Tuning issues 2v 4.6

Slygt

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Hello first time posting just trying to get little tuning help. First time tuning a maf car and having issues tuneing idle afr. I have came from the dodge speed density tuning super easy so tuning in the maf transfer function is new to me. Car is a 2001 mustang gt built bottom end stock everything else. Vortech v2 , Walbero 250 pump 42lb injectors and lighting maf. OK I know one thing different then most is my maf is located in a 3.5 pipe rather then 90mm normal housing so I figured I would just scale for smaller pipe. Pipe only 13.5% smaller I think. Now I am tuning with sct prp. I used there blower gt value tune for base tune. I also put in values for injectors and 90mm maf curve, then modified curve 13.5% . Car starts idles then surges to 1k repeatedly afr 10.3 on wideband till warm up then 11.4 after warm up. I data log my maf counts are high like 409 max. Point is do I pull fuel on base tabLe or mod the maf transfer function more?
 

robert presti

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If you're seeing 409 at around 1000 rpm idle I would think you have something wrong. clocking of the MAF or lack of bypass or something. I'm new to this as well, so it is just an opinion. My procharged 2000 GT is bouncing around 150-190 add counts at 1100 rpm.
 

Slygt

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I tore everything down on intake side I pulled the 3.5 pipe and replaced with 95mm maf housing now. And loaded the normal 90mm inputs and it's working great I think my 3.5 pipe was so small it thrown maf counts off bad. I sitting around 140 160 now. Made my first pull today on 3.33 pulley made 6.5 lbs boost tune is spot on but I think I running into belt slip.
 

robert presti

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I tore everything down on intake side I pulled the 3.5 pipe and replaced with 95mm maf housing now. And loaded the normal 90mm inputs and it's working great I think my 3.5 pipe was so small it thrown maf counts off bad. I sitting around 140 160 now. Made my first pull today on 3.33 pulley made 6.5 lbs boost tune is spot on but I think I running into belt slip.
There are some high dollar tensioners for the cars, you can convert to eight rib set up pretty cheap ( because trucks are), I think they make 10 rib kit?, My car has the AC pump deleted and it tensions the belt there. 6 rib belt yet and zero belt slip. I do worry the belt is so tight it might hurt the main bearing though. Running over 12psi on a built engine with a D1sc.
 

robert presti

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If you want a cleaner look I'd run a BA5000 in the smaller pipe. That's what I did. Not sure yet that I won't peg it though. I have 3 inch pipes . SCT has values for a lot of size pipes for that MAF.
 

Slygt

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Are the vortech belts junk? It seems to slip a lot with decent amount of tension.I gonna try a shorter gates belt this weekend see if it helps. If not I gonna go junk yard shopping. What year 4.6 truck pulleys?
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Slygt

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Ya I has aluminum custome done to give clean look
If you want a cleaner look I'd run a BA5000 in the smaller pipe. That's what I did. Not sure yet that I won't peg it though. I have 3 inch pipes . SCT has values for a lot of size pipes for that MAF.
 

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