tuning VE, question about disconnecting maf
12-14-2004, 10:34 PM
#21
If VE's are correct then yes, you can set your IFR table. The problem is, most people assume their IFR table is correct when they set their VE table. If you have a stock engine you might as well assume the VE table is correct, but if you're modded but have stock injectors you can assume your IFR table is correct. If neither are stock, you're kind of in a Catch 22 situation. Unless I'm misunderstanding what you're saying.
12-14-2004, 10:39 PM
#22
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Originally Posted by gojo
I'm interested.
I think when you say disconnected it's confusing. May be the reason for no response. With no MAF you can't get VE's or MAF frequency. With the MAF zeroed you get it all.
I think when you say disconnected it's confusing. May be the reason for no response. With no MAF you can't get VE's or MAF frequency. With the MAF zeroed you get it all.
What caught my interest was realizing IFR's could be checked for correctness. I'm not sure of the formulas and their accuracy for calculating IFR's for bigger injectors. This new idea seems very important to me. If VE's are corrected then IFR's can be set with the MAF 0'd. When the MAF is hooked up again the trims should then reflect the inaccuracy of the MAF. My hangup is IFR's since if they are right setting AFR gets easier.
I have dialed in my car and my IFR table has be rescalced for 32 lbs injectors @ 4 bar. Once that was doen i forgot about the IFR table and now i am concetrating on the ve table (iam SD) and I have a buddy and another friends car that i am tuning concentrate on the MAF table and back caluculating it to get good values. Even when my injectors was stock I never messed with them I used the ve table to tune everything with great sucess (kinda like you do with the idle setting and such). If i ahd a maf (gave mine away) I would have way more data a little faster for the masses but since idont I have othe people schedules to work with
One more thing I also think the computer when the maf is hooked up and functional defaults the dyn pids to whatever the maf is reading (this is why they are the same). I think this is to save processing cycles for more imortant things. The calculation could be a little intesensive since it has to look at a few more sensors and do some calculations to derive a value. But when the Maf performance code is throw the computer then deafult back to doing the calculations at it need to know how much air the engine is injesting to shoot the appropriate amount of fuel.
I've had a few beers so feel free to ask me to clarify my thought if they seem a little bunched or so
12-14-2004, 10:41 PM
#23
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Originally Posted by P Mack
If you have a stock engine you might as well assume the VE table is correct, but if you're modded but have stock injectors you can assume your IFR table is correct. If neither are stock, you're kind of in a Catch 22 situation. Unless I'm misunderstanding what you're saying.
You'd be suprised how rich the stock ve table is. I think after GM calibrated it they added a **** load of fuel just to make sure in case the maf failed they would only be replacing a MAF and not pistons......
12-14-2004, 10:42 PM
#24
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Originally Posted by P Mack
If VE's are correct then yes, you can set your IFR table. The problem is, most people assume their IFR table is correct when they set their VE table. If you have a stock engine you might as well assume the VE table is correct, but if you're modded but have stock injectors you can assume your IFR table is correct. If neither are stock, you're kind of in a Catch 22 situation. Unless I'm misunderstanding what you're saying.
12-14-2004, 11:09 PM
#25
Humpin, you're probably right, judging from the 1.25 PE tables they also put in stock. I didn't have hptuners when I was stock so I don't know first hand.
gojo, Ok that makes sense if you could log actual VE's, but where do those come from? To calculate actual VE the pcm would have to know the massflow of the engine, which leads to another catch 22 situation with the MAF.
gojo, Ok that makes sense if you could log actual VE's, but where do those come from? To calculate actual VE the pcm would have to know the massflow of the engine, which leads to another catch 22 situation with the MAF.
12-14-2004, 11:13 PM
#26
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Originally Posted by P Mack
Humpin, you're probably right, judging from the 1.25 PE tables they also put in stock. I didn't have hptuners when I was stock so I don't know first hand.
gojo, Ok that makes sense if you could log actual VE's, but where do those come from? To calculate actual VE the pcm would have to know the massflow of the engine, which leads to another catch 22 situation with the MAF.
gojo, Ok that makes sense if you could log actual VE's, but where do those come from? To calculate actual VE the pcm would have to know the massflow of the engine, which leads to another catch 22 situation with the MAF.
The PCM does know mass flow. It back calculates this from teh ve table(this is why this needs to be dialed in as close as posible preferably with a WB). It is represented as dyncylair or dynair
12-14-2004, 11:21 PM
#29
Originally Posted by gojo
You understand me. But, if you log actual VE's and input those values the IFR's don't matter at that point. If you use trims to set VE's then it will.
Regardless of how you want to use it, the IFR table shouldn't be touched IMO if the injectors are stock. You want to change the fueling with the VE table regardless if you are tuning with trims or SD/Open Loop.
12-14-2004, 11:23 PM
#30
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The IFR table is a set it and forget i thing. Once you have it dialed in for your injectors everything else is ve and if you are trying to reclibrate the maf, those are the nly tables tha need to be touched
12-14-2004, 11:24 PM
#31
Yes, I understand it calculates mass flow from VE. That is why it would be circular to calculate VE from massflow and assume its right. Another catch 22. The only way to not end up with a catch 22 is assuming some table is right.
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
12-14-2004, 11:27 PM
#33
Originally Posted by P Mack
Yes, I understand it calculates mass flow from VE. That is why it would be circular to calculate VE from massflow and assume its right. Another catch 22. The only way to not end up with a catch 22 is assuming some table is right.
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
12-14-2004, 11:28 PM
#34
Originally Posted by P Mack
Damn, you guys managed to squeeze 4 posts in on me before i responded to post 26. I think we all agree that the right way to do things is assume the ifr table is right (or scale it for bigger injectors) then do ve, then do MAF. Not ve then ifr.
We're fast.
12-14-2004, 11:30 PM
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Originally Posted by P Mack
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
No matter what the IFR tables look like you can still fuel the car. IMO the IFR table dictate how hard the injectors work and a lot of tuners use this as a bandaid to + trims. Excesivly large ve values my indicate a problem in the IFR table but they can still be fixed via the ve table.
12-14-2004, 11:46 PM
#38
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Originally Posted by P Mack
Yes, I understand it calculates mass flow from VE. That is why it would be circular to calculate VE from massflow and assume its right. Another catch 22. The only way to not end up with a catch 22 is assuming some table is right.
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
You said to dial in VE with WB which I agree with. But to do that you have to assume your IFR tables are right.
VEpcm 0.0 3000.0 .2 "{SAE.MAF.gps}*({SAE.IAT.C}+273.15)/(346*{SAE.RPM}*{SAE.MAP.kPa})*6155274.2"
I agree that other methods of correcting VE are problematic. I did not find the WB tuning method too accurate and had the circular problem to which you allude. That's why this new find is exciting to me.
Let me start some trouble. If you're going to run in SD then tune using all the SD steps and WB. If you are going to use the MAF then use this new find and only zero the MAF. Just come close and let the multi million $ PCM do it's job. By the way, my car with the MAF disconnected runs as if it's connected. It seems that my VE table is at least close. But I'm not sure if the IFR and MAF values are correct. I don't think they are. The reason I prefer manually inputting VE values is that other systems average in outlier numbers, such as transition values from cell to cell. A comparison of those averages shows a significant difference from stable values logged within each cell. I guess EFI is needed to see it.
12-15-2004, 12:09 AM
#40
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I agree that other methods of correcting VE are problematic. I did not find the WB tuning method too accurate and had the circular problem to which you allude. That's why this new find is exciting to me.
Let me start some trouble. If you're going to run in SD then tune using all the SD steps and WB. If you are going to use the MAF then use this new find and only zero the MAF. Just come close and let the multi million $ PCM do it's job.
By the way, my car with the MAF disconnected runs as if it's connected. It seems that my VE table is at least close. But I'm not sure if the IFR and MAF values are correct. I don't think they are. The reason I prefer manually inputting VE values is that other systems average in outlier numbers, such as transition values from cell to cell. A comparison of those averages shows a significant difference from stable values logged within each cell. I guess EFI is needed to see it.
When your ve table is close you will see this what you wont see is the the throttle response (it suffers when the maf is plugged in (the heated elemet sucks for a fast reacitn g system that is why there is blending under 4K above 4k the maf takes over because it can heat up and cool downfast enough to be soewhat accurate). If you have your sotck injectors then the IFR table is spot on. If you have upgraded there are formulas to figure out the new injectors. what i did after that was find out the percentage differnce between the new and the old and scale the whole table by this value. Then checked the % difference bettween the min value and max value of the old and did this for the new. This confirmed to me that the forumula was right and in the ball park....
With open loop there are no outside influences set the table to 1.13 which is 12.96: and tune for that when you are done you can bet your right arm everythihng will fall into place....