PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

help info need on 85 MM MAF

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Old Aug 30, 2007 | 08:55 AM
  #1  
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Default help info need on 85 MM MAF

1999 SS, SLP LT's, SLP LM exhaust, LID, K&N filter, CAI, SLP 85 MM MAF, still using the stock hood ram air as well as the CAI, diablo tuner.

With the stock MAF I get nice response from the LTFT's and can tune them with the diablo.....when I put on the SLP 85 MM MAF, my fule trims go to values of + 20 and I'm not sure that the car is actually running that lean, so I put back the stock MAF and the trims go back to normal values +/- 1-2 range. What gives, anyone out there have a thought? Also, I have read a few places where it said to cut out the resitor in the 85 MM MAF, what does that do for you? I'm want to use the thing as it cost me $185. I see this with both the stock tune and the diablo performance tune.

Any help is appreciated........
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Old Aug 30, 2007 | 09:34 AM
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Cutting out (or desoldering cleanly) the resistor makes it
a plain old known-quantity Delphi truck MAF that anybody
can find a valid MAF table for, for tuning.

There are two SLP MAF versions, the "'98-'00" one jacks
the frequency more than the "'01-'02". How much voodoo
do you do? PCM says, "get that **** out of here!".

You can change that resistor and change your luck, some.
I went as far as making mine adjustable, back when all I
had for tools was the Predator. If you see a 2.4K resistor
(red/yellow/red) try a 2.7K instead, this is what the '01-'02
version uses. I ported mine and had to go up to a 3K to get
the trims back to zero-range after that. This was all so long
ago that you can't even find the post by searching anymore.
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Old Aug 30, 2007 | 10:06 AM
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From: mcallen tx
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i noticed that on a stock car with slp 85mm that the trims were maxed out on the positive side, would that be taken car of if i tune the car like you normally would with hptuners? or would you still have to take that resistor off
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Old Aug 30, 2007 | 01:13 PM
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You can tune it out as-is but it will be a one-off deal,
no chance of just snarfing a truck or Z06 table off the
Interweb and slapping it on for good-enough. Getting
to nearly-right for free is mighty appealing.
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Old Aug 31, 2007 | 06:52 AM
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seems to me that staying with the stock MAF is best...I posted this same thread on the Diablo web site and the conclusions there were to stay stock....
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Old Aug 31, 2007 | 06:54 AM
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BTW...thanks Jimmy
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Old Sep 2, 2007 | 05:06 PM
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i decreased my injector slope negative ten -10 and upped my PE to positive nine +9, so far i have no problems with my LTFT, now they go -10 , +10 like normal during normal driving. it idles correctly now.

i got the slp maf, ls6 intake with slp headers on my 99.
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