EFIDynoTuning Forum

So I am finally uncorking the terrible factory exhaust system on my my marauder which has a 2.65 TVS blower. I’m installing long tube headers and a full 2.5 inch dual exhaust system. So, my question is… What “tuning” changes are congruent with this improved performance exhaust system? Obviously boost levels will drop because of the improvement in pumping efficiency. Is there a way to take advantage of this improvement in the tune? I’m trying to improve my understanding of the implications of this mechanical engine pumping improvement and how it relates to making more power when “tuning”. Thank you 👍

following topic, I have a much simpler setup, but know there are some changes to be made, and I want to learn more.

The safe way would be add some fuel at higher loads and then retune as needed. Make short pulls and be ready to get out of the throttle. Give her what she wants more or less fuel.

I appreciate that help. Fatten the top of the curve up a bit and cut or add fuel from there. I’m also wondering though… So the heated O2 sensors (upstream) have been moved further away from the combustion chambers. And they need heat to work properly. Is there an O2 heater function that can be modified to correct for this? Also, I imagine there may be a delay in fueling corrections as the closed loop has become bigger with that distance of the O2 sensors moved lower in the exhaust stream. But I’m a newbie so just trying to learn

I was wondering how far the WB O2 sensors could be from the combustion chamber, but I have "shorty" headers, so I think I'm close enough installing in the shorty collector. I was going to install one additional bung for a dash mounted AFR gauge but now after purchasing the Moates Quarterhorse I'm going to add 2 bungs. One for the stand-alone gauge and the 2nd to feedback to the Moates QH during real-time tuning. Correct me if I'm wrong but I think I can use wire/pin 47, the old EGR/DPFE, to wire the "2nd" wideband O2 sensor to feedback to the PCM. The header is still on the vehicle so I will be able to pick a spot that won't interfere with anything under the hood.

no need to fatten the curve the maf measures airflow any increase in airflow will correspond with more air and likewise fuel.

if the headers move the o2s farther back then yes kick up the hego delay thats the FNTDSEC8x10 table. Kick it up a percentage say 50% or globally add 0.35 msec to start and then use the hego delay histogram on eec-v to dial it in from the ecu's learned corrections over time.

the hego heater can also be kicked up as well search for hego heater and FN_USHTR_DC should pop up which is the hego heater duty cycle for time. Kick up the duty cycle so the heater keeps it hotter as its farther back. 85% should be good, most tuners just set them to 100%.

you may need to delay closed loop as well if the o2s are farther back since it will take them longer to heat up. search CL Delay (FN_TCSTRT) and kick up the delay time.

make sure you update the inferred load table FN1036A for the new load