stretchnuts Posted December 2, 2013 Share Posted December 2, 2013 Not sure if this belongs in the Mega Squirt forum or not but I have a feeling it could be related. I recently acquired a 77 with an 83zxt motor ms1v3 and had run for years. Was parked for a while, nothing was done to it, and now it wont run. Getting fuel, injectors are definitely firing, but no spark. I am getting ~11.7v between the black/w wire at the positive of the coil and the blue wire at the negative with the IGN ON. It appears that the car uses a 77 harness (from looking at the FSM diagram) with the MS wired onto where the old ecm was. While cranking it drops a little due to the extra starter load. Pulled a plug, and no spark. I ordered a serial cable to get tunerstudio up and make sure I am getting a tach signal, however the red led blinks while the motor is turning over so this leads me to believe it is getting a good tach signal. When the key is on there are no lights on the module. Its been a while since I fiddle with MS and cant remember if that was normal or not. What could have happened in the time it sat to cause it to not run all of a sudden, honestly I am kinda at a wall. My next step is going to be to rip the harness out and redo it with the MS relay board. I am eventually going to do that anyway but would really like to get it running the way it was before drastically changing too much. Quote Link to comment Share on other sites More sharing options...
Metro Posted December 2, 2013 Share Posted December 2, 2013 If the fuel pump is on and the injectors are firing, you have an RPM signal. You should start trouble shooting from MS to your coil. If the LEDs haven't been used for other things, left to right: D14 - INJ (pulsing when running), D15 - Warmup Mode (on until the engine is out of warm up mode), and D16 - Accel (on when you blip the throttle). If the PO used D14 for spark output, it will flicker as it attempts to fire the coil. Quote Link to comment Share on other sites More sharing options...
winstonusmc Posted December 2, 2013 Share Posted December 2, 2013 Definitely neew to get the serial cable so you can test out the spark circuit. Are you using the internal igniter or an external one neer the coil? The ignition module could have fried, or even the coil. Quote Link to comment Share on other sites More sharing options...
stretchnuts Posted December 2, 2013 Author Share Posted December 2, 2013 I am assuming the aftermarket coil has an internal igniter as I don't see an external one anywhere. Its an accel supper sport. Which wire should I be looking for coming from the MS to the coil, and should there be two wires to the positive terminal? I.e. a 12v signal wire from MS and a constant 12v from the car (fuel pump + is what the MS diagram states). PO said the coil tested good, and I threw in a zxt coil that is probably good and nothing still. Is there a way to test the coil itself while its hooked up and trying to start? The spark could be grounding out somewhere in between the coil and the plugs. D14 does flash rapidly when trying to start. As for the fuel pump and I think it was wired directly to the ignition and is not being controlled by megasquirt, however I dont think this should affect anything as I am definitely getting fuel in the cylinders. Smells great. Quote Link to comment Share on other sites More sharing options...
Metro Posted December 2, 2013 Share Posted December 2, 2013 (edited) You're probably using the built in ignitor that comes with the v3 board. You should have a wire running from the coil (-) to pin #36 (last pin, bottom right corner) on the ECU. If that's the case, then D14 is showing spark output and since you mentioned it's flickering, at least you know it's trying to fire the coil. If it's not going to pin #36 then it could have been setup to use the FIDLE output using an external ignitor. Could be a GM HEI, stock ignitor, or MSD box - basically any ignitor you can think of will work with MS. Your fuel pump should be connected to a relay which is grounded by pin #37 on MS, if it's not, then I suggest you do that. MS will only turn the fuel pump on when it detects an RPM signal. Once you get your cable, you can see exactly how the software was configured and then you can check to see if the hardware matches up. I suggest you spend some time reading the MS-extra manual while you wait. You could also double check and clean all of the grounds from megasquirt if you haven't. Edited December 3, 2013 by Metro Quote Link to comment Share on other sites More sharing options...
stretchnuts Posted December 3, 2013 Author Share Posted December 3, 2013 (edited) Ok, the diagram for ms i think shows pin 37 for the coil. Either way would i be able to disconnect the wire from that pin and just run a brand new wire from that pin to the positive of the coil without hurting anything? And if i do that and it still doesnt fire how woukd i check to see if the coil is actually producing a spark signal? Edit : it is pin 36 for the coil and 37 for fuel pump Edited December 3, 2013 by stretchnuts Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted December 3, 2013 Share Posted December 3, 2013 You should have switched 12v at coil +. You can disconnect the - and momentarily jump ground to the coil neg. That should produce a spark. If there is not an open circuit between pin 36 and coil neg I would look in ms using tuner studio to see which circuit ms is using a spark output. It's usually D14. Also double check all the grounds to ms. if all is ok I would suspect something inside ms is causing the problem. Quote Link to comment Share on other sites More sharing options...
stretchnuts Posted December 3, 2013 Author Share Posted December 3, 2013 I ran a wire directly to pin 36 on the MS to the - of the coil and after a cough and sputter, she runs! Lol. There's some sort of disconnect between the 77 harness, and the MS. D14 is solid d15 is solid until its warmed up, and d16 lights when the throttle is blipped as mentioned above. Car wont idle and runs super rich even though the wideband indicates between, 13-14.5. Rich, but not as rich as it smells lol. My next question is would the aforemention idle problem be related to old nasty gas? Car revs really well and smoothly so maybe not the case? Either way my cable will be here tomorrow to hook up to tunerstudio and see whats going on. Its been about 9 yrs since ive even glanced at tuner studio so there will be another slight learning curve... Quote Link to comment Share on other sites More sharing options...
mobythevan Posted December 4, 2013 Share Posted December 4, 2013 Get tuner studio hooked up and check out all the basics. Read over the beginning tuning notes again and you will be right back in it. Quote Link to comment Share on other sites More sharing options...
stretchnuts Posted December 5, 2013 Author Share Posted December 5, 2013 I have the usb to serial adapter reading properly in megatune, but is it true I cant use usb for tunerstudio lite? I am assuming I have to buy the full version? Quote Link to comment Share on other sites More sharing options...
mattb3562 Posted December 6, 2013 Share Posted December 6, 2013 If it'll communicate with megatune properly, it should work with tunerstudio just fine. Quote Link to comment Share on other sites More sharing options...
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