Engine Control Unit / Injection Mondial SMX 125i

Hello everyone,

A Mondial SMX 125i is now available for use within the family, and of course, I had to try it out. It will likely be used more often by me and my wife.

The "Renner" performs reasonably well on a 125cc 4-stroke engine, although the engine behaved strangely.
- At temperatures below 10°C, the engine was prone to unexpectedly stalling. You could be cruising slowly in first gear, almost at idle speed, when suddenly the engine would cut out. At the same time, sudden bursts of gas from the idle position were also met with a "plop" sound and engine stalling.
- Cold start in the morning at 6°C: Starts up perfectly, but immediately stalls if you don't give it any gas.

After the error memory (which contained a non-existent error related to the radiator fan) was cleared, the idle speed and overall engine behavior changed slightly for the better. I don't understand why, but it's a positive change.

The sensor values read via OBD-2 appear plausible. However, the short-term and long-term adaptation values for the lambda control system do not seem realistic. For example, the short-term value is -6%, while the long-term value is 5%. Everything is highly volatile.

I think the engine runs very lean in cold conditions, and the response to sudden throttle openings isn't optimal. The unit has an ECU located under the seat (presumably a Marelli MIUG4 VARROC DELLORTO, with a Calibration ID of MLMO125E50010090). Fuel injection, and apparently a mechanical throttle valve with a position potentiometer, meeting the EU5 emissions standard.

I think it's good that the equivalent of a pack of cigarettes had to be paid when filling up the tank completely.

Does anyone have a workshop manual/maintenance manual that contains more information than the user manual?

Theoretically, the same engine should also be used in the current Aprilia 125cc 4-stroke models, and according to my research, it should be sourced from Piaggio.

Thank you and best regards, Rainer.

Hello Rainer,

I'm quite familiar with the Marelli fuel injection systems used in Ducati and Moto Guzzi motorcycles. They are actually quite reliable.
However, a potential weakness is: the engine temperature sensor.
I've experienced this problem with several motorcycles, and a variety of issues can arise.
- completely dead -> ECU shows -40° and is severely over-fueling.
- Much too low resistance -> Engine runs too lean, starts poorly, poor throttle response.
- Sensor readings are okay at 20-25°C, but no signal is received at higher temperatures.
The same applies to the air temperature sensor, so it's also worth measuring.
The curious thing is that, despite everything, they somehow still work, but just poorly.

The price is quite reasonable, so I always keep a supply at home.
All temperature sensors (water/oil/air) that Marelli uses have the same resistance: 3 kOhms at 25°C.

The best option is to use the ones from the manufacturer FACET, as they are specifically designed to fit the curve perfectly. I had it tested at our lab .

If you have a number for that thing, I'd be happy to help you find out more about it.

I've attached the curve for you, in case you want to measure it.

Regards, Mpire.

Cool, thanks!

News: The engine control unit is from VARROC DELLORTO.

As the engine accumulates more mileage, it runs more smoothly and responds better to acceleration. Unfortunately, even in a cold state, it still tends to spontaneously die.

Hello Rainer,
Has the error been fixed?

You learn to live with it...

Has anything been exchanged or repaired yet?

Hello.

What do you want to repair if the sensor readings are correct? I suspect the engine control unit (ECU) has an overly lean fuel mixture setting.


The ECU was developed through a collaboration between Dellorto and an Indian company, the name of which I can't recall at the moment. I have refrained from using fake temperature values so far.

It just needs to be warm enough for it to work properly.

Best regards, Rainer.

Hello Rainer,
"Mine is still under warranty, but no dealer has been able to fix it."
As I've read in other forums, Aprilia motorcycles also had the same problem with the Euro5 software. Only they managed to fix it with an update.
Correspondence with Mondial Vertrieb in Weiden was unsuccessful, despite them being aware of the issue.
Best regards, Frank.

Newman wrote:

Hello Rainer. "Mine is still under warranty, but no dealer has been able to fix it." As I've read in other forums, Aprilia motorcycles also had the same problem with the Euro5 software. Only they managed to fix it with an update. Correspondence with Mondial Vertrieb in Weiden was unsuccessful, despite them being aware of the issue. Best regards, Frank

It would be interesting to compare the software version you read via OBD2 with the version that was installed to fix the issue.

The easiest solution would probably be to flash the current software version, which fixes the error.

TODO:
- Find a suitable flashing tool for the ECU (at an affordable price).
- Read the error-corrected original state.
- Flash these devices in the vehicles with jerky movements.

I don't have much hope with my dealer, and frankly, I don't feel like standing around and explaining the problem a thousand times, nor do I want to explain the solution. For that, the price was great.
I've already dealt with the annoying issue of the side stand spring breaking, and I fixed it by using a properly sized M8 8.8 screw. My suggestion to the dealer is that they should accept the warranty claim for the damage to the rear of the vehicle (which makes it undriveable) and allow me to fix it myself, and they should also send me a brake and clutch lever because the one I have is clogged.

Oh my god, I'll just order the original levers from Ali and save myself the trouble and hassle in the future... I wanted to be nice, but also get something in return for my work.

That was the point where I decided to skip the following dealer service and do it myself. Mondial SMX125i Service Reset. After more than 40 years of experience working on motorcycles, it's not really rocket science.

I believe the original diagnostic tool/flashing tool is not cheap, and some dealers try to find ways to profit unfairly from the situation.