MoTeC Global Forum

Hello everyone,

I'm currently utilizing the MoTeC M800 for my research engine project at Ghent University. While filling in the Fuel Main table, I encounter an issue where 'RPM limit active' pops up on my screen when the RPM drops from f.i. 1100 to 1050 rpm. Despite clicking "OK," the warning persists, rendering me unable to control my MoTeC file due to its continuous appearance.

Below, I've included my RPM limit settings as per my knowledge (Adjust -> General Setup -> RPM limit -> Setup). It's puzzling to me that the RPM limit warning appears since, as far as I understand, the settings only account for an upper limit RPM (2000 rpm (heavy duty engine) because of safety). At 1050 rpm f.i., I'm not reaching that upper limit. However, I can't seem to locate how to configure the lower RPM limit as well as the upper RPM limit, since this problem also occurs at f.i. 1250 rpm.

Could someone offer assistance with this issue? Any help would be greatly appreciated.

Thank you in advance.

Do you have an RPM Limit table setup?

Dear Stephen

Thank you for your reply.

In the picture, you can find the RPM limit setup table.

Can you post your config?

Where can I find the config?

In the picture I sent in the previous post, only 1 value is set in the table (do you mean this with 'config'?). In the picture I sent in my first message, you can find the settings concerning RPM limit.

Hi,

The default directory for the configuration files is C:\motec\M800-v35\Configs. The file name is the name of the file that you have in the M800.

Dear Stephen

In the attachment, you can find the current config file.

As per you config, you have DBW configured, and a failsafe limit of 1000rpm if the drive by wire system is in error.

This is likely the source of the RPM limit you are experiencing.

This is also why Stephen requested a config rather than just screenshots.

Your drive by wire configuration is likely the cause of the issue.

The next step would be to provide us information on the throttle used to see if we have calibration settings for it we can provide.

Hi NathanB,

Thank you for your input on this matter.

In my research project, the engine underwent a conversion from diesel to spark ignition operation, necessitating the installation of a throttle body. During my search for a suitable PWM throttle body online, I didn't come across any information indicating that some PWM throttle bodies might not be compatible with MoTeC. My understanding was that the throttle body should possess two throttle position sensors (TP1 and TP2). Based on this, I ordered the SI throttle valve (normally closed) with six wires (M+, M-, 0V, 5V, TP1, and TP2) (MEAT & DORIA 89335 (https://www.autodoc.be/meat-doria/12887355)).

Unfortunately, the throttle body failed to respond and defaulted to a closed position. Upon contacting the MoTeC support team, I learned that they did not have calibration data for this specific throttle body. Their recommendation was to opt for a Bosch throttle body (as also mentioned in my other post: Compatible M800 SI Throttle Valves (Diameter: 50 mm)).

To summarize, I have not yet ordered a new throttle valve. Instead, I've devised a workaround by implementing the throttle control using National Instruments, where I've created a PID controller loop in LabVIEW. Currently, I'm in the process of fine-tuning the PID parameters, which is proving to be quite challenging.

While I continue to utilize MoTeC for functions such as the Fuel Main table and Ignition table, I am not utilizing it to control the throttle body.

Given this context and your insights, I suspect that, to solve the issue, the DBW setup should be disabled. How can I do this?

Thank you for your assistance.

Hi all,

The issue has been resolved. Thank you for your assistance.

To conclude the thread: I set the fail-safe RPM to 2000 (which is sufficient for my heavy-duty engine). As a result, I no longer encounter pop-ups.

FYI: When the pop-ups occur, MoTeC enters safety mode and injects less fuel than what is indicated in your fuel map. This caused problems with engine revving. Now, those issues have been eliminated!