covered.
Just a note, are you intending to have Table Switching enabled (Table Choices tab)? I would probably not enable it yet unless you are intending to, Tune just Ign Table 1 and VE Table 1, when tune is better then copy them over and make adjustments for the table switch.
Table 1 feels a bit hot on the timing, Table 3 feels better, not sure which is TruboKitty basemap.
Idk where you are located and whether our timezones would line up (I'm NZ so GMT+12) but if you have a laptop, can hotspot it and setup remote access software like teamviewer, I can give you a quick remote tune.
For sure man, I would definitely appreciate that! I'll shoot you over my discord (if you have one), phone number in a PM. That would help a lot! I'm getting just a little hesitation when I hit 10ish psi. Like it stutters real hard, almost like spark is being cut. Maybe its my coil pack, idk. That's the only gripe I have right now though, that latest tune worked really well! I'm EST so 8 hours ahead of you. Well ,16 hours behind. Its 9AM here Tuesday, 1AM where you are Wednesday. Definitely doable, I can stay up late or wake up early, or even hit you up this weekend! Whatever works for you. Appreciate it man!
07-15-2022, 12:08 AM
Anyone mind double checking a noobies first tune?
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You can scale your spark table bigger and use all of the cells for more resolution.
