dizwiz24

ok. i had battery disconnected and then fired up the car after letting it sit for awhile.

the car has an open loop idle tune below 1200 rpm.

at idle:
left blm says 160, right blm says 160

left integrator says 128, right integrstor varies between 180 and 190.

car idles fine (in this temp).

most importantly, i dont have a choking exhaust smell at idle. smells fine for what it is (a cam'd car with batch fire speed density inj).....

its weird that every time i have an open loop idle tune (by setting power enrichment to 0% throttle under 1200 rpm), i see left integrator at 128 and right integrator fluctuating slightly somewher >160

would you all mess with anything?

cardo0

BLM is the long term fuel trim and the neutral/median value is 128. So long term is a bit rich (160/128 = 25%). Integrator is short term trim and your right integrator saying rich. But ya know when in open loop the short term/integrator defaults to 128 so your right bank is behaving as closed loop - don't ask me why. Something maybe wrong with the fuel map at idle.

You could tinker and swap O2 sensors or maybe even fuel injectors. Or you may have an exhaust leak on the right bank or a vacuum leak on the right bank causing lean bank and forcing integrator to go rich.

What does the O2 sensors output look like? If it's integrating it will be all over the place from 125mv to almost 900mv. If right bank is stuck low below 450mv then that bank is lean and the integrator is trying to richen the fuel mixture. Again this is usually in closed loop but for cold idle not so sure what it does.

Hope this can help.

dizwiz24

thanks for the reply

there has always been a split blm issue (just usually not this bad).

am i going to get blm and integrators on both sides to 128 at idle? i dont think so. ive tried for years.

im convinced some of it is normal wih a cam and batch fire.

92-93 speed density batch fire cars just dont idle as good as maf/ sequential cars

idle smell and my wideband afr is the main metric i use to judge idle quality.

Kevova

With cold/open loop operation you have to take into account AIR system. AIR is pumping air into exhaust manifolds in an effort to speed up O2 activity to enter closed loop operation sooner. It's also why INT BLM aren't normally looked at in open loop.

tequilaboy

Integrator activity suggests closed loop control.

How does your power enrichment afr target (below 1200 rpm) compare to your closed loop stoichiometric afr target? If these are the same value, learn control may still be active while in Pe mode. Check your settings/logs to be sure you really have a different target afr in pe mode.

As already mentioned, the max positive Blm indicates that the underlying tune is lean. If your intention is to lock-in a lean idle in this manner, it does not appear to be a success, since it can't get much richer, as evidenced by the fuel trims.

For this idea to work, you want to disable learn control before the Blm has a chance to climb.

I'd be inclined to richen it up to bring the blm down and let closed loop do its thing.

dizwiz24

the car has always had a stink to the idle this is what im trying to get rid of.

in closed loop the afr is all over the place at idle. wideband 13.x to 15.x . the blms are split and the right side blm will climb over, peak out, and then fall below 128, constantly hunting.

this is why i have been experimenting with open loop tuning. i would agree with you that, even though i have commanded pe mode to be active at 0% throttle below 1200 rpm, i do not appear to be running in pure open loop.

again, there is an idle smell that i hate. once on the road (rpm above 1200), its wonderful. afr is arnd 14.7 and both blm/int arnd 128.

i have 60 lb/hr inj and a 224/236 cam on my supercharged 93 6 spd.

you do have an interesting point....my idle afr (around 13.0:1 ) was around my pe mode targt afr (i am spraying meth/water, so its really richer than that)

tequilaboy

Maybe just raise your Min MAP for BLM Update setting.

dizwiz24

ok so unhook the battery (to delete any stored corrections), get rid of the open loop idle and raise min block update to above 60 kpa ??? (at idle its around 58 kpa)

.....

or to ask another way:

you recommend running traditional closed loop idle, but set min map block update to a point just above where it idles at?

so it wont be updating blms at idle but still run closed loop for idle ???)

Dominic Sorresso

Open Loop idle doesn't use INT or BLM. It just uses whatever is in the VE or LV tables depending on whether u r using MAP or MAF. Also, tuning idle for a cam requires adjusting the O2 sensor swing points because greater overlap causes a false lean condition that the ECM tries to correct. Therefore, more fuel. My suggestion is to go read up on tuning over at thirdgen.org.