Megasquirt two key issues, communication with the laptop and the ECU drops out
two key issues, communication with the laptop and the ECU drops out
I have had some challenges with my Megasquirt, and I thought I would ask for your thoughts. There are two key issues, communication with the laptop and the ECU drops out.
MS2 v3 with MS2Extra. The ECU fires the coil, and I am using a Rx7 CAS with 2 teeth cut. I installed the ECU and soldered each joint. Got the car running and did some tuning, yet stopped because the ECU would just drop out and come back on right away.
I ran a data log (8/5 I think) and what I saw was the voltage drop from 12v to .2v and then it would bounce back (this is attached). When I disconnected the alternator, it would drop off a bit less. Yet, it did keep dropping off. I figured it was a lose wire somewhere and it would clear up if I cleaned up the wiring.
I used a grounding model suggested by Aaron Cake. I have run a heavy duty cable from the battery to the engine block (both ends are soldered). From the same spot of the block I have run all the ground wires from the ECU. I have wired all of the sensors to a common sensor ground wire from the ECU.
When I started the car it would go lean and backfire over and bounce from AFR would reading 16 and 19; down to 12 and 13. Then all of a sudden (maybe after the engine became just a bit warmer), the engine stopped leaning out. The engine would run well again (accept for the continued drop outs).
I was told that older alternators tend to have brushes “bounce” causing sudden shifts in the electrical flow. I also was told the earlier alternators would not keep up enough juice to keep an even stream of juice to the ECU.
One of my solutions was to change the alternator from an old first gen Rx7 alt (55 amp), to a newer 100 amp third gen alt (with far more advanced internal electronics, which should generate less noise). This did not help, and again the car runs better when the alt is disconnected and the car is just on the battery. Note it still drops out.
My next solution was to run the ECU power directly from the battery with a simple on/off switch, trying to see if the power blip was in the main relay system. Again this did not help.
Little bits of info that may help.
- Communication can drop off while cranking even before the engine has started.
- The guy who is doing the tuning thought is was like something was loading up, sending the ECU into a safe mode for a moment, or something like that.
- The fuel pump control wire stays grounded so I am not using it for fuel control.
Later today, I went out to try to get a datalog and I was able to get a few. Again it started with the lean/normal stuff. Communication was still a challenge. Drop out was there. The first logs of today were without the alternator connected. The last one has the alternator connected.
Please take a look and tell me if you see anything.
Thanks ~ JEB
MS2 v3 with MS2Extra. The ECU fires the coil, and I am using a Rx7 CAS with 2 teeth cut. I installed the ECU and soldered each joint. Got the car running and did some tuning, yet stopped because the ECU would just drop out and come back on right away.
I ran a data log (8/5 I think) and what I saw was the voltage drop from 12v to .2v and then it would bounce back (this is attached). When I disconnected the alternator, it would drop off a bit less. Yet, it did keep dropping off. I figured it was a lose wire somewhere and it would clear up if I cleaned up the wiring.
I used a grounding model suggested by Aaron Cake. I have run a heavy duty cable from the battery to the engine block (both ends are soldered). From the same spot of the block I have run all the ground wires from the ECU. I have wired all of the sensors to a common sensor ground wire from the ECU.
When I started the car it would go lean and backfire over and bounce from AFR would reading 16 and 19; down to 12 and 13. Then all of a sudden (maybe after the engine became just a bit warmer), the engine stopped leaning out. The engine would run well again (accept for the continued drop outs).
I was told that older alternators tend to have brushes “bounce” causing sudden shifts in the electrical flow. I also was told the earlier alternators would not keep up enough juice to keep an even stream of juice to the ECU.
One of my solutions was to change the alternator from an old first gen Rx7 alt (55 amp), to a newer 100 amp third gen alt (with far more advanced internal electronics, which should generate less noise). This did not help, and again the car runs better when the alt is disconnected and the car is just on the battery. Note it still drops out.
My next solution was to run the ECU power directly from the battery with a simple on/off switch, trying to see if the power blip was in the main relay system. Again this did not help.
Little bits of info that may help.
- Communication can drop off while cranking even before the engine has started.
- The guy who is doing the tuning thought is was like something was loading up, sending the ECU into a safe mode for a moment, or something like that.
- The fuel pump control wire stays grounded so I am not using it for fuel control.
Later today, I went out to try to get a datalog and I was able to get a few. Again it started with the lean/normal stuff. Communication was still a challenge. Drop out was there. The first logs of today were without the alternator connected. The last one has the alternator connected.
Please take a look and tell me if you see anything.
Thanks ~ JEB
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