Is there any way to correct for a descreened MAF?
03-25-2009, 03:27 PM
#1
Is there any way to correct for a descreened MAF? So i ported and ported and descreened my MAF just like it says how to do on installuniversity.com. Now i can't quite be sure if i am throwing a P0171 and P0174 code (banks 1 and 2 lean) because of this or something else. My LTFTs go up to 25 mostly when im idling or driving slowly. Anyone have any ideas on how i can correct for this? ...Please don't tell me i need to get a new MAF, cuz i put quite some work into this. Also the wires are not damaged at all. Thanks
03-26-2009, 07:03 PM
#7
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Since you altered the MAF, you should alter the MAF table. Its fairly simply. You just let the LTFTs guide you in how much to change the MAF table and where in the table. I have had couple different MAFs over the years. This approach has always worked out best for me.
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03-27-2009, 10:57 AM
#8
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LTFT creep at low airflows is more likely an exhaust
gas temperature, O2 sensor performance problem
(mistrimming). If you look at the STFTs and LTFTs
coming into idle from hot running, and they swing
low / negative and then creep positive over time,
this points to that.
On my car I've found that the MAF has a minimal
weight for low-RPM fueling.
I would definitely realign your FTC (furl trim cell)
boundaries, esp. the RPM ones, from stock if you
have not. Lumping 0-2500RPM and 2500-6000 into
two of the 4 possible "bins" and throwing away the
others, makes for a pretty poor trimming (idle and
2000RPM are nothing alike, for true VE and VE
error). Crowd the resolution down to where you live
on the street and you will have less "history effect"
and trim cleaner, and segregate areas where the
O2s are having trouble from areas where it runs
hot enough to work well, etc.
gas temperature, O2 sensor performance problem
(mistrimming). If you look at the STFTs and LTFTs
coming into idle from hot running, and they swing
low / negative and then creep positive over time,
this points to that.
On my car I've found that the MAF has a minimal
weight for low-RPM fueling.
I would definitely realign your FTC (furl trim cell)
boundaries, esp. the RPM ones, from stock if you
have not. Lumping 0-2500RPM and 2500-6000 into
two of the 4 possible "bins" and throwing away the
others, makes for a pretty poor trimming (idle and
2000RPM are nothing alike, for true VE and VE
error). Crowd the resolution down to where you live
on the street and you will have less "history effect"
and trim cleaner, and segregate areas where the
O2s are having trouble from areas where it runs
hot enough to work well, etc.
03-27-2009, 02:49 PM
#9
LTFT creep at low airflows is more likely an exhaust
gas temperature, O2 sensor performance problem
(mistrimming). If you look at the STFTs and LTFTs
coming into idle from hot running, and they swing
low / negative and then creep positive over time,
this points to that.
On my car I've found that the MAF has a minimal
weight for low-RPM fueling.
I would definitely realign your FTC (furl trim cell)
boundaries, esp. the RPM ones, from stock if you
have not. Lumping 0-2500RPM and 2500-6000 into
two of the 4 possible "bins" and throwing away the
others, makes for a pretty poor trimming (idle and
2000RPM are nothing alike, for true VE and VE
error). Crowd the resolution down to where you live
on the street and you will have less "history effect"
and trim cleaner, and segregate areas where the
O2s are having trouble from areas where it runs
hot enough to work well, etc.
gas temperature, O2 sensor performance problem
(mistrimming). If you look at the STFTs and LTFTs
coming into idle from hot running, and they swing
low / negative and then creep positive over time,
this points to that.
On my car I've found that the MAF has a minimal
weight for low-RPM fueling.
I would definitely realign your FTC (furl trim cell)
boundaries, esp. the RPM ones, from stock if you
have not. Lumping 0-2500RPM and 2500-6000 into
two of the 4 possible "bins" and throwing away the
others, makes for a pretty poor trimming (idle and
2000RPM are nothing alike, for true VE and VE
error). Crowd the resolution down to where you live
on the street and you will have less "history effect"
and trim cleaner, and segregate areas where the
O2s are having trouble from areas where it runs
hot enough to work well, etc.
i can see i still have much to learn
03-27-2009, 03:58 PM
#10
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That installuniversity how-to is 3 days older than Christ. It was made before people knew that porting the MAF causes more problems than it is worth. Save yourself a bunch of aggravation in tuning for a dicked up MAF and just get another stock one. Save the tuning for making horsepower and fixing drivabilty on real mods.
03-27-2009, 04:02 PM
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That installuniversity how-to is 3 days older than Christ. It was made before people knew that porting the MAF causes more problems than it is worth. Save yourself a bunch of aggravation in tuning for a dicked up MAF and just get another stock one. Save the tuning for making horsepower and fixing drivabilty on real mods.
