PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

tunning the maf

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Old Feb 23, 2006 | 03:04 PM
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Default tunning the maf

i have a 383 with a procharger. i am having troble with the 85mm slp maf, need to know how to tune it. right now i just leave the maf unplugged, but i would like for the maf to operate properly agian. is this possible??
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Old Feb 23, 2006 | 03:47 PM
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You're going to need to probably upgrade to a 2-bar system...i'm sure someone else with more experience in this will chime in!

best Regards,
Adrian
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Old Feb 23, 2006 | 05:35 PM
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Yeah MAF frequency peaks out near 1 atmos, maybe a little over depending on your engine. You will want to permanently lose the maf and get a 2bar MAP sensor as mentioned
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Old Feb 23, 2006 | 07:12 PM
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where can i get more info on the 2 bar map system??
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Old Feb 23, 2006 | 07:29 PM
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The SLP MAF is a mystery. You would be better off
desoldering the resistor and loading a truck MAF table,
like the one I have posted here several times before.

2-bar pertains mainly to the speed density mode, MAP
reads true instead of pegging. I expect there may also
be some other bonuses likie extending the IFR table into
negative vacuum (boost) ranges. It is something you
want to do, just to eliminate hokiness from the boosted
setup.

Either HPTuners or EFILive should have a 2-bar MAP
"mini-license" add-on feature for you, check whichever
tool vendor is yours.
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Old Feb 23, 2006 | 09:59 PM
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does EFI live increase the IFR table to boost? I asked about this for HPTuners a few months back, with no as the responce.

Granted when you go boosted, you really need a rising rate regulator, but figured if the pcm knew it would be 'good enough'

Tuning the maf is easy, imho, Just change a few numbers so it has more control without bad influence from wrong VE table numbers, and your're good to go for wot tuning.

Ryan
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Old Feb 23, 2006 | 10:40 PM
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using the correct MAF there is no way you should "peg" at 440 and dont have to go into SD tuning with a centrifigul supercharger.especialley with a procharger...like jimmyblue says thats one voodoo MAF i LOVE the metal MAF on procharged cars it likes the 511GMS/sec table and is silky smooth
of topic what do you MAF guys think about a 100mm GM MAF?
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Old Feb 24, 2006 | 01:50 AM
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With efilive IFR does not get extended from what I can see, but you get a full VE table out to almost 3 bar. The "mini-licence" with efilive is free you can use all the custom os's you want.
You can use this to adjust for fueling. Im pretty sure IFR will continue to run at its max setting once you hit the end of the table.
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Old Feb 24, 2006 | 11:32 AM
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what metal mafs are you talking about brent? i would like to keep the maf if possible because i am using ls1edit for the time being. but if i cant use a maf easily how do i put car into speed density
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Old Feb 24, 2006 | 06:11 PM
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does no one know step by step how to put a car into speed density???
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Old Feb 24, 2006 | 06:38 PM
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you will have no probs running of the MAF with the procharger ,the meteal MAF has the ability to read 511 GMS/sec I could send you a MAF table in excell, Just call me at work on monday ...
Brent@ exoticperformanceplus.com 260-244-2808
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Old Feb 25, 2006 | 07:17 PM
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thanks for the help brent. i will give you a call on monday.
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Old Feb 28, 2006 | 01:52 PM
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Originally Posted by edstrokedta
does no one know step by step how to put a car into speed density???
Unplugging the MAF will force the PCM to operate in SD mode on LS1s.
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Old Feb 28, 2006 | 02:29 PM
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i have a question, can the a/f ratio change when the car is put into speed density even if nothing else is changed?
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Old Feb 28, 2006 | 03:20 PM
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Originally Posted by edstrokedta
i have a question, can the a/f ratio change when the car is put into speed density even if nothing else is changed?
Yup, especially if you have a MAF related issue.
On the dyno my AFR wouldn't go below 13.5. Unplugging the MAF only resulted in the AFRs dropping to 11.8-12.0. To verify the change we plugged the MAF in and AFRs went back up. Why??? No idea. As soon as I get my tuner software I'm going to dig into it though.

I've been driving around for the last three months in SD mode with MAF disconnected. No issues. Well gas mileage is a bit worse, but I'm not complaining.
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Old Feb 28, 2006 | 04:44 PM
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on a stock pcm you will drop to the secondary spark table and likely sub optimal timing if you unplug the maf
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Old Feb 28, 2006 | 06:26 PM
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ok that makes me feel better. i thought i was going crazy when it got richer when i unplugged the maf
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