Grant B

I'm considering getting an ASA cam (226/236 110 LSA, .525/.525) for my daily driver and occasional road course car. Some people say it will suck to daily drive, others say you can make anything perfectly streetable with good enough tuning. I've got HPTuners and a FJO wideband, so tuning it won't be a problem.

Now I'm no stranger to tuning ECUs. I've messed with tons of different types of piggybacks and standalones on DOHC turbo motors. Never anything with a really aggressive cam though, and never touched a pushrod motor. One thing I can't figure out, why would a MAF car would require a different fuel map with a cam? Seems odd. If it were speed density I would understand... I haven't read much about the details of tuning these ECUs, but I'm guessing the ECU can ignore the MAF if its readings get really out-of-wack with the MAP sensor.

I wish there was someone near me with a cammed LS1, but there isn't. I'm worried the car will shake violently at idle, or buck like crazy under 2000 rpm. I guess what I want to know is, will I be able to tune out the drivability problems? Even with no cats, the car should be pretty quiet with stock Z06 mufflers, so an idle of 900 or 1000 rpm would be fine.

Thanks for any help.

monodax

The GM code weights the speed density tables much greater than the MAF input in the lower RPM ranges. Once over 4000 RPM it is almost totally based on the MAF input while in steady state mode. It uses the speed density tables almost always to sanity check for transient conditions such as throttle blades closing.

MECHAM

iTrader: (4)

i think people have different interpratations of what driveable is nowadays.

your cam with 110 lobe...wow. i wanna hear a video/sound clip of that bad boy idling

Mark98SS

iTrader: (1)

After tuning my 230/224/111 setup is quite drivable altho nut much power below 1500rpm, sounds bad ***.

wait4me

iTrader: (10)

get the cam. ill help you tune it and you wont even know its there. jes

soslo

iTrader: (12)

tuning will make a night/day difference. I have a TSP225 on 112 and that thing would buck under ~2200 rpms, Hunt for idle, Die in the parking lot, die backing up, die coming to a stop. Shake like Catherine Hepburn at idle....with tuning it is not too far from stock. Only slight bucking occasionally, and periodic idle hunt. SES light now and then from the shake. You can do it, but it will not be "stock" - but it can be driveable.

HumpinSS

iTrader: (1)

I got my 230/232 idling just fine with a 110 +4

Grant B

Thats.... strange. Most MAF cars just use a TPS sensor for transient stuff. But it explains a lot, thanks. Maybe there is a way to make the ECU ignore the MAP for fueling? I guess I'll have to do some searching.

I know big cams can be a problem for speed-density setups with big cams because of the vacuum fluctuations at low RPM. More intelligent sampling of the MAP sensor is needed, I know some ECUs pick a specific crank position to sample the MAP sensor voltage to calculate load, instead of a fixed frequency. Others can perform software filtering based on RPM, which is what I've done in the past.

Flyin'Brian

Another_User

Ewwww. I just realized something. You can't tune LTFTs without knowing if it is going off the sensors or VE. The average will be wrong. Sheeeeet.