X64v Posted January 24, 2009 Share Posted January 24, 2009 Alright, well I've had this annoying problem where when I drive the car in the rain (L28et, VR dizzy, MS I V3.0, MSnS-E), it will sometimes die, and the car won't restart until it 'dries out'. When this happens, Megasquirt won't read any rpm signal, and usually the LEDs are just all off. This happened for the third time ever yesterday, but now the accel LED (far right, LED16) is always on, and it still doesn't read the incoming rpm signal, so the car won't start at all. The box didn't get wet at all, nor has it ever been wet. The circuit board looks great, no cold/broken solder joints. It did start and run for a few seconds, but the accel LED was still stuck on, and the pulsewidths were super rich. I reflashed the firmware (029y4) and reloaded the .msq, no help. I changed LED 16 from accel to spark output B, no change. I tried plugging the ecu into the harness on my friend's megasquirt'd Mercedes, the LED still stays on. Likewise, his ecu plugged into my harness works fine (no LEDs on). Main problem/question: What could be wrong to always keep LED16 lit/not read rpm input? Quote Link to comment Share on other sites More sharing options...
mikeatrpi Posted January 24, 2009 Share Posted January 24, 2009 Sounds like you have a problem in humid weather. My initial thought is that LED16 is on because it should be on - IE, the problem is not in the output circuitry but rather an input is causing accel enrichment to be on. This agrees with your comments about it running extremely rich for a short time. If you have a stim, can you play with the RPM and TPS pots to see if you can get the LED to go out? However - you changed the function of LED16 and yet you said "no change". No change = it still won't run, or the LED was still on? I would reflow any joints that looked remotely suspect around your input circuitry. I would also consider using a conformal coating. And for good measure, stash a desiccant bag where you mount the MS box. I'm going at this from the EE perspective, hopefully someone with more MS experience than I will tell you more. Quote Link to comment Share on other sites More sharing options...
X64v Posted January 24, 2009 Author Share Posted January 24, 2009 However - you changed the function of LED16 and yet you said "no change". No change = it still won't run, or the LED was still on? Both, the LED was still fully lit, the rpm read zero during cranking, and so it would not run. Also, I can connect my lap top - MegaTune says that accel enrichments are off. I usually run in MAP-based accel; switching to TPS-based accel doesn't change anything. Also I connected it to my friend's Mercedes, light stays on. Connect his MS to my car, accel light stays off on his. I will probably add a desiccant bag, but I wonder why I have to when no one else does. Quote Link to comment Share on other sites More sharing options...
24OZ Posted January 24, 2009 Share Posted January 24, 2009 Could you have a leak that is coming into the car? Is it damp by the MS box, how is it mounted? Quote Link to comment Share on other sites More sharing options...
X64v Posted January 24, 2009 Author Share Posted January 24, 2009 Yeah, the weatherstripping leaks all over the place, but the box doesn't get wet. Quote Link to comment Share on other sites More sharing options...
X64v Posted January 25, 2009 Author Share Posted January 25, 2009 Fixed it. I looked up the schematic for the LED circuits (here) and found that it's a very simple circuit switched by a transistor that's controlled directly by the processor. So, I pulled the processor and powered up MS, and the LED still came on, which told me that the transistor had shorted out or something. Replaced the transistor, all is well. Hopefully this fixed the problem of dying when it rains, but I'll be putting a desiccant pack in there just in case. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.