m142 engine rough idle when M1 Tune disconnected

[ScAuto]

Hi ! I'm having an weird issue with a M142 GPR-DI (it's my first time working with a Motec) : Car runs fine when the laptop is connected to the ECM but when I disconnect it (not physically unplugging the cable from the laptop) after 3 seconds the car starts having a rough idle and poor running conditions (throttle response stays OK) and the second I reconnect M1 Tune everything runs fine again.

I was wondering if there's some kind of Auto Debug mode whenever M1 Tune is connected to the ECM that ignores some parameters / settings ?

Anyone had that kind of issue before ? I'm having a hard time finding the problem since I can't get any data when the issue happens .

Thank you !

[NathanB]

All M1 ECU's are sold with diagnostic logging, so provided your logging parameters are set to run, you will be able to download the diagnostic logging from the ECU to see if there is a change in behaviour.

There are some things that change between being disconnected and connected to the M1, such as the fuel closed loop bank n trim average, however the engine run behaviour shouldn't change if the ECU is installed correctly.

Does your configuration have an ECU power hold relay setup? How is power supplied to the ECU?

[ScAuto]

Thank you for you answer !

I've looked through all the logged data that I have when the problem occurs but there's nothing of interest. We are using Motec USA's Mazdaspeed 3 Gen 1 firmware for our application and the logging channels are very limited (60 channels total... I can't event log manifold pressure, engine coolant temp, oil temp or throttle position just to name a few).

Fuel closed loop is disabled at the moment since I'm still in the first stages of tuning.

The M142 is installed in a street car application so it is power by fused key ACC/ON/RUN 12v+ source with all the proper pins as per Motec instructions. The ECM then drives the Main Relay... pretty standard stuff. We are not using a power hold relay setup. I've also wired the Battery Backup to a fuse 12v+ source... that's the only thing I wasn't really sure about.

Is there any other parameters that could be ignored when M1 Tune is connected to the ECM while the engine is running ?

Thanks !

[David Ferguson]

You probably need to work with MoTeC USA directly on this.

Did you close the ECU connection (causing the changes to be saved to the ECU) before you unplug? Plugging back it would re-instate those changes if you had not closed the project yet.

[ScAuto]

Just closing the connection with everything saved makes the problem happens … no need to unplug.

Since this firmware isn’t used on a Mazdaspeed 3 Motec USA sold us the package with no strings attached so they won’t offer any support. We agreed to this condition that’s why I’m trying to find help here. I was able to find solutions for most of the issues we had so far on this project but this one is leaving me clueless.

[David Ferguson]

I believe there is probably only one person that can help you with this -- the developer at MoTeC USA that did the package. If I were trying to debug this problem, I would have level 2 logging (you need this to debug this issue -- it allows you to select channels to be logged), and would work with the developer to log whatever he suggested to determine the issue. If you can't work with them, and have to figure this out yourself...

First -- runs rough. Look for every channel with "diag", "State" or "Status" in the name -- log those that may be used at 50 hz.. Look for the problem. If no clues -- then decide if it's related to engine speed (Ref/Sync issues), DBW movement (idle control?), Cam control, Fueling (DI timing or pressure?) or ignition. Go down those paths to home in on what's not happy. Something must be changing over time -- figure out what it is..

There are some channels with info on "missed events" -- I suspect that more of that happens with communicating with M1 Tune. Also, look at View->Show Messages for any clues...

Good Luck!

[ScAuto]

Thank you for your answer ! I appreciate it !

All the available diag channels in my log are OK so I’ll have to go step by step with each systems as you said. I’ll keep an eye on messages also and try to solve it. I also had the tracking of the throttle pedal popping the Check engine light each time I disconnected M1 Tune but I was seeing error messages while connected with this one. Might try the DBW tracking… anyways if I find anything I’ll keep you updated. This might help somebody else in the future !

Thanks again !

[ScAuto]

Update on the problem : we have found which setting is causing our rough idle / drivability condition but we still don’t know why.

We suspected a CAN bus problem so we’ve worked a lot on trying to figure out what could be wrong with it including sniffing the CAN while the issue was there but without results. After that we started to disable every settings that could potentially cause a problem even if it made no logical sense and ended up finding that the Secondary Injection was the source of our problem.

I’ve used the fuel calculation in the context help menu to come up with a 23% contribution on the secondary injection and as long as M1 Tune is connected everything runs fine and I can see both Primary and Secondary injection pulsewidth and fuel calculations but It’s like if the Secondary injection is disabled. If I run a 100% DI everything works well when connected and disconnected.

I’ve played a bit with Contribution numbers and when disconnected, I can add up to 10% contribution from the Secondary injection without an issue… higher than that the issue comes back when disconnected.

I really don’t get why the secondary injection would automatically be disabled when connected to M1 tune tho but at least the car runs fine now!

Hope this can help somebody in the future !

[David Ferguson]

Sounds like a bug report to MoTeC USA is in order...