Do u raise or lower the Fuel Injector Flow Rate
Staging Lane
Joined: Nov 2001
Posts: 83
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From: jawja
Re: Do u raise or lower the Fuel Injector Flow Rate If you have a A4 tranny and you go over 10% on the maf tables be prepared to buy another tranny!Be prepared to have bad timing tables.Be prepared to have a rich or lean condition at WOT.ASK ME HOW I KNOW!!!!! <img border="0" alt="[Banging Head]" title="" src="graemlins/gr_banghead.gif" /> The best and only way (IMO)is to adjust LTFT`s thru the injector flow rate tables.
If you are within +or- 5% of your desired LTFT number use the MAF table to get it dialed in. If you are over the 5% ,start with the IFR table and get it close,then fine tune with the MAF table.There are lots of theories out there but do what has been done and learn from others mistakes.
If you are within +or- 5% of your desired LTFT number use the MAF table to get it dialed in. If you are over the 5% ,start with the IFR table and get it close,then fine tune with the MAF table.There are lots of theories out there but do what has been done and learn from others mistakes.
Staging Lane
Joined: Nov 2001
Posts: 83
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From: jawja
Re: Do u raise or lower the Fuel Injector Flow Rate Daily
If you have +15 you are lean and the computer is adding fuel,if the pcm is adding fuel at WOT you wont have all your timing and it will be inconsistent.
If you have +15 you are lean and the computer is adding fuel,if the pcm is adding fuel at WOT you wont have all your timing and it will be inconsistent.
TECH Apprentice
Joined: Dec 2001
Posts: 314
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From: Salisbury, Md
Re: Do u raise or lower the Fuel Injector Flow Rate My ltrims are now around -2 because I have ls1 edit. I just stated that to explain that that was the current level of a lean condition that I have compensated for by adjusting the injector flow rate tables.
Teching In
Joined: Aug 2002
Posts: 44
Likes: 0
From: Dearborn, Michigan
Re: Do u raise or lower the Fuel Injector Flow Rate The fuel injector table is taylor made by the factory for the factory injectors that we have in our engines. This table is very accurate and should not need to be modified unless we changed the injectors or changed the fuel pressure.
I can see where the fuel pressure might very a little from car to car so in that case a minor change to the fuel injector table would be good. But ther is no way that the injector table is so far off that we have to correct it for +20% LTFTs.
By contrast, the MAF table can be way off based on the mods that we have done, descreening, GMAF, LS6 intake, heads, cam, etc. This is why I had my LTFTs at +20%. The fuel injector table was correct, but the MAF table was not. By modifing the MAF table you are calibrating the MAF sensor for your specific mods.
I dont see why someone would change a table which is very good from the factory before they change a table that we know is off. There is so little varibility in the manufacturing of fuel injectors, they are a very precise instrument. Even though the MAF is well made and precise, it is not as precise as the fuel injector.
Also, I do not believe that we are "tricking" the PCM concerning the MAF flow rate, we are (if we know what we are doing) actually calibrating the MAF for our specific mods.
99blackSS: I read that post, very interesting stuff. But, I do think that something else was at play in that case whereby he got back his timing.
I dont think that all of the facts are known. It deserves more consideration.
So,,,, it looks like I am alone on this issue.
I can see where the fuel pressure might very a little from car to car so in that case a minor change to the fuel injector table would be good. But ther is no way that the injector table is so far off that we have to correct it for +20% LTFTs.
By contrast, the MAF table can be way off based on the mods that we have done, descreening, GMAF, LS6 intake, heads, cam, etc. This is why I had my LTFTs at +20%. The fuel injector table was correct, but the MAF table was not. By modifing the MAF table you are calibrating the MAF sensor for your specific mods.
I dont see why someone would change a table which is very good from the factory before they change a table that we know is off. There is so little varibility in the manufacturing of fuel injectors, they are a very precise instrument. Even though the MAF is well made and precise, it is not as precise as the fuel injector.
Also, I do not believe that we are "tricking" the PCM concerning the MAF flow rate, we are (if we know what we are doing) actually calibrating the MAF for our specific mods.
99blackSS: I read that post, very interesting stuff. But, I do think that something else was at play in that case whereby he got back his timing.
I dont think that all of the facts are known. It deserves more consideration.
So,,,, it looks like I am alone on this issue.
Teching In
Joined: Aug 2002
Posts: 44
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From: Dearborn, Michigan
Re: Do u raise or lower the Fuel Injector Flow Rate BTW: My LTFTs are between -4% and -2%, timing at WOT is 27.5* or 28* and I'm pulling 400.3Hp at the drive wheels with AFR @ WOT of 13.2:1.
Teching In
Joined: Aug 2002
Posts: 44
Likes: 0
From: Dearborn, Michigan
Re: Do u raise or lower the Fuel Injector Flow Rate SuperZ:
You should not change the MAF table while on the chassis dyno due to the learn process. When I'm on the chassis dyno, I work only with the timing table and the WOT fuel table.
The main reason why you shouldn't modify the MAF table on the chasis dyno is that the PCM will begin to learn about the new values and begin to update the LTFTs. If you are running positive LTFTs, the PCM is adding fuel during part throotle and also during WOT. If the LTFTs are negative, the PCM is taking fuel away during part throotle, but not during WOT.
You need to get your LTFTs slightly under 0% during part throotle cruising. You do this on the street, never on the dyno. Once you get the LTFTs under control (less than 0%), you can work on the WOT fuel table. With negative LTFTs, you are assured that a change to the WOT fuel table is solely responsible for a change in the WOT AFR. You can work on the WOT fuel table by making CAREFUL WOT runs on the Xway while taking ATAP readings and then going back home to make your changes. Then another street run. When you get down to the lowest mV on the O2s with no KR, its time to go to the dyno. Do not rely on your O2 sensors to be accurate, they are not. For example, my O2s put out 960mV when I'm on the dyno with an AFR of 13.2:1.
Getting the correct MAF table for your car can take 10 to 20 cruising runs on the street. After each modification to the MAF table, you should allow the PCM to relearn to redo the LTFTs (at least 15 minutes on the street)or you should do a PCM reset. Also, you should check for MAF table values in the graph mode, you must have a smooth curve or you are screwed up. (I think that for those who have had problems with changing the MAF table do not know how to go about it properly. There are many people on this board and LS1.com, as well as, many tuner shops who have great success with re-calibrating the MAF table.) As for me when I started my MAF re-calibration, my LTFTs were +20%. I made a cross the table change of 15% increase (by multipling the entire table by 115%). With this big change, I recommend a PCM reset. If you do changes to the MAF table of less than 5%, I do not do a PCM reset. I just drive the car around for 15 minutes, then I take more ATAP readings.
Enough said on this topic, you guys do what you think is best. I was giving my take on the issue.
You should not change the MAF table while on the chassis dyno due to the learn process. When I'm on the chassis dyno, I work only with the timing table and the WOT fuel table.
The main reason why you shouldn't modify the MAF table on the chasis dyno is that the PCM will begin to learn about the new values and begin to update the LTFTs. If you are running positive LTFTs, the PCM is adding fuel during part throotle and also during WOT. If the LTFTs are negative, the PCM is taking fuel away during part throotle, but not during WOT.
You need to get your LTFTs slightly under 0% during part throotle cruising. You do this on the street, never on the dyno. Once you get the LTFTs under control (less than 0%), you can work on the WOT fuel table. With negative LTFTs, you are assured that a change to the WOT fuel table is solely responsible for a change in the WOT AFR. You can work on the WOT fuel table by making CAREFUL WOT runs on the Xway while taking ATAP readings and then going back home to make your changes. Then another street run. When you get down to the lowest mV on the O2s with no KR, its time to go to the dyno. Do not rely on your O2 sensors to be accurate, they are not. For example, my O2s put out 960mV when I'm on the dyno with an AFR of 13.2:1.
Getting the correct MAF table for your car can take 10 to 20 cruising runs on the street. After each modification to the MAF table, you should allow the PCM to relearn to redo the LTFTs (at least 15 minutes on the street)or you should do a PCM reset. Also, you should check for MAF table values in the graph mode, you must have a smooth curve or you are screwed up. (I think that for those who have had problems with changing the MAF table do not know how to go about it properly. There are many people on this board and LS1.com, as well as, many tuner shops who have great success with re-calibrating the MAF table.) As for me when I started my MAF re-calibration, my LTFTs were +20%. I made a cross the table change of 15% increase (by multipling the entire table by 115%). With this big change, I recommend a PCM reset. If you do changes to the MAF table of less than 5%, I do not do a PCM reset. I just drive the car around for 15 minutes, then I take more ATAP readings.
Enough said on this topic, you guys do what you think is best. I was giving my take on the issue.
Staging Lane
Joined: Nov 2001
Posts: 83
Likes: 0
From: jawja
Re: Do u raise or lower the Fuel Injector Flow Rate you can without a doubt change the MAF table to adjust LTFT`s ,But when you change them it also changes line pressure to the trans,timing tables, and you will have to change WOT AFR .Since we are only trying to get the LTFT`s to near zero or slightly less,why not just use the IFR table? This way the only change made is injector pulse times.It get the LTFT`s correct and keeps everything else inline?
Old school days when you add a cam/headers ect... you need to richen the jets in the carb so it wont be lean ,this is basicly the same thing!
Old school days when you add a cam/headers ect... you need to richen the jets in the carb so it wont be lean ,this is basicly the same thing!
Re: Do u raise or lower the Fuel Injector Flow Rate THERE IS A LOT OF MIS-INFORMATION IN THIS THREAD
Doc99SS:
Changing the MAF table to compensate for LTerms is an out-dated method of adjusting fueling and has been thrown out because people have killed tranny's, low timing etc... Your adjustments to the MAF table worked for you becuase you are using a Granetelli MAF. This MAF is known to mis-report air flow ~10%.
You should not make changes greater than 5% to the MAF table unless you are running a ported MAF, aftermarket MAF, or have altered your MAF in some fashion.....period.
Doc99SS:
Changing the MAF table to compensate for LTerms is an out-dated method of adjusting fueling and has been thrown out because people have killed tranny's, low timing etc... Your adjustments to the MAF table worked for you becuase you are using a Granetelli MAF. This MAF is known to mis-report air flow ~10%.
You should not make changes greater than 5% to the MAF table unless you are running a ported MAF, aftermarket MAF, or have altered your MAF in some fashion.....period.
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Verdad Gallardo Re: Do u raise or lower the Fuel Injector Flow Rate DailyAluminumBlock:
A ported MAF cannot be corrected for by a block adjustment to the MAF table (ie multiplying the entire table by 20%). In actuality a ported MAF will misreport airflow more the more air you flow though it. By your multiplying of your MAF curve by a block value you have made your air curve accurate at top, but very innaccurate down low. This will falsly lower timing down low and make your car feel like a dog. You also overadjusted the MAF curve which is what dropped your timing. Timing is referenced from your octane table according to the equation
G/cyl & RPM = 15 * MAF(g/sec) / RPM
Having a falsly high reported MAF flow will reference timing too low. Check out your High Octane Timing table to see what I mean.
The best way to fix a ported MAF is to get rid of it. There is no one easy way to compensate for a ported MAF in LS1 edit. It requires an algorithim adjustment to the MAF table.
You should also return your Low Octane Table to normal. It is a safety measure for when bad gas ends up in the car.
A ported MAF cannot be corrected for by a block adjustment to the MAF table (ie multiplying the entire table by 20%). In actuality a ported MAF will misreport airflow more the more air you flow though it. By your multiplying of your MAF curve by a block value you have made your air curve accurate at top, but very innaccurate down low. This will falsly lower timing down low and make your car feel like a dog. You also overadjusted the MAF curve which is what dropped your timing. Timing is referenced from your octane table according to the equation
G/cyl & RPM = 15 * MAF(g/sec) / RPM
Having a falsly high reported MAF flow will reference timing too low. Check out your High Octane Timing table to see what I mean.
The best way to fix a ported MAF is to get rid of it. There is no one easy way to compensate for a ported MAF in LS1 edit. It requires an algorithim adjustment to the MAF table.
You should also return your Low Octane Table to normal. It is a safety measure for when bad gas ends up in the car.
Re: Do u raise or lower the Fuel Injector Flow Rate Supercharged Z:
Kickass setup.
+8% LTerms on a NA car are no big deal. Adjustments to your WOT fueling should be made via your PE vs RPM table, not your MAF. Your a/f on the dyno is all over the map because you have a supercharger (starts lean goes way rich, goes lean, goes rich)
You should really give a professional a call about supercharger tuning.
TByrne, one of our sponsors is a supercharging maniac.
<small>[ October 31, 2002, 08:30 AM: Message edited by: NoGo ]</small>
Kickass setup.
+8% LTerms on a NA car are no big deal. Adjustments to your WOT fueling should be made via your PE vs RPM table, not your MAF. Your a/f on the dyno is all over the map because you have a supercharger (starts lean goes way rich, goes lean, goes rich)
You should really give a professional a call about supercharger tuning.
TByrne, one of our sponsors is a supercharging maniac.
<small>[ October 31, 2002, 08:30 AM: Message edited by: NoGo ]</small>
Re: Do u raise or lower the Fuel Injector Flow Rate You do not need larger than stock injectors unless
1) You have charted out your injector pulswidths and you see them go (IMHO) +90% for extended periods in the high RPM
2) You start making your peak power well beyond 6000 rpms.
1) You have charted out your injector pulswidths and you see them go (IMHO) +90% for extended periods in the high RPM
2) You start making your peak power well beyond 6000 rpms.
Re: Do u raise or lower the Fuel Injector Flow Rate There seems to be a rising concern for low LTerms.
LTerms are there to adjust your fueling for you. It is not uncommon to have LTerms +/- 15%. I have a-tapped bone stock cars with LTerms greater than +10%. Unless your LTerms are on the hairy edge (close to +/- 25%) there is no reason to monkey with your tuning to get them to zero.
Don't stress about your LTerms +/- 15%, worry about your WOT a/f ratio. As long as your LTerms are within -/+ 25% your car is going to be at a 14.8 a/f ratio.
LTerms are there to adjust your fueling for you. It is not uncommon to have LTerms +/- 15%. I have a-tapped bone stock cars with LTerms greater than +10%. Unless your LTerms are on the hairy edge (close to +/- 25%) there is no reason to monkey with your tuning to get them to zero.
Don't stress about your LTerms +/- 15%, worry about your WOT a/f ratio. As long as your LTerms are within -/+ 25% your car is going to be at a 14.8 a/f ratio.
On The Tree
Joined: Dec 2001
Posts: 186
Likes: 0
From: San Diego, CA, USA
Re: Do u raise or lower the Fuel Injector Flow Rate </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by NoGo:
<strong>Supercharged Z:
Kickass setup.
+8% LTerms on a NA car are no big deal. Adjustments to your WOT fueling should be made via your PE vs RPM table, not your MAF. Your a/f on the dyno is all over the map because you have a supercharger (starts lean goes way rich, goes lean, goes rich)
You should really give a professional a call about supercharger tuning.
TByrne, one of our sponsors is a supercharging maniac.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks!
So are you saying I should increase my Pe vs RPM table down low. ie:say 0-2400rpm? Instead my changing my MAF table to lower my Ltrims?
I did have a professional tune it Ed Wright. I have two PCM's. One with his tuning and another with edit. I was actually able to copy most of what Ed did to my edit pcm. His MAF table was stock. When I would A-tap with Ed's pcm in the car, the Ltrims were +8.8%. So, I am assuming thats where they should be, then it must be ok?
Jason
<strong>Supercharged Z:
Kickass setup.
+8% LTerms on a NA car are no big deal. Adjustments to your WOT fueling should be made via your PE vs RPM table, not your MAF. Your a/f on the dyno is all over the map because you have a supercharger (starts lean goes way rich, goes lean, goes rich)
You should really give a professional a call about supercharger tuning.
TByrne, one of our sponsors is a supercharging maniac.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks!
So are you saying I should increase my Pe vs RPM table down low. ie:say 0-2400rpm? Instead my changing my MAF table to lower my Ltrims?
I did have a professional tune it Ed Wright. I have two PCM's. One with his tuning and another with edit. I was actually able to copy most of what Ed did to my edit pcm. His MAF table was stock. When I would A-tap with Ed's pcm in the car, the Ltrims were +8.8%. So, I am assuming thats where they should be, then it must be ok?
Jason
On The Tree
Joined: Dec 2001
Posts: 186
Likes: 0
From: San Diego, CA, USA
Re: Do u raise or lower the Fuel Injector Flow Rate </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by NoGo:
<strong>You do not need larger than stock injectors unless
1) You have charted out your injector pulswidths and you see them go (IMHO) +90% for extended periods in the high RPM
2) You start making your peak power well beyond 6000 rpms.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I am actually using what came with the blower kit from Vortech. Lucas 38lb injectors.
<strong>You do not need larger than stock injectors unless
1) You have charted out your injector pulswidths and you see them go (IMHO) +90% for extended periods in the high RPM
2) You start making your peak power well beyond 6000 rpms.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I am actually using what came with the blower kit from Vortech. Lucas 38lb injectors.
Re: Do u raise or lower the Fuel Injector Flow Rate </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by superchargedZ: </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><strong>
So are you saying I should increase my Pe vs RPM table down low. ie:say 0-2400rpm? Instead my changing my MAF table to lower my Ltrims? </strong>
The PE vs RPM table will only make adjustments to WOT fueling; it will not affect LTerms. Your LTerms are fine. Positive LTerm of 8% just means that your O2's are perciving a slight lean condition which is being corrected with an 8% adjustment to fueling. If your car is ALWAYS running with at least an +8% LTerms, then you MAY want to consider adjusting your injector flow table slightly just to bring it back to zero, but it is not necessary. Your car will be fine with +8% LTerms. LTerms change with air pressure / temperature / quality etc...
If your a/f ratio on the dyno was way off, then you need to adjust your PE vs RPM table, considering you have a proper tune in for injector flow rate. At the RPMs in which you are running rich, you need to adjust the PE table down in SMALL increments (ie 1 to 2 %). At the rpms in which you are running lean you need to adjust the PE table up in SMALL incremements. The target is to obtain a fairly flat a/f ratio. Ask Vortech or an experienced sponser what a/f ratio they recommend for your setup.
In addition, your situation can become complicated with maxing out the MAF, MAP as well as some other items. This is why I recommend calling a professional. Yours may not be a strait forward tune like most of us naturally aspirated folks.
So are you saying I should increase my Pe vs RPM table down low. ie:say 0-2400rpm? Instead my changing my MAF table to lower my Ltrims? </strong>
The PE vs RPM table will only make adjustments to WOT fueling; it will not affect LTerms. Your LTerms are fine. Positive LTerm of 8% just means that your O2's are perciving a slight lean condition which is being corrected with an 8% adjustment to fueling. If your car is ALWAYS running with at least an +8% LTerms, then you MAY want to consider adjusting your injector flow table slightly just to bring it back to zero, but it is not necessary. Your car will be fine with +8% LTerms. LTerms change with air pressure / temperature / quality etc...
If your a/f ratio on the dyno was way off, then you need to adjust your PE vs RPM table, considering you have a proper tune in for injector flow rate. At the RPMs in which you are running rich, you need to adjust the PE table down in SMALL increments (ie 1 to 2 %). At the rpms in which you are running lean you need to adjust the PE table up in SMALL incremements. The target is to obtain a fairly flat a/f ratio. Ask Vortech or an experienced sponser what a/f ratio they recommend for your setup.
In addition, your situation can become complicated with maxing out the MAF, MAP as well as some other items. This is why I recommend calling a professional. Yours may not be a strait forward tune like most of us naturally aspirated folks.
Re: Do u raise or lower the Fuel Injector Flow Rate </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DailyAluminumBlock:
<strong>What do you think about replacing the ported maf with a calibrated unit (i.e. slp ls6 maf). Thanks for all of the info.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Just make sure that it is accurate. My best advice would be to do some research on the boards about it to make sure no one has put it on and reported a lean condition.
You can run a ported MAF, you just have to make the necessary adjustments to the PCM MAF tables. It is pain in the butt, and it doesn't always work.
This is the way that I do it, but there really is not blanket solution for all ported MAF's. Some MAF's, once ported, are just erratic.
Put a stocker or other accurate MAF on your vehicle. Drive around and develop an accurate curve for recorded MAF flow for all possible combinations of TPS and RPM. Once you have done this, put your MAF back on and record the same data. At every frequency (according to the increments in your LS1 edit table), determine the percent deviation in flow between your ported MAF and the accurate MAF. Adjust your frequency at this point to the pre-determined percentage. If you did it right, the new curve will look alot like the stocker, except around 4000-6000 hz it will really begin to deviate up.
Good Luck,
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
I just wanted to add that there is no right way to tune these cars. There is the complicated way to do it, and then there is the not-so-complicated way to do it.
Either way, if your car is working with the current tune that you have in it, then fine.
If your LTerms are under control and your WOT a/f isn't all over the map, and you are happy with the power that it is making, then leave it.
The last thing I want is people reading this who have adjusted their MAF curve got the car to work and now feel the need to go back and change it.
<small>[ October 31, 2002, 11:52 AM: Message edited by: NoGo ]</small>
<strong>What do you think about replacing the ported maf with a calibrated unit (i.e. slp ls6 maf). Thanks for all of the info.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Just make sure that it is accurate. My best advice would be to do some research on the boards about it to make sure no one has put it on and reported a lean condition.
You can run a ported MAF, you just have to make the necessary adjustments to the PCM MAF tables. It is pain in the butt, and it doesn't always work.
This is the way that I do it, but there really is not blanket solution for all ported MAF's. Some MAF's, once ported, are just erratic.
Put a stocker or other accurate MAF on your vehicle. Drive around and develop an accurate curve for recorded MAF flow for all possible combinations of TPS and RPM. Once you have done this, put your MAF back on and record the same data. At every frequency (according to the increments in your LS1 edit table), determine the percent deviation in flow between your ported MAF and the accurate MAF. Adjust your frequency at this point to the pre-determined percentage. If you did it right, the new curve will look alot like the stocker, except around 4000-6000 hz it will really begin to deviate up.
Good Luck,
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
I just wanted to add that there is no right way to tune these cars. There is the complicated way to do it, and then there is the not-so-complicated way to do it.
Either way, if your car is working with the current tune that you have in it, then fine.
If your LTerms are under control and your WOT a/f isn't all over the map, and you are happy with the power that it is making, then leave it.
The last thing I want is people reading this who have adjusted their MAF curve got the car to work and now feel the need to go back and change it.
<small>[ October 31, 2002, 11:52 AM: Message edited by: NoGo ]</small>
TECH Regular
Joined: Mar 2002
Posts: 433
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Re: Do u raise or lower the Fuel Injector Flow Rate What I understand from this thread and information I've filtered from other posts I'd say calibrating MAF table is the right way of tuning for intake only changes like MAF,lid etc. If calibrating MAF table in this case causes trouble it is because of bad PCM code parametrization. However, using MAF table calibration to tune a/f for heads, cam or headers clearly leads to wrong engine load calculation and therefore timing, tranny etc. problems.
Ideally you would make all intake changes you are planing and then calibrate MAF table. Then you do the rest of the modifications and use other tables for tuning. I'm a beginner though and this is just the way I understand this using my limited tuning knmowledge.
Ideally you would make all intake changes you are planing and then calibrate MAF table. Then you do the rest of the modifications and use other tables for tuning. I'm a beginner though and this is just the way I understand this using my limited tuning knmowledge.
