Idle Ignition State random fluctuations

[Suprafied]

First off, I've successively been using M1 tune for the last 8 years on my personal car and multiple customer cars with great success. The tune in my personal car has been the same for most of those years while using a M130 for the first 4 years and then migrating over to a M150 since late 2018. Its been trouble free over those years even with migrating to DBW and adding other inputs for data gathering.

Last week I was presented an issue that has baffled me and others in many ways. After a short drive a problem resulted when I went to restart it from filling up with E85. The car struggled to idle which I thought it was heat soak/hot restart (150F IAT) so I usually get to moving to cool off the intake charge. During my drive home the off idle and idle behavior seemed normal with respect fuel, spark and drive-ability. When I pulled into the garage the car struggled to idle and died. I tried to restart but to no avail.

The next day I discovered the following:

- Will randomly go out of ignition timing state and default to the main ignition timing table while still in idle.
- You can see the Ignition time state bouncing from "idle" to "normal" when this occurs.
- Issue is random as sometimes it will start normally and idle as it should for minutes. Then it will result to the idle ignition state to start changing and making it a struggle to idle.
- I forced the main and flex fuel ignition tables to be a 10-degs vs. 20-degs for idle. The car tolerated that and eventually idled on its own. I then switched it back to the normal 20-deg target and it idled for sometime on its own before it started switching idle states again and eventually shutting down.

To rule out as much as possible, the following has been checked to ensure mechanical confidence and eliminate electrical issues:

Mechanical:
- Compression checked
- Timing checked
- Fuel pressure and injectors checked
- Replaced e85 with new fuel


Electrical
- No REF/Sync issues but some threshold noise on synchronization channel
- DBW setup using Hitachi 75mm unit and Lexus SC430 pedal. Replaced DBW throttle body with same, yet new unit.
- Cam sensor just replaced with new OEM Denso unit.
- Crank sensor was replaced 8 years ago with OEM Denso unit.
- Coil packs were replaced 8 years ago with OEM Denso units. They ohm out within acceptable range.
- Plugs checked and gap correctly. No fouling.

The tune is same firmware for some time from John Reed supporting the 2JZGTE platform (01.02.0006). I've contacted him in the interim to get a new license file for my ECU since he updated his firmware (01.03.0000) earlier this year. You'll see I attached a snapshot of the datalog showing this issue. I also attached my M150 package as well to see if anyone can help.

I also have another M150 I'm going to swap out to see if its a hardware issue later this week. Until then are there any other ideas/areas I should check? Any thoughts to what may be triggering this issue?

Long shot but whats the likelihood a general update from MoTeC created a bug in a user's custom firmware?

[NathanB]

Idle timing.jpg (923.78 KiB) Viewed 3172 times

Reviewing the logging shows a few items that could do with adjustment to aid in your idling issues you are experiencing. You can see at the bottom of the time graph above that the idle mass flow is higher than the idle mass flow feed forward, and with a 5% cap on the amount of positive integral, the throttle is not able to effective respond to any changes in airflow demand.

As the throttle is essentially unable to respond for any demand for any increase in idle speed, the system has to rely on the ignition timing along to try and maintain idle speed. The idle control is not allowed to command any more ignition timing than what is in the main table, so if the timing is increased to the main table value, the idle timing state changes from "idle" to "normal". As the idle state is still active, the timing will be reduced if not needed and change states back.

In you log, whilst idling the manifold pressure changes for 51 to 58kpa, a 13% change in load, with no throttle change. with the channels that are logged, i can't determine what has caused this change (no fans configured, AC doesn't appear to come on as the idle aim speed did not change.) This is what caused the ignition timing to change suddenly.

This looks like it could be largely rectified by correcting the idle mass flow main table and increasing the idle integral positive maximum.

As for your threshold noise issue, I would recommend completing an input capture at idle and checking your signal. You may need to adjust your threshold levels at 1000rpm, otherwise increase or decrease your debounce numbers accordingly.

The only MoTeC updates than can possibly influence the behaviour in a partner package is if you have updated the system version. If this is the case, which is plausible as it sounds like you are running an older version of the partner firmware, you should try returning to previous system version, which can be completed by going to File > Override ECU system version.

[Suprafied]

Nathan,

Thanks for the advice to address this issue. I applied your recommendations but I believe I discovered something else in the firmware or possibly the ECU causing my issues. I replaced the ECU with another M150 unit and was able to get the car to act as it did prior to this poor idle situation. This ECU was also using John's latest firmware as well.

When I attempted to update my ECU with the new firmware it faulted out so I'm not sure if this has something to do with it. I going to try to update it again today after I complete the migration of my settings into the new firmware.

*added after posting*

Updated the firmware to the latest rev from John and my ECU started the engine right up and idled normally as it had done. The higher debounce values on the sync pin definately helped out to eliminate the noise.

Doug

[NathanB]

Hi Doug,

Glad you got everything sorted. The failed send of the firmware is an unrelated issue that has a solution currently in testing.

For anyone that experiences this issue, they should clear the logging memory and power cycle the ECU. If you check under View > show messages you will have an error that the data acquisition failed to configure. Clearing existing logging out of the memory assists in this error until a solution is released.