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?

Thanks

Response:

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?