O2 SENSOR CAUSING SLIGHT SURGE

**ony** · 03-13-2014

BEEN PLAYING with 747 sync bin I noticed that when the o2 sensor switches rich to lean I get a slight surge, what can I adjust to help this smooth out?

**EagleMark** · 03-13-2014

Going CL is when you should see the switching O2 sensor reading and it should not be the cause of surging... if VE fueling at idle is in order?

Before you start changing and chasing let's look at IAC count, you've probably heard me say this before but it's the only way to use IAC counts to accuratly adjust throttle plate.

At the end of a data log, engine completly warmed up and driven, like after a warm up and short highway drive. Get 30 seconds to a minute of idle in Drive and 30 seconds to a minute in Park if an Auto trans. If a Manual trans then a minute at end of log.

Around 20 in drive and anything in park or neutral if your a manual trans. Just want asa few IAC counts as neccesery for IAC to still help control IDle. As much air to mix with fuel as it goes over the throttle plates! This is for a built motor, with a stock engine and fuel pressure IAC counts can be a little higher. If you have to much IAC counts like 40? Then turn in throttle plate Min Air Adjustment screw 1/2 turn... with engine off! Then start up and let warm up a little, rev engine and make sure your CL. If they are down to say 10, your done. Look at TPS voltage and if it's under .70? My testing has shown it's fine. If you want it perfect then turn TPS to get .54v. You may have to remove TPS and file out the holes oblong for some more travel.

Once that is done see how your surging issue is then and we'll move on to other adjustments. Post a log of the idle at end.

**lionelhutz** · 03-13-2014

This surging occurs under light throttle or cruise conditions? In Tunercat the lean/rich O2 voltage threshold tables can be used to fix that. Just bump the switching voltages a little higher. Not sure what it's called if you're using Tunerpro.

**steveo** · 03-13-2014

if you're logging a surge associated with the o2 swinging rich or lean and then holding there, that's a symptom, not a problem. the o2 is for fine adjustments.

you should never "feel" an o2 switching, if you notice a surge accompanying it switching from rich to lean, that means something happened that made it fairly lean/rich during the surge, and the o2 measured it, not caused it.

**RobertISaar** · 03-13-2014

the code and calibration responsible for how much pulse width is added/subtracted to injector on-time for closed loop operation will do it.

**ony** · 03-15-2014

I have played with this thing for a couple days, switch to my 288 ecm don't feel it driving but setting still holding throttle steady it palsates from 825-950 rpms. above 1100 nether ecm does the palsating. more of wondering why than a problem thanks for all the advice.