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Messages posted by: cav
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We are currently working on a "hot tune" for owners of after-market torque converters. This should be available within a month. The hot tune only changes the WOT performance and will still have the same fuel economy benefits as the standard tune in normal driving conditions. The hot tune will have slightly more smoke under heavy accelerations.

Do you normally drive for fuel economy or for the performance pleasure? Have you experienced "shudder" with the Inmotion tune and Suncoast TC? We are not sure if Suncoast increased the damper springrates as this is the main issue with the stock converter.
In this section of the forum we want to inform potential customers about the specific changes we performed with the KJ CRD tune. To begin with we fully map the engine using a standard 16-mode test cycle, picking 16 points in the operational map of rpm vs. load. This gave us a baseline of output torque and fuel consumption for the production configuration. Each point was then put through a design of experiments to map all the trade-offs for the following parameters: injection timing, boost setpoint, pilot injection quantity, pilot injection timing, fuel rail pressure, EGR rate, and using 1 or 2 pilot injections. In the end, we were able to find the optimium engine settings to maximize fuel economy at every operating point in a warm engine. All engines have software that controls the warm-up operating parameters. Most of these are corrections to the warm operating mode. For example: Lets say at idle the injection timing is at TDC (0 degrees advance) in a warm engine state. In cold conditions a correction to the base timing will be required due to cold fuel, cold chamber and cooler air. The colder everything is, the longer the ignition delay (time from injecting fuel to start burning that fuel). So a typical correction in cold would be to advance the timing by 2 degrees and in very cold situations maybe up to 7 degrees. Since we changed all the warm parameters, it became vital to change all the warm-up corrections to have the system match and provide smooth transitions.

Peak power tuning requires other factors that need to be addressed including turbo speeds, peak cylinder pressure and exhaust temp limits. We used pressure sensors in the cylinder and turbo speed sensors to tune the system to be very close to the design limits. There is no sense putting out a product that may cause an engine to fail! An aluminum head engine can only handle so much pressure before reaching fatigue limits. Improved performance is always a good thing, but it is important not to sacrifice everyday drive ability in order to achieve the performance.

We had a goal to ensure linear torque progression with increasing pedal input, minimizing holes or dead spots in the throttle and lessening abruptness in the driveline. We drive our KJs every day and want it to be an enjoyable experience.

Another consideration we focused on dealt with how to acheive performance gains without risking damage to the transmission torque converter. With the trans in "unlock" there are no risks and full power is available everywhere. However, when the converter clutch is in "lock-up" the engine torsionals can cause the springs in the damper to bottom out and cause the chattering "shudder" feeling, which will eventually lead to a failure in the damper springs and clutch facing material. With our tune, the transmission will "unlock" or downshift prior to the engine torque reaching a level that could cause significant damage to the torque converter.

Feel free to ask questions about the tune or comments on our methodology and we will do our best to respond in a timely manner.

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