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Thread: MDS - 2006 Jeep SRT8 - HP Tuner Activation

  1. #1
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    MDS - 2006 Jeep SRT8 - HP Tuner Activation

    I just ordered the MPVI2 setup so that I can do my own logs for ease of diagnosing a weird issue. But I am curious if, from stock, can the HP Tuner software be used to turn on, either permanently or intermittently, MDS on a 2006 Jeep SRT8. From what I see so far, our jeep were not programmed with it, but that doesn't mean there isn't a way.

    I ask, because while my jeep now has turbos, tunes, and various upgrades which should put it into the 12-13 second range, I actually went from 14.2 bone stock to 14.9-15.3 with my fuel economy going from 12MPG to 25MPG.
    Thoughts? If you know where I should look in the VCM software to see if this is off or on once I get the new package, please let me know. I am seriously curious. Thanks

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    6.1l engines did not come with MDS. No MDS lifters, solenoids or oil passages installed in those engines either to make it possible. Which btw the MDS seems to have caused quite a few 5.7 fleet and pursuit vehicles (even RAMS) to experience valvetrain failure.

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    That's good to know. So now I am even more at a loss, at least MDS would explain the fuel economy in my mind. I know the increased air would improve it as well, but to more than double the fuel economy, feels like something is off. I guess I will have to wait until I can get a data log and send it off to have someone look at it. Thanks for your help.

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    How are you determining that you're getting that good of fuel economy... Dividing miles and gallons uses after filling up over a drive?

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    I did it two ways because I thought my digital display could be off.
    Display shows 25MPG average, miles to empty starts at 400, I put 16.5 gallons of 93 in.
    Then I track my mileage A/B and compare that with my next fill up.

    Honestly, I am lost on how. Doesn?t make sense at all.

  6. #6
    You likely have your cats either removed or the rear o2s are disconnected or bad plugs.. causing it to remove fuel while cruising. Log your vehicle while driving i can almost guarantee your ltft will be at -30%. Get someone knowledgeable to tune the vehicle. They aren't toys and should be adjusted by someone with experience.

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    Quote Originally Posted by luciddeath View Post
    You likely have your cats either removed or the rear o2s are disconnected or bad plugs.. causing it to remove fuel while cruising. Log your vehicle while driving i can almost guarantee your ltft will be at -30%. Get someone knowledgeable to tune the vehicle. They aren't toys and should be adjusted by someone with experience.
    Its funny you said ALL of that.

    I had a pro shop do the work, yes, I believe the CATs and Rear O2 is removed. Not 100% on the O2, I will have to look deeper. Kind of hard with no lift and a short garage. But I will find a way. As for the LTFT, using my blue driver OBDII live report, it shows a LTFT -18% on bank 1 and LTFT -32% bank 2.

    By the sounds of it, something is very wrong. Not going to drive it again until my tuner kit comes in and I can do a data log and send off to another tuner to review. Thanks for the input.

  8. #8
    Senior Tuner Ben Charles's Avatar
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    Wayyy too rich

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    How can the OP see a 2x improvement in MPG if the engine is running too rich?

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    At first I thought it was scaling in tune causing fuel consumption to be way off actual but if you are calculating it off miles driven and gallons added then I guess not. I don't see how you are getting that kind of economy increase though
    Last edited by tbrtuning; 07-06-2020 at 09:32 PM.

  11. #11
    Senior Tuner Ben Charles's Avatar
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    He’s not... the calculation is off...

    I can make GM cars that make 4 digit power show hybrid fuel mileage if I want, doesn’t make it accurate

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    I agree, that something is off. Just not sure what yet. My tuner (after I asked them about the MPG) said "No the MPG would be better cause the tune". Needless to say, that's why I purchased the device which should arrive tomorrow. Going to do a log and send it to a tuner that has a lot of recommendations on my turbo jeep group. He said he will look it over for me. I don't think a second opinion is a bad thing at this point. As for running rich or lean, I think I am using the stock O2 sensor. But I will be looking to install a wideband next to make sure I have good data or at least better data. Along with some other data. Once I get the log, I will post it. I will also let you guys know what the second opinion says. I am not sure what the result will be but it could be something super dumb or super bad.

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    Quote Originally Posted by Ben Charles View Post
    He’s not... the calculation is off...

    I can make GM cars that make 4 digit power show hybrid fuel mileage if I want, doesn’t make it accurate
    Yeah. I did it on accident one time. Scaled tune with big injectors and forgot one of the tables. Customer messaged me saying his estimated MPG and miles to empty were way off and I realized what I had done

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    Then the OP's hand calculation must be off too as he said he checked MPG the fill and drive way as well.

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    Quote Originally Posted by Homer View Post
    Then the OP's hand calculation must be off too as he said he checked MPG the fill and drive way as well.
    inside the tuning, can something be changed that would affect the digital readouts on mileage? as my only inputs for the math are what is displayed on the dash. travel A, Travel B, and over all mileage. I am using travel A/B.

    formula is pretty basic, if I travel 250 miles and my fill up requires 10 gallons, this tells me 25 miles per gallon. combined with dash display, I figured it was accurate.

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    Attached is the log file I ran. Not sure if I captured the PIDs or did the right format, still learning on this stuff. Learned the hard way that you need to save the file before you exit.Test_Log_2-070720_445pm.hpl

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    What's up with LTFT on bank 2? It is way negative compared to bank 1.

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    Quote Originally Posted by Homer View Post
    What's up with LTFT on bank 2? It is way negative compared to bank 1.
    I see that too, but I have no idea how to interpret the data yet. Still learning. I rely on the people I pay that have a shop and a track record of producing power with very little if any issues. I also noticed that after a certain RPM at WOT, the LTFT on bank 1 and 2 both go to 0.00

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    LTFT will go to 0 at WOT as O2 sensors are ignored and fueling is handled by power enrichment table.

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    I pulled the current tune out of the jeep to look it over. Watching videos is kind of hard as software updates have changed the verbiage and clickable areas enough to where they are not intuitive enough for me to understand.

    Although, a few things did jump out at me. The main General tab shows 6.1L engine size, but shows 5.7 displacement. Also, on the PE tab, RPM MAX is set at 8,160. I know previous versions used RPM as the starting point and would be between 4000-5000 rpm. I didn't see an area for throttle position %, only tps voltage.

    I think I will be taking the HP Tuner class as soon as I save up for it. Just for the knowledge.