Re: EFI
[Re: Mopar_Rich]
#1740306
01/28/15 01:29 AM
01/28/15 01:29 AM
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Joined: Nov 2006
Posts: 733 jacksonville,FLORIDA
slammedR/T
super stock
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super stock
Joined: Nov 2006
Posts: 733
jacksonville,FLORIDA
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I just started running EFI.. but I MIGHT have to make a fuel table just for racing... in open loop its trying to drive the A/F to stoichiometric all the time and in a max power condition you want somewhere in the 12.5 range... so just for racing I might have to with a fuel table... it can be way more consistent if you stay in open loop and let the O2 do the work.. I'll tell you come spring time which way I go on the loop thing
You definitely want to stay in closed loop with a target A/F ratio in the mid 12s, but you also want a base fuel table that doesn't require that closed loop does all the work. You want the base fuel table to be close to ideal. This is because the closed loop correction is always "behind the curve" because it only sees what has already happened. You don't want to run a race engine lean at any time.
do the aftermarket efi ecu's control fuel like the oem's do with short term and long term fuel trims??? If so then it can calculate fuel trims from engine load, map and/or maf, ect and tps position. short term is real time fuel trim and long term is the correction table to correct the short term. The computer can actually figure out a long term fuel trim at a given engine load and tps position to compenste for "future table corrections" if that makes sense. I would assume a self learning efi system in closed loop would do the same??
2000 Dakota R/T, 408 magnum, 727, Indy heads 1000cfm 4150 carb, 93 octane fuel. motor; 10.258 @ 132.78 200 shot; 9.262 @ 144.69 racemagnum
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Re: EFI
[Re: slammedR/T]
#1740307
01/28/15 01:38 AM
01/28/15 01:38 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Romeo MI
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Quote:
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I just started running EFI.. but I MIGHT have to make a fuel table just for racing... in open loop its trying to drive the A/F to stoichiometric all the time and in a max power condition you want somewhere in the 12.5 range... so just for racing I might have to with a fuel table... it can be way more consistent if you stay in open loop and let the O2 do the work.. I'll tell you come spring time which way I go on the loop thing
You definitely want to stay in closed loop with a target A/F ratio in the mid 12s, but you also want a base fuel table that doesn't require that closed loop does all the work. You want the base fuel table to be close to ideal. This is because the closed loop correction is always "behind the curve" because it only sees what has already happened. You don't want to run a race engine lean at any time.
do the aftermarket efi ecu's control fuel like the oem's do with short term and long term fuel trims??? If so then it can calculate fuel trims from engine load, map and/or maf, ect and tps position. short term is real time fuel trim and long term is the correction table to correct the short term. The computer can actually figure out a long term fuel trim at a given engine load and tps position to compenste for "future table corrections" if that makes sense. I would assume a self learning efi system in closed loop would do the same??
From what I was told it does it much like you said and yes the self learn is in closed loop... it does use the TPS, map and O2 .. right now I'm not using the timing control
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Re: EFI
[Re: slammedR/T]
#1740308
01/28/15 03:06 AM
01/28/15 03:06 AM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
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Balt. Md
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Quote:
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I just started running EFI.. but I MIGHT have to make a fuel table just for racing... in open loop its trying to drive the A/F to stoichiometric all the time and in a max power condition you want somewhere in the 12.5 range... so just for racing I might have to with a fuel table... it can be way more consistent if you stay in open loop and let the O2 do the work.. I'll tell you come spring time which way I go on the loop thing
You definitely want to stay in closed loop with a target A/F ratio in the mid 12s, but you also want a base fuel table that doesn't require that closed loop does all the work. You want the base fuel table to be close to ideal. This is because the closed loop correction is always "behind the curve" because it only sees what has already happened. You don't want to run a race engine lean at any time.
do the aftermarket efi ecu's control fuel like the oem's do with short term and long term fuel trims??? If so then it can calculate fuel trims from engine load, map and/or maf, ect and tps position. short term is real time fuel trim and long term is the correction table to correct the short term. The computer can actually figure out a long term fuel trim at a given engine load and tps position to compenste for "future table corrections" if that makes sense. I would assume a self learning efi system in closed loop would do the same??
I wondered this myself as all I have worked with is the Mopar OEM systems with the long and short term addaptive fuel trims. On the factory system I would consider the 02 sensor itself not a wide band as it really only has a small amount of control to fine tune the fuel mixture. But the 02 sensor does cause the short and long term fuel trims to drive into different cells and once in the proper full addaptive cell the 02 sensor will fine tune for the best fuel mixture as the 02 itself only can control a small amount of fuel trim within the addaptive fuel cell its in. I wondered if the aftermarket systems many use work about the same as the OEM system that Mopar uses ?
I have to admit with the technology today the fuel injection will tune better then a carb can for sure and its great to have the fuel injection systems for the hot rodders to use. But I would not use it on a car like my 63 as I still love the old school carbs on my older muscle cars and hot rods. I have to admit though that I saw a 64 Plymouth with a 426 Hemi and the crossram and it had fuel injection on it but you had to look hard to realize it had fuel injection as he hid the harness real good and the throttle bodies were about the same size as the carbs were and with the factory chrome air cleaner on it if you did not look hard you would have though it just had two carbs on it.
And for the OP question I would say if the carb is tuned good it most likely wont be any faster but even if you have the carb tuned perfect the EFI will be as good or better all the time since it can adjust and tune for weather and all without you having to lift a screw driver. If you get a good system and once it has learned all the fuel trims it will work good all the time as where you would have to stay on top of a carb to keep the right adjustment in different weather conditions all. I still love using carbs but its tuff to beat technology. Ron
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Re: EFI
[Re: Duner]
#1740310
01/28/15 09:24 PM
01/28/15 09:24 PM
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Joined: Nov 2006
Posts: 733 jacksonville,FLORIDA
slammedR/T
super stock
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super stock
Joined: Nov 2006
Posts: 733
jacksonville,FLORIDA
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Quote:
The factory stuff is only making changes to an overall multiplier in the short and long term trims. It's only "trimming" the fuel where it sees you drive it all the time in closed loop all the time - and changing the overall multiplier. At WOT it's going off the established fuel table - while using that same multiplier, but it can't change the table itself based on O2 sensor info. If it trimmed fuel at idle and cruise - it's going to pull fuel away at WOT too.
The modern standalone stuff looks at what your target AFRs are throughout the rpm range and load settings, and re-writes the tune to get it closer while it "learns". It learns at WOT as well as idle and cruise. Depending upon how much authority you let it have - it can change the fuel table slowly or quickly to get it pretty darn close. Of course, you can also pull up the logs and manually change the fuel tables to speed up the process.
It still has seperate fuel tables for idle and cruise and WOT, while the O2's are narrow band(unless factory turbo car) it still tries for a predetermend fuel trim from fuel maps in the software. Now it can alter the fuel maps over time from learning how you drive, but OE's are based on fuel milage and emmisions production and don't set for best performance.
2000 Dakota R/T, 408 magnum, 727, Indy heads 1000cfm 4150 carb, 93 octane fuel. motor; 10.258 @ 132.78 200 shot; 9.262 @ 144.69 racemagnum
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Re: EFI
[Re: slammedR/T]
#1740311
01/28/15 09:51 PM
01/28/15 09:51 PM
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Joined: Nov 2003
Posts: 1,969 Chandler, AZ
Duner
top fuel
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top fuel
Joined: Nov 2003
Posts: 1,969
Chandler, AZ
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The factory stuff is only making changes to an overall multiplier in the short and long term trims. It's only "trimming" the fuel where it sees you drive it all the time in closed loop all the time - and changing the overall multiplier. At WOT it's going off the established fuel table - while using that same multiplier, but it can't change the table itself based on O2 sensor info. If it trimmed fuel at idle and cruise - it's going to pull fuel away at WOT too.
The modern standalone stuff looks at what your target AFRs are throughout the rpm range and load settings, and re-writes the tune to get it closer while it "learns". It learns at WOT as well as idle and cruise. Depending upon how much authority you let it have - it can change the fuel table slowly or quickly to get it pretty darn close. Of course, you can also pull up the logs and manually change the fuel tables to speed up the process.
It still has seperate fuel tables for idle and cruise and WOT, while the O2's are narrow band(unless factory turbo car) it still tries for a predetermend fuel trim from fuel maps in the software. Now it can alter the fuel maps over time from learning how you drive, but OE's are based on fuel milage and emmisions production and don't set for best performance.
My Dakota would slow down by 2 full tenths if I let the factory PCM "learn" while idling up the return road. It trimmed the multiplier - that also affected WOT operation. So every time I was in the staging lanes - I'd reset the PCM and let it start fresh. I finally just "forced" it to stay in open loop by unplugging the factory O2 sensors when I was at the track. It was very hard to go rounds with it slowing down every pass!
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Re: EFI
[Re: Duner]
#1740313
01/29/15 02:19 AM
01/29/15 02:19 AM
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Joined: Jan 2003
Posts: 1,938 Sonora CA
Mopar_Rich
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,938
Sonora CA
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Quote:
My Dakota would slow down by 2 full tenths if I let the factory PCM "learn" while idling up the return road. It trimmed the multiplier - that also affected WOT operation. So every time I was in the staging lanes - I'd reset the PCM and let it start fresh. I finally just "forced" it to stay in open loop by unplugging the factory O2 sensors when I was at the track. It was very hard to go rounds with it slowing down every pass!
You really can't use OEM ECUs for racing unless you can get into the program and change the target A/F ratios and the strategy whose objective was related to the control of emissions, not WOT operation. GM guys can do this easily, but not so easy with Mopar ECUs. I have done it but it wasn't easy nor legal for street operation. If you are in a state that does not have strict emission laws the way to go is with an aftermarket ECU that you can tune.
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Re: EFI
[Re: Mopar_Rich]
#1740315
01/29/15 02:37 AM
01/29/15 02:37 AM
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Joined: Nov 2003
Posts: 1,969 Chandler, AZ
Duner
top fuel
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top fuel
Joined: Nov 2003
Posts: 1,969
Chandler, AZ
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Quote:
You really can't use OEM ECUs for racing unless you can get into the program and change the target A/F ratios and the strategy whose objective was related to the control of emissions, not WOT operation. GM guys can do this easily, but not so easy with Mopar ECUs. I have done it but it wasn't easy nor legal for street operation. If you are in a state that does not have strict emission laws the way to go is with an aftermarket ECU that you can tune.
I finally gave up and went to a standalone setup that I could control. MUCH better!
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Re: EFI
[Re: Duner]
#1740316
01/29/15 06:22 AM
01/29/15 06:22 AM
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Joined: Nov 2004
Posts: 6,890 North Alabama
Monte_Smith
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Posts: 6,890
North Alabama
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As already stated, with EFI, you likely won't make any more PEAK power, but you usually make more usable and manageable power. So while there may not be a peak power increase, the car is usually a little faster because of better tunability. As good as they CAN be, a carb is still just a somewhat controlled fuel leak on top of your motor. Even on the BEST carb, the fuel curve usually sucks. There is no spot in the fuel curve that you can't address with EFI if you put in the time.
As far as the "learn" mode on the Holley, that is just a drivability thing for street use. You turn it on, set the sensitivity, drive the car normally and the system "learns" and puts that info in the learn table. It is then up to you to transfer as little or much of that table as you choose, to the base fuel table. It works very well.
In "race" trim, you will run the car off the base fuel table, in closed loop, to a target A/F. It will "correct" within a percentage that you ALLOW it to, but it doesn't learn anything, nor make any permanent changes to the table. You want your base table VERY close. Myself, I set my "window" of correction at + or - 5%. That means I have a 10% correction window. If it bottoms or tops the correction factor at any time during the run, I come back and make changes to the map in those areas.
You will need a street map and a race map............because you will likely run it in cruise mode at a much leaner A/F ratio for mileage. But changing from one to the other is simply a couple keystrokes on the computer.
I have run our car in both closed loop with correction on and in open loop, strictly off the map. It runs the same either way
Monte
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Re: EFI
[Re: Monte_Smith]
#1740317
01/29/15 10:01 AM
01/29/15 10:01 AM
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Joined: Nov 2003
Posts: 1,969 Chandler, AZ
Duner
top fuel
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top fuel
Joined: Nov 2003
Posts: 1,969
Chandler, AZ
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Thanks Monte! I do in fact have separate tunes for street and track. Street - less timing, less boost, less fuel - 91 octane Track - more timing, more boost, more fuel - 100 octane While I don't have the suspension sorted enough to set it on kill out of the gate (best 60' is 1.43, with best mph of 133.65 mph @ 4200#) - the ability to soften the hit on launch has helped it a bunch. The launch mode allows me to ramp in boost and timing that track conditions will allow for. No active traction control yet - but simply "managed" launch. I haven't played with carbs in forever - but the switch from a factory OEM control to standalone EFI has been huge. Once I buy me some good shocks.... Oh wait, wrong thread. hahaha.
Last edited by Duner; 01/29/15 10:03 AM.
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Re: EFI
[Re: 68cuda440]
#1740318
01/29/15 11:45 AM
01/29/15 11:45 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Romeo MI
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Thanks... I dont know why I can never remember the loop and I worked with injection for over 20 years.. but I did the mechanical part.. nothing on the electrical part
"closed loop" is controls terminology, it means that the feedback control loop is being used. In other words the controller is looking at the output of the system and feeding that information back and adjusting the input. In this case injector duty cycle is the input and O2 is the output. If you are "open loop" you are working purely off a control map based on the inputs of all the other sensors to determine duty cycle and not using the feedback of the O2 to adjust.
-Michael
For some reason I use to think of it as open loop = open minded... looking at everything... I just have to get that way of remembering it out of my head
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Re: EFI
[Re: MR_P_BODY]
#1740319
01/29/15 12:25 PM
01/29/15 12:25 PM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
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Posts: 27,421
Balt. Md
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I am curious about some operation on the aftermarket EFI systems. I have never run one or even worked on any aftermarket EFI systems as I have only worked with Mopar OEM EFI units up to 2011 when I retired. From what I figure the Mopar performance PCM controllers can only give performance boost at wide open throttle since all OEM controllers go in open loop at WOT as far as I know. So if you bought a Mopar performance PCM if can give more power at WOT but in normal drive modes it still has to meet emission standards as far as I know so it has to shoot for the perfect air/fuel ratio of about 14 to 1 which there is a word for it that I know I cant spell correct right now. That I know of OEM controllers in most modes are closed loop where the 02 feedback is used to control air/fuel for the best ratio to meet emission standards and make decent but not the most power. Most OEM will be in closed loop by the time the eng is about 120 degrees or even sooner. At WOT the controller has a program for the eng it has in it to give so much fuel in reference to MAP , ECT , RPM , TPS and any other sensor that it may use in the air/fuel ratio as it will ignor the 02 input at WOT. My question is with the aftermarket controllers can you put it in open loop anytime you want to run off the program you have in it ? Like at the track when you come up on the converter will it be in an open loop program you have in it when you launch before you are at full throttle ? And does it learn at all in an open loop program you put in it ? The Mopar system I worked with of course will instantly learn in closed loop by first short term if a air/fuel ratio is changed for any reason and then if it stays that way long enough then by long term to drive the short term back to zero and then fine tuned by the 02.
So I am curious on the aftermarket performance EFI units if you can run it on a program anytime you want that you have in it thats an open loop type program and from what I have heard most aftermarket EFI units shoot for about 12 to 1 ratio for the most power ? Also will the aftermarket EFI units still adjust any by the 02 in an open loop you have in it at all or stick to the full program in it at that time ? I dont mean to go off track but I figure this may help the OP with his question about EFI some anyway and can help me or any of us that may use an aftermarket EFI unit sometime. Thanks , Ron
Last edited by 383man; 01/29/15 12:32 PM.
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Re: EFI
[Re: 383man]
#1740321
01/29/15 12:51 PM
01/29/15 12:51 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
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Posts: 52,972
Romeo MI
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Ron this is the word your looking for "stoichiometric" and yes the open or closed can be turned on or off with a laptop.. I'm still learning the Holley multipoint system I bought but just from reading it has WAY MORE than I need at this time but will allow me to add things down the road..it will control boost or nitrous and many other functions.. turn on the fans, control timing with and without boost... like I said... I'm still learning.. I'll take it out in the spring and start to learn what I can do
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Re: EFI
[Re: MR_P_BODY]
#1740322
01/29/15 03:14 PM
01/29/15 03:14 PM
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Joined: Nov 2004
Posts: 6,890 North Alabama
Monte_Smith
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master
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Posts: 6,890
North Alabama
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Open loop is open loop........meaning it runs on the map with no adjustments, no learn. It reads the 02 of course, but makes no changes based on the info.
With aftermarket EFI, you can turn on closed loop whenever you want, based on the parameters you program it to recognize. On our own car, which leaves at 3400 on the brake, I delay the closed loop until 5000 when on the race tune. This keeps the 02 from "chasing" and trying to correct on the brake, plus lets the motor accelerate clean OFF the brake. Of course it reaches 5000 quickly, but the car is already moving well at that point. Others might need this number higher or lower, depending on converter. Ours is REALLY tight
Monte
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Re: EFI
[Re: Monte_Smith]
#1740325
01/29/15 07:42 PM
01/29/15 07:42 PM
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Joined: Nov 2006
Posts: 733 jacksonville,FLORIDA
slammedR/T
super stock
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super stock
Joined: Nov 2006
Posts: 733
jacksonville,FLORIDA
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Some real good info in here, hopefully I will be going dominator efi real soon on my truck and sorry in advance as i will be asking you question Monte Smith
2000 Dakota R/T, 408 magnum, 727, Indy heads 1000cfm 4150 carb, 93 octane fuel. motor; 10.258 @ 132.78 200 shot; 9.262 @ 144.69 racemagnum
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