MAFT help - need advice
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TECH Apprentice
Joined: Dec 2001
Posts: 369
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From: Waldorf, Maryland
MAFT help - need advice I posted earlier about an SES code being thrown (basically was a misfire code). Took the car to the track on Sat to run it looking for some new bests due to installing the Hooker headers/y-pipe.
Well - they didnt come. My previous best was a 12.65 @ 112.8 mph with my average being in the mid/low 12.7's right around 112.x (average weather).
Saturday in decent weather I posted three mid-12.8 second runs with a best of 111.3 mph and one 12.71 sec at 111.8 mph. WTF?
I was very dissapointed - I was looking for a solid low-12.6 run at least if not into the 12.5's at around 113-114mph. Wasnt even close.
Well, we autotapped the car to check the O2 readings and I was extremely rich (.985's to even over 1.000!). I think that this is the reason my times sucked @ss (compared to what I was looking for).
This upcoming week (next week at latest) we are gonna throw the car on the dyno for a couple wideband runs and to play with the MAFT (just put back on the car) to lean the sucker out and get some power back.
My two questions are:
1) What settings are most appropriate and what have you guys had the most luck with (looking for your recomendation or suggestion) in cars with similar mods (see sig).
2) Would being this rich be the main culprit for the slower than expected ET's and traps speeds?
Any input would be appreciated.
Thanks.
<small>[ September 10, 2002, 07:29 AM: Message edited by: Hannibal ]</small>
Well - they didnt come. My previous best was a 12.65 @ 112.8 mph with my average being in the mid/low 12.7's right around 112.x (average weather).
Saturday in decent weather I posted three mid-12.8 second runs with a best of 111.3 mph and one 12.71 sec at 111.8 mph. WTF?
I was very dissapointed - I was looking for a solid low-12.6 run at least if not into the 12.5's at around 113-114mph. Wasnt even close.
Well, we autotapped the car to check the O2 readings and I was extremely rich (.985's to even over 1.000!). I think that this is the reason my times sucked @ss (compared to what I was looking for).
This upcoming week (next week at latest) we are gonna throw the car on the dyno for a couple wideband runs and to play with the MAFT (just put back on the car) to lean the sucker out and get some power back.
My two questions are:
1) What settings are most appropriate and what have you guys had the most luck with (looking for your recomendation or suggestion) in cars with similar mods (see sig).
2) Would being this rich be the main culprit for the slower than expected ET's and traps speeds?
Any input would be appreciated.
Thanks.
<small>[ September 10, 2002, 07:29 AM: Message edited by: Hannibal ]</small>
Re: MAFT help - need advice I can't give you any recommendations as to what settings to use for your MAFT, but I can give you an overview of what to shoot for while you are on the dyno.
Your target a/f should be 12.8
3% on your MAFT will be about 1 point a/f ratio (ie if you have an 11.8 a/f ratio leaning things out 3% should give you 12.8).
An overly rich condition will KILL your HP in the upper end. I was on the dyno the other day, and was able to pick up 8 HP just by dialing my a/f ratio in closer to 12.8.
Soooo, if you are running somewhere in the low 11's / 10's for your a/f ratio, you could expect to see around 15 hp by just getting your a/f ratio dialed in, not including what your headers have added.
Good Luck
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
<small>[ September 10, 2002, 01:31 PM: Message edited by: NoGo ]</small>
Your target a/f should be 12.8
3% on your MAFT will be about 1 point a/f ratio (ie if you have an 11.8 a/f ratio leaning things out 3% should give you 12.8).
An overly rich condition will KILL your HP in the upper end. I was on the dyno the other day, and was able to pick up 8 HP just by dialing my a/f ratio in closer to 12.8.
Soooo, if you are running somewhere in the low 11's / 10's for your a/f ratio, you could expect to see around 15 hp by just getting your a/f ratio dialed in, not including what your headers have added.
Good Luck
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
<small>[ September 10, 2002, 01:31 PM: Message edited by: NoGo ]</small>
Re: MAFT help - need advice It'll take some trial and error to set it up properly with a MAFT. There are no "standard settings" since each car and mods are different.
When I do MAFT tuning I start with the LTFTs. I will do a good amount of "around town" driving while logging B1 and B2 LTFT's. Then I average the numbers for fuel cells 1-19. You're goal is to be around 0.0 - seems like slightly negative will make WOT tuning more consistent. Adjust the base setting in 5% increments until you get as close as you can to LTFT = 0. Once you've got that then put a few miles on it and re-log to confirm that nothing's changed.
Now you can go to WOT, which is easy. If you're on a dyno w/wideband then just adjust the WOT settings in 2% increments until you've achieved the desired afr. If you're not on a dyno then shoot for .880-.910 B1S1 and B2S1 without KR. This should get you in the ballpark, but obviously wideband is preferred.
HTH <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
When I do MAFT tuning I start with the LTFTs. I will do a good amount of "around town" driving while logging B1 and B2 LTFT's. Then I average the numbers for fuel cells 1-19. You're goal is to be around 0.0 - seems like slightly negative will make WOT tuning more consistent. Adjust the base setting in 5% increments until you get as close as you can to LTFT = 0. Once you've got that then put a few miles on it and re-log to confirm that nothing's changed.
Now you can go to WOT, which is easy. If you're on a dyno w/wideband then just adjust the WOT settings in 2% increments until you've achieved the desired afr. If you're not on a dyno then shoot for .880-.910 B1S1 and B2S1 without KR. This should get you in the ballpark, but obviously wideband is preferred.
HTH <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Re: MAFT help - need advice I have had similar problems with my mph lately..before longtubes got like a best of 110mph corrected with my b1 cam and other mods..
after headers best so far is the same..so where is the extra power.Was very rich when they were first put on..car was doggy..have recently leaned it out a lot and think I have my mph back..will give it a try shortly..No dyno near me to run my car on..only me and my tazzo and autotap and scanmaster.I have my maft right now set to 4 clicks lean at wot,base is set at zero.seems to give slightly negative ltrims when I go part throttle..I don't average stuff just watch the numbers..its usually pretty consistent.I ignore idle and decel..the ltrims go to zero at wot if you have the ltrims close I think thats why they say to get slightly negative ltrims as if they are positive it can add fuel at wot and screw up the consistency..I was running 5 clicks down before the hpp tuning and think I can go down another one or so maybe.No significant knock retard showing up yet..so doubt anyone can throw on longtubes and get much better numbers without tuning ..maybe you can lean with hpp like I did but that don't seem to lean enough or home ported maf stuff that might do it.My gms doesn't lean my car much if at all. My mods are lid,holley filter,
gms maf,ported tb,ls6 intake,b1 cam,tts longtubes,tts cats,b and b ,cutout,hpp ,maft,scanmaster and autotap and tazzo vpc.No track or dynos anywhere near me.
after headers best so far is the same..so where is the extra power.Was very rich when they were first put on..car was doggy..have recently leaned it out a lot and think I have my mph back..will give it a try shortly..No dyno near me to run my car on..only me and my tazzo and autotap and scanmaster.I have my maft right now set to 4 clicks lean at wot,base is set at zero.seems to give slightly negative ltrims when I go part throttle..I don't average stuff just watch the numbers..its usually pretty consistent.I ignore idle and decel..the ltrims go to zero at wot if you have the ltrims close I think thats why they say to get slightly negative ltrims as if they are positive it can add fuel at wot and screw up the consistency..I was running 5 clicks down before the hpp tuning and think I can go down another one or so maybe.No significant knock retard showing up yet..so doubt anyone can throw on longtubes and get much better numbers without tuning ..maybe you can lean with hpp like I did but that don't seem to lean enough or home ported maf stuff that might do it.My gms doesn't lean my car much if at all. My mods are lid,holley filter,
gms maf,ported tb,ls6 intake,b1 cam,tts longtubes,tts cats,b and b ,cutout,hpp ,maft,scanmaster and autotap and tazzo vpc.No track or dynos anywhere near me.
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Joined: Dec 2001
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From: Plainville,MA
Re: MAFT help - need advice http://www.c5forum.com/diy/ltft.php
This was very helpful in helping to get my car tuned properly ! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
This was very helpful in helping to get my car tuned properly ! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
