Tuning for Power and Economy
08-21-2020, 08:20 AM
#1
Super Moderator
Thread Starter
Tuning for Power and Economy
The heading is sure to grab a lot of attention.
With my conversion to Chev I have acquired HPTuners to both turn off codes in the Jeep and to turn on codes and change programming in the Chev motor and tranny. HPT also has a Scanner feature that logs files while driving with HPT and with live real time graphics. It allows playback in slow or fast motion to diagnose what is happening in engines to determine what needs to be corrected.
Recently we downloaded my son's file from his 2016 3.6 Ruby and went for a 25 minute drive to log in real time. We gave this file to a fellow who is an expert on HPT and tuning (in particular LS series Chev engines) for all common NA engines. He looked at the file and stated the following;
1. there was a lot of knock happening and timing was being turned back.at higher throttle opening. That is where you want the timing for power. He asked if we need to run premium.
2. He needs to read Pressure ratio of Barometric pressure vs Manifold pressure as Jeep do not have a Mass Airflow Sensor. That is all calculated by the ECU.
3. Once he gets a re-log of driving he will work on fuel first then timing and stated it is easy to get 10-15HP at a lower RPM and around 20lbs ft of torque also down lower.
4. Tuner guy notes that the same V6 in a heavier 1/2 ton pickup will spank the JK in performance. And the JK is about 500lbs lighter with 4.10 gears so something is wrong.
For power (EG passing, hills etc) there is a feature called Power Enrichment (PE). Note the following;
a. The factory settings for PE are 5600rpm, 95% throttle, delay 48 seconds, FA ratio of 1.05 from Stoich. So this means when you want most power you have to be above 5600rpm, with throttle almost to the floor, for 48 seconds to get some power like passing power.
b) You also get a very lean FA ratio of around Stoich 14.06/1.05 = 13.4 which makes the engine run hot hence the knock at high throttle opening mentioned above.
c) What the Tuner guy will do for changes is the next 4 lines (d -g)
d) Lower the throttle setting to 2800RPM. Below this setting will keep the Jeep in lean mode while on cruise control. Makes sense. Legal speeds above 75mph may take this setting higher.
e) Change the throttle setting for PE to start to 65% for same reason as d)
f) Change the delay to 0. That means power right now.
g) Change the divider ratio of 14.06 Stoich from 1.05 to 1.13 which gives a FA ratio of 12.44. Carburetted and early FI cars had this FA ratio. This will allow a richer fuel mixture and keep the high timing advance settings without knock.
Now the son will get way more power at 2801 RPM, at throttle above 65% and instantly with a good power FA mixture. And the RPM band will pull way better as it gets up there past 4000-4500RPM.
So what has happened here is we are only playing with fuelling. Have not touched Volumetric efficiency or timing which comes next. The advice is to keep the changes to a minimum to be able to measure progress. And of course we keep the stock program for backup warranty as the changes are in the Jeep code so no footprint left here for FCA to see. Also the above PE relates closely to my Chev engine settings (except my delay is 180 seconds ) so similar changes are going to happen this weekend. I can keep this article running for progress so that others can follow if they choose to do so.
Another benefit for our US cousins is if the pollution checks are done below 2800RPM it will be invisible to the testing facility.
With my conversion to Chev I have acquired HPTuners to both turn off codes in the Jeep and to turn on codes and change programming in the Chev motor and tranny. HPT also has a Scanner feature that logs files while driving with HPT and with live real time graphics. It allows playback in slow or fast motion to diagnose what is happening in engines to determine what needs to be corrected.
Recently we downloaded my son's file from his 2016 3.6 Ruby and went for a 25 minute drive to log in real time. We gave this file to a fellow who is an expert on HPT and tuning (in particular LS series Chev engines) for all common NA engines. He looked at the file and stated the following;
1. there was a lot of knock happening and timing was being turned back.at higher throttle opening. That is where you want the timing for power. He asked if we need to run premium.
2. He needs to read Pressure ratio of Barometric pressure vs Manifold pressure as Jeep do not have a Mass Airflow Sensor. That is all calculated by the ECU.
3. Once he gets a re-log of driving he will work on fuel first then timing and stated it is easy to get 10-15HP at a lower RPM and around 20lbs ft of torque also down lower.
4. Tuner guy notes that the same V6 in a heavier 1/2 ton pickup will spank the JK in performance. And the JK is about 500lbs lighter with 4.10 gears so something is wrong.
For power (EG passing, hills etc) there is a feature called Power Enrichment (PE). Note the following;
a. The factory settings for PE are 5600rpm, 95% throttle, delay 48 seconds, FA ratio of 1.05 from Stoich. So this means when you want most power you have to be above 5600rpm, with throttle almost to the floor, for 48 seconds to get some power like passing power.
b) You also get a very lean FA ratio of around Stoich 14.06/1.05 = 13.4 which makes the engine run hot hence the knock at high throttle opening mentioned above.
c) What the Tuner guy will do for changes is the next 4 lines (d -g)
d) Lower the throttle setting to 2800RPM. Below this setting will keep the Jeep in lean mode while on cruise control. Makes sense. Legal speeds above 75mph may take this setting higher.
e) Change the throttle setting for PE to start to 65% for same reason as d)
f) Change the delay to 0. That means power right now.
g) Change the divider ratio of 14.06 Stoich from 1.05 to 1.13 which gives a FA ratio of 12.44. Carburetted and early FI cars had this FA ratio. This will allow a richer fuel mixture and keep the high timing advance settings without knock.
Now the son will get way more power at 2801 RPM, at throttle above 65% and instantly with a good power FA mixture. And the RPM band will pull way better as it gets up there past 4000-4500RPM.
So what has happened here is we are only playing with fuelling. Have not touched Volumetric efficiency or timing which comes next. The advice is to keep the changes to a minimum to be able to measure progress. And of course we keep the stock program for backup warranty as the changes are in the Jeep code so no footprint left here for FCA to see. Also the above PE relates closely to my Chev engine settings (except my delay is 180 seconds ) so similar changes are going to happen this weekend. I can keep this article running for progress so that others can follow if they choose to do so.
Another benefit for our US cousins is if the pollution checks are done below 2800RPM it will be invisible to the testing facility.
Last edited by Sixty4x4; 08-21-2020 at 08:39 AM.
08-23-2020, 06:05 PM
#2
Super Moderator
Thread Starter
Made the PE changes today and what a difference on my Cheveep. Accelerates from 75kph to 105kph in 2.5 seconds and that is verified on the scan log for HP Tuners. That's 47mph to 65mph. Not bad for a Jeep. We have a mountain pass to cross before winter next weekend so will be back on son's 3.6 in 2 weeks from now.
08-25-2020, 06:43 PM
#3
Super Moderator
Thread Starter
UPDATE: With the change to the Chev PE on last weekend and about half a fuel tank remaining the mileage went up (over the total full tank capacity) by 2 mpg (imperial) about 1.6mpusgal. I also turned off Displacement on Demand which is the 4 cyl mode. So over a full tank I should get 4mpg difference. And power is right there. I will get way more mileage by switching to an all MAF tune which is going to be tested soon. As stated we are doing this Rocky Mountain trip this weekend and will start on the son's 3.6 next week with PE to start with.