baggedgoods Posted May 25, 2017 Share Posted May 25, 2017 Hey guys, I had the car running and driving pretty decent. Late Sunday night, while out tuning, the car suddenly died under normal acceleration. Cranks but does not start and I'm getting a tach reading in TunerStudios. I checked my datalog and looked at the area it died. Everything looks fine up except for my afrs jumping from 14.4:1 to 19.0:1. Duty cycle and PW jumped a couple ms as well. I first thought they jumped because the car died and my wideband lost power. That would have been the case if they dropped to 10:1. I'd post up my datalog but it's about 4 hours long because I'm an idiot and didn't the logging off while I wasn't driving the car. Plus I'm on mobile at the moment. Mind you, I was adjusting the fuel and ignition tables only, nothing else. I've confirmed that I'm not getting spark and as for fuel I'm not 100% but I smell a strong gas smell when I crank it. I've replaced the coil and plug wires and rewired the coil wires with fresh ones. I've confirmed 12v at the coil but still no spark. This is leading me to the megasquirt itself. I soldered in a bip373 into q16 and have js10 controlling spark. To my understanding, these transistors are bulletproof and I'd fry my coil before I'd fry this transistor. What could be causing my no spark issue? Could the transistor have gone bad? I've triple checked all my wires and grounds. I'm running the MS2 V3.57 with the 3.4.2 firmware and the bip373 mod. Thanks a bunch guys. Edit: will post up tune later, but I don't think that is the problem here. Also, the car is a 1985 Nissan 300zx turbo. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted May 25, 2017 Share Posted May 25, 2017 They are robust, but I've seen them fried before. Granted I'm not sure that is the case here. What ignition setup are you running? 3 spots it can be failing. 1st is a physical connection. A break or something in the circuit. Second is a logic based break. The ECU itself is not triggering the spark Last is a hardware failure whether it is the ECU itself, a bad coil, dizzy, or fouled spark plugs First thing to do would be to turn your car onto ignition on, then go to can/input and enter test mode. Then fire the spark output you should be able to to see spark on whichever cylinder the dizzy if you have it is pointed to with an inline sparkplug tester or an inductive timing light. If that works then you know the failure is most likely a result of a logic based break, the ECU is not firing when it should be. If you do not get a spark, then you want to trigger a manual discharge. If a manual discharge does not generate a spark then you have a fault in the connection or the coil/dizzy/sparkplug are not cooperating. Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 25, 2017 Author Share Posted May 25, 2017 I'm running a single coil with a distributor. Stock coil and dizzy. I just replaced the coil today and tried it, but I'm not getting spark. I disconnect the coil wire to the dizzy and put it to ground and then crank it over while watching for a spark. (No spark). I tried manually firing the old coil but it didn't spark so I believe it had a voltage leak of some sort. So I replaced the coil and I'm not getting a spark out of the new one. That's why I believe I traced it back to the ms box itself. I opened the box and the only modification I made was putting the bip373 in slot q16 controlled with js10. The wire looks fine, resistance is fine. I'm not sure how I would go about testing everything on the board itself unless I send it in to diy. Keep in mind, everything was working properly (to my knowledge) and suddenly it stopped. Under hardly any load and slow acceleration. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted May 25, 2017 Share Posted May 25, 2017 Well if the coil isn't firing manually then your problem is with the coil/dizzy as the ECU is no longer sending a signal, no? What keeps bringing you back to the ECU being at fault? Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 26, 2017 Author Share Posted May 26, 2017 (edited) I've replaced the coil as well as the wires to it. Its a brand new coil. Edited May 26, 2017 by baggedgoods Quote Link to comment Share on other sites More sharing options...
seattlejester Posted May 26, 2017 Share Posted May 26, 2017 Check the dizzy? A worn rotor or cap would cause a sudden failure. Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 26, 2017 Author Share Posted May 26, 2017 I checked the coil using the main wire from the coil to the dizzy. Not any individual spark plug wire. I'll check the rotor and cap itself sometime soon but the problem is that there is absolutely no spark coming out of the new coil while cranking. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted May 26, 2017 Share Posted May 26, 2017 Oh the coil isn't firing at all? Have you tried putting like an inductive pickup to see if it will trigger a timing light? Did you replace the ground you took off earlier to test it manually? Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 26, 2017 Author Share Posted May 26, 2017 I haven't tried using my timing light on the wire. The plug wires are brand new as well. And yes, I reconnected the ground wire to the coil going to the ms Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted May 26, 2017 Share Posted May 26, 2017 Ohm the wire from pin 36 on the db37 to the coil negative. If that's good power up the coil and touch the negative to ground and see it if fires. I that's good ohm all the circuits on the ms board for the ignition circuit using the schematics online. Quote Link to comment Share on other sites More sharing options...
Chickenman Posted May 26, 2017 Share Posted May 26, 2017 (edited) Replace the BIP-373. S**T happens. They are supposed to have a Thermal protection circuitry to shut them down if they over heat..... but S**T happens A BIP-373 is what $8.50?? 5 minutes with a soldering gun and you'll have either fixed it or not. Weren't we discussing this in another thread or Forum?? Edited May 26, 2017 by Chickenman Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 31, 2017 Author Share Posted May 31, 2017 I ordered 2 and they should be showing up today. I'll update once I install it. Another thought, would it seem plausible that the transistor burned through some thermal grease and is just grounding out on the heat sync? I know I made sure to put plenty of compound on so I could avoid that problem. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted May 31, 2017 Share Posted May 31, 2017 It should have a mica insulator. If not that could be your problem. Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 31, 2017 Author Share Posted May 31, 2017 It does and it's installed. I noticed a few hardware pieces on the heat sync that had the mica insulator as well as heat sync grease/thermal compound so I put some on as well. But that would make sense, thanks for clearing that up. Also, I bought the board preassembled so that would explain my lack of knowledge towards the board side of things. Quote Link to comment Share on other sites More sharing options...
seattlejester Posted May 31, 2017 Share Posted May 31, 2017 Just for reference The Bosch BIP373 ignition module is nearly a drop in replacement for the VB921, with one exception: you must use a mica insulator kit between the BIP373 and heat sink when you mount it because the mounting tab is 'live'. Does the unit appear damaged? The only one I found burnt was physically burnt and smoldering. Still curious if this is the actual cause, because where we left off it seems like you can't get the coil to fire manually. Which would indicate the hardware on the engine side being at fault. Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted May 31, 2017 Author Share Posted May 31, 2017 It looks fine to me. I used the mica insulator as well as thermal compound. And yes, that was one part of the problem. I replaced the coil but have not tested it manually because it's a Brand new coil. Also, for some weird reason, my power wire to my coil wasn't getting power to the coil anymore so I replaced that as well and have confirmed 12v at the coil. So this leads me back to the coil not getting grounded by the megasquirt which is through the bip373. And I made sure my js10 to igbtin was connected and looked physically okay and tested okay. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 1, 2017 Share Posted June 1, 2017 What's the primary resistance of your coil? As I understand things, you can still burn up even the bulletproof ignition transistors if you have a low resistance coil, or set your dwell too long. Even with current-limiting transistor assemblies. They generally don't like stray sparks either. They're bulletproof when everything is working like it's supposed to, otherwise they're sensitive. Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted June 3, 2017 Author Share Posted June 3, 2017 Off the top of my head, the primary coil is about 1 ohm and the secondary around 10k ohms. So it is a low resistance coil and I ran 3.1ms of dwell through it. That doesn't seem like too much dwell time to me. I don't even touch 6k rpms so I don't believe it would harm anything being that long at higher rpms. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 3, 2017 Share Posted June 3, 2017 There's probably a method for testing the BIP373. That seems to where you're at. DIY says that they are the shit though. One simple test would be to see if it gets hot and shuts itself off. Touch it after trying to start and see if it's hot. You might also test the coil power circuit and spark path. Ground the coil yourself with a jumper wire on the coil negative. Be the BIP. See if you get single sparks where you should get sparks. Smart people have been known to leave the rotor off. Once you put the cap on, outofsight-outofmind. You never confirmed your rotor check. https://www.diyautotune.com/support/tech/other/bosch-bip373-ignition/ http://www.megamanual.com/ms2/bip373.htm Quote Link to comment Share on other sites More sharing options...
baggedgoods Posted June 3, 2017 Author Share Posted June 3, 2017 (edited) I haven't found any test procedures for the transistor so I'm just going to replace it and see where it gets me. I'd very much like to know what or how it failed. But sometimes if it works it works. What really puzzled me was, after the car died, I was checking my wires and the power wire to the coil wasn't getting power to the coil. Fuse was fine. So immediately I replaced that wire and confirmed 12v at the coil. Still no spark. I'm not sure if that had something to do with the transistor failing or just the wire had gone bad (even though it was a brand new wire.) Edited June 3, 2017 by baggedgoods Quote Link to comment Share on other sites More sharing options...
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