:Bang Head: idling issues just may be solved
06-16-2008, 09:07 PM
#11
First...it's manifold VACUUM in kpa. You know that right? 0 is really 100 absolute. 80 is really 20 absolute. Absolute being what you'd compare to the VE table.
But for the most part, you sound like you have the idea. If at a lower voltage you are leaner, you can raise the offset to richen it up a little. Same the other way, if at higher voltages you are richer, then you can lower the vlaues to lean it out. But unless you have voltages that are all over the place (like me which is bad anyways) most people will never need to do that. Again, past 100kpa on your ve table, you won't to see the benefits of this table.
But for the most part, you sound like you have the idea. If at a lower voltage you are leaner, you can raise the offset to richen it up a little. Same the other way, if at higher voltages you are richer, then you can lower the vlaues to lean it out. But unless you have voltages that are all over the place (like me which is bad anyways) most people will never need to do that. Again, past 100kpa on your ve table, you won't to see the benefits of this table.
06-17-2008, 05:55 AM
#12
I am way beyond worrying about sound like an idiot so let me ask a couple questions that may clear up some things for me .....and maybe a few others.
Here are the options in my "INJECTOR" section in EFILive:
-Injector pulse width voltage adjustment
-Injection timing
-Injection timing trim
-Injection Bank adjustments
-Injector flow rate
-Injector voltage correction
-Minumum injector pulse width
-Default minimum injector pulse width
-Small pulse adjust
Anyone wanna take a stab at explaining a few ofthese and how they react with your tune? I understand a few (2 really), but the others I am unsure of.
Here are the options in my "INJECTOR" section in EFILive:
-Injector pulse width voltage adjustment
-Injection timing
-Injection timing trim
-Injection Bank adjustments
-Injector flow rate
-Injector voltage correction
-Minumum injector pulse width
-Default minimum injector pulse width
-Small pulse adjust
Anyone wanna take a stab at explaining a few ofthese and how they react with your tune? I understand a few (2 really), but the others I am unsure of.
06-19-2008, 05:36 PM
#13
Well apearantly i have found an alternate way to close a thread....LMAO!!!
From now on, if a MOD wants to close a thread, there is no need to actually lock it.....just copy and paste the post right above this one and it should efficiently stop all communication with in..
From now on, if a MOD wants to close a thread, there is no need to actually lock it.....just copy and paste the post right above this one and it should efficiently stop all communication with in..
06-19-2008, 05:53 PM
#14
I laughed at this very thing this morning. LMAO
Back to me JUST for a second...I went and bought #4AWG battery wire and replaced the #8AWG wire going from the alternator to the battery block (red box). I didn't have time to test all the different points, wife was leaving and I have to watch the sick 3 yr old. BUT, I did hop in and start it up and test the junctions I have under the dash. Yesterday they had 12.8ish volts, they now have 14.3 volts. Again, not much time to put it to a real test of time and load, but that is sweet sweet news to me.
So....this wire....
is clogging up the works? hmmmm
Back to me JUST for a second...I went and bought #4AWG battery wire and replaced the #8AWG wire going from the alternator to the battery block (red box). I didn't have time to test all the different points, wife was leaving and I have to watch the sick 3 yr old. BUT, I did hop in and start it up and test the junctions I have under the dash. Yesterday they had 12.8ish volts, they now have 14.3 volts. Again, not much time to put it to a real test of time and load, but that is sweet sweet news to me.
So....this wire....
is clogging up the works? hmmmm
06-19-2008, 06:09 PM
#15
-Injector pulse width voltage adjustment
I say this amount is added to correct for voltage to the injectors. That simple?
-Injection timing
"This table will offset the actual opening of the injector referenced to the reference pulses and engine coolant temperature." Yeah, what he said.
-Injection timing trim
Apparently if the PCM is still looking for Injector timing adjustments passed the "injector Timing" table, it will reference here. sigh
-Injection Bank adjustments
The PCM assignment for wher ethe injectors belong on what bank. It adjusts trims by banks, so it needs to know this I imagine.
-Injector flow rate
Well, this is probably on of the two you do know. The calc for the injectors flow as various vacuum levels.
-Injector voltage correction
This is making corrections as per the voltage to the fuel pump. I'd imagine it's only helpful in P/T. This is probably a good reason why we never realize pumps are failing unless we have forced induction.
-Minumum injector pulse width
This is the minimum injector setting. Pretty much what YOU are looking for as a minimum.
-Default minimum injector pulse width
If for some reason the PCM calculates a lower PW than what you have setup in the minimum Inj pw table, it will look at this table.
-Small pulse adjust
If for some reason the calculations call for a very small open time, too small, it will use these adjustments or adders to the opening time.
I say this amount is added to correct for voltage to the injectors. That simple?
-Injection timing
"This table will offset the actual opening of the injector referenced to the reference pulses and engine coolant temperature." Yeah, what he said.
-Injection timing trim
Apparently if the PCM is still looking for Injector timing adjustments passed the "injector Timing" table, it will reference here. sigh
-Injection Bank adjustments
The PCM assignment for wher ethe injectors belong on what bank. It adjusts trims by banks, so it needs to know this I imagine.
-Injector flow rate
Well, this is probably on of the two you do know. The calc for the injectors flow as various vacuum levels.
-Injector voltage correction
This is making corrections as per the voltage to the fuel pump. I'd imagine it's only helpful in P/T. This is probably a good reason why we never realize pumps are failing unless we have forced induction.
-Minumum injector pulse width
This is the minimum injector setting. Pretty much what YOU are looking for as a minimum.
-Default minimum injector pulse width
If for some reason the PCM calculates a lower PW than what you have setup in the minimum Inj pw table, it will look at this table.
-Small pulse adjust
If for some reason the calculations call for a very small open time, too small, it will use these adjustments or adders to the opening time.
06-19-2008, 06:16 PM
#16
I'll post this up since its appropriate in this thread now. This is from a very good tuner in my area. It has really helped me understand some of the tables. I don't think he will mind.
The SPA table axis is time in milliseconds.
Since I think you have a good grasp on the airflow part, let me explain the core of how the fueling works.
First the computer arrives at an airflow number. How ever the means being implimented, MAF or SD, it comes to a number that it thinks the engine is ingesting. Broken down to the air breathed per cylinder, for your average 6.0L at idle it would be around 0.17 g/cly.
The first part of the fueling process is to take the commanded AFR and determine the amount of fuel to be delivered. At an AFR of 14.7 to 1, your wanting to have 14.7 times more air than fuel, so you divide my the AFR.
0.17 / 14.7 = 0.0115g of fuel
Now the computer knows the mass of fuel it wants to add, is has to calculate how long the injector needs to be open to deliver it. The first part is the simple part, it comes to a pulsewith size base on the injectors flow rate. 70 lb/hr = 8.82 g/sec. If we want 0.0115g of fuel and the injector flows 8.82 g/sec, then we divide desired amount by the flow rate to get the time.
0.0115 / 8.82 = 0.001303 s or 1.303 ms
(Side note: this is where the min/default pw come into play. The stock value of 1.2 was almost reached at idle. During light throttle driving or slight decel the fuel value would be much smaller. If the computer comes up with 1.0, the min table would have bumped it back to 1.2 making the truck go rich. Changing the VE or MAF would have no effect because the calced number is being overridden. This is were most people run into problems with big injectors. Rule of thumb, if your new injectors are twice as big as stock, you need to cut the min/default numbers in half. Theres more to it than that, but thats a good start. Numbers like 1.0 or 0.9 that I see people wanting to use with the 60#er's just isn't small enough. There is also a value in transient fueling that limits the low floor, but the trucks don't use it.)
Now the complication of injector characteristics comes into play. We know we want 1.3ms worth of fuel, but how long does the injector really need to be powered so that we get 1.3ms worth of fuel?
Any injector takes time to open and close. Thats were the offset comes from, but during short pulses you get into partial openings, so besides the offset you get into this non-linear part of the world that has to be compensated for by the SPA table. Techically it's all offset, but because the offset is different by voltage, pressure, and pulse time the injector offset table would be 3 diminsional. GM engineers don't like greater than 2d tables any more then we do so the end result is a 2d table that corrects for voltage and pressure (offset table) and a seperate table that corrects for the partial opening (SPA table). Put the 2 tables results together and you get a total offset that gets added to the calced pulsewith that should make the injector deliver the desired amount of fuel.
I'll use numbers from the spreadsheet I sent you to continue the example. Let's say your truck is charging to the tune of 13.5 volts. Because your fuel pressure is vacumm referenced the relative pressure is constant and irrelivent. Your base offset is 0.457
Lookup 1.3ms in the SPA table and we get the number that corrects for the non-linear aspect caused by partial openings. 0.106
0.457 + 0.106 = 0.563ms total offset
1.303 + 0.563 = 1.866 final pulsewidth
So if the numbers are tailored to the injectors, a pw of 1.866 should give us 0.0115 worth of fuel. And assuming the air was estimated right, an observed AFR of 14.7
Since I think you have a good grasp on the airflow part, let me explain the core of how the fueling works.
First the computer arrives at an airflow number. How ever the means being implimented, MAF or SD, it comes to a number that it thinks the engine is ingesting. Broken down to the air breathed per cylinder, for your average 6.0L at idle it would be around 0.17 g/cly.
The first part of the fueling process is to take the commanded AFR and determine the amount of fuel to be delivered. At an AFR of 14.7 to 1, your wanting to have 14.7 times more air than fuel, so you divide my the AFR.
0.17 / 14.7 = 0.0115g of fuel
Now the computer knows the mass of fuel it wants to add, is has to calculate how long the injector needs to be open to deliver it. The first part is the simple part, it comes to a pulsewith size base on the injectors flow rate. 70 lb/hr = 8.82 g/sec. If we want 0.0115g of fuel and the injector flows 8.82 g/sec, then we divide desired amount by the flow rate to get the time.
0.0115 / 8.82 = 0.001303 s or 1.303 ms
(Side note: this is where the min/default pw come into play. The stock value of 1.2 was almost reached at idle. During light throttle driving or slight decel the fuel value would be much smaller. If the computer comes up with 1.0, the min table would have bumped it back to 1.2 making the truck go rich. Changing the VE or MAF would have no effect because the calced number is being overridden. This is were most people run into problems with big injectors. Rule of thumb, if your new injectors are twice as big as stock, you need to cut the min/default numbers in half. Theres more to it than that, but thats a good start. Numbers like 1.0 or 0.9 that I see people wanting to use with the 60#er's just isn't small enough. There is also a value in transient fueling that limits the low floor, but the trucks don't use it.)
Now the complication of injector characteristics comes into play. We know we want 1.3ms worth of fuel, but how long does the injector really need to be powered so that we get 1.3ms worth of fuel?
Any injector takes time to open and close. Thats were the offset comes from, but during short pulses you get into partial openings, so besides the offset you get into this non-linear part of the world that has to be compensated for by the SPA table. Techically it's all offset, but because the offset is different by voltage, pressure, and pulse time the injector offset table would be 3 diminsional. GM engineers don't like greater than 2d tables any more then we do so the end result is a 2d table that corrects for voltage and pressure (offset table) and a seperate table that corrects for the partial opening (SPA table). Put the 2 tables results together and you get a total offset that gets added to the calced pulsewith that should make the injector deliver the desired amount of fuel.
I'll use numbers from the spreadsheet I sent you to continue the example. Let's say your truck is charging to the tune of 13.5 volts. Because your fuel pressure is vacumm referenced the relative pressure is constant and irrelivent. Your base offset is 0.457
Lookup 1.3ms in the SPA table and we get the number that corrects for the non-linear aspect caused by partial openings. 0.106
0.457 + 0.106 = 0.563ms total offset
1.303 + 0.563 = 1.866 final pulsewidth
So if the numbers are tailored to the injectors, a pw of 1.866 should give us 0.0115 worth of fuel. And assuming the air was estimated right, an observed AFR of 14.7
06-19-2008, 06:38 PM
#17
That's pretty cool...hmmm. SPA table...hmmm. That does simplify it doesn't it. Is he saying most rich idle cases are just a minimum/default issue? I've always had low numbers in there. I am kinda excited to get my voltage right (kinda like you and your pressure) I can actually dive into the inj tuning with a consistent tuning platform.
06-20-2008, 07:18 AM
#20
That's pretty cool...hmmm. SPA table...hmmm. That does simplify it doesn't it. Is he saying most rich idle cases are just a minimum/default issue? I've always had low numbers in there. I am kinda excited to get my voltage right (kinda like you and your pressure) I can actually dive into the inj tuning with a consistent tuning platform.