So my fully rebuilt engine in my 89' SPG with the common mods 8.25:1 compression ratio 2.1 head 3.0bar FPR, 24LB injectors Modded APC.I run about 1/2 way into red and hold at the yellow red border, at over 75 I got more boost. I am not getting the kind of gas milage I hoped for with this set up. I have new O2 sensor, fresh distributor with the stopper bent back. All new plugs wires etc. I am getting around 23MPG with mostly freeway driving at 70MPH and no crazy full boost pulls to 100+. My old 84 8 valve turbo would get 28-30 going 80+. I realize my set up now can really burn gas if I drive the car hard but I am not. I moved my timing up to 20BTDC it was at 15 this did help but had taken the edge of my boost, I was getting more at 15BTDC. The vaccum advance seems to work, I hear the engine rev up when I putt a vacuum source on it, but I suspect it might not be working right. The only other issue is my turbo bypass valve I am almost certain it is bad, I get a moaning sound under high boost, it seems to hold vacuum when I suck or blow on the small vacuum line, but I have been told this does not mean it is good. Can this effect the MPG with a vacuum leak. The only thing that is not been replaced is the AMM how do I check this?

Any thoughts would be great

posted by 69.110.1...

• What else can cause me low MPG on SPG?-long, TSR, Thu, 3 Feb 2005 15:19:44 <-- Viewing This Message
  • low MPG on SPG and AMM Testing, eingang, Sun, 6 Feb 2005 06:49:45
  • 4 speed?, Jordan, Fri, 4 Feb 2005 09:07:41
    • Re: 4 speed?, gorper, Fri, 4 Feb 2005 10:49:02
      • I don't know man..., Jordan, Fri, 4 Feb 2005 17:56:44
        • So you're saying..., gorper, Fri, 4 Feb 2005 19:02:59
        • the final drive is lower, jak , Fri, 4 Feb 2005 18:35:50
  • Re: What else can cause me low MPG on SPG?-long, kooch, Fri, 4 Feb 2005 02:58:10
    • How to check AMM? Everything else I checked, TSR, Fri, 4 Feb 2005 09:03:47
      • Re: How to check AMM? Everything else I checked, Dean, Fri, 4 Feb 2005 13:24:04
        • 2.4LH isent realy adaptive ........, jak , Fri, 4 Feb 2005 18:55:20
  • If my 85 got 23MPG I would be stoked...., Jordan, Thu, 3 Feb 2005 20:54:01
  • Re: What else can cause me low MPG on SPG?-long, Dean, Thu, 3 Feb 2005 16:20:40
  • Re: What else can cause me low MPG on SPG?-long, MoonRacer96, Thu, 3 Feb 2005 16:11:04
    • Engine has 13,000 miles? Maybe the HIgher ratio gears?, TSR, Thu, 3 Feb 2005 20:43:12
    • AMMs can be tricky to diagnose esp on 2.4 LH, jak , Thu, 3 Feb 2005 18:23:40

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