Custom Tuning Step 2 of 3

by Michael Decipha Ponthieux
Last Updated: 2018-09-16

This page ONLY applies to those whom were directed here AFTER receiving a custom tune from me and have completed step 1.

Part Throttle Fuel and Spark

Now that step 1 is complete and low load fuel is dialed in, now is the time to verify IPSIBR and dial in the isc multiplier if it is, part throttle fuel, and spark.

Before writing the updated tune or turning the ignition key on, adjust the throttle stop screw if instructed to. If you were instructed to clear the KAM's (not usually) they can be cleared by doing any of the following outlined here in the Fuel Write Up - Reset KAMs

If all is a go be sure to start the log BEFORE you start the engine. Let the engine idle and datalog until the engine reaches warm operating temperature, DO NOT TOUCH THE THROTTLE DURING THIS TIME, once the engine reaches warm operating temperature and has likely been idling for 10-15 minutes or so stop the log and save it as Log 2A.

Idle in Drive for Automatic Electronic Controlled Transmissions (94+ only)

If you have a 94+ ecu with an electronically controlled automatic transmission or if I've written custom code to differentiate drive and park; shut the engine off, wait approx 20 seconds and restart the warm engine. Immediately put the vehicle in drive and hold the brake, include a 5 minute datalog of it idling in gear. Do not move the vehicle or take your foot off the brake. We need this to dial in the isc drive multiplier (airflow in gear)

Once that is completed, (If applicable), we can then proceed to dial in the fuel.
Remember, the engine has to reach a warm stable idle (not surging) before dialing in fuel otherwise the datalog is useless.

For the step 2 log you must drive the vehicle, but you must verify the ecu is in closed loop first this can be observed by LAMBSE1 jumping around constantly increasing and decreasing instead of staying at one set value.

While shes warming up, I recommend checking over the tire pressure, lug nuts, etc if you hadn't already in step 1.

If the car has been sitting a while or if you hadn't put fresh fuel in the tank recently then now is the time to do so, your first trip should be to the gas station to fill up with fresh premium fuel (low grade fuel can only be used if discussed and the tune is setup for it). Now that you have fresh fuel, Hopefully you have a nearby patch of road you and your comrades use for testing and tuning, you know what im talkin' bout! Go ahead and cruise on out there to perform the step 2 log. If you don't have an area you play around in, you can take her out on the highway where you have a straight patch that you can safely do some playing.

For the step 2 log lock her in gear lugging at the slowest speed you can and start a new log, once the log starts, wait 3 seconds then stab her at HALF throttle and HOLD it there until you get to your max rpm (6k or so) let her coast back down to a safe speed (say 35mph or so) then pull over safely when you can and stop the log.
Post it in your Private Tune Progress Thread. I'll shoot you back a revision with more detailed instructions after I review it

If you hear any detonating during this time (that unmistakable piston ring flutter sound) stop the pull and do not touch the throttle again until you can pull over safely and stop the log and save it. Post back with the log so I can post up a revised tune with spark adjusted.

Its always good practice to check for any coolant, oil, powersteering, or any other leaks underneath the car. Pop the hood and make sure nothing has come loose; just give it a good double over. If you do find something amiss be sure to inform me.

Note: Its not uncommon to verify another step 2 log if fueling is too far out or inconsistent.


If you have any issues along the way don't hesitate to give me a shout on my mobile: five zero four six zero six zero five three two

Note: Nowhere in this step does it say anything about going WOT. DO NOT for any reason go WOT as it can damage the engine.
Understanding Step 2 Changes
After getting the fuel close I return some values back to a sane value.
Hego Min SwitchesI usually set it between 3 to 8 switches dependent on how well the hegos respond.
BYPLESI drop it back down to 15 sec or so depending on how the hegos respond.



Return to Step 1
Continue to Step 3


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