PE/RPM Change
Thread Starter
Joined: Apr 2003
Posts: 2,597
Likes: 4
From: Lawrenceville, GA
PE/RPM Change I finally have my LTrims below 0. I have modified my timming. My O2's at WOT are running rich. My PE/RPM table is currently at 1.2171 across the table. If my O2's are at 930 how much should I change my PE table by?
BowlingSS
BowlingSS
I have 1.18 in my PE vs RPM table and the O2s read 940 to 950mV when a wide band says that I'm at 13.0 AFR and the engine makes 400RWHP. So, O2s are not accurate enough to tune by. For me, getting on a chassis dyno helped my to determine what my O2s read when I'm close to 13.0:1 AFR.
Before getting on the chassis dyno, I tried to street tuning the AFR (getting the O2s at 980mV at WOT). However, when I tried reduceing the PE vs RPM table lower so get to 890mV on my O2s, when the O2s actually read 910mV, I got KR of about 4 degrees (PE vs RPM table at 1.12). The wide band said I was at 13.8 AFR. SOO, I would quess that if you keep lowering the PE vs RPM table until KR set in at WOT (you are now too lean), then you should add back in some fuel to increase the O2s values by about 30mV,, enough a remove all KR.
When you think you are close to the right WOT AFR, get on a chassis dyno for final confirmation. Data log the O2s during the chassis dyno pulls so you can get a good comparison.
Before getting on the chassis dyno, I tried to street tuning the AFR (getting the O2s at 980mV at WOT). However, when I tried reduceing the PE vs RPM table lower so get to 890mV on my O2s, when the O2s actually read 910mV, I got KR of about 4 degrees (PE vs RPM table at 1.12). The wide band said I was at 13.8 AFR. SOO, I would quess that if you keep lowering the PE vs RPM table until KR set in at WOT (you are now too lean), then you should add back in some fuel to increase the O2s values by about 30mV,, enough a remove all KR.
When you think you are close to the right WOT AFR, get on a chassis dyno for final confirmation. Data log the O2s during the chassis dyno pulls so you can get a good comparison.
TECH Regular
Joined: Nov 2003
Posts: 434
Likes: 0
From: Dallas
I agree with Doc. The stock O2s are not accurate for AFR tuning. My O2s like to be around 940 to make all the KR go away. I spent lots of time chasing KR when trying to tune the O2s around 890-910. Once I decided to ignore the O2s tuning got easier...
