8hp90 hellcat transs , down shift issues

[Hmbinamro]

DrEFI-Hammam-6-7-26.bin

DrEFI-Hammam-6-7-26.bin

ubject: Request for Assistance – 8HP90 Automatic Downshift Strategy (LT4 / Holley ECU / Nissan Patrol)


I’m looking for some guidance regarding the calibration of my TurboLamik TCU. I’ve spent a significant amount of time tuning the transmission, but I’m experiencing an issue with the automatic downshift strategy that I have not been able to resolve.

Vehicle Setup

* Vehicle: Nissan Patrol
* Engine: GM LT4 Gen V (Supercharged)
* ECU: Holley EFI
* Transmission: ZF 8HP90 (Hellcat)
* Valve Body: Stock
* Differential Ratio: 4.10
* Tire Size: 30.6”
* Use: Street + Performance

Current Issue #1 – Automatic Downshift Under Full Throttle

The main issue is not kickdown activation, but the automatic downshift decision.

For example:

* Driving in D (Automatic Mode).
* Cruising in 7th or 8th gear.
* Applying 80–100% throttle.

The transmission will often remain in the current gear instead of automatically downshifting for maximum acceleration.

The engine RPM increases slightly, but the TCU continues to hold the gear.

Important Observation

If I switch to Manual Mode, everything works correctly.

* Manual downshifts happen immediately.
* The transmission pulls very hard after the downshift.
* It will accelerate all the way to the rev limiter without any issue.

Because of this, I do not believe the problem is mechanical.

It appears to be related to the automatic gear selection logic.

Current Calibration Investigation

I have already reviewed or adjusted:

* Automatic Target UP RPM
* Automatic Target DOWN RPM
* Automatic Maps Selection
* Kickdown TPS Threshold
* Minimum Gear Down (Kickdown ON/OFF)
* Maximum Down Target RPM
* Torque Calculation

None of these changes have completely resolved the issue.

Current Torque Model

The transmission is using TurboLamik Internal Torque Calculation.

I understand that torque calculation is fundamental because it influences:

* Line pressure
* Shift quality
* Clutch control
* Automatic shift decisions

If there are recommended torque model settings specifically for an LT4 + Holley combination, I would appreciate your advice.

Current Downshift Behavior

Another issue is the harsh automatic downshift during deceleration:

* 3 → 2 is noticeably harsh.
* 2 → 1 is also harsh.

I’m trying to achieve an OEM-quality calibration where:

* Full-throttle automatic downshifts are quick and responsive.
* Highway passing is immediate.
* Part-throttle driving remains smooth.
* Deceleration downshifts are smooth with no harsh engagement.

Request for Advice

Could you please advise:

1. Which base BIN is recommended for my combination?
* LT4
* Holley ECU
* 8HP90 Hellcat
* Nissan Patrol
* 4.10 differential
* 30.6” tires
2. Is there a preferred Automatic Downshift Strategy for high-torque engine swaps?
3. Are there additional tables (not obvious in the XDF) that influence:
* Automatic gear selection
* Full-throttle automatic downshift
* Highway passing response
* Downshift decision logic
4. Are there recommended settings for the Torque Calculation when using a Holley ECU with TurboLamik?

My goal is to achieve an OEM-like driving experience with:

* Fast and intelligent automatic downshifts.
* Smooth part-throttle operation.
* Strong full-throttle acceleration.
* Smooth 3→2 and 2→1 coastdown downshifts.
* Reliable clutch control based on accurate torque estimation.

Any recommendations regarding the correct base calibration or the key tables that control the automatic downshift logic would be greatly appreciated.

Thank you very much for your support

[M4comp]

'Enable KickDOWN RPM limit switch' is active, which uses different tables for Auto UP/DWN. Looks like you need to be over 5800 for a kick down to happen.

I also think you need to have a look at your TQ settings. All of them

Your lockup is turned off which I agree should only come on at light load. But yours is disabled, would be fine to cruise with it on and save some fuel. Unless you have an aftermarket convertor with no lock up.

Your diff ratio is set to 2.6 in the TCU

My opinion would be to get the latest default file for your trans and adjust your TQ tables, Automatic tables, Lockup, and learn how the table switching works. Make sure the TCU firmware matches the ADX and Bin as well.

[Hmbinamro]

Hi,

Thank you very much for reviewing my BIN and for your feedback. I really appreciate your help.

I have a few follow-up questions to better understand the TurboLamik strategy.

1. KickDOWN RPM Limit Switch

You mentioned that “Enable KickDOWN RPM limit switch” is active and that it uses different Auto UP/DOWN tables.

Could you please clarify:

* When this switch is enabled, which exact tables does the TCU use for the kickdown decision?
* If I disable this switch, which tables will the TCU use instead?
* Is disabling it recommended, or should I leave it enabled and adjust the correct tables?

My goal is to have fast and reliable automatic kickdown during full throttle and highway passing.

⸻

2. Base BIN

You recommended using the latest default BIN.

For my setup:

* Nissan Patrol
* LT4 Gen V
* Holley ECU
* 8HP90 Hellcat
* 4.10 differential
* 30.6” tires

Would you recommend staying with my current base BIN, or is there another base BIN that would be more suitable for this combination?

⸻

3. Lockup

You mentioned that my lockup is disabled.

Could you please explain the correct way to enable it?

Should I simply change the Program Selector LOCK value from 0 to 1 or 2, or are there additional Lockup Maps and Lockup RPM tables that also need to be configured?

I would like to retain smooth driving while allowing lockup during light-load cruising.

⸻

4. Differential Ratio

Regarding the differential ratio showing 2.60, I believe that may have changed during one of the BIN uploads or conversions.

I’ll verify and correct that value.

⸻

5. Torque Tables

I’m currently recalibrating all of the torque tables based on my LT4 engine output, so I’m already working on that area.

⸻

6. My Main Concern

My highest priority is solving these two issues:

1. Automatic kickdown sometimes does not occur at full throttle (especially during highway passing).
2. Harsh automatic downshifts from 3→2 and 2→1 while driving in P1/Drive.

If you could point me toward the specific tables responsible for these behaviors, or recommend the proper strategy to tune them, I would really appreciate it.

Thank you again for your support. Your guidance is greatly appreciated

[M4comp]

When ‘Enable KickDOWN RPM limit switch’ is active the TCU only uses 'Max. RPM Limit, Semi-Auto UP' for up shifts and 'Max. RPM DOWN Allowance, torque higher than 0 TQ> 0' for downshifts.

The bin is fine but I was recommending you use the matching set meaning dont grab a 10.73 ADX and use a 10.75 bin with some other firmware. They should match. The reason is the ADX file is a descriptor file like an A2L file does for an OEM. It contains the addresses for memory and the tables/scalars/variables with all their min/max values and formulas to convert it from human readable to correct format for the ecu during uploads. When a new firmware version is generated the ADX is created at the same time. To make it more confusing the Bin file is just the tables and configurable portions of the firmware exported so the user can edit it. Long story short they all should match due to the firmware memory locations can be changed for a single table or variable. Using an unmatched ADX would cause you to write data to the wrong location resulting in odd behaviors or errors.

You are correct on the Program Selector table value of 0 is off and 1 being on for the Lockup. But I would recommend getting the TQ and Auto shifting and KickDown right first. Then come back and do lockup. You said your engine is an LT4. That engine makes more TQ than what you have in the tables. I would be cautious when going WOT to ensure it's not slipping.

If your TQ tables are not correct you're wasting your time on the other tables. Have a look at the manual
https://manual.turbolamik.eu/docs/tunin ... lculation/
Follow these steps to get your Idle and light load values correct ( which also affects downshifts ). Then look up your version of the LT4. You can get the dyno numbers from GM performance to start but if you have a high duration CAM you'll need to dyno it. If the values are wrong you'll just break the trans and you never want the trans slipping.

[Hmbinamro]

Hi,

Thank you very much for the detailed explanation! I am going to download a completely fresh, matching firmware and ADX/Bin set to fix those address conflicts, and I will get the Torque tables dialed in perfectly first before touching anything else. If I need more clarification as I move forward, I will definitely contact you.
One final thing I noticed during my initial tuning runs is a noticeable rattling noise coming from the transmission area.

Could this noise be related to the tune itself (for example, the torque converter clutch hunting/slipping due to the lockup settings being disabled or configured wrong), or does a rattle usually point to a mechanical issue like a damaged converter or worn internal clutches?

I would appreciate your insight on what typically causes an 8HP90 to rattle under these conditions so I know what to inspect.Thanks again for your support!

[M4comp]

Typically the rattle is the lockup but to truly confirm it you would need to get under the car.

[Hmbinamro]

Appreciate the support. Thank you so much