hodge9386

I am running a SNS stage 3 235/243 .631/.610 with a ported ls2 intake, ported ls2 tb, longtubes, cattless x pipe, mildly hand ported 243 heads. 99% of my tune is good, it will drive part throttle in 6th gear at 45mph with no bucking, wot is good, it even comes back to idle without searching or any of that crap. The only thing that is bugging me is the actual idle, I want a nice even steady chop but it wont do it. It will start to idle nice and steady then it will sound like its fighting with itself and the engine and car will start shaking. The idle dosent search, it stays right around 900 rpm and my spark is steady at 25/26*. Iv tried close loop idle at 14.7 but my o2 sensors are very erratic so i thought the 17* of overlap was causing the o2s to throw my idle off so I tried open loop and leaned it out to 16.3 which it seemed to like but it still kicks into this quick chop/struggle and shakes the car. Im not sure what to do with it anymore. Any body have some suggestions?

My tune is attached.

phils C5 vette

see if these idle characteristic help it settle in. If not no harm no foul.

Though I do like when the car rocks at idle

hodge9386

Thanks I'll look at it when I get home. It just wanted more timing. I set it to 30* and it does much better, exhaust quit pinging and everything.

tblu92

Saying that it idles better in Open Loop when you command a LEANER AFR tells me that in Closed Loop you need MORE "Idle Airflow " In EFILIVE it's called "desired airflow" not sure what the table is called in HP----It is scaled in 2 tables---In gear and P/N--
and then by engine coolant temp-----
ADDING a % to both will add idle airflow both in CL and OL----I would start with at least a 20-25% increase across the board--
If you go too far--you will get the opposite affect ---a hanging idle--then simply start taking some % out--