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Need help tuning CRX si Turbo

Discussion in 'Forced Induction' started by gettocrx, Feb 11, 2004.

  1. gettocrx

    gettocrx Member

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    Hey guys! I need your help! I have a 88 CRX Dx with a Si head thats boosting 5psi. My car was running fine till I installed a Skunk2 manifold. Everytime I try to floor it, at a certain rpm (5000) it starts bogging out. But when i dont floor it (half throttle) pass 5000 rpm, it doesnt bog. Is my fuel pressure?? It is set at 40psi and I have a vortech 8:1 fmu! Do i need more gas?? Do I retard the timing?? (timing is 2 degees advanced right now cause it was running better this way with stock manifold). What should I do??

    P.S. My air fuel gauge reads on the rich side when I floor it!

    Thanks for all your help! :D
     
  2. reckedracing

    reckedracing TTIWWOP VIP

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    i do not know for sure, but i think you are drowning your motor

    8:1 for only 5 pounds of boost?
     
  3. Loco Honkey

    Loco Honkey Banned

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    Sounds like a fuel issue. What kind of AFG do you have? Autometer? They're semi- unreliable at best. If you can't afford a wideband O2, get yourself an EGT gauge and watch that. Also, an 8:1 is pretty low, especially if that's your only source of fuel enrichment. Get yourself a 12:1 disc for the FMU. Do you have a HIGH PRESSURE inline pump? If not, you *NEED* one. Let's do some simple math and look at fuel pressures...

    Your stock in tank pump is good for about 60 PSI worth of pressure. At WOT on a stock engine, you're looking at about 55 PSI. The purpose of an FMU is to add fuel pressure based on boost pressure and this ratio is indicated by the numbers. A 12:1 will raise the fuel pressure 12 PSI for every 1 PSI of boost. Since you're running 5 PSI of boost, the FMU is raising your fuel pressure (5*12) 60 PSI. Add that to the 55 PSI that the OEM FPR is producing and you're at 115 PSI worth of fuel pressure at the rail. The *ONLY* way you're going to get that is with a high pressure inline pump.
     
  4. gettocrx

    gettocrx Member

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    ohh yeah! I also have a MSD inline pump! with stock injectors.
    And my 8:1 FMU cant be drowning my motor because I had no problems with it with my stock intake manifold.
     
  5. reckedracing

    reckedracing TTIWWOP VIP

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    my mistake, its not drowning the motor, its running lean...

    you put intakes on for better air flow right?

    and now because you have the new intake you're getting that much more air into the motor with the same amount of fuel as the stock intake...

    bump the fmu to a 12:1 disc like loco said and see what happens...
     
  6. Crazyrex

    Crazyrex Junior Member

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    when i had that problem i put a missing linke in and it cured the problem
     
  7. gettocrx

    gettocrx Member

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    Thanks for all your help. I found out that the fuel inlet and outlet was switched on the FMU, now it runs good! But car still lags in top end! probably timing?? and I also have a missing link, without it, check engine will go on!
     
  8. Loco Honkey

    Loco Honkey Banned

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    Define lag. Tell me EXACTLY what the car does at the top end. Otherwise, you're too vague.
     
  9. gettocrx

    gettocrx Member

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    lag in top end meaning in high rpm (6500 and up) car doesnt pull as hard as it does in mid range rpm (4500-6000)." I think it might be my timing"
     
  10. Loco Honkey

    Loco Honkey Banned

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    If you have a stock exhaust, there's the problem. If you have a cat, it could be clogged. If the turbo is small, that could be it. As for your timing, if it's advanced, that's very bad and could quite possibly be dedonating so bad, you're losing power. Retard your ignition 2° to 4° from factory specs and run plugs that are two steps colder than stock.

    Also, you mentioned twice that you have an Si head on it... I'm not sure if you're aware of this, but the Si and DX heads are EXACTLY identical to each other, with the only difference being the cam. Saying you have an Si head really doesn't mean anything as it's not a modification.

    Why are you revving a D15 beyond 6500, anyway?
     
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