Closed-loop Tuning - E-manage, Vafc, Etc..
07-08-2004, 08:36 PM
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Closed-loop Tuning - E-manage, Vafc, Etc..
I just hooked up a Wideband o2 to my SC'd MY01 and noticed that during closed-loop, the AFR resides around 14.7:1 (stoich). From what I understand, this is normal in closed-loop operations.
What I want to discuss is what affects piggy back systems like e-manage and VAFC have on closed-loop tuning or does everyone just leave it alone allow their car to run at stoich.
Most of below is in reference to an e-manage point of view. I do not have one yet, but am debating on getting one....
1. Since all the e-manage is doing is intercepting the real signal and adding/subtracting to it, won't an closed-loop situation sooner or later tune out the altered map settings?
2. Is there anyway to or even a good idea to alter the TPS or if possible, RPM, signal so that open-loop kicks in earlier so you can have more control?
Hopefully this will spark some other questions/answers for everyones benefit.
What I want to discuss is what affects piggy back systems like e-manage and VAFC have on closed-loop tuning or does everyone just leave it alone allow their car to run at stoich.
Most of below is in reference to an e-manage point of view. I do not have one yet, but am debating on getting one....
1. Since all the e-manage is doing is intercepting the real signal and adding/subtracting to it, won't an closed-loop situation sooner or later tune out the altered map settings?
2. Is there anyway to or even a good idea to alter the TPS or if possible, RPM, signal so that open-loop kicks in earlier so you can have more control?
Hopefully this will spark some other questions/answers for everyones benefit.
07-08-2004, 08:37 PM
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That is not normal. stoich isn't perfect in real world situations. It's actually considered lean.
It is always in closed loop no matter the RPM's or throttle position.
It is always in closed loop no matter the RPM's or throttle position.
07-08-2004, 09:25 PM
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Where's the Quick Reply box? 
Anyway, closed loop just means the engine has reached operating temperature; the PCM is finally using and interpreting signals such as ECT, IAT, etc. and adapting the AFR and timing to accommodate.
Your engine probably reaches closed loop (rather than open loop) within a minute or two. In open loop, you're running rich regardless (to help turn over on first and/or cold starts) so manufacturers are shortening the time in open loop to help with emissions and fuel economy. Also, the quicker the engine gets to operating temperature, the better.
Anyway, closed loop just means the engine has reached operating temperature; the PCM is finally using and interpreting signals such as ECT, IAT, etc. and adapting the AFR and timing to accommodate.
Your engine probably reaches closed loop (rather than open loop) within a minute or two. In open loop, you're running rich regardless (to help turn over on first and/or cold starts) so manufacturers are shortening the time in open loop to help with emissions and fuel economy. Also, the quicker the engine gets to operating temperature, the better.
07-09-2004, 07:01 AM
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Originally Posted by alexf20c,Jul 8 2004, 09:25 PM
Where's the Quick Reply box?
Anyway, closed loop just means the engine has reached operating temperature; the PCM is finally using and interpreting signals such as ECT, IAT, etc. and adapting the AFR and timing to accommodate.
Your engine probably reaches closed loop (rather than open loop) within a minute or two. In open loop, you're running rich regardless (to help turn over on first and/or cold starts) so manufacturers are shortening the time in open loop to help with emissions and fuel economy. Also, the quicker the engine gets to operating temperature, the better.
Anyway, closed loop just means the engine has reached operating temperature; the PCM is finally using and interpreting signals such as ECT, IAT, etc. and adapting the AFR and timing to accommodate.
Your engine probably reaches closed loop (rather than open loop) within a minute or two. In open loop, you're running rich regardless (to help turn over on first and/or cold starts) so manufacturers are shortening the time in open loop to help with emissions and fuel economy. Also, the quicker the engine gets to operating temperature, the better.
Doesn't the ECM go into open-loop at WOT as well?
Has anyone used a wide-band and piggy-back system and tuned the car during closed-loop operation and over time seen the afr slowly return to 14.7?
Am I brining up a mute point? Should I not even worry about the 14.7 numbers during non-WOT.
07-09-2004, 07:15 AM
#5
no matter what piggy back your using...... without pulling the reset fuse, the stock ecu will monitor the AFR ratio and compare it to its desired AFR. when the stock ecu detects that the AFR is off from the desired AFR, it will work its way towards the desired number gradually....... this is the definition of closed loop or also known as correction loop..... this is why so many have opted to go with a stand alone system. although there is alot of upfront and ongoing effort put into setting up an ideal map, it is much safer than a piggy back solution.....
07-09-2004, 07:58 AM
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Originally Posted by beroznikmal,Jul 9 2004, 07:15 AM
no matter what piggy back your using...... without pulling the reset fuse, the stock ecu will monitor the AFR ratio and compare it to its desired AFR. when the stock ecu detects that the AFR is off from the desired AFR, it will work its way towards the desired number gradually....... this is the definition of closed loop or also known as correction loop..... this is why so many have opted to go with a stand alone system. although there is alot of upfront and ongoing effort put into setting up an ideal map, it is much safer than a piggy back solution.....
on it as well... so I"m trying to confirm. I do realize if I want total control, then go with a stand-alone and I am debating it. Unfortunately, I want the car to run like stock unless I'm at WOT and I'm not sure if I have the time to play with a stand-alone to fine tune/tweak it.
07-09-2004, 02:02 PM
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Before the LS6 swap in my S2000, I was considering a stand-alone to help me to 300whp naturally-aspirated. The basic bolt-ons (cams, sheetmetal intake, exhaust, throttle body, etc.) weren't getting me very far, and it was turning out to be far too expensive for the horsepower; I chunked that idea.
I researched the options for stand-alone ECUs (FAST, DFI, MoTeC, EMS, etc.) and from what I read/heard, only they can offer you full control of the air/fuel mixture and ignition timing. The piggy-back systems, though they may have the adaptability of the full stand-alones, can not override the PCM parameters. (They can adjust, but only within the PCM-allowed spec.) The advantage of the piggy-back system is that they are 100% OBDII-compliant. They will - if tuned properly - allow you to pass inspections. OBDII-equipped vehicles are not hooked up to a 5-gas to check for emissions; rather, they hook up a scanner and pull codes. No codes = pass.
So, you have to decide if you want full control over the engine operations (stand-alone) at the expense of inspection failure, or if you want the car to pass inspection, but still have relative control over the engine (piggy-back). It really comes down to what you're using the car for. Daily driver or track car? Weekend project or full-on custom?
I would recommend the stand-alone ECU (and figure out later on how to cheat OBDII, like leave the original ECU in place, with the ALDL, and dummy sensor signals which fool the ECU into thinking everything is working correctly). It's not difficult to learn the software, as long as you have a basic understanding of the theory and principles behind the 4-stroke spark-ignition engine. MoTeC has an excellent user interface (3D) as does FAST and DFI Gen7, but MoTeC would be your best bet for user friendliness. For better programmability and fine tuning (smaller increments), I'd recommend FAST.
They'll all run you $1500+ turn-key, and some like MoTeC with wideband O2 can be upwards of $3000 for a complete kit.
I believe S2ki user cjb80 uses Accel's DFI Gen7 on his ~560whp turbo S2000. You can PM him for more detailed info on that system. I'm not sure of the rest. AEM's EMS comes in an S2000-specific kit, but FAST and MoTeC are a "universal" type. There's also rumors of a kit from Hondata, but I've yet to see anything from them.
BTW, most of the stand-alone manufacturers have free downloadable "trial" versions of their tuning software on their websites. You should check them out.
I researched the options for stand-alone ECUs (FAST, DFI, MoTeC, EMS, etc.) and from what I read/heard, only they can offer you full control of the air/fuel mixture and ignition timing. The piggy-back systems, though they may have the adaptability of the full stand-alones, can not override the PCM parameters. (They can adjust, but only within the PCM-allowed spec.) The advantage of the piggy-back system is that they are 100% OBDII-compliant. They will - if tuned properly - allow you to pass inspections. OBDII-equipped vehicles are not hooked up to a 5-gas to check for emissions; rather, they hook up a scanner and pull codes. No codes = pass.
So, you have to decide if you want full control over the engine operations (stand-alone) at the expense of inspection failure, or if you want the car to pass inspection, but still have relative control over the engine (piggy-back). It really comes down to what you're using the car for. Daily driver or track car? Weekend project or full-on custom?
I would recommend the stand-alone ECU (and figure out later on how to cheat OBDII, like leave the original ECU in place, with the ALDL, and dummy sensor signals which fool the ECU into thinking everything is working correctly). It's not difficult to learn the software, as long as you have a basic understanding of the theory and principles behind the 4-stroke spark-ignition engine. MoTeC has an excellent user interface (3D) as does FAST and DFI Gen7, but MoTeC would be your best bet for user friendliness. For better programmability and fine tuning (smaller increments), I'd recommend FAST.
They'll all run you $1500+ turn-key, and some like MoTeC with wideband O2 can be upwards of $3000 for a complete kit.
I believe S2ki user cjb80 uses Accel's DFI Gen7 on his ~560whp turbo S2000. You can PM him for more detailed info on that system. I'm not sure of the rest. AEM's EMS comes in an S2000-specific kit, but FAST and MoTeC are a "universal" type. There's also rumors of a kit from Hondata, but I've yet to see anything from them.
BTW, most of the stand-alone manufacturers have free downloadable "trial" versions of their tuning software on their websites. You should check them out.
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07-09-2004, 02:37 PM
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Thanks alexf20c. Thats exactly what I was looking for. I guess, all along, I knew that the piggy backers couldn't fully control fuel/ignition (except at open-loop) but it was hard to get the confirmation.
The questions you pose "Daily driver or track car? Weekend project or full-on custom?" is exactly my delimma. I want the solution I choose to be reliable, streetable and allow the car to run smooth yet allow my FI'd car to run safely.
Couple question that hasn't been answered or I can't find an answer to is: Is it normal to tune closed-loop operations at 14.7? For example, in EMS, when you use their UEGO, can you tune it so closed loop always stays around 13:1 or 13.5:1? Is 14.7:1 ok during closed-loop operations and should I just not worry about closed loop?
The questions you pose "Daily driver or track car? Weekend project or full-on custom?" is exactly my delimma. I want the solution I choose to be reliable, streetable and allow the car to run smooth yet allow my FI'd car to run safely.
Couple question that hasn't been answered or I can't find an answer to is: Is it normal to tune closed-loop operations at 14.7? For example, in EMS, when you use their UEGO, can you tune it so closed loop always stays around 13:1 or 13.5:1? Is 14.7:1 ok during closed-loop operations and should I just not worry about closed loop?
07-09-2004, 03:05 PM
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Well, according to stoichiometry, an air/fuel ratio of 14.7:1 is ideal for optimum burn (emissions and economy), but not for performance. You want to run a bit richer than stoich, definitely not leaner. With FI (or anything that increases cylinder pressures) the last thing you want to do is run lean. You'd rather foul your plugs from too rich air/fuel, than burn holes through pistons from too lean, right?
As for tuning an AEM EMS... If it is a stand-alone ECU, you should be able to map your fuel plot in very fine increments (for rpm and injector pulse width). A stand-alone that's not capable of such is a piece of shit.
You most definitely SHOULD worry about closed loop. The engine is in closed loop 99% of its life. It's difficult, though, to say if it's OK to tune your air/fuel to 14.7 during normal operation. You want to adapt your air/fuel mixture to accommodate your EGT, timing, IAT, MAP, etc. For example, if you notice your EGT a little high, and your plugs are reading lean, it's only obvious to run a little richer. But that's such a broad example and should not be taken as hard fact.
Simply put, though, you can tune it to run at 13.5:1, or 13.7:1, or whatever the heck you want, whenever the heck you want it.
The question of reliability depends more on the tuning than it does the actual componentry. If you over-advance your timing and lean it out too much, your engine will most likely go into destruction mode, but you can't blame the ECU. It'll be your own fault for letting it happen.
"Streetable" is a relative term. I'm pretty sure my definition of streetable is a bit different from yours. Before I finished my S2000, my daily driver was a 530whp '69 Camaro that turned 9000rpm. I don't know many that would consider it streetable, but I did. Then again, I'm crazy.
A properly tuned ECU will run smoothly and safely. Again, it's a question of the tuning. Tuning. Tuning.
Take, for example, my bud's '90 Fox-body Mustang. It's a door-slammer, full chassy car with a steel body, opening windows, complete interior. It passes emissions (we hooked it up to a 5-gas and though NOx were a bit high, it did pass) and averages 16-17mpg. Nothing spectacular, pretty average, but it makes 1400hp from a twin-turbo 347 on 23psi, and 118-octane gasoline. He runs an 8.60/143 on street tires. He = Joe Rivera, former owner of EFI Motorsports and tuning guru. His Mustang held the title of Fastest Street Car for 9 years.
My point is that with proper tuning, you'll make crazy power without sacrificing driveability, streetability, reliability, and so on, so forth.
As for tuning an AEM EMS... If it is a stand-alone ECU, you should be able to map your fuel plot in very fine increments (for rpm and injector pulse width). A stand-alone that's not capable of such is a piece of shit.
You most definitely SHOULD worry about closed loop. The engine is in closed loop 99% of its life. It's difficult, though, to say if it's OK to tune your air/fuel to 14.7 during normal operation. You want to adapt your air/fuel mixture to accommodate your EGT, timing, IAT, MAP, etc. For example, if you notice your EGT a little high, and your plugs are reading lean, it's only obvious to run a little richer. But that's such a broad example and should not be taken as hard fact.
Simply put, though, you can tune it to run at 13.5:1, or 13.7:1, or whatever the heck you want, whenever the heck you want it.
The question of reliability depends more on the tuning than it does the actual componentry. If you over-advance your timing and lean it out too much, your engine will most likely go into destruction mode, but you can't blame the ECU. It'll be your own fault for letting it happen.
"Streetable" is a relative term. I'm pretty sure my definition of streetable is a bit different from yours. Before I finished my S2000, my daily driver was a 530whp '69 Camaro that turned 9000rpm. I don't know many that would consider it streetable, but I did. Then again, I'm crazy.
A properly tuned ECU will run smoothly and safely. Again, it's a question of the tuning. Tuning. Tuning.
Take, for example, my bud's '90 Fox-body Mustang. It's a door-slammer, full chassy car with a steel body, opening windows, complete interior. It passes emissions (we hooked it up to a 5-gas and though NOx were a bit high, it did pass) and averages 16-17mpg. Nothing spectacular, pretty average, but it makes 1400hp from a twin-turbo 347 on 23psi, and 118-octane gasoline. He runs an 8.60/143 on street tires. He = Joe Rivera, former owner of EFI Motorsports and tuning guru. His Mustang held the title of Fastest Street Car for 9 years.
My point is that with proper tuning, you'll make crazy power without sacrificing driveability, streetability, reliability, and so on, so forth.
07-10-2004, 04:07 AM
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I've been using the emanage for the last 13 months so I have some experience. During close loop conditions, the factory ecu will compensate for any changes you program into the piggyback to maintain 14.7. If it has to correct too much, you will get CEL lights for short term fuel trim, which will eventually lead to a long term long term fuel trim CEL. With larger injectors, ittook me a while to get it right.