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 ****.

 

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.

 

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.

 

or -4, -1.5

-shahul

 

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

 

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

 

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

 

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

-shahul

 

s-afr

 

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

-shahul

 

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.

 

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.

 

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?

 

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.

 

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.