backfiring...what should my fuel pressure be set to with AFPR?

Discussion in 'The Garage' started by Matt94GT, May 23, 2006.

  1. Matt94GT

    Matt94GT Legend SN95 Supporter Retired Staff

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    Well lately my cars been backfiring on me. Its when I giver in 1st up to about 5,000rpm+ then drop it in 2nd and floor it (ie, racing etc).

    Any suggestions? I did install a adjustable fuel pressure regulator and fuel rail pressure gauge and my mechanic said he bumped it up for me a bit. I did notice a bit of a power gain to tell ya the truth, but mabye its a bit too high and thats whats causing this? What should I set it to? I have a Mild H/C/I setup.

    Thanks
     
  2. rgs

    rgs Well-Known Member

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    matt our combos are a lot alike.

    i got mine set to around 37-38 i believe with vac on
     
  3. EThorpe

    EThorpe New Member

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    Sounds like it's a bit rich, don't blow the mufflers out :p

    Did this happen after the new Regulator was installed? Bump it back to stock and see it the backfire goes away? I think the normal pressure is about @36-40psi and drops to about 30'ish psi on the stomp. If it still backfires after you put it back to stock? then maybe a Plug wire is biting the dust under a load?

    Do you have a timing adjuster+chip in that car? Bump the timing up a little when you rich'n that shit up.
     
  4. Matt94GT

    Matt94GT Legend SN95 Supporter Retired Staff

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    yeah my timing is at stock right now, it was at 16* before. I got my tweecer now so I set it to base, I gotta bump it up I know. Thanks man.
     
  5. EThorpe

    EThorpe New Member

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    Well? what happen'd? Did you fix it? What was it :dunno: To rich?
     
  6. Matt94GT

    Matt94GT Legend SN95 Supporter Retired Staff

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    Well it wasnt doing it for a while but did it the other day when I ripped 2nd gear. My fuel pressure is at 40, should I drop it down a bit?
     
  7. Matt94GT

    Matt94GT Legend SN95 Supporter Retired Staff

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    WOW....My fuel pressure must of been at like 45ish before because it was @40 with the vaccume line on.

    Anyways I bumped it down to 38 with the line off, it didnt back fire in 2nd any more but i got some backfiring on light throttle at lower rpms in 3rd and 4th. I put it up to around 40 and got a bit of both now, I just turned it down to 39 hopefully thats the sweet spot.

    BUT hot damn, the car pulls like I remember it pulling when it had the stock AFPR and then some, wow feels like its got a lot more balls now.
     
  8. adjust yer timing...

    if you want you could increase the timing a bit and run 93... thats what i did... felt much nicer after i did that... first free mod i did to my car, lol...

    but i think it could use a nice timimg adjust and what octane fuel do you run?
     
  9. 97vertstang

    97vertstang Well-Known Member

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    bump ur timing back to 16 and make sure ur whole ignition is in good working order.coil, wires, cap, and rotor.if evrythings good it shouldnt backfire at all at 35-40 vac off.
     
  10. Matt94GT

    Matt94GT Legend SN95 Supporter Retired Staff

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    I got the pressure at 42 now and it doesnt backfire at all. Seemed to pull a bit harder down at like 39 but I got some backfiring? I got fairly new plugs, wires, cap & rotor. I run 94 Octaine. I think I might put my timining up even more from 14 to mabye 16* again???