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

Matt94GT · May 23, 2006

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

rgs · May 23, 2006

matt our combos are a lot alike.

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

EThorpe · May 26, 2006

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

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.

Matt94GT · May 27, 2006

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.

EThorpe · Jun 1, 2006

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

Matt94GT · Sep 9, 2006

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?

Matt94GT · Sep 9, 2006

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.

GREG@SN95 · Sep 9, 2006

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?

97vertstang · Sep 10, 2006

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.

Matt94GT · Sep 10, 2006

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???