letitsnow Posted September 14, 2009 Share Posted September 14, 2009 I recently bought a non working MS1 v3.0, I got most of it working, however, the injector drivers overheat after 30 sec of my car running. I have low z injectors, so I'm assuming the PWM circuit is not working correctly. Both drivers overheat at the same time. It doesn't happen on the stim, and nothing else appears to get hot. The current limit circuit is installed along with the active flyback circuit. This is the schematic for the injector circuit, I've checked the resistor values and they appear to be correct, I also checked for bridged pins on the tiny transistors, no dice. The tip125's are insulated correctly as well, could they be bad? I have some tip120's here, could I try them as a replacement? Could the drivers themselves be bad? Everything has heatsink compound. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 14, 2009 Share Posted September 14, 2009 How many squirts per cycle are you set for? Post up your data logs and configs so we can get a better idea of the problem. It sounds to me like the injectors are staying open too long. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 14, 2009 Author Share Posted September 14, 2009 2 squirts simultaneous, I'll do a datalog tomorrow, but the PW was about 2-2.5ms and the current limit is 30%. It's DEFINITELY a hardware issue on this board, using the exact same msq on my(good) MS1 all is well. When they get hot, the car stumbles and breaks up. This is my msq. running l28 letitsnow.zip Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted September 15, 2009 Share Posted September 15, 2009 What kind of resistors do you have in line for the injectors? Too low and you can cause heating up and frying circuits... Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted September 15, 2009 Share Posted September 15, 2009 He's trying to use the integrated PWM circuit, not inline resistors. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 15, 2009 Author Share Posted September 15, 2009 Yup, trying to use on board PWM. I checked all the transistors today, they seem to be working correctly. I think the drivers are bad. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 15, 2009 Share Posted September 15, 2009 Just at a glance the first thing I notice is you're set for 8 cylinders. You have a spark cut rev limiter set to 25,000 RPMs must be a well built L28... Fix the number of injectors and cylinders and you might be ok. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 15, 2009 Author Share Posted September 15, 2009 Weird, my megatune says it's set for 6cyl/6injectors, rev limits are at 16k/25k so I know that they're out of the way. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted September 15, 2009 Share Posted September 15, 2009 Hey I know you couldn't know all of this, you might want to call me so I can fill you in on the rest, but the guy I bought it from was running Supra 440s WITHOUT the PWM circuit installed. I added it when I got the board, that might be causing this issue. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 15, 2009 Share Posted September 15, 2009 That is weird because the msq says 8 Cylinders 8 Injectors...Oh well. Can we get some high def pics of the front and back of the board? If it is a possible hardware config problem I might be able to point it out from pics. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 15, 2009 Author Share Posted September 15, 2009 http://img190.imageshack.us/img190/1045/dsc00090kj.jpg http://img190.imageshack.us/img190/7246/dsc00091l.jpg 4.0mp is the best I can do for now, all I have is the camcorder around, I could do some hi def video though . I know that d19 is missing, I burnt it out poking around. It's not important to the injector circuit anyhow. Some of the transistors look like they might be bridged, but none of the. Hey I know you couldn't know all of this, you might want to call me so I can fill you in on the rest, but the guy I bought it from was running Supra 440s WITHOUT the PWM circuit installed. I added it when I got the board, that might be causing this issue. The PWM circuit seems to be alright, I just think the drivers are failing. I'm going to try and track something similar down tomorrow. The first guy could have injured them running low z injectors. If you want, PM me your number and when is a good time to call tomorrow. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 15, 2009 Share Posted September 15, 2009 4mp is great. I'll have to look a little more closely at it when I've had a bit more rest, however you need D19. It is important to the circuit because it controls voltage spikes on the 5v. Might not seem important to the injectors, but it is important to the system as a whole. You'd be surprised what kind of havoc an unclean 5v reference can cause on an MS unit. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 15, 2009 Share Posted September 15, 2009 Also, here's a quote from the troubleshooting section of http://www.megamanual.com 16) If you have MAP sensor spikes that aren't traceable to back-fires, etc, and you are using PWM to limit the current to low impedance injectors, you might have to modify flyback circuit. The fix for this specific problem (noise in the sensor signals, and a noisy +12v battery signal, spikes to 17v, dips to 7v) was to decouple the flyback +12v lines (both TIP125's) from the MS +12v input pin, and run them back to before a noise filter on the +12v input of the MegaSquirt. To do this, lift the +12v pin of each of the TIP125's in the flyback circuit. The TIP125 are Q9 and Q12 (the ones with the mica insulators). The 12V pin on the TIP 125 is the pin in the middle - melt the solder and pull the pin up with needle nose pliers. Then run a wire from each of the pins you pulled up independently back to the raw +12v supply (outside of the box), and before the noise filter. You can ran the wires through the spares (SPR3 and SPR4, which go to DB37 #5 and #6). 20ga is just fine. The point to that quote is to show what noise in the circuit can do. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 15, 2009 Author Share Posted September 15, 2009 I know, however, it was doing the same thing before I burned out d19. I was using the 5v to activate the pwm circuit and accidentally touched it to +12v. It should be alright on the stim with a fairly clean input, in the car with the noisy alternator might be different. I'm going to see if I can find a replacement tomorrow. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 15, 2009 Share Posted September 15, 2009 From the back of the board it looks like there's a lot of cold solder joints and a whole lot of flux all over. A good clean up and re-flowing some joints might help too. Quote Link to comment Share on other sites More sharing options...
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