Tuning Questions
05-29-2013, 12:19 AM
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Tuning Questions
Quick history and pertinent information: Been using forum to diagnose issues on my '81 7 and my '05 8 for a few years now. The 8's engine was rebuilt July of '12 and had some mild porting done to it. After receiving it, the fuel injectors were crossed and I was able to diagnose and fix the problem (eventually). During the diagnosing, I bought a Cobb through MM but his tight scheduling doesn't allow for us to meet. So I am beginning the long project of learning EFI and the rx-8's ecu (already have carburation down). The goals for tuning are as follows:
Consistent AFR's during WOT, lean out the cruise sections to around 15.4 with real gas (14.87 for E10), and extend closed loop to include 80 mph w/o drafting.
Before I started messing with AFR's, i am double checking all the sensors / equipment. MAF is spot on at 5g/s at idle and over 200 g/s at 8300 rpm WOT. I didn't expect a change since intake is bone stock.
Next piece are the fuel injectors. I just did a highway trip and used some Lucas FI cleaner, so I know they are clean. I am noticing the LTFT's weren't close enough to 0 for my liking (around 6%), so I am slowly tweaking the theoretical size in the ECU to match reality.
Question: when the fuel trim is positive, should I reduce the ECU size of the Bank 1 Injector Size?
Once I get the injectors scaled properly, what would the next step be?
I am thinking that confirming the Fuel VE map would be of priority due to some porting done during the rebuild. I have already made a stab at deriving the g/s at various rpm in the attached excel spreadsheet. It does have variables for air pressure and IAT. I was thinking this can be used to confirm the WOT portion of the Fuel VE map. Any suggestions or corrections to the spreadsheet? (I got this idea from Hymee and r0tor and the corresponding thread: https://www.rx8club.com/series-i-tec...iciency-33370/ )
Another purpose of the Fuel VE map that came to mind is to take care of rogue AFR cells when surrounding cells are behaving (close to actual).
What is the accepted use of the Fuel VE map?
When finally getting around to the Air/Fuel Gear x-y maps, what stoich, rich best torque, and lean mixture should be used? Real gas is 14.7 stoich, RBT in the upper 12's ( i know there is some debate on it), and a lean mixture i found in a book was using 15.4. But in my area E10 is the standard, so since ethanol's stoich is 9, it brings the total mixture stoich to around 14.2. Should this 3.4% decrease be propagated to the RBT and lean mixture to give low 12's as RBT and 14.87 as lean?
Thanks for reading the long post. I have done my best to apply liberal use of the google search "site:rx8club.com/series-i-engine-tuning-forum-63/" but some of this info is buried deep and doesn't come to the surface easily.
Consistent AFR's during WOT, lean out the cruise sections to around 15.4 with real gas (14.87 for E10), and extend closed loop to include 80 mph w/o drafting.
Before I started messing with AFR's, i am double checking all the sensors / equipment. MAF is spot on at 5g/s at idle and over 200 g/s at 8300 rpm WOT. I didn't expect a change since intake is bone stock.
Next piece are the fuel injectors. I just did a highway trip and used some Lucas FI cleaner, so I know they are clean. I am noticing the LTFT's weren't close enough to 0 for my liking (around 6%), so I am slowly tweaking the theoretical size in the ECU to match reality.
Question: when the fuel trim is positive, should I reduce the ECU size of the Bank 1 Injector Size?
Once I get the injectors scaled properly, what would the next step be?
I am thinking that confirming the Fuel VE map would be of priority due to some porting done during the rebuild. I have already made a stab at deriving the g/s at various rpm in the attached excel spreadsheet. It does have variables for air pressure and IAT. I was thinking this can be used to confirm the WOT portion of the Fuel VE map. Any suggestions or corrections to the spreadsheet? (I got this idea from Hymee and r0tor and the corresponding thread: https://www.rx8club.com/series-i-tec...iciency-33370/ )
Another purpose of the Fuel VE map that came to mind is to take care of rogue AFR cells when surrounding cells are behaving (close to actual).
What is the accepted use of the Fuel VE map?
When finally getting around to the Air/Fuel Gear x-y maps, what stoich, rich best torque, and lean mixture should be used? Real gas is 14.7 stoich, RBT in the upper 12's ( i know there is some debate on it), and a lean mixture i found in a book was using 15.4. But in my area E10 is the standard, so since ethanol's stoich is 9, it brings the total mixture stoich to around 14.2. Should this 3.4% decrease be propagated to the RBT and lean mixture to give low 12's as RBT and 14.87 as lean?
Thanks for reading the long post. I have done my best to apply liberal use of the google search "site:rx8club.com/series-i-engine-tuning-forum-63/" but some of this info is buried deep and doesn't come to the surface easily.
05-29-2013, 06:51 AM
#3
The Maf scale has different break points where it will build LTFT.
You should be scaling the Maf and not the Injectors.
For example you may well have +6 LTFT at idle and +8 LTFT in the cruise range.
You could start with an idle log -- warmed up engine 10 seconds everything on, like the lights and A/C.
Then do a cruise log at 4500 rpm, make sure you're in OL and use that to determine the Maf scaling for the mid range area.
Since the VE has been impacted due to porting, I would likely due incremental cruise logs.
Do this for CL and OL all the up to 8500 rpm if you can.
You can use this to help determine VE changes comparing the command afr to the measured afr.
To be honest I would just leave the injectors alone. I know they can be off from the factory but changing injector size is a sweeping change.
That being said changing the injector sizes might achieve what you're looking for as there are tonnes of ways to skin this cat, it's just not the way I've done it or been taught when dealing with a NA car with Stock injectors.
Like I stated above if you have +6 LTFT at idle you may well be able to get rid of the trim by removing 6% from the P1 injectors.
However that will not likely get rid of your cruise trim of +8 LTFT, yes it will likely impact it to some degree but know your stuck changing the Secondaries.
Sounds like you're trying to change to much at once.
Take one step at a time
--- Other stuff you asked about ---
This is what I go for on AFR's and I'm not going to debate it as I don't want to turn this in to a oil thread and I don't know any better
My figures are from Mazda Maniac:
Best torque for Cruise = 13.8-14.1 in the sub 5k rpm range
LBT = 13.2
MBT = 12.9
RBT = 12.5
Use the Closed Loop Exit Tables, Closed Loop Exit Throttle and Closed Loop Exit rpm to change the Closed Loop area.
Use the Closed Loop - A/F Target tables to adjust the fueling. IMPORTANT these are not Lambda values (well not on my 05 map). These are fueling multipliers. If you want more fuel increase the value.
You should be scaling the Maf and not the Injectors.
For example you may well have +6 LTFT at idle and +8 LTFT in the cruise range.
You could start with an idle log -- warmed up engine 10 seconds everything on, like the lights and A/C.
Then do a cruise log at 4500 rpm, make sure you're in OL and use that to determine the Maf scaling for the mid range area.
Since the VE has been impacted due to porting, I would likely due incremental cruise logs.
Do this for CL and OL all the up to 8500 rpm if you can.
You can use this to help determine VE changes comparing the command afr to the measured afr.
To be honest I would just leave the injectors alone. I know they can be off from the factory but changing injector size is a sweeping change.
That being said changing the injector sizes might achieve what you're looking for as there are tonnes of ways to skin this cat, it's just not the way I've done it or been taught when dealing with a NA car with Stock injectors.
Like I stated above if you have +6 LTFT at idle you may well be able to get rid of the trim by removing 6% from the P1 injectors.
However that will not likely get rid of your cruise trim of +8 LTFT, yes it will likely impact it to some degree but know your stuck changing the Secondaries.
Sounds like you're trying to change to much at once.
Take one step at a time
--- Other stuff you asked about ---
This is what I go for on AFR's and I'm not going to debate it as I don't want to turn this in to a oil thread and I don't know any better
My figures are from Mazda Maniac:
Best torque for Cruise = 13.8-14.1 in the sub 5k rpm range
LBT = 13.2
MBT = 12.9
RBT = 12.5
Use the Closed Loop Exit Tables, Closed Loop Exit Throttle and Closed Loop Exit rpm to change the Closed Loop area.
Use the Closed Loop - A/F Target tables to adjust the fueling. IMPORTANT these are not Lambda values (well not on my 05 map). These are fueling multipliers. If you want more fuel increase the value.
Last edited by wcs; 05-29-2013 at 12:35 PM.
05-29-2013, 01:16 PM
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I'll look into the MAF vs Injector scaling. I agree that the injectors will cause a change over the entire operating range, so I just need to make sure that the 3 LTFT's need the same change. I'm quite leary of messing with the MAF calibration since the intake is stock.
Once the fuel trims are dealt with, you would start using the fuel VE map to make actual AFR meet commanded AFR?
And I have found the help file for the AccessTuner and can now remove a ton of mystery of the purpose of each map.
Once the fuel trims are dealt with, you would start using the fuel VE map to make actual AFR meet commanded AFR?
And I have found the help file for the AccessTuner and can now remove a ton of mystery of the purpose of each map.
05-31-2013, 06:06 AM
#5
Don't be leary of messing with the Maf on a Stock box.
It's what all the top tuners around here start with... Brettus, MM, Kane, 9K
Dwet dewd
Break points for the Maf are:
Idle range = 1.02v to 1.48v IMPORTANT Don't change the first 2 values on the Maf. Throws the ECU in to some sort of turmoil.
Cruise = 1.56v to 2.54v
WOT = 2.66v to 4.69
Remember to smooth thing out at the edges where you scaled using the Horizontal Interpolation.
Example. LTFT = +3 at idle. Multiply the idle range by 1.03 and smooth it out to the right one or two cells using the Horizontal Interp.
It's what all the top tuners around here start with... Brettus, MM, Kane, 9K
Dwet dewd
Break points for the Maf are:
Idle range = 1.02v to 1.48v IMPORTANT Don't change the first 2 values on the Maf. Throws the ECU in to some sort of turmoil.
Cruise = 1.56v to 2.54v
WOT = 2.66v to 4.69
Remember to smooth thing out at the edges where you scaled using the Horizontal Interpolation.
Example. LTFT = +3 at idle. Multiply the idle range by 1.03 and smooth it out to the right one or two cells using the Horizontal Interp.
Last edited by wcs; 05-31-2013 at 06:32 AM.
05-31-2013, 09:15 AM
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Thanks for the information. I am noticing that LTFT's change throughout the day, so I'm watching them to find trends. Since the three zones are different values, I will be following your advice and the stickied thread in Engine Tuning on How to Scale Your MAF.
In a rather bold move, I also took all leading timing values from 1500+ in all loads and removed 2* of advance. It seems I had some very slight knocking in the sub 5k rpm and medium to high load. The car sounds happier when at WOT and it doesn't seem to pull less (which is consistent with what I read about Mazda having pushed the limits of advanced timing).
As usual, comments are appreciated
In a rather bold move, I also took all leading timing values from 1500+ in all loads and removed 2* of advance. It seems I had some very slight knocking in the sub 5k rpm and medium to high load. The car sounds happier when at WOT and it doesn't seem to pull less (which is consistent with what I read about Mazda having pushed the limits of advanced timing).
As usual, comments are appreciated
05-31-2013, 10:03 AM
#7
Ouch ... knock ... if that was indeed what you heard is hard to do on a NA 8.
But that's the area of the RPM band were its most likely to occur 5k-6.5k rpm
What's the gasoline like where you live?
On the timing topic, rumor has it that retarding the Lead Ignition by a couple of degrees can actually gain you some horse power.
As I've not been on a dyno to experiment with this I'm only just repeating what I was told.
But that's the area of the RPM band were its most likely to occur 5k-6.5k rpm
What's the gasoline like where you live?
On the timing topic, rumor has it that retarding the Lead Ignition by a couple of degrees can actually gain you some horse power.
As I've not been on a dyno to experiment with this I'm only just repeating what I was told.
05-31-2013, 03:45 PM
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max grade gas is 92-93 and all of it has the "Up to 10% ethanol added" sticker. I've been getting the cheap stuff though, (87ish), and I bet that's why it feels better now. It feels a tad more sluggish in the 3-5k range, so I may put 1* back, but I like the safety factor the -2 from stock allows.
I too read some posts by MM and bretus indicating HP increases by retarding stock timing, which goes along with racingbeat not being able to get any more power from advancing the timing.
Just a confirmation here, for closed loop, does the computer use an OR function for going into open loop? As in: if rpm OR Calc load OR Throttle goes above the specified value, then go to open loop.
If this is the case, then setting the closed loop rpm to 1500 should make testing nearly every voltage cell of the MAP plausible. Using the guide in the engine tuning forum, I would ensure open loop via STFT = 0 (or .16), set med to low load AFR to a set value (λ=0.95 since i know FT's are around 5% and i'll use excel to calc the % difference) and the high load to .78 (5% off 12 is 11.4 = safe), and set the throttle fuel gear x-y to 1.00 (pretty sure this is a multiplier to the AFR).
I too read some posts by MM and bretus indicating HP increases by retarding stock timing, which goes along with racingbeat not being able to get any more power from advancing the timing.
Just a confirmation here, for closed loop, does the computer use an OR function for going into open loop? As in: if rpm OR Calc load OR Throttle goes above the specified value, then go to open loop.
If this is the case, then setting the closed loop rpm to 1500 should make testing nearly every voltage cell of the MAP plausible. Using the guide in the engine tuning forum, I would ensure open loop via STFT = 0 (or .16), set med to low load AFR to a set value (λ=0.95 since i know FT's are around 5% and i'll use excel to calc the % difference) and the high load to .78 (5% off 12 is 11.4 = safe), and set the throttle fuel gear x-y to 1.00 (pretty sure this is a multiplier to the AFR).
06-01-2013, 07:43 AM
#11
max grade gas is 92-93 and all of it has the "Up to 10% ethanol added" sticker. I've been getting the cheap stuff though, (87ish), and I bet that's why it feels better now. It feels a tad more sluggish in the 3-5k range, so I may put 1* back, but I like the safety factor the -2 from stock allows.
I too read some posts by MM and bretus indicating HP increases by retarding stock timing, which goes along with racingbeat not being able to get any more power from advancing the timing.
Just a confirmation here, for closed loop, does the computer use an OR function for going into open loop? As in: if rpm OR Calc load OR Throttle goes above the specified value, then go to open loop.
If this is the case, then setting the closed loop rpm to 1500 should make testing nearly every voltage cell of the MAP plausible. Using the guide in the engine tuning forum, I would ensure open loop via STFT = 0 (or .16), set med to low load AFR to a set value (λ=0.95 since i know FT's are around 5% and i'll use excel to calc the % difference) and the high load to .78 (5% off 12 is 11.4 = safe), and set the throttle fuel gear x-y to 1.00 (pretty sure this is a multiplier to the AFR).
I too read some posts by MM and bretus indicating HP increases by retarding stock timing, which goes along with racingbeat not being able to get any more power from advancing the timing.
Just a confirmation here, for closed loop, does the computer use an OR function for going into open loop? As in: if rpm OR Calc load OR Throttle goes above the specified value, then go to open loop.
If this is the case, then setting the closed loop rpm to 1500 should make testing nearly every voltage cell of the MAP plausible. Using the guide in the engine tuning forum, I would ensure open loop via STFT = 0 (or .16), set med to low load AFR to a set value (λ=0.95 since i know FT's are around 5% and i'll use excel to calc the % difference) and the high load to .78 (5% off 12 is 11.4 = safe), and set the throttle fuel gear x-y to 1.00 (pretty sure this is a multiplier to the AFR).
That being said, we have a Shell product ummm Vpower 91 which they state is just gas no ethanol. Works great IMO.
At one point before the government F'd it up we use to have stations that sold Sunoco 94 which is awesome. (it's still around but blah blah blah just not as common)
About the CL function is the Cobb AP - ATR
So MM has mentioned that he doesn't believe that we have access to all the CL functions. It's not a OR state if you will that determines when CL occurs. There is also TIME value we do not have access to. Therefore even after we pass the EXIT RPM, LOAD and THROTTLE on the CL Tables there is still a TIME before the engine will drop to OL.
If you set all the values to 0 the engine will run in OL I've tested this, by accident at first then later on purpose.
And yes it was to do an OL on low load and RPM cells, I didn't try and hit every cell possible I was just street tuning but I suppose if you had a chasis dyno ....
Now if you're going to reference other material you need to provide links. I think you're talking about Kane's How to Scale the Maf Thread?
And I'm sorry but this from the quote above makes ZERO sense to me
"set med to low load AFR to a set value (λ=0.95 since i know FT's are around 5% and i'll use excel to calc the % difference) and the high load to .78 (5% off 12 is 11.4 = safe), and set the throttle fuel gear x-y to 1.00 (pretty sure this is a multiplier to the AFR)"
Set what values on what tables? What is FT?
What is 5% of 12 is 11.4?
11.4 AFR is way to rich IMO for a NA engine. That AFR is what I aim for at 9psi of boost!
Set the Throttle fuel gear x-y to 1.0?
I think to what you refer to are basic the "Tip-In" tables.
AKA Mashing the throttle. I would not flat line those to 1.0 nor will you see a large effect in your AFR's.
These are not Multiplier tables.
Unless however you are referencing the Closed Loop Tables which are multipliers as previously mentioned.
I'm a bit confused about what you are exactly talking about in your latest post.
Last edited by wcs; 06-01-2013 at 07:57 AM.
06-01-2013, 09:29 AM
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Sorry for the cryptic post, I'll clarify:
Timing references: https://www.rx8club.com/series-i-eng...-108455/page3/
MM: "...The OEM ignition timing is unbelievably aggressive. In the past, rotary tuners shot for no more than 28° to 30° of total timing with 8° to 15° of trailing gap."
Rotary Tech Tips: RX-8 Ignition
First paragraph
I did test the CL OR function and agree that is not the correct method. By putting the RPM to 1000, it wouldn't leave CL until i put a load on the engine. After setting the load A,B, and C to 0, then it came out of CL easily.
For my λ values, I was following Kane's advice in this thread: https://www.rx8club.com/series-i-eng...-hymee-169597/
He recommended λ of 1 to make the math easier. I already know my Fuel Trim (That's the FT) wants to sit near 5%, so without CL it will be lean. So to force the actual mixture to be near 14.7, I multiplied it by .95 and got 13.96. Then 13.96 / 14.7 yields λ=.95. So in the cruise area (4000rpm and under and .5 calc load and under) I plugged .95 into the AFR map for each set of gears.
For the higher load areas, I wanted the AFR to be in the low 12's for safety's sake. Applying the 5% fuel trim idea to it, 12*.95=11.4. 11.4/14.7= .77. So I plugged .77 into the higher rpm and load areas.
The lack of "tip in" tables came from https://www.rx8club.com/series-i-eng...-hymee-169597/ step 2. He was eliminating them so true AFR could be read. I tried it, but didn't like how lean it got even in the parking lot. Since I will be testing on very steep hills and not having a bunch of throttle changes, I feel I can get good results with the "tip in" still active. My "tip in" / accelerator pump / throttle enrichment is hidden in the table named "Throttle Fuel Gear 1-2". There are 2 more for 3-4 and 5-6. The values in it are primarily 1.00 with one area in the .9x's. The explanation in the help file (attached) states: "This table behaves like the “accelerator pump” function found on some engine management systems (analogous to the pump found on old carbureted systems). The modifies the target Lambda while in closed loop and first or second gear." So I'm still not sure if they are modifiers or what, but they seem set up to do just that.
The whole purpose of all this is to scale the MAF, but in my nature, I want to be more than thorough and will attempt to make logs holding the MAF Voltage constant via the footfeed on the road.
And do pardon the use of variable throughout the posts, that's my physics / math degree coming out.
Timing references: https://www.rx8club.com/series-i-eng...-108455/page3/
MM: "...The OEM ignition timing is unbelievably aggressive. In the past, rotary tuners shot for no more than 28° to 30° of total timing with 8° to 15° of trailing gap."
Rotary Tech Tips: RX-8 Ignition
First paragraph
I did test the CL OR function and agree that is not the correct method. By putting the RPM to 1000, it wouldn't leave CL until i put a load on the engine. After setting the load A,B, and C to 0, then it came out of CL easily.
For my λ values, I was following Kane's advice in this thread: https://www.rx8club.com/series-i-eng...-hymee-169597/
He recommended λ of 1 to make the math easier. I already know my Fuel Trim (That's the FT) wants to sit near 5%, so without CL it will be lean. So to force the actual mixture to be near 14.7, I multiplied it by .95 and got 13.96. Then 13.96 / 14.7 yields λ=.95. So in the cruise area (4000rpm and under and .5 calc load and under) I plugged .95 into the AFR map for each set of gears.
For the higher load areas, I wanted the AFR to be in the low 12's for safety's sake. Applying the 5% fuel trim idea to it, 12*.95=11.4. 11.4/14.7= .77. So I plugged .77 into the higher rpm and load areas.
The lack of "tip in" tables came from https://www.rx8club.com/series-i-eng...-hymee-169597/ step 2. He was eliminating them so true AFR could be read. I tried it, but didn't like how lean it got even in the parking lot. Since I will be testing on very steep hills and not having a bunch of throttle changes, I feel I can get good results with the "tip in" still active. My "tip in" / accelerator pump / throttle enrichment is hidden in the table named "Throttle Fuel Gear 1-2". There are 2 more for 3-4 and 5-6. The values in it are primarily 1.00 with one area in the .9x's. The explanation in the help file (attached) states: "This table behaves like the “accelerator pump” function found on some engine management systems (analogous to the pump found on old carbureted systems). The modifies the target Lambda while in closed loop and first or second gear." So I'm still not sure if they are modifiers or what, but they seem set up to do just that.
The whole purpose of all this is to scale the MAF, but in my nature, I want to be more than thorough and will attempt to make logs holding the MAF Voltage constant via the footfeed on the road.
And do pardon the use of variable throughout the posts, that's my physics / math degree coming out.
06-01-2013, 11:46 AM
#13
Thanks for the links.
I'm pretty sure Kane is trying to convey the point of scaling the Maf not adjusting the Closed loop tables to compensate for LTFT.
So take you Maf in that g/s range and multiply by 1.05
I've never flattened the tip-in tables.
I guess I'm just lazy.
I'm pretty sure Kane is trying to convey the point of scaling the Maf not adjusting the Closed loop tables to compensate for LTFT.
So take you Maf in that g/s range and multiply by 1.05
I've never flattened the tip-in tables.
I guess I'm just lazy.
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