Should I reset the PCM?

Discussion in 'SRT10 and SRT10 Coupe Discussions' started by MoparMap, Jan 16, 2013.

  1. MoparMap

    MoparMap VCA President

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    So I just got my first Viper of my very own a little over a week ago (my mom has a 94). It's an 04 that's mostly stock aside from a K&N intake and a set of Borla mufflers (fairly sure all the cats are still there). The gentleman I bought it off of had an SCT tuner with two customs tunes that he gave me as well, one for hot weather and one for cold. Since it's mostly been under 50 here in Kansas I originally put in the cold tune, but the more I thought about it and because I didn't know where the tune came from I decided to go back to the stock tune and mess with a custom tune later where I'd know what I was getting. That being said, since the car came from a different region (bought it out of Mississippi), I got to wondering if resetting the PCM and all the adaptives would serve me any good so the car could "learn" the new environment quicker from a blank slate or if I'm better off leaving it as is.

    On another note, part of this comes from the fuel mileage I've seen with the car. Granted I know it's a Viper and believe me, I plan to have my fun with it, but in the 13 hours I drove it home I was only seeing around 16 mpg on the highway when I hear a lot of you are getting closer to 20. Since I'm pretty much daily driving it to work (around 5-10 miles in town and ~20 on the highway), it never hurts to be able to go a little longer between fill ups.

    One last observation I've had is that I don't know how people can complain about the skip shift. Unless there is something way messed up with my car I cannot seem to make it go off if I try. I've tried lugging it down as slow as I can in first and it won't even light up. Not to mention shifting out of first under 20 mph would pretty much mean by the time my foot is off the clutch I'd have to be pressing it right back down ;).
     
  2. Wiretech

    Wiretech Enthusiast

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    Congratulation on your new viper and welcome first of all getting 16 mpg on a viper is good and not sure what tune you have on your sct tuner it could have eliminated the skip shift and if it is messed up I suggest you can get another tune done the way you want.
     
  3. MoparMap

    MoparMap VCA President

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    I ended up putting the car back to stock (at least I think/hope so) on the tuner. I was trying to confirm that it was indeed stock by getting the skip shift to trigger, but I haven't had any luck. Part of my hesitance to go with a custom tune I don't know about is that the highest octance gas readily available around here for me is 91 and it seems like a lot of tunes are based on 93. I don't know how much difference it actually makes day to day (temperature, humidity, etc. can have a lot to do with what's needed from what I've read), but since I don't have knock sensors I figured I'd play it safe for now with the factory tune.
     
  4. Steve M

    Steve M Viper Owner

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    If the skip shift is still disabled, one of two things could have happened:

    1. The stock tune did not flash back properly
    2. He had a skip shift eliminator installed (although I think the light will still turn on with one of these installed, but it won't lock you out of 2nd or 3rd)

    Not sure on the mileage...my Gen IV has gotten better highway only (I've seen a best of 24 MPG over about a 300 mile stretch), but it's a different motor with a different calibration. I wouldn't be too concerned about it though...I can quickly make 24 look a whole lot closer to 10 by wiggling my big toe.
     
  5. mjorgensen Woodhouse

    mjorgensen Woodhouse VCA Member - West

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    Most of the canned tunes that are out are pretty safe for all fuels 91 and higher, the PCM will pull timing if something is out of whack.
     
  6. 345s-bspinnin

    345s-bspinnin Viper Owner

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    Mark, the OPs car is an '04, and thus they don't have a knock sensor. Not sure that any of the other mechanism in the PCM's feedback loop will protect the engine if knocking is present.
     
  7. MoparMap

    MoparMap VCA President

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    I can't say for sure if the tune came from them or not, but the programmer at least had JMSChip.com on it in the menus if anyone has ever heard of them. The weird part that got me on it though was that when I flashed the cold tune it went from 2 changes remaining to 1 on the programmer menu, leading me to think that the previous owner never actually flashed a tune so the unit may have been used since I thought they were supposed to start at 3 changes left. I looked up JMSChip and didn't really see anything along the lines of Viper tuning on their website, so I'm leaning toward the programmer being a used piece. I may try to ask the previous owner if he remembers where he got the tune from for some piece of mind.

    Edit: Just confirmed with the owner that he bought the programmer blank and had JMS Chip and Performance do the tunes. Anyone ever heard of them or have any opinions one way or the other about them?
     
    Last edited: Jan 16, 2013
  8. slysnake

    slysnake Viper Owner

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    Hard to resist driving your new car, but, under 50 take it careflully, under 40 drive like a granny, under 30 leave it in the garage.
     
  9. MoparMap

    MoparMap VCA President

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    Yeah, I've been taking it easy. My other cars are a 67 Dart with a 5.7 Hemi swap I did and a 71 Corvette, but they're not exactly as comfortable to drive every day. Not to mention the Dart has similar traction issues as the Viper. I sold my daily driver (2000 Jag XKR) to buy the Viper, so it's on daily duty. I make sure to take it easy until things warm up, and even then I know the tires don't hold too much. What surprised me is how soft the car seems under half throttle or so. I thought I remembered my mom's 94 having a lot more response no matter where the pedal is, but on mine if you're under half throttle or so it drives like a fairly normal car. I think some of that is where the throttle cable comes off of the little cam peg on the linkage.
     

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