MAF scaling or injector scaling/latency
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Joined: Jun 2005
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From: Chico, CA (NOR-CAL)
MAF scaling or injector scaling/latency
Im about to tune this 05 MR with GT30 and a bunch of mods, including intake/intake pipe and upgraded injectors (the owner of the car doesnt know the exact cc). They are scaled at 713 in the ROM. I dont know if the scaling is correct, cuz most of the tune is "weird" and "off". The MAF scaling is still stock.
Now the LTFT low is pegged at +12.6. LTFT Mid and LTFT High are near 0
I know that I need to either
-adjust the injector scaling and latency
-rescale the MAF to compensate for the intake and piping
What I dont know if which method should I use to correct the fuel trim? MAF or injectors? Or both? If both, what one do I start with first?
TIA
Now the LTFT low is pegged at +12.6. LTFT Mid and LTFT High are near 0
I know that I need to either
-adjust the injector scaling and latency
-rescale the MAF to compensate for the intake and piping
What I dont know if which method should I use to correct the fuel trim? MAF or injectors? Or both? If both, what one do I start with first?
TIA
Last edited by Evo_Jay; Oct 25, 2009 at 11:31 PM.
Assuming the WOT is correct, then latency is the key. If the whole thing is wonky then it will be a combination of both. Latency is your idle/cruise correction (more or less) independent of your WOT fueling (scaling...more or less).
Thread Starter
Joined: Jun 2005
Posts: 3,419
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From: Chico, CA (NOR-CAL)
What about scaling the MAF? I think i read a quote by you about how you dont believe in rescaling the MAF , IIRC. But people say if you have an intake/intake pipe you need to rescale your MAF. Whats your take on it?
Last edited by Evo_Jay; Oct 25, 2009 at 11:22 PM.
Ummm I dont believe in rescaling the MAF 
It affects too many other things that we have only begun to get into to. Most of the time it will only affect where the MAF puts the load, and it is usually very linear. For instance the HKS & ARC induction box makes a car read VERY low from where it should be for the airflow actually going through the MAF. Some go the opposite way and make it ALOT higher than where it should be.
I just tune the car where it actually is and dont sweat the details.
It affects too many other things that we have only begun to get into to. Most of the time it will only affect where the MAF puts the load, and it is usually very linear. For instance the HKS & ARC induction box makes a car read VERY low from where it should be for the airflow actually going through the MAF. Some go the opposite way and make it ALOT higher than where it should be.
I just tune the car where it actually is and dont sweat the details.
Thread Starter
Joined: Jun 2005
Posts: 3,419
Likes: 14
From: Chico, CA (NOR-CAL)
Ummm I dont believe in rescaling the MAF
It affects too many other things that we have only begun to get into to. Most of the time it will only affect where the MAF puts the load, and it is usually very linear. For instance the HKS & ARC induction box makes a car read VERY low from where it should be for the airflow actually going through the MAF. Some go the opposite way and make it ALOT higher than where it should be.
I just tune the car where it actually is and dont sweat the details.
It affects too many other things that we have only begun to get into to. Most of the time it will only affect where the MAF puts the load, and it is usually very linear. For instance the HKS & ARC induction box makes a car read VERY low from where it should be for the airflow actually going through the MAF. Some go the opposite way and make it ALOT higher than where it should be.
I just tune the car where it actually is and dont sweat the details.
Last edited by Evo_Jay; Oct 25, 2009 at 11:48 PM.
Thread Starter
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From: Chico, CA (NOR-CAL)
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If a hardpipe is causing issues it will throw off both the load low and low freq MAF values (because MAF frequency used in the ROM is calculated from load). What load value range are you getting at (a decent) idle? Is it a stock-ish load value?
Thread Starter
Joined: Jun 2005
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From: Chico, CA (NOR-CAL)
It idles around 30 load, which seems pretty normal to me.
That is normal to every evo i have logged.
I sometimes, rarely, but sometimes mess with MAF scaling. I haven't found anything over 13% off but if so i usually get it <10 closer to 5%. It isn't difficult and i just smooth the curve from the adjusted idle and cruise values to the other values. I don't typically touch anything over cruise.
I sometimes, rarely, but sometimes mess with MAF scaling. I haven't found anything over 13% off but if so i usually get it <10 closer to 5%. It isn't difficult and i just smooth the curve from the adjusted idle and cruise values to the other values. I don't typically touch anything over cruise.
Another option is to change the MAF compensation table. (MAF Adjusment is what I call it). By increasing by only 1 point you affect fuel trims by 5-8%. For those of you that are way out on your fuel trims, a minor tweek here could help.
JohnBradley,
Have you ever used latency on stock injectors to correct low and mid LTFTs? I am running stock injectors with an open cone filter and my LTFT's are pegging at 12 and 9 for low and mid.
Have you ever used latency on stock injectors to correct low and mid LTFTs? I am running stock injectors with an open cone filter and my LTFT's are pegging at 12 and 9 for low and mid.
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