45.6 Miles Per Gallon
Member
Joined: Aug 2007
Posts: 98
Likes: 0
From: Denver, CO
Aside from poorly-conceived dilusions of grandeur from our new fear-inspiring prez, manufacturing will always operate under certain rules governed by human nature.
EMS Tuning:
My favorite subject of all time! I would love to teach anybody who is in/near the Denver area just how to tune their spark maps! If you aren't, I can coach over the phone. Drop me a line if you are interested. damon.becker (at) comcast (dot) net.
To quickly answer your question, spark timing has a "sweet" range. When you go outside that range on the low end, your EGT will go up and your fuel mileage will go to hell. When you go on the overly-advanced side and you have sufficient manifold pressure, you will wind up with a very expensive and heavy door stop.
In order of preference, here is the tool used to tune the spark advance:
-load-holding and reporting engine dyno
-load-holding and reporting chassis dyno
-Accelerometer (dynojet)
-Street
-EGT/knock detection equipment (like the Chassis Ear that I use on the dyno)
-guessing
A load-holding dyno is ABSOLUTELY the best way to tune spark advance! Notice, I said load-holding. Non-LC Dynojets need not apply. Even the LC dynojets aren't my favorite. If you are doing WOT tuning with dynojets for spark advance, you are basically guessing at anything non-WOT, making it inheritantly less-than-perfect. That's fine if you just want a power monster, but if you want part throttle mileage, then it might be worthwhile to find a tuner with the right equipment.
Here's why street tuning really doesn't get close to optimum spark advance. The only thing you can look at are EGT and knock on the street. If you tune for knock on a motor that has a great combustion chamber design, then you will be overloading the bearings and introducing much more heat in the engine coolant than necessary! Additionally, you will actually make the engine MORE knock-prone than it was with correct timing! Tuning for knock at part throttle is a HUGE no-no, and it is mostly a no-no at full throttle. As you further reduce the manifold pressure and idle the motor, you will NEVER knock. You can reduce the fueling and advance the timing all you want, and the motor will only start to idle like A$$ and die.
With the load-holder, you tune cams then fuel then spark, re-visiting the previous step as necessary. If you tune for peak torque in each part-throttle cell below 4500 RPM, then you will yield a motor that has FANTASTIC mileage! You will also blow the HELL out of your NOx emissions, so be fore-warned.
You can go beyond this and setup a lean-burn motor. However, you have to REALLY know what you are doing here! Lean mixtures in the right parts of the engine's operating envelope will yield fantastic mileage, and in the wrong parts will yield the afore-mentioned door stop.
Procedure:
When tuning, you always want to go from known-conservative values to less conservative values, not the other way around.
To tune for spark advance at part-throttle, set the motor in a given load/RPM cell (say 2500 RPM and 5" vacuum). Start by PULLING the timing until the dyno registers a reduction in torque. Re-advance the timing until the torque stops increasing. You will notice the torque will continue to be flat as you continue to add timing, then start to drop off again. Set the timing at MBT, or Minimum Best Torque. This is the ABSOLUTE MINIMUM amount of timing to achieve that torque plateau.
Do this while watching air temp, coolant temp and listening for knock. You want to keep air and coolant temps consistent, as this heavily influences the results.
For full-throttle stuff, you usually do full-RPM sweeps because load-holding at high loads might hurt the motor.
I don't usually bother with part-throttle stuff above 4500 RPM because the driver won't stay there long enough to matter, and sitting there at 10" vacuum and 5000 RPM isn't great for the motor.
I will usually PURPOSELY heat-soak the intercooler and set the temp fuel and spark compensation curves to keep the motor out of detonation when it gets good and HOT. The reason for this is I live in Colorado, which has mountains. People frequently peg-leg it up the hills, which is horrible for the motor. However, it's even worse if the motor detonates under these circumstances!
I wanted to add another comment. While it's true your setup won't perfectly match someone else's and it's generally a bad idea to use someone else's map to drive around on indefinitely, you can make someone else's map "safe" by pulling the full-load spark timing by 3 degrees or so on a known-safe tune and 5 degrees on a known-aggressive tune, then reset the fuel using a wideband. This will PROBABLY yield a motor that will at least run acceptably well.
Please notice my subjective ceaveats like PROBABLY and "safe". Also, if you intend on using someone else's known-good map, make sure their mods are at least close to yours. Huge things that impact timing are:
-cam profiles
-cam timing
-manifolds and head work
-turbo selection
There are other things, but these are probably the biggest.
EMS Tuning:
My favorite subject of all time! I would love to teach anybody who is in/near the Denver area just how to tune their spark maps! If you aren't, I can coach over the phone. Drop me a line if you are interested. damon.becker (at) comcast (dot) net.
To quickly answer your question, spark timing has a "sweet" range. When you go outside that range on the low end, your EGT will go up and your fuel mileage will go to hell. When you go on the overly-advanced side and you have sufficient manifold pressure, you will wind up with a very expensive and heavy door stop.
In order of preference, here is the tool used to tune the spark advance:
-load-holding and reporting engine dyno
-load-holding and reporting chassis dyno
-Accelerometer (dynojet)
-Street
-EGT/knock detection equipment (like the Chassis Ear that I use on the dyno)
-guessing
A load-holding dyno is ABSOLUTELY the best way to tune spark advance! Notice, I said load-holding. Non-LC Dynojets need not apply. Even the LC dynojets aren't my favorite. If you are doing WOT tuning with dynojets for spark advance, you are basically guessing at anything non-WOT, making it inheritantly less-than-perfect. That's fine if you just want a power monster, but if you want part throttle mileage, then it might be worthwhile to find a tuner with the right equipment.
Here's why street tuning really doesn't get close to optimum spark advance. The only thing you can look at are EGT and knock on the street. If you tune for knock on a motor that has a great combustion chamber design, then you will be overloading the bearings and introducing much more heat in the engine coolant than necessary! Additionally, you will actually make the engine MORE knock-prone than it was with correct timing! Tuning for knock at part throttle is a HUGE no-no, and it is mostly a no-no at full throttle. As you further reduce the manifold pressure and idle the motor, you will NEVER knock. You can reduce the fueling and advance the timing all you want, and the motor will only start to idle like A$$ and die.
With the load-holder, you tune cams then fuel then spark, re-visiting the previous step as necessary. If you tune for peak torque in each part-throttle cell below 4500 RPM, then you will yield a motor that has FANTASTIC mileage! You will also blow the HELL out of your NOx emissions, so be fore-warned.
You can go beyond this and setup a lean-burn motor. However, you have to REALLY know what you are doing here! Lean mixtures in the right parts of the engine's operating envelope will yield fantastic mileage, and in the wrong parts will yield the afore-mentioned door stop.
Procedure:
When tuning, you always want to go from known-conservative values to less conservative values, not the other way around.
To tune for spark advance at part-throttle, set the motor in a given load/RPM cell (say 2500 RPM and 5" vacuum). Start by PULLING the timing until the dyno registers a reduction in torque. Re-advance the timing until the torque stops increasing. You will notice the torque will continue to be flat as you continue to add timing, then start to drop off again. Set the timing at MBT, or Minimum Best Torque. This is the ABSOLUTE MINIMUM amount of timing to achieve that torque plateau.
Do this while watching air temp, coolant temp and listening for knock. You want to keep air and coolant temps consistent, as this heavily influences the results.
For full-throttle stuff, you usually do full-RPM sweeps because load-holding at high loads might hurt the motor.
I don't usually bother with part-throttle stuff above 4500 RPM because the driver won't stay there long enough to matter, and sitting there at 10" vacuum and 5000 RPM isn't great for the motor.
I will usually PURPOSELY heat-soak the intercooler and set the temp fuel and spark compensation curves to keep the motor out of detonation when it gets good and HOT. The reason for this is I live in Colorado, which has mountains. People frequently peg-leg it up the hills, which is horrible for the motor. However, it's even worse if the motor detonates under these circumstances!
I wanted to add another comment. While it's true your setup won't perfectly match someone else's and it's generally a bad idea to use someone else's map to drive around on indefinitely, you can make someone else's map "safe" by pulling the full-load spark timing by 3 degrees or so on a known-safe tune and 5 degrees on a known-aggressive tune, then reset the fuel using a wideband. This will PROBABLY yield a motor that will at least run acceptably well.
Please notice my subjective ceaveats like PROBABLY and "safe". Also, if you intend on using someone else's known-good map, make sure their mods are at least close to yours. Huge things that impact timing are:
-cam profiles
-cam timing
-manifolds and head work
-turbo selection
There are other things, but these are probably the biggest.
Thread Starter
Senior Member
Joined: Feb 2009
Posts: 194
Likes: 0
I bought a book from Amazon instead, which covered the points that Enthalapy mentioned. I was hoping for some more "tricks", as the book already had the guidelines you provided wink1.gif Nevertheless, it's still helpful to hear someone who has experience in this field say that what I've been reading is still correct and valid... More than once I've paid too much attention to a book, when other experts were telling me that the book was old news and I needed to consider some other things.
Anyway, I won't be driving it much until I can get the coilovers / swaybars / endlinks installed and spend the money for a 4-wheel alignment. The alignment doesn't seem too bad right now, but the camber is visibly off, so I don't want to kill my $170-each Eagle F1 GS-D3's.
Anyway, I won't be driving it much until I can get the coilovers / swaybars / endlinks installed and spend the money for a 4-wheel alignment. The alignment doesn't seem too bad right now, but the camber is visibly off, so I don't want to kill my $170-each Eagle F1 GS-D3's.
Member
Joined: Aug 2007
Posts: 98
Likes: 0
From: Denver, CO
Sure, there are tons of tricks. I guess I can rattle off a few specifically for spark timing. There are a ton of other fueling things you can do, but you requested spark tricks.
1.) Turbos spool using exhaust enthalpy. Enthalpy is a measure of fluid energy. Increasing exhaust enthalpy can be achieved by retarding the timing, making the mixture leaner and advancing the exhaust cam (if you have a system with 2 independantly variable cams). The reason is you are starting the ignition later, the piston is aborbing less energy, leaving more for the turbo. You can't create or destroy energy (2nd thermo law), so it has to go somewhere.
To impliment this, I sometimes pull about 3-4 degrees in the +2 psi range, and then restore the timing to what it would normally be about 3 psi shy of the target. This makes the turbo spool faster. Note it also has some negative side effects:
-EGTs can get hot QUICKLY! Don't go too far with this! Don't go leaner than 13.0 and don't pull more than 4 degrees. You can cook exhaust values and turbo oil seals, among other things.
-The driver will experience less torque as the turbo spools. The idea is to transfer energy from the crankshaft to the turbo to increase spool.
-If you really push the limits here, encourage the driver to stay away from this boost region as much as he can for extended periods.
2.) Excessive ignition timing can cause the motor to hunt at idle and light cruise. It also has an impact on engine longevity and cooling. Pulling timing here won't impact mileage but will improve emissions and drivability. Remember: Give the engine the amount of spark timing it wants and NO MORE!!
3.) When the engine is cold, you have to give the motor more torque when cold to overcome the colder, more viscous oil and its drag on the engine. To overcome this, you simply open up the idle air valve more. What if it doesn't have an idle air valve? A way around this can be to use very LITTLE spark timing when warm. For example, if the motor wants 18 degrees, then give it 5-8 when warm! Open the throttle stop so the motor won't stall under these circumstances. Set the AFR as lean as it will go WITHOUT MISFIRE.
Then, when the motor is cold, feed back in ALL of that spark timing and set the AFR to 13.5-13.8. This will give a ton of extra torque when cold and help with cold drivability when you don't have the luxury of an idle air valve.
The negative aspect of this is you will have crappier emissions and use more fuel than necessary whenever you idle.
Of course, you can just ask the cheap ass owner to spend the $50 for a GM idle air valve and plumb it in.
4.) The more spark timing you have, the earlier in the engine cycle the peak temps are reached. When you reach these peak temps earlier during the power stroke, you "expose" more of the cylinder's walls to the higher temps for a longer period of time. This can be a neat trick to use when the motor is cold to get it to pop up to temp quicker. In this case, your exhaust temps will be lower, the turbo will be laggier, but you shouldn't be using the turbo on a cold motor anyway. Don't go to excess with this. You would prefer to use this on an EMS that gives you 3D mapping of spark offsets. AEMs don't do this, but Haltechs do. The reason is you don't want all that extra spark timing if the owner DOES hit boost.
5.) As the coolant gets really HOT (say +10 *C above normal operating conditions), you will want to DECREASE spark timing. The reason? Hot coolant means everything in the combustion chamber is hotter and more likely to DETONATE. I usually pull up to 4 degrees of timing at the extreme upper ends of the map that adjusts spark timing based on coolant temps. The same applies to really hot air temps.
6.) As the air temp gets really COLD, the combustion actually happens slightly faster. I will pull a degree or two at cool air temps for this reason to avoid excessive timing. I usually do this below the freezing mark.
7.) If you are having issues with the engine dying on idle transitions, there can be a fueling reason. The Haltech allows for these types of fueling issues, but others like AEM do not allow for this. To correct this, you can set the spark timing at warm idle to be 3 degrees less than what you need. Then, add an RPM row about 300 RPM below where you idle and put that 3 degrees back in. This way, as the motor dips below the idle target, it gets a surge of torque to prevent it from stalling.
8.) Catalytic converters operate only when they are WARM. If the cat cools off when idling and you fail emissions because of it, you can pull a ton of timing at idle and open the idle air valve more. This will dump a bunch of hot gasses down the exhaust pipe and allow the cat to remain hot. The same is true for startup. If you want the cat to fire quicker for the emissions testing, pull a bunch of timing during the startup and immediately post-start routine. Most EMSes allow for things like this.
1.) Turbos spool using exhaust enthalpy. Enthalpy is a measure of fluid energy. Increasing exhaust enthalpy can be achieved by retarding the timing, making the mixture leaner and advancing the exhaust cam (if you have a system with 2 independantly variable cams). The reason is you are starting the ignition later, the piston is aborbing less energy, leaving more for the turbo. You can't create or destroy energy (2nd thermo law), so it has to go somewhere.
To impliment this, I sometimes pull about 3-4 degrees in the +2 psi range, and then restore the timing to what it would normally be about 3 psi shy of the target. This makes the turbo spool faster. Note it also has some negative side effects:
-EGTs can get hot QUICKLY! Don't go too far with this! Don't go leaner than 13.0 and don't pull more than 4 degrees. You can cook exhaust values and turbo oil seals, among other things.
-The driver will experience less torque as the turbo spools. The idea is to transfer energy from the crankshaft to the turbo to increase spool.
-If you really push the limits here, encourage the driver to stay away from this boost region as much as he can for extended periods.
2.) Excessive ignition timing can cause the motor to hunt at idle and light cruise. It also has an impact on engine longevity and cooling. Pulling timing here won't impact mileage but will improve emissions and drivability. Remember: Give the engine the amount of spark timing it wants and NO MORE!!
3.) When the engine is cold, you have to give the motor more torque when cold to overcome the colder, more viscous oil and its drag on the engine. To overcome this, you simply open up the idle air valve more. What if it doesn't have an idle air valve? A way around this can be to use very LITTLE spark timing when warm. For example, if the motor wants 18 degrees, then give it 5-8 when warm! Open the throttle stop so the motor won't stall under these circumstances. Set the AFR as lean as it will go WITHOUT MISFIRE.
Then, when the motor is cold, feed back in ALL of that spark timing and set the AFR to 13.5-13.8. This will give a ton of extra torque when cold and help with cold drivability when you don't have the luxury of an idle air valve.
The negative aspect of this is you will have crappier emissions and use more fuel than necessary whenever you idle.
Of course, you can just ask the cheap ass owner to spend the $50 for a GM idle air valve and plumb it in.
4.) The more spark timing you have, the earlier in the engine cycle the peak temps are reached. When you reach these peak temps earlier during the power stroke, you "expose" more of the cylinder's walls to the higher temps for a longer period of time. This can be a neat trick to use when the motor is cold to get it to pop up to temp quicker. In this case, your exhaust temps will be lower, the turbo will be laggier, but you shouldn't be using the turbo on a cold motor anyway. Don't go to excess with this. You would prefer to use this on an EMS that gives you 3D mapping of spark offsets. AEMs don't do this, but Haltechs do. The reason is you don't want all that extra spark timing if the owner DOES hit boost.
5.) As the coolant gets really HOT (say +10 *C above normal operating conditions), you will want to DECREASE spark timing. The reason? Hot coolant means everything in the combustion chamber is hotter and more likely to DETONATE. I usually pull up to 4 degrees of timing at the extreme upper ends of the map that adjusts spark timing based on coolant temps. The same applies to really hot air temps.
6.) As the air temp gets really COLD, the combustion actually happens slightly faster. I will pull a degree or two at cool air temps for this reason to avoid excessive timing. I usually do this below the freezing mark.
7.) If you are having issues with the engine dying on idle transitions, there can be a fueling reason. The Haltech allows for these types of fueling issues, but others like AEM do not allow for this. To correct this, you can set the spark timing at warm idle to be 3 degrees less than what you need. Then, add an RPM row about 300 RPM below where you idle and put that 3 degrees back in. This way, as the motor dips below the idle target, it gets a surge of torque to prevent it from stalling.
8.) Catalytic converters operate only when they are WARM. If the cat cools off when idling and you fail emissions because of it, you can pull a ton of timing at idle and open the idle air valve more. This will dump a bunch of hot gasses down the exhaust pipe and allow the cat to remain hot. The same is true for startup. If you want the cat to fire quicker for the emissions testing, pull a bunch of timing during the startup and immediately post-start routine. Most EMSes allow for things like this.
Super Moderator
Joined: Sep 2001
Posts: 10,795
Likes: 5
From: Pflugerville, TX
Vehicle: 2000 Elantra
MAN that's a lot of things to consider. I'm guessing the answer is "Not just no" but is there any sort of an EMS that you can install on your car, set the car on a dyno, let the car & dyno have a friendly chat, and it tunes itself?
. . .AND have it not throw a constant CEL because the stock ECM is no longer the boss?
. . .AND have it not throw a constant CEL because the stock ECM is no longer the boss?
Senior Member
Joined: May 2006
Posts: 1,497
Likes: 0
Vehicle: 1998/Hyundai/Tiburon FX
Hey Damon!
Good to see you're still frequenting the RDTiburon website!! As usual you're posting up some damn good information and putting it in more lamens terms that most of us could find in a book so THANKS!!!
BTW: My tib is still running GREAT, fuel mileage is shyt, (18mpg average), but I do drive it pretty hard so that probably explains it. I just can't get lucky with transmissions, I have gone through 2 since it's been boosted, and I've probably only driven 10,000 miles. Both were catastrophic failures. I think I just need to start driving it more like a street car rather than a track car lol.
Anyway, good to see you posting and glad to hear you're still employed at Seagate.
Good to see you're still frequenting the RDTiburon website!! As usual you're posting up some damn good information and putting it in more lamens terms that most of us could find in a book so THANKS!!!
BTW: My tib is still running GREAT, fuel mileage is shyt, (18mpg average), but I do drive it pretty hard so that probably explains it. I just can't get lucky with transmissions, I have gone through 2 since it's been boosted, and I've probably only driven 10,000 miles. Both were catastrophic failures. I think I just need to start driving it more like a street car rather than a track car lol.
Anyway, good to see you posting and glad to hear you're still employed at Seagate.
