FC tuning question
02-09-08, 10:29 AM
#1
FC tuning question
It seems that rx7 ems tuning is kept in a closet locked..But I don't see why because even if the knowledge was open to the public people are either
A. Too lazy to do it them selves
B. Will perfer a professional to do it or don't have the means (Dyno/wideband)
C. Too scared to pop their motor
I understand each tuner has their own recipe...but what about the basics? Excuse for the noobism, but I have little knowledge in tuning..and I know im not alone. I just want to learn how to make chicken..not open a restaurant.
Your sitting in your car...idle....you have the laptop, wide band and a basic map.
What next?
Assuming you have a map that is set a little rich. Keep leaning until you are at the A/F @ the recommend Load? In other words Do you keep blowing up the ballon before u pop than let just a little air out?
While I understand that in its basic form..."Ok Im driving adjusting fuel...ohh nooes what about timing. That is where im confused. (flame suit) When do u touch timing and when do you touch fuel.
So while im driving and my A/F starts showing lean what on my logs on an EMS do i look at to determine if its a fuel issue or timing issue cause it seems like a fine line.
A. Too lazy to do it them selves
B. Will perfer a professional to do it or don't have the means (Dyno/wideband)
C. Too scared to pop their motor
I understand each tuner has their own recipe...but what about the basics? Excuse for the noobism, but I have little knowledge in tuning..and I know im not alone. I just want to learn how to make chicken..not open a restaurant.
Your sitting in your car...idle....you have the laptop, wide band and a basic map.
What next?
Assuming you have a map that is set a little rich. Keep leaning until you are at the A/F @ the recommend Load? In other words Do you keep blowing up the ballon before u pop than let just a little air out?
While I understand that in its basic form..."Ok Im driving adjusting fuel...ohh nooes what about timing. That is where im confused. (flame suit) When do u touch timing and when do you touch fuel.
So while im driving and my A/F starts showing lean what on my logs on an EMS do i look at to determine if its a fuel issue or timing issue cause it seems like a fine line.
02-09-08, 10:36 AM
#2
well a lot of the tricks are EMS specific. For example, injector staging in a Haltech is different from a Power FC. Some EMS's have an actual volumetric efficiency table (Megasquirt for example) that is used to calculate injector pulsewidth while others have a fuel map directly in pulsewidth (AEM EMS, Power FC, other ones I'm not familiar with).
02-09-08, 10:49 AM
#3
well a lot of the tricks are EMS specific. For example, injector staging in a Haltech is different from a Power FC. Some EMS's have an actual volumetric efficiency table (Megasquirt for example) that is used to calculate injector pulsewidth while others have a fuel map directly in pulsewidth (AEM EMS, Power FC, other ones I'm not familiar with).
Not really looking for any tricks...just the basics. I guess if u wanted to get EMS specific you could gather that info from the EMS section.
02-09-08, 11:07 AM
#4
The first thing you do is make sure everything is mechanically and electrically sound. That means your timing is dead on, all your sensors are in spec, your wideband is hooked up correctly, etc. If you have other issues (especially bad sensors) your car will NEVER run right. You also need to make sure you have no vacuum leaks.
Then the tuning process proceeds in the same way as the process of actually driving the car. First you try to get the thing started. You will have to play with the cranking fuel map. Generally if it takes a while to start it needs more fuel (but too much and it will flood). Then you try to get the thing to have a stable idle. That is really damn tricky sometimes. You generally have a cold start enrichment table plus the actual fuel map that you have to play with. Usually you want it to idle on our cars at maybe 13:1 ?
After the car warms up you have to tune it for around town, low load driving. This means datalogging what AFR's the car reaches in various cells of the fuel map. You want to get that decently dialed into the 13's and 14's for light acceleration, while steady-state cruising can be over 15:1 AFR. You also have to deal with acceleration enrichment, which is the amount of extra fuel put in as you move the pedal. This is really important for smooth starts from a dead stop or for when you quickly hit the throttle for performance driving. This process can take a long time. You will find your AFR's jumping all over the place for a while because there are a few cells that aren't tuned just right.
Then when you're ready you have to deal with injector staging and WOT tuning. You generally want to run a rich map and then slowly dial back the fuel to what AFR you desire. You will also have to play with whatever injector staging system your EMS has to make sure you smoothly transition primary and secondary duty cycles without a lean or rich spot.
After you have the AFR's where you feel they should be (and this is going to depend on octane and boost level, and of course timing) you will have to play with timing, usually on a dyno. Then you just have to go back and forth between messing with fuel and timing (leading but also split) and try to maximize power given all your constraints (octane level and your tolerance for a risky tune).
That's a really broad outline of the basic process on a speed density standalone system. On other cars you may have MAF voltage scaling to set up properly, fuel trims, transmission control, etc.
Then the tuning process proceeds in the same way as the process of actually driving the car. First you try to get the thing started. You will have to play with the cranking fuel map. Generally if it takes a while to start it needs more fuel (but too much and it will flood). Then you try to get the thing to have a stable idle. That is really damn tricky sometimes. You generally have a cold start enrichment table plus the actual fuel map that you have to play with. Usually you want it to idle on our cars at maybe 13:1 ?
After the car warms up you have to tune it for around town, low load driving. This means datalogging what AFR's the car reaches in various cells of the fuel map. You want to get that decently dialed into the 13's and 14's for light acceleration, while steady-state cruising can be over 15:1 AFR. You also have to deal with acceleration enrichment, which is the amount of extra fuel put in as you move the pedal. This is really important for smooth starts from a dead stop or for when you quickly hit the throttle for performance driving. This process can take a long time. You will find your AFR's jumping all over the place for a while because there are a few cells that aren't tuned just right.
Then when you're ready you have to deal with injector staging and WOT tuning. You generally want to run a rich map and then slowly dial back the fuel to what AFR you desire. You will also have to play with whatever injector staging system your EMS has to make sure you smoothly transition primary and secondary duty cycles without a lean or rich spot.
After you have the AFR's where you feel they should be (and this is going to depend on octane and boost level, and of course timing) you will have to play with timing, usually on a dyno. Then you just have to go back and forth between messing with fuel and timing (leading but also split) and try to maximize power given all your constraints (octane level and your tolerance for a risky tune).
That's a really broad outline of the basic process on a speed density standalone system. On other cars you may have MAF voltage scaling to set up properly, fuel trims, transmission control, etc.
02-09-08, 12:23 PM
#6
Lives on the Forum
The info is out there - you just gotta look for it.
BASICALLY, adjust fuel in vacuum so that...
1) The car runs okay.
2) Gets you the best gas mileage (i.e. lean as possible).
BASICALLY, adjust fuel and ignition timing under load so that...
1) The car runs okay.
2) The EGT's aren't too high.
3) You're not detonating.
BASICALLY, adjust ignition timing in vacuum so that...
1) Run it as advanced as possible.
2) EGT's aren't too high.
Last issue is trailing timing split...
There's two camps on this issue.
I'm trying negative trailing split, and I don't like it.
I feel that my car runs a better with positive trailing split (under vacuum).
That's tuning BASICALLY in a nutshell.
-Ted
BASICALLY, adjust fuel in vacuum so that...
1) The car runs okay.
2) Gets you the best gas mileage (i.e. lean as possible).
BASICALLY, adjust fuel and ignition timing under load so that...
1) The car runs okay.
2) The EGT's aren't too high.
3) You're not detonating.
BASICALLY, adjust ignition timing in vacuum so that...
1) Run it as advanced as possible.
2) EGT's aren't too high.
Last issue is trailing timing split...
There's two camps on this issue.
I'm trying negative trailing split, and I don't like it.
I feel that my car runs a better with positive trailing split (under vacuum).
That's tuning BASICALLY in a nutshell.
-Ted
02-09-08, 01:05 PM
#7
A little bit on timing and fuel/air mixture. This is more of the "why" than the "how":
Timing: Ignition always occurs before compression finishes. That's b/c fuel takes time to burn. In fact, as the engine spins faster you need more advance just to keep up. Increasing advance beyond that means more power and more mpg from higher combustion temps and pressure and less unburnt fuel. The higher temps as compression finishes can also lead to detonation, and the high T & P during combustion will increase NOx emissions. Retarding the timing does the opposite. Retarding the timing won't really increase HC or CO as you might think, since all that simply burns outside of the engine or in the cat. And NOx won't form under low T & P (i.e., outside the engine). But that might also lead to heat problems in the exhaust/cat.
Unlike the piston, the rotary has 2 spark plugs per rotor since the combustions chamber is long and thin. The flame would have trouble traveling so far otherwise, though a rotor can still run semi-ok on 1 plug. The negative split timing RETed talked about means firing the trailing spark plug before the leading during high vacuum (low throttle). The RX-8 uses it to improve fuel economy, but I could guess why the engine wouldn't run as smooth when firing backwards like that.
Fuel/Air: Extra fuel will provide cooling as it vaporizes which will prevent detonation but reduce power thanks to lower combustion temps. Naturally mpg is also lower. But on a turbo extra detonation protection means you can safely run more boost and thus get more power. Ditto for retarding the timing, I'd think. Running richer will increase CO and HC emissions (from unburnt fuel) while reducing NOx (from insufficient oxygen). The reverse of all that goes for running lean. The RX-7 runs a bit rich from the factory to keep the engine safe - rotaries are very detonation sensitive - so it has an air pump to pump air into the exhaust to improve emissions.
Thus a lot of people will lean out an NA or advance the timing and talk about all the power & mpg they get. And thanks to that huge safety net you can dip into, it won't detonate for a while (ever?). But it's a risk. You may toast your motor and end up paying 2-3 g's to rebuild it. Tune carefully.
Timing: Ignition always occurs before compression finishes. That's b/c fuel takes time to burn. In fact, as the engine spins faster you need more advance just to keep up. Increasing advance beyond that means more power and more mpg from higher combustion temps and pressure and less unburnt fuel. The higher temps as compression finishes can also lead to detonation, and the high T & P during combustion will increase NOx emissions. Retarding the timing does the opposite. Retarding the timing won't really increase HC or CO as you might think, since all that simply burns outside of the engine or in the cat. And NOx won't form under low T & P (i.e., outside the engine). But that might also lead to heat problems in the exhaust/cat.
Unlike the piston, the rotary has 2 spark plugs per rotor since the combustions chamber is long and thin. The flame would have trouble traveling so far otherwise, though a rotor can still run semi-ok on 1 plug. The negative split timing RETed talked about means firing the trailing spark plug before the leading during high vacuum (low throttle). The RX-8 uses it to improve fuel economy, but I could guess why the engine wouldn't run as smooth when firing backwards like that.
Fuel/Air: Extra fuel will provide cooling as it vaporizes which will prevent detonation but reduce power thanks to lower combustion temps. Naturally mpg is also lower. But on a turbo extra detonation protection means you can safely run more boost and thus get more power. Ditto for retarding the timing, I'd think. Running richer will increase CO and HC emissions (from unburnt fuel) while reducing NOx (from insufficient oxygen). The reverse of all that goes for running lean. The RX-7 runs a bit rich from the factory to keep the engine safe - rotaries are very detonation sensitive - so it has an air pump to pump air into the exhaust to improve emissions.
Thus a lot of people will lean out an NA or advance the timing and talk about all the power & mpg they get. And thanks to that huge safety net you can dip into, it won't detonate for a while (ever?). But it's a risk. You may toast your motor and end up paying 2-3 g's to rebuild it. Tune carefully.
Last edited by ericgrau; 02-09-08 at 01:29 PM.
Trending Topics
02-09-08, 02:18 PM
#8
FYI, Racing Beat gives some timing recommendations in their catalog. From what I remember, they recommend 10 degrees advance at 10 psi at 6000 RPM for turbocharged rotaries.
My car likes to idle at about 10-20 degrees advance, and 12.5-13.5 AFR. To help the car idle smoothly, I found it helpful to keep the timing map "flat" at idle: if the timing increases or decreases during idle RPMs and loads, the car might surge.
If you're lucky, your engine management will include a datalogger of some sort, which can help you measure how the engine responds to the changes in your fuel map. Remember that your wideband O2 gauge measures how much fuel was consumed, so a misfire will show up as a lean spike (because there aren't any burnt fuel vapors coming into contact with the O2 sensor).
My car likes to idle at about 10-20 degrees advance, and 12.5-13.5 AFR. To help the car idle smoothly, I found it helpful to keep the timing map "flat" at idle: if the timing increases or decreases during idle RPMs and loads, the car might surge.
If you're lucky, your engine management will include a datalogger of some sort, which can help you measure how the engine responds to the changes in your fuel map. Remember that your wideband O2 gauge measures how much fuel was consumed, so a misfire will show up as a lean spike (because there aren't any burnt fuel vapors coming into contact with the O2 sensor).
02-11-08, 11:39 PM
#9
The first thing you do is make sure everything is mechanically and electrically sound. That means your timing is dead on, all your sensors are in spec, your wideband is hooked up correctly, etc. If you have other issues (especially bad sensors) your car will NEVER run right. You also need to make sure you have no vacuum leaks.
Then the tuning process proceeds in the same way as the process of actually driving the car. First you try to get the thing started. You will have to play with the cranking fuel map. Generally if it takes a while to start it needs more fuel (but too much and it will flood). Then you try to get the thing to have a stable idle. That is really damn tricky sometimes. You generally have a cold start enrichment table plus the actual fuel map that you have to play with. Usually you want it to idle on our cars at maybe 13:1 ?
After the car warms up you have to tune it for around town, low load driving. This means datalogging what AFR's the car reaches in various cells of the fuel map. You want to get that decently dialed into the 13's and 14's for light acceleration, while steady-state cruising can be over 15:1 AFR. You also have to deal with acceleration enrichment, which is the amount of extra fuel put in as you move the pedal. This is really important for smooth starts from a dead stop or for when you quickly hit the throttle for performance driving. This process can take a long time. You will find your AFR's jumping all over the place for a while because there are a few cells that aren't tuned just right.
Then when you're ready you have to deal with injector staging and WOT tuning. You generally want to run a rich map and then slowly dial back the fuel to what AFR you desire. You will also have to play with whatever injector staging system your EMS has to make sure you smoothly transition primary and secondary duty cycles without a lean or rich spot.
After you have the AFR's where you feel they should be (and this is going to depend on octane and boost level, and of course timing) you will have to play with timing, usually on a dyno. Then you just have to go back and forth between messing with fuel and timing (leading but also split) and try to maximize power given all your constraints (octane level and your tolerance for a risky tune).
That's a really broad outline of the basic process on a speed density standalone system. On other cars you may have MAF voltage scaling to set up properly, fuel trims, transmission control, etc.
Then the tuning process proceeds in the same way as the process of actually driving the car. First you try to get the thing started. You will have to play with the cranking fuel map. Generally if it takes a while to start it needs more fuel (but too much and it will flood). Then you try to get the thing to have a stable idle. That is really damn tricky sometimes. You generally have a cold start enrichment table plus the actual fuel map that you have to play with. Usually you want it to idle on our cars at maybe 13:1 ?
After the car warms up you have to tune it for around town, low load driving. This means datalogging what AFR's the car reaches in various cells of the fuel map. You want to get that decently dialed into the 13's and 14's for light acceleration, while steady-state cruising can be over 15:1 AFR. You also have to deal with acceleration enrichment, which is the amount of extra fuel put in as you move the pedal. This is really important for smooth starts from a dead stop or for when you quickly hit the throttle for performance driving. This process can take a long time. You will find your AFR's jumping all over the place for a while because there are a few cells that aren't tuned just right.
Then when you're ready you have to deal with injector staging and WOT tuning. You generally want to run a rich map and then slowly dial back the fuel to what AFR you desire. You will also have to play with whatever injector staging system your EMS has to make sure you smoothly transition primary and secondary duty cycles without a lean or rich spot.
After you have the AFR's where you feel they should be (and this is going to depend on octane and boost level, and of course timing) you will have to play with timing, usually on a dyno. Then you just have to go back and forth between messing with fuel and timing (leading but also split) and try to maximize power given all your constraints (octane level and your tolerance for a risky tune).
That's a really broad outline of the basic process on a speed density standalone system. On other cars you may have MAF voltage scaling to set up properly, fuel trims, transmission control, etc.
Thread
Thread Starter
Forum
Replies
Last Post
Skeese
Adaptronic Engine Mgmt - AUS
65
03-28-17 03:30 PM