fixing idle with crower 404 cams_LS motor

2224 Views 7 Replies 6 Participants Last post by White98LS, Jul 20, 2004

1 O.G teg

Discussion Starter · Sep 13, 2002

Ok i was thinking that using a fpr at low presure at idle and also use the sfc after 1500 rpm to give the cams the added fuel they will need up top.I thought this might clear up the idle problems please give me some feed back on how you fixed your idle with 403 or 404 ls cams.

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JAYMAN320

· #2 · Sep 13, 2002

"These street/strip-mild race cams here, have a rough idle, an operating range from 1200rpm to 8500rpm+ and have shown improvements as high as 21 horsepower. Must be used with high performance valve springs and light weight retainers are highly recommended."

-quote taken from Crower

The only way to improve the idle is by adjusting the idle screw and cam gears. No matter what you do these cams will have a bad idle, its profile is what cause this..ie;late intake valve closing

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allmotor_integ

· #3 · Sep 13, 2002

fixed your idle with 403 or 404 ls cams.

the 403s dun idle that rough but the 404s is a full race race application and met for the track use.................i am planning to get the 403s cause they are street/track.........so i dun think you could really fix the idling prob like the earlier post said high profile cams

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scoob_dawg

· #4 · Jul 16, 2004

heh, not one of you guys has a clue.

i have 404's, stock CR and the idle is damn-near stock,

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ABCsR2EZ4Me

· #5 · Jul 17, 2004

scoob_dawg said:
heh, not one of you guys has a clue.

i have 404's, stock CR and the idle is damn-near stock,

Thats real helpful

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scoob_dawg

· #6 · Jul 19, 2004

how's it NOT helpful?

i just told the guy there IS NO idle problems with the 404's, god forbid someone with some ACTUAL experience tell it like it is,

i hate bench racers saying stuff like "404s is a full race race application " or "No matter what you do these cams will have a bad idle", it's just complete crap, if you don't know what you're talking about then keep your opinion to yourself cause you're probably gonna be wrong!

My car idles between 740-760 according to my vafc, steady always, only mods are bolt-ons, 404's, vafc, and FPR. and it's a 90, 140,000miles,

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scoob_dawg

· #7 · Jul 19, 2004

JAYMAN320 said:
The only way to improve the idle is by adjusting the idle screw and cam gears.

actually, they idle best when the cam gears are UN-ADJUSTED, and the idle-rpm really doesn't need to be raised,

all you need to do is bump up your fuel pressure, then using an afc lean out the 1000rpm narrow-band setting until you get a solid idle. easy.

if you still can't get a decent idle it's not the cams, it's another component that's failing, i've heard of everything from a shitty timing-belt tensioner, to the obvious IAC valve,

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White98LS

· #8 · Jul 20, 2004

scoob_dawg said:
actually, they idle best when the cam gears are UN-ADJUSTED, and the idle-rpm really doesn't need to be raised,

all you need to do is bump up your fuel pressure, then using an afc lean out the 1000rpm narrow-band setting until you get a solid idle. easy.

if you still can't get a decent idle it's not the cams, it's another component that's failing, i've heard of everything from a shitty timing-belt tensioner, to the obvious IAC valve,

Beat me to it! Yeah, the original poster is doing it the opposite, and much less effective way. You need much higher than stock fuel pressure and then just lean the shit out of it at 1000rpm. On lower fuel pressure, you simply cannot get enough fuel in the mid and upper range by just relying on the S-AFC - it may keep the injectors open more, but they are flowing a lot less. Also beyond +13% fuel increase with the S-AFC, the stock ECU detects boost and retards timing.

Don't copy my settings, but just as an example with 403s on stock compression with just bolt-ons/cam gears and stock redline, I have my FP at 46psi and S-AFC leaned out like -22% at idle (still idles somewhat rich but quite steady - doesn't stall), little or no change 3-5k or so, then leaning out again 7-10% or thereabouts in the high end. Up the fuel pressure, then lean it back down at select points (on the DYNO) with the S-AFC.

EDIT: ...and I just realized that this post was from 2 years ago. :mad

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