MAF loction and tube shape? Driveability Issues....
09-05-2010, 02:29 PM
#1
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MAF loction and tube shape? Driveability Issues.... Curious how important it is, and if it could relate to my problem.
I have an LS2/T56 in an RX7 with a GM Performance Parts LS2 harness. It uses the blade style LS7 MAF.
At full throttle the car runs beautiful, but at low rpms while at a steady speed with almost no throttle imput I get alot of bucking to the point that driving the car isn't exactly enjoyable. I also get pretty damn poor gas mileage. I'm not expecting anything great, but 10-12mpg im getting isn't what I should be seeing. The only mods are LT headers, and a custom intake setup. I get maybe 17mpg on the highway, and that is with nice driving.
I think the shape and length of the intake tube is the source of my problem, but would like some advice. These images should give you an idea of what I am working with.
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I have an LS2/T56 in an RX7 with a GM Performance Parts LS2 harness. It uses the blade style LS7 MAF.
At full throttle the car runs beautiful, but at low rpms while at a steady speed with almost no throttle imput I get alot of bucking to the point that driving the car isn't exactly enjoyable. I also get pretty damn poor gas mileage. I'm not expecting anything great, but 10-12mpg im getting isn't what I should be seeing. The only mods are LT headers, and a custom intake setup. I get maybe 17mpg on the highway, and that is with nice driving.
I think the shape and length of the intake tube is the source of my problem, but would like some advice. These images should give you an idea of what I am working with.
Uploaded with ImageShack.us
Uploaded with ImageShack.us
09-05-2010, 02:48 PM
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thats most likely a problem, I know of other types of vehicles that maf clocking and location causes issues. A good tune may solve the issue once the maf is re-curved or you could go speed density.
09-07-2010, 10:36 AM
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If the MAF is screened (don't know the LS2 hardware)
then tract geometry influence is minimized.
I have seen people with other opinions but my experience
says the MAF is only a minor component of the dynamic
airflow calculation at low RPMs. You have the speed
density accuracy as a bigger piece, and any meddling
from the closed loop trimming (accurate or not, LTs and
thermal effects?).
You could see whether it runs better in open loop with
trims zeroed, and you could see whether it runs better
with the MAF faulted out. These would point you at the
likely culprit.
then tract geometry influence is minimized.
I have seen people with other opinions but my experience
says the MAF is only a minor component of the dynamic
airflow calculation at low RPMs. You have the speed
density accuracy as a bigger piece, and any meddling
from the closed loop trimming (accurate or not, LTs and
thermal effects?).
You could see whether it runs better in open loop with
trims zeroed, and you could see whether it runs better
with the MAF faulted out. These would point you at the
likely culprit.
09-07-2010, 06:47 PM
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Yes the blade style maf's are real sensitive to bends, and any type of disturbance. They don't like being right behind the filter either.
They need to have a straight section in front and behind for them to read correctly.
They need to have a straight section in front and behind for them to read correctly.
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09-07-2010, 07:20 PM
#8
I use this one and my LS3 MAF logs are very smooth. The hz log used to be like a saw blade that got he crap beat out of it.
The bottom is the hz log.
I do have a nice straight tube in front and behind the MAF.
100 mm Air Straightener
The bottom is the hz log.
I do have a nice straight tube in front and behind the MAF.
100 mm Air Straightener
09-07-2010, 07:38 PM
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Thanks for the replies!
09-07-2010, 07:41 PM
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I think I am going to try a new intake with the MAF repositioned, and then tuning.
I may try disconnecting the MAF to see if it makes a difference. I'm not sure of what kind of limp mode the car goes into though. First I have to get the trans back into the car...thats a whole nother' story.
I may try disconnecting the MAF to see if it makes a difference. I'm not sure of what kind of limp mode the car goes into though. First I have to get the trans back into the car...thats a whole nother' story.
