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Thread: idle issues after installing fast 102/102 ls3 headed 408

  1. #1
    Advanced Tuner
    Join Date
    Mar 2010
    Posts
    227

    idle issues after installing fast 102/102 ls3 headed 408

    swapped intakes from an ls3 with a fast 90 to a fast 102 with a nw 102 tb and now have major idle issues. The engine is a drive by cable 408 with ported ls3 heads. Idle was great before with the ls3 intake and fast 90mm tb. Now with the 102 set up it sux. It has a lot of surge to it now. I haven't even tried to drive the car yet. There was also an issue with the tps voltage being high as well. I ended up slotting the mounting holes for the tps sensor just so I could crack the tb open some. I have tried adding base idle air also which doesn't seem to help. I have done every thing but drill a hole in the tb blade which I was hoping not to have to do. I have also noticed at idle the tps keeps going to 1-2%. I will add a scan log along with the tune and configuration. Whats the secret to tuning a damn 102 intake? This thing is kicking my ass. I didn't have any trouble dialing in the idle with the ls3 intake and fast 90. I know I will need to retune the VE and maf for the 102 but I wanted to try to dial in the idle first.
    Do you pretty much have to drill a hole in the blade on the 102 tb?
    1993 reef blue Mustang coupe
    Ls1 conversion
    1 7/8 cooks headers
    AFR 205 heads
    Fast 92/92 intake
    PAT G./ EPS Custom cam 230/234 .600”/.602” 112LSA +2 advance
    century Built 4l60e with Circle D 3500 converter
    4.11 gears

  2. #2
    You could have cracked the throttle blade and then unplugged the TPS switch for 10-20 seconds with the key on then turned it off then plug it back in. That would reset the TPS to 0.
    I did one a last week on an LS1 and had to play with throttle cracker, throttle follower decay and delay just to get it drivable with a 1000 rpm idle.
    I would think it would be easier on a larger motor.
    First I got the voltage and IAC count where it should be.
    You probably won’t get much help here.
    I personally feel that the NW 102 cable driven TB is a bit too much for a 346 cubic inch motor.
    It helps greatly to get fueling spot on first.

  3. #3
    Potential Tuner
    Join Date
    Sep 2012
    Posts
    4
    I'd go back through with the install of the intake. Ensure the vacuum port and brake booster hose on back is plugged or routed correctly as well as the PCV ports on front. Check all the gaskets etc.