Ported MAF with resistor mod and LTRIMs?
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
Likes: 0
From: New Jersey
Ported MAF with resistor mod and LTRIMs? I have a 99 T/A which has the following mods: FTRA, MTI Lid, Airflow Research bellows, Ported Maf w/1K ohm 1/2 watt resistor mod, Predator Tune and Magnaflow Catback, 180 T-stat w/reprogrammed fans
I have been monitoring my LTRIMs and have noticed that at idle I am between -8 and -12 since doing the MAF resistor. (Used to be +6 to +8 before resistor at idle) My cruise LTRIMs seem to hover around +4 to +7 now. I have not had enough time to test for O2s with the weather around here.
My question is should I get a MAFT for additional tuning for the LTRIMs or should I just get a stock MAF to replace the ported MAF I currently have?
Could the FTRA be causing my LTRIMs to be off at 60 Mph +?
mike
I have been monitoring my LTRIMs and have noticed that at idle I am between -8 and -12 since doing the MAF resistor. (Used to be +6 to +8 before resistor at idle) My cruise LTRIMs seem to hover around +4 to +7 now. I have not had enough time to test for O2s with the weather around here.
My question is should I get a MAFT for additional tuning for the LTRIMs or should I just get a stock MAF to replace the ported MAF I currently have?
Could the FTRA be causing my LTRIMs to be off at 60 Mph +?
mike
Whose ported MAF?
I know about tuning the 85mms but only in the lean
direction. If this is a stocker, where did you put the
resistor and how much did it pull the tune?
BTW, I only need a 3K resistor on my ported SLP/
Delphi, up from the standard 2.7K that SLP uses. A
1K on that MAF would truly whack the mixture lean.
On my MAF, hacked as it it, I have idle LTFTs about
-10 and -1 to -1.5 right before rolling into WOT.
FTRA might present more air but it's the MAF's job
to tell the truth and it isn't.
I know about tuning the 85mms but only in the lean
direction. If this is a stocker, where did you put the
resistor and how much did it pull the tune?
BTW, I only need a 3K resistor on my ported SLP/
Delphi, up from the standard 2.7K that SLP uses. A
1K on that MAF would truly whack the mixture lean.
On my MAF, hacked as it it, I have idle LTFTs about
-10 and -1 to -1.5 right before rolling into WOT.
FTRA might present more air but it's the MAF's job
to tell the truth and it isn't.
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
Likes: 0
From: New Jersey
It is a stocker that I home ported. then I added a 1K Ohm 1/2 Watt resistor to the side spaning 2 arms. BTW my timing at idle is also around 20-22 degrees.
should I remove the resistor and swap it? or should I just replace the MAF? or even get a used MAFT?
thanks
mike
should I remove the resistor and swap it? or should I just replace the MAF? or even get a used MAFT?
thanks
mike
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
Likes: 0
From: New Jersey
Originally Posted by Red01Chevy
Where can you put a resistor in the maf to"fool" the pcm?? and what tables would it change
I used instructions like this http://www.ls1.com/forums/showthread...t=MAF+Resistor
do a search there is one there with a picture
Trending Topics
Originally Posted by greatwhite99
I used instructions like this http://www.ls1.com/forums/showthread...t=MAF+Resistor
do a search there is one there with a picture
do a search there is one there with a picture
it's still interesting. I think the guy could have gone further
with resistor value (lower) and gotten to all LTFTs < 0.
The value you'd need will vary with how you port.
This seems to be the flip side of what SLP does, and I've done
to my 85mm (pull lean, on the 3-leg side)
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
For what its worth, the resistor goes between the two longer bars that span both sides of the MAF. If the 1K ohm is not enough, find a slightly lower value resistor, or calculate two resistors in parallel (ohms law) that will give you a value slightly lower than 1k. I used alagator clip leads while I was experimenting so that I could easily and quickly change resistor values.
I was running around 880 ohms over the winter (parallel resistor setup) and my LTFTs were all between -1 and -5. I did have to dial in some more at WOT using my MAFT however.
-Tony
I was running around 880 ohms over the winter (parallel resistor setup) and my LTFTs were all between -1 and -5. I did have to dial in some more at WOT using my MAFT however.
-Tony
TECH Apprentice
Joined: Jul 2002
Posts: 393
Likes: 0
From: Tucson, AZ
Originally Posted by greatwhite99
I have a 99 T/A which has the following mods: FTRA, MTI Lid, Airflow Research bellows, Ported Maf w/1K ohm 1/2 watt resistor mod, Predator Tune and Magnaflow Catback, 180 T-stat w/reprogrammed fans
I have been monitoring my LTRIMs and have noticed that at idle I am between -8 and -12 since doing the MAF resistor. (Used to be +6 to +8 before resistor at idle) My cruise LTRIMs seem to hover around +4 to +7 now. I have not had enough time to test for O2s with the weather around here.
My question is should I get a MAFT for additional tuning for the LTRIMs or should I just get a stock MAF to replace the ported MAF I currently have?
Could the FTRA be causing my LTRIMs to be off at 60 Mph +?
mike
I have been monitoring my LTRIMs and have noticed that at idle I am between -8 and -12 since doing the MAF resistor. (Used to be +6 to +8 before resistor at idle) My cruise LTRIMs seem to hover around +4 to +7 now. I have not had enough time to test for O2s with the weather around here.
My question is should I get a MAFT for additional tuning for the LTRIMs or should I just get a stock MAF to replace the ported MAF I currently have?
Could the FTRA be causing my LTRIMs to be off at 60 Mph +?
mike
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
Likes: 0
From: New Jersey
I have a predator and I have replaced the MAF with the stocker and I am still reading like 4.6 - 6.5 + LTrims at crusing speed. I am thinking that I must have a vacuum leak that I need to resolve since at idle it is - and my timing is like 20 - 22 degrees @ idle as well. Once I nail that down I will do some more experimenting with the Ported vs Stocker MAF. I did read somewhere that someone had setup a Ghetto flow test with a shop vac to test the two calibrations for the MAF signal.
mike
mike
Thread Starter
On The Tree
Joined: Dec 2001
Posts: 147
Likes: 0
From: New Jersey
Found the problem... EGR Gasket was starting to suck in and was a vacuum leak. Diagnosed that using a bike tube cut and attached to the air bellows using duct tape 
Pumped up with pressure and the EGR started whistling... Now LTrims are mostly 0 or -
mike
Pumped up with pressure and the EGR started whistling... Now LTrims are mostly 0 or - mike
