Onboard Diagnostics - Tuning OBD1

[RobertISaar]

big read here. i'm just posting the TXT version of it along with a few pics to help understand a few things...

this took some type to type...

[tornado_735]

I know you hate the engine, but I wonder what I could do to my Ninety Eight.

[RobertISaar]

I know you hate the engine, but I wonder what I could do to my Ninety Eight.

drop it in a lake???

what year is it?

[RobertISaar]

we should probably keep this thread on topic, though i have yet to add in the MAF info that the 3800 and 94-95 3.4 guys would be using...

PM.

[RobertISaar]

slight update to the first TXT i posted:

when entering PE, if the BLM is less than 128, the ECM forces it to 128, then adds the additional fueling caused by entering PE mode. this essentially means it is going entirely off of your VE tables.

if the BLM is more than 128(meaning the engine WAS running lean), the ECM locks it there, and then adds PE fuel. this is to prevent leaning out when going WOT, but will need to be accounted for when tuning WOT.

example being that the BLM was 140 at the time of entering PE: that means the motor was running 9.375% lean before O2 correction. let's assume you want a Target AFR of 12.5:1, and the actual AFR is 13:1. that means that even after the ECM accounted for the 9.375% lack of fuel, the engine was still 4% lean. you will need to add the two together to get a corrected VE number.

[RobertISaar]

had to add the TXT again...