bishiboy

iTrader: (10)

I've noticed that when my car is idleing (HKS 272 cams, straight-up (no gears)), my wideband shows drastic swings from super rich (10-11:1) to super lean (20:1). And the rpms surge up and down between 600 and 1200rpms.
Anybody else having this problem?
Anything above idle is excellent, it just idles like ****.

MalibuJack

iTrader: (5)

What adjustments have you made for the bigger cams and fuel injectors? The poor idle has to do with cam overlap and possibly the ECU trying to find a miture with the bigger injectors.. I won't speculate any further until you let me know.. If you have not already done so, you might have to get your ECU flashed (or a piggyback or standalone) to scale your injectors otherwise it'll be REALLY rich.. and it'll hunt in closed loop for a good mixture since it may be unable to compensate.

Also, there's a thread on adjustable cam gears, and there have been some possible recommendations for cam timing (-4, -1) to reduce the cam overlap slightly to smooth out the idle.

bishiboy

iTrader: (10)

I have a custom tuned dynoflash, although, AL said he doesn't tune for Idle.
I have an HKS S-AFR to adjust idle fuel rates, but before the flash, I actually had to add fuel at idle to help it stablize.
I also noticed that it's not too bad until I turn on the AC or when the cooling fans kick in , then it really runs ****ty.
I saw the thread on the cam gear set-up, but I don't want my car tuned for mid range, I like the top end rush from the cams.
I guess I'll deal with it until I get my UTEC, then I can adjust the idle afr.
I was just hoping for a temp fix.
I'm not giving up. I'll keep messing with the idle air bleed screw and idle fuel amounts.

Shahul X

iTrader: (3)

or -4, -1.5

-shahul

umiami80

iTrader: (1)

I have 272's, Flashed at Turbo Trixx, idle is ALMOST stock like, very slight lop but is present. I couldn't be happier.

gunzo

iTrader: (2)

bishiboy, my AF when the car cannot idle is just like yours
After dialling in .. the AF is around 14.x stable .. occasional stumble shows around 12-13.0 ..

coincidence or cam specs .. but what I had was the similar to what some of the guys found here

nastea1

i'm adding about 8% fuel at idle, it seems to help out my 272's its still lopy but..

Shahul X

iTrader: (3)

nastea, what are you using ...? an AFC?

-shahul

nastea1

s-afr

Shahul X

iTrader: (3)

ah, no cam gears? 272 intake as well as exhaust I guess....

-shahul

93civEJ1

iTrader: (7)

put mine in this weekend as well. Same exact thing. 272 no gears...same exact idle quality. I did move the idle up a hair but its still pretty much acting the same. Guess its just the nature of these cams without tuning.

superz

iTrader: (7)

YOu need to add about +10 to +14 fuel percentages on the safc to get a better idle. That's just the way it goes with cams. Dont worry too much about AFR since the ecu will always try and achieve around a 14:5-8 mixture although this number will fall down or up quite a bit with cams.

93civEJ1

iTrader: (7)

yeah.. I really wish adding about 10 or 14 on the safc down low was possible at 0% Throttle, but the car will just correct itself back with it running in closed loop correct??? I have tried this and yet it will just correct itself. A couple of people have mentioned to me about vacuum reserves?

superz

iTrader: (7)

At 1000 rpm's its very possible and it wont try and correct since you're actually trying to help the ecu get close to stoch.

93civEJ1

iTrader: (7)

hmmm, so are you saying i should up my idle a little more to around 950-1k rpm and adjust the lo throttle 0% tps ?? Each time I do this in closed loop/idle operation it just always seems to adjust itself back. Maybe i should just play with it some more. Hmmmmm i guess i know what ill be doing this afternoon after work today.