idosubaru Posted November 21, 2005 Share Posted November 21, 2005 i have no spark from the ignition coil and it will not start. either the power transistor or the ignition coil get extremely hot while the car is ON or trying to be started. i believe it's the power transistor getting hot...it's very hot, can't touch it, smoking off hot. i installed another power transistor and coil (known good units) and it did the same thing....got really hot again? i looked through the FSM and can't really see what would cause that to overheat like that. EDIT - this is for an XT6 Link to comment Share on other sites More sharing options...
nipper Posted November 21, 2005 Share Posted November 21, 2005 Sounds like maybe a short someplace in the primary circuit. i cant tell from your post what car this is, but thats where i would look first. nipper Link to comment Share on other sites More sharing options...
idosubaru Posted November 21, 2005 Author Share Posted November 21, 2005 i edited the first post to include what car. primary circuit what does that mean? i went through the FSM testing of the grounds and power circuits and the fuel injectors as well and all tested out good...but that was last week when i was at least getting spark. guess i'll start over. any suggestions on that power transistor/ignition coil burning up would be great. Link to comment Share on other sites More sharing options...
nipper Posted November 22, 2005 Share Posted November 22, 2005 The primary circuit is the low voltage side of the ignition. the secondary circuit is the high side. http://abbysenior.com/mechanics/ignition.htm start off there nipper Link to comment Share on other sites More sharing options...
idosubaru Posted November 22, 2005 Author Share Posted November 22, 2005 oh my goodness that's alot of info! anyone speak english? just kidding...i'll get on it tomorrow. thanks! Link to comment Share on other sites More sharing options...
naru Posted November 22, 2005 Share Posted November 22, 2005 Your CAS or wiring harness is shorted out.Try another disty. Link to comment Share on other sites More sharing options...
idosubaru Posted November 22, 2005 Author Share Posted November 22, 2005 Okay, i went through the starting troubleshooting diagrams and everything tested fine? the power transistor probably just overheated from too much attempted starting. swapped in a good unit and all is well now...except the car won't start. I have spark at each cylinder (new plugs, cap, rotor). I have fuel after the pressure regulator. I have near perfect compression. The fuel injectors all tested good and open/close with 12 volts applied? any ideas? the crank angle sensor testing in the FSM says to rotate engine and see that the pin-out at the ECU alternates between 0 and 5 volts as it's rotated. mine alternates between 0 and like 3.x volts at the highest...never makes it to 5. But i connected another distributor and got about the same values so i can't imagine that would be the cause. maybe i'll swap it anyway. not sure where to go from here, anyone know how to verify the injectors are trying to open? Link to comment Share on other sites More sharing options...
robm Posted November 22, 2005 Share Posted November 22, 2005 That low voltage could indicate the problem No 5 V, no injection. Or it could be working perfectly, and the low voltage due to a "slow" voltmeter, it doesn't get up to reading 5 V before it drops again, so it gives you an "average" of 3.X volts. Is there evidence of injection occurring? Smell of gas in the intake or exhaust? Could you drip a bit of gas or spray some starter fluid into the intake, to see if it fires? I am not sure how to fool the MAF while doing this. FI makes some things easier, some harder... Link to comment Share on other sites More sharing options...
nipper Posted November 22, 2005 Share Posted November 22, 2005 Okay, i went through the starting troubleshooting diagrams and everything tested fine? the power transistor probably just overheated from too much attempted starting. swapped in a good unit and all is well now...except the car won't start. I have spark at each cylinder (new plugs, cap, rotor). I have fuel after the pressure regulator. I have near perfect compression. The fuel injectors all tested good and open/close with 12 volts applied? any ideas? the crank angle sensor testing in the FSM says to rotate engine and see that the pin-out at the ECU alternates between 0 and 5 volts as it's rotated. mine alternates between 0 and like 3.x volts at the highest...never makes it to 5. But i connected another distributor and got about the same values so i can't imagine that would be the cause. maybe i'll swap it anyway. not sure where to go from here, anyone know how to verify the injectors are trying to open? What is the cranking voltage. If it drops below 9 volts you wont have enough voltage to start the car. ALso spark may look good but may be not enough to start the car. What kind of condition are your battery cables in. i'm begining to think this is a low voltage issue at cranking more then anything else. nipper Link to comment Share on other sites More sharing options...
NorthWet Posted November 22, 2005 Share Posted November 22, 2005 Could also be distributor is in 180 degrees off... spark on exhaust stroke. I would also agree that the 3.xV reading might be due to testing methodology, as in trying to use a digital meter on a changing voltage. Digital meters have a sampling time-window, and tend to average out voltage changes/swings. (Regarding your original problem: The ECU or Distributor controls the drive to the power transistor, which grounds the coil's primary circuit. Overheating would be an indication that the power transistor is "ON" too much, or simply that it was handling the full unballasted ignition current during cranking.) Link to comment Share on other sites More sharing options...
nipper Posted November 22, 2005 Share Posted November 22, 2005 Im not seeing a voltage called out, but it is an AC voltage, and should be tested at the sensor and not the ecu. Personally knowing how these things work, as long as there is a high/low (low being zero) signal it is ok. You need an analog meter to this test the correct way as your looking for a pulse. The sampling rate of a DVM may miss the signal. You can use a DVM with max hold button, that would capture it, but you need to cycle it longer. ARe you turning the engine using the starter or the wheel. I can email you a set of directions if you wish frm the haynes manual. It takes three things to run an engine, Fuel, SPark and Oxygen. SInce we are sure you have two of them, have you checked the intake to be sure its clear of any obstructions, and that those sensors are in good shape? nipper Link to comment Share on other sites More sharing options...
Cougar Posted November 23, 2005 Share Posted November 23, 2005 The fact that you have spark to the plugs means the ignition is ok. As stated earlier the slightly low voltage you read may have been due to your meter but since you have spark it is not of much concern. I would guess that the injectors are not working for some reason. Have you tried spraying some starter fluid into the intake to see if that will make things fire up? If that makes the engine fire then you will need to see what is going on with the injectors. You stated you have 12 volts to them and I think the ground for the injector circuit is controlled through the ECM. Some designs use external termination resistors and I'm not sure if your model uses those or not. Link to comment Share on other sites More sharing options...
idosubaru Posted November 23, 2005 Author Share Posted November 23, 2005 Problem solved, thanks guys for the support. Pulled the distributor cap and the new rotor was torn to bits on the end and the new distributor cap was gouged up as well? The rotor was perfectly seated and bolted on tight. I have no idea what happened. So i installed an entirely new disrtributor along with a new cap and rotor obviously. It started right up. I'm thinking the distributor was to blame becuase even when i had spark it never even thought about starting. Who knows maybe someday i'll drop that old distributor in one of my motors to see if it works. Link to comment Share on other sites More sharing options...
Cougar Posted November 23, 2005 Share Posted November 23, 2005 The rotor may have been the wrong one for the disty. Link to comment Share on other sites More sharing options...
idosubaru Posted November 23, 2005 Author Share Posted November 23, 2005 i laid it against two others and all looked the same. i have another rotor of the same part number and all, i'm taking it back and checking it out again. bought same time as distributor so should be for the 6 cylinder but who knows. Link to comment Share on other sites More sharing options...
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