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  1. #1

    Prodigy Performance Turbo Driveability Issues

    After almost a year with the turbo kit, sending data logs to Prodigy, and testing updated tunes, I think it's time to come to terms with the fact that there are some driveability issues that are unlikely to be solved. YMMV.

    My Jeep is a light-weight 2-Door soft top Sport with stock 29" tires, 3.21 gears, and manual transmission.

    The very first time I drove with the turbo kit installed, I experienced an annoying hesitation/jerk in acceleration somewhere around 2500-2700 rpm. A year later and many tune updates later, it's still there.

    I also get another weakness/hesitation as I pass through about 1500 rpm.

    Both of these are most severe in 1st gear. Also sometimes in 2nd gear.

    It happens during light-to-moderate acceleration (normal daily driving type acceleration, driving around a parking lot, etc).

    It's most severe when the engine is cold, and even while the engine mostly warmed up. Once the engine is fully up to operating temperature, the hesitations are more rare and less noticeable.

    But before the engine is fully warmed up, it can be quite severe sometimes. It can even be embarrassing. I'll often pull out of the parking lot at work onto the road on my way home, and I hit the 1500 rpm hesitation, immediately followed by the 2700 rpm hesitation on a freshly started cold engine. At each of those RPMs, it will suddenly rock/jerk, as if I had quickly completely lifted off the throttle, then immediately jabbed hard at the throttle. It physically rocks the Jeep, like a newbie learning how to shift gears with a manual transmission.

    About 2 months ago, I sent many very detailed data logs and descriptions of these and some similar/related situations. I've asked for news on the progress of tracking down/solving these issues a few times and only got basic "we don't have a solution yet" responses.

    I finally pressed for an update on the situation. Rather than risking presenting potentially biased paraphrasing, I'll just share my exact email and the response I received:

    I would appreciate an update on the status of the driveability issues. I'd like to get an understanding of how likely it is that the issues are actually solvable (should I assume that this may be the best it can be?).

    1) Have you concluded that it is most likely an issue with the tune/calibration, rather than an issue with my vehicle/installation?

    If this is being treated as a tune/calibration issue, then:

    2) What is the nature of the difficulty of the issue? Limitations with the framework of the OEM software algorithms and calibration tables that it can work with? Limitations with Diablosport's CMR software and its ability to fully manipulate the OEM calibrations? Or is it just in need tedious (time-consuming and lower priority than other projects) fine tuning that is fully within the capabilities of the available tools?

    3) Are these issues very difficult or nearly impossible to troubleshoot remotely via data logs? Would it be more cost-effective (time/money) to cooperate with a local tuner that can directly test/monitor conditions with my vehicle in real-time under controlled conditions on a dyno?

    4) Are there any plans to work on the issues in the near future?



    We have made several updates with your help. These tune revisions have greatly improved the product. Thank you for your hard work. We cannot find any area in CMR to correct the millisecond issues you took the time to datalog. As we move forward, any revisions will be reported to you promptly.

    So this is as good as it gets for now, with no foreseeable solution.

    When the engine is fully warmed up, I honestly rarely notice any issues. If it drove that way all of the time, I would be perfectly happy and willing to accept the occasional very minor hesitation as just "the price to pay" for having an awesome amount of bolt-on power that relies on a handheld tuner that reverse-engineers/hacks the stock ECM.

    But during the week when I drive my Jeep to/from work, it's a fairly short drive each way (<10 miles). It takes about half the trip to fully warm up the engine. The by the time I drive home in the evening, it's a fresh cold start again. So about half the total time I spend driving my Jeep during the week, it is susceptible to very annoying jerks/hesitations in acceleration.

    The best way for me to avoid the issue while waiting for my engine to fully warm up is to always upshift around/below 2500 rpm. But that's no fun. 2500 rpm is right around where the turbo really starting to ramp up power gains. So it's just a big tease to just start getting a taste of the turbo, then upshift and drop down around/below 2000 rpm where there's not noticeable gains.

    So... does anyone else have similar issues with the Prodigy Turbo. If so, have you come up with any good ways to avoid the issues or reduce their impact?

  2. #2
    I also asked about the possibility of a local tuner being able to track down the problem more easily by experiencing the problem in person, in a controlled environment on the dyno, while watching data in real-time.

    There is near zero chance of a local tuner "tuning", or solving your issue. We will not aid 3rd party tuning at any point.

    So I either accept the way it is, or I take a big gamble on paying a local tuner to take a look at it. I don't want to spend a few hundred dollars on little/no improvements. I doubt a local tuner would agree to try fixing it, but only charge me if they can actually solve the problem.

  3. #3
    Senior Member
    Join Date
    Feb 2014
    MD/PA line
    I have the same issue of "hesitation" at a couple rpm "areas" below 2500 rpm. Honestly, the last tune improved upon them a great deal. Honestly, of course I'd prefer to have zero issues anywhere with my system. Nevertheless, I feel its completely drive-able as I have it now. Once the turbo starts pulling, there is no problem running it up as high as you want to go.

    I took mine to a local tuner, a turbo specialist. They offered some good advice, which I won't get into, but didn't want to attempt a tune on a jeep. Its not a regular source of business for them, therefore they lack the essential knowledge and technical interface needed to work with a jeep system, and one that is relatively new. They said they could do it, but the juice probably won't be worth the squeeze.

    My thoughts are that this new turbo option Prodigy may offer, spools up sooner. If thats the case, and its somewhere around 1800rpm..then that would theoretically solve the one minor hesitation issue around 2450rpm as I'd already be under boost. They other hesitation was just south of that rpm mark so no idea how that might affect it. Of course, there could be a new spot, but I'd love to give it a shot. The turbo is too much fun to ignore as an option. V8 power at less than 20% of the cost.

  4. #4
    I bet the difference in tire size and gearing between us is probably shifting exactly where the hesitations happen and how significant they are. Mine is perfectly driveable once fully warmed up, but often quite irritating a couple times a day when the engine is not yet fully warmed up.

    I was actually thinking the same thing about the new Precision turbo. If it spools up at low rpms AND solves the remaining hesitation issues I have, then I'd gladly pay whatever it costs. If it had been available as an option to begin with, I would have definitely paid the extra upcharge for the Precision. Paying for a new Precision at full cost will be a tougher pill to swallow, but I'm in this deep, so I might as well go a bit deeper to get something that is truly amazing through the entire usable rpm range (still waiting for dyno results proof of this though).

    Selling the used Garrett might help with the cost of the Precision a bit, but it will probably be hard to sell it. From what I understand, it's not exactly an off-the-shelf model that I can easily list for sale and refer to manufacturer specs. Prodigy won't divulge full specs on it either ("trade secret"), so it will be a risky purchase for anyone buying it used

  5. #5
    Dont let them tell you that third party tuning i not available. My 13 ripped jk had serious tuning issues when installed in august of 2014 wouldnt rev above 5k rpm with out falling on its face and so on. A local and reputable shop near me (i live on long island new york). The shops name is chris miller racing out of deer park long island new york. He brought my jeep in put it on the dyno first pass from ripps tune made 250 wheel. After 5 passes on the dyno and fine tuning my ecu thru the diablo i made 344 on 8psi running conservatively. My truck still is a little hesitant to go above 2500rpm when cold but once my scangauge gauge reads about 150 coolant temp it will let me open it up nut you should always let the engine warm up prioir to romping on it

  6. #6
    If a tuning shop could guarantee results (i.e., not charge me if they can't figure out how to fix the issue), I'd be willing to pay for custom tuning to fix the issues. I doubt any shop will agree to that though. I suppose I can at least ask.

  7. #7
    One more variable to include in the mix: I have an exhaust leak.

    Here, you can see me exposing the leak by blowing air INTO the tail pipe with a shop vac (hose partially duct-taped onto the tail pipe, but not fully sealed), then spraying soapy water on the welds of a pipe:

    That is a pretty significant leak right next to the O2 sensor, so it is possible that it's causing some slightly false readings at certain rpm ranges if fresh air gets sucked in through those leaks.

    Good news: Prodigy is replacing this pipe under warranty.

    It will be interesting to see if my hesitation issues become less of a problem after getting rid of that leak. From talking to other people with the turbo kit, I get the feeling that my complaints are exaggerated compared to theirs. This leak could possibly explain that.

  8. #8
    I have to admit when I first read this thread I was not happy. But really I should thank Jeff for holding us accountable. We have improved the product repeatedly thanks to him. Little things that i was ready to overlook he simply would not let me do so. He just bombarded me with information and every time I thought i was ready to move on BAM here comes some more and some more and some more. He is an excellent advocate for our turbo system and critical at times. He has stated the good, the bad and everything in between which is what i think people want to see in forums. We will continue to use feedback from our customers to deliver the very best product possible. Though i dont think this is deserving of its own thread titled "Prodigy Performance Turbo Driveability Issues" It is what it is. I will take notes and make changes everywhere possible.

    I am looking forward to Pickles Precision turbo install, then changing his 3:21 gears and 28" tires. This will dramatically improve performance and driveability.


  9. #9
    Quote Originally Posted by boosted1 View Post
    I have to admit when I first read this thread I was not happy.
    And I was not happy when when I created the thread, so I think we're even

    Please let me know if you believe I have unfairly skewed/biased any of the facts I have presented. I'm just trying to honestly share my experience.

    I'm really hoping that my exhaust leak is amplifying what might otherwise be a very minor issue that really isn't deserving of a thread like this. But the reality is that what I am currently experiencing IS worthy of this thread.

    Quote Originally Posted by boosted1 View Post
    I am looking forward to Pickles Precision turbo install, ...
    Me too! Is it here yet?

    Unfortunately, I will be installing the new pipe together with the Precision turbo (sorry, I just want to get it done; don't have the time/patience to do a two-stage install to limit variables). So if these driveablity issues disappear or greatly diminish after the install, it will be impossible to determine whether it was the new pipe or the different turbo that solved the problem. It will at least suggest that an exhaust leak could be the cause for some annoying driveability issues. Anyone else with similar complaints will at least have reason to check for exhaust leaks.

    Quote Originally Posted by boosted1 View Post
    ... then changing his 3:21 gears and 28" tires.
    You and everyone else! I can't even tell you how many times I've heard that I need bigger tires. Mostly from my wife, children, and parents. My wife is a bit irritated that I spent money on a new turbo that was being saved up for tires. Tires and gears will now be further in the future. Realistically probably in 1-2 years. I still need to decide whether to wait longer to save up for TrueTrac LSD to get installed at the same time as the gears.

    My current stock tire/gear combo is overall about 9.7% "taller" than what I'll probably end up with (3.73 gears and 33x12.5x15 Duratracs). That should be a pretty good increase in around-town pep and slow off-road performance when I finally make the switch.

  10. #10
    Here's an update...

    The Precision turbo definitely improved overall lower RPM driveability because it spools more quickly at low RPM.

    Adding a boost controller improved responsiveness of the throttle in certain conditions because it forces the wastegate to stay fully closed until target boost is nearly reached (improves spool time when spooling up to higher boost levels).

    Putting the correct spring in my BOV made another incremental improvement to initial throttle response starting from low engine load conditions (cruising gently around town). I somehow ended up with a BOV that had the wrong spring in it. The spring was too weak and allowed the BOV to stay wide open at idle and other light engine load conditions.

    After all of this, I'm quite happy with overall driveability. But that stupid jerk in acceleration still does exist around 2700 under some conditions, and I still occasionally experience a glitch in power delivery around 2200 rpm (certain amounts of engine load, etc., worse when the engine is not fully warmed up). Subjectively, these issues seem a bit more subdued now with the quicker spooling Precision turbo, but they are not solved.

    I may be onto a new clue. First, I recently figured out how to monitor/log the physical pedal position with the Android Torque app. Until now, I have only been able to monitor/log the position of the throttle blade itself, which is commanded by the ECU based on pedal position and probably a hundred other factors. We can't assume that throttle blade position is directly proportional to the physical pedal position.

    Additionally, I noticed a new driveability quirk. In 5th gear on the freeway, I slowly press the pedal to accelerate. At first, everything works as expected. Push the pedal a bit more -> a bit more boost -> a bit more acceleration. But it soon falls apart. At some point, boost and acceleration both DECREASE a bit as I push the pedal further, then it seeems to just get stuck. There's a wide range of pedal positions in the mid-travel area that seems to have zero impact on acceleration. Then as I approach full throttle, BAM! I suddenly get full boost and full throttle acceleration.

    This same thing happens every time I try it. Very easy to reproduce. So I data logged it, including both the physical pedal position and the throttle blade position:

    click for full size

    Note: this acceleration started around 2700 rpm and ended around 3300 rpm at freeway speeds in 5th gear.

    Well that doesn't look right! It's a perfect visual representation of what I experience. There's clearly nothing wrong with the pedal position sensor. It reports a smoothly increasing pedal position. The actual throttle position commanded by the ECU is where the problem lies. There seems to be a problem somewhere in the ECU's decisions about how much to open the throttle. I suspect it's not as simple as a stupid mistake in a throttle mapping/curve lookup table. I'd guess it's a much more complicated interaction with other calibrations about how much torque the ECU thinks the engine is capable of vs what it thinks is acceptable to to provide (some kind of torque management?), or an even more abstract problem with some other seemingly unrelated calibration that gets taken into consideration when the ECU decides how much throttle to allow.

    I'm waiting for a response from Prodigy about this. In the meantime, I'm playing around with more effectively using the Torque app for data logging, and then I want to try to capture some detailed data logs of the other remaining "hiccups" around 2200 and 2700 rpm. I'm hoping to find another odd relationship between pedal position and ECU-commanded throttle position that could explain those issues.

    I'm really hoping this throttle mapping issue is the key to solving the remaining issues with the tune.

    BTW, if you are wondering why the manifold throttle position only goes up to just under 80%, it's because of the thickness of the blade and the shaft. Opening the throttle blade beyond 80% would not increase airflow, or the cross-sectional area of the throttle opening. So somewhere just under 80% throttle blade opening is actually effectively 100% throttle.

    Here's a long paper all about it:

    And a side observation... once the ECU does finally decide to really go full throttle, it was interesting to see the turbo quickly spool up to a full 9.2 psi at only 3200 rpm
    Last edited by UselessPickles; 10-19-2015 at 04:20 PM. Reason: Combined triple post into one

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