Mudge Posted April 20, 2003 Share Posted April 20, 2003 Troubleshooting as to why no spark on my 82 ZXT --> 73 240Z car. I've tested diz pulses, I've turned it by hand to do this, and heard injector activity, yet still no spark. So I tested my old 240 coil and my ZXT coil, resistance figures are lower for the 82 coil so I think its workable, and I have seen spark once from the output, but only when shutting the car off. Neg to output 8.6k ohm Neg to pos 1.5 ohm Coil transistor lead to lead is 4.14k ohm, but I dont know if there is a method of testing that? To coil transistor negative I have pin 5 (YW), and to coil transistor + I have the old wire, as well as IGN (BW I believe but have to check my notes). I do see voltage at the coil when IGN is in RUN and START. One thing I'm curious about is pin 16, this goes to LR on the fuel relay, and to "coil +", I'm not sure if this is neccessary or not, I am not using the stock fuel modulator or relay, however they are all left in place. I can't find any diagram which actually shows this LR going to the coil however, I've only seen it in text, so I dont know if its even important. The fuel relay gets its power elsewhere, so I am thinking its a signal to power the fuel relay only, and then goes back to pin 16 to tell the ECU what exactly? Or perhaps this is simply how the ECU actuates the fuel relay if the inhibitors are active or not, dont know. Quote Link to comment Share on other sites More sharing options...
fl327 Posted April 21, 2003 Share Posted April 21, 2003 whasup? jump coil to battery on positive., no start try to jump one of the pins from key on power with a long wire to the positive to ignition switch pin. make sure that key on is working. ive bypassed that transistor more than once with a wire from the battery, to avoid being stranded. the one time this happened it was a loose/dirty pin from ign switch. good luck. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 21, 2003 Author Share Posted April 21, 2003 Some more testing, which leaves me puzzled. Pin 5 I thought, only shorts to ground to trigger a firing event, however I find that with key ON it is a constant short to ground??? With key OFF I show about 1200 ohms to ground at the intake manifold. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted April 21, 2003 Share Posted April 21, 2003 ok, I'll throw some speculation in here to confuse you more. I didn't test the signal on Pin 5 that fires the transistor and coil, but it is my impression that you should get some kind of pulse on this pin to the transistor. That pulse turns the transistor on, when the transistor is turned on it shorts the coil to ground to fire the plugs. I think if you see ground on pin 5 all the time then the ECU is not turning on the transistor. I also hooked up the wire that gets 12volts from the fuel pump relay when the relay is turned on. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 21, 2003 Author Share Posted April 21, 2003 I also hooked up the wire that gets 12volts from the fuel pump relay when the relay is turned on. Hooked it up where? Are you using the stock fuel relay/modulator setup? Or do you mean pin #9 start ign signal? I'm good there... I made sure to write down every pin and check them out. Or are you saying pin 16 (blue red/LR) gets + from the fuel relay? I wasn't sure what this was for, I can try feeding it + on RUN though... So Pin #16 should see + when IGN is ON? I will try this. Pin #5 goes to the ground side of the transistor, the + is above it, so I thought it only pulsed a ground signal - or is it a constant ground and shorts out to +, which would make zero volts??? Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 21, 2003 Author Share Posted April 21, 2003 Pin 16 shows + on RUN, I still have the fuel pump relay wired up even though I'm not using it, oh well. Someone on ZCar says this is an output, not input, I did not unhook the ECU connector to verify. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted April 21, 2003 Share Posted April 21, 2003 Yes the LR wire is the wire that turns on the relay for the fuel pump(it is an output from the ECU), so if you wired the relay some other way then you don't need to use this wire. The start signal is what I meant. I have the start signal hooked up to the fuel pump relay so that when the relay is on the ECU gets the start signal, this is what the wiring diagram showed for correct hook up. As for transistor I am only confusing you I guess. There should be some kind of pulse on pin 5 that works the transistor. It should either be a high pulse or a low pulse. Depending on whether the transistor turns on to fire or off to fire(that I am not sure about without more info). But regardless, if pin 5 is stuck high or low all the time I don't see how the transistor is going to work, therefore no spark. If it was me I would hook a scope to pin 5 and crank the engine to see if I get pulses, but you probably don't have a scope. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 21, 2003 Share Posted April 21, 2003 As for transistor I am only confusing you I guess. There should be some kind of pulse on pin 5 that works the transistor. It should either be a high pulse or a low pulse. Depending on whether the transistor turns on to fire or off to fire(that I am not sure about without more info). But regardless, if pin 5 is stuck high or low all the time I don't see how the transistor is going to work, therefore no spark. If it was me I would hook a scope to pin 5 and crank the engine to see if I get pulses, but you probably don't have a scope. The transistor is an NPN, requiring 1 volt forward drop to turn on the current through the coil. It will have to drop to 0 in order to shut the coil off and fire the ignition. Not sure of the color or pin, but that is the ignition signal from the ECU. If you have a test lamp, disconnect the wire from the transistor and put the test lamp across it, then check for a flashing as you crank. This will isolate the problem to either the transistor (get flashing) or the ECU or it's inputs (no flashing). Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 21, 2003 Author Share Posted April 21, 2003 Pin 5 is YW, I'll try a light on it, with the DVM I only saw a solid 13v or so, but I know the reaction time of the DVM may not be sufficient. If its the computer what could it be? Oh, only a million things... I feel like a retard, this is the 4th week now going on 5, oy. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 23, 2003 Author Share Posted April 23, 2003 No pulse from the ECU, just a solid ground Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 23, 2003 Share Posted April 23, 2003 Well, if injectors are firing, and you have no signal to the coil, it sounds like your ECU may have a blown driver. If you have a DVM, put it in diode mode and measure the coil transistor to ground - you should get a short beep, and measure 0.5-0.8 volts - that will rule out a bad transistor causing your ignition driver to fail. If your transistor checks outs, try to get another ECU to test in circuit, see if it drives the ignition. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 23, 2003 Author Share Posted April 23, 2003 Thanks Sleeper, I will try that tomorow. I was tearing apart my coil today to look for this bullet connector http://www.zcar.com/forums/read.php?f=1&i=349816&t=349374 Now I dont have a bullet connector but it looks like that is simply coming off the blue wire which also goes to the coil negative. Will the tach unhooked cause the plugs not to fire? Quote Link to comment Share on other sites More sharing options...
mobythevan Posted April 23, 2003 Share Posted April 23, 2003 I don't have the bullet wire connected to anything, like you say this wire use to go to the 280zxt tachometer. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 23, 2003 Author Share Posted April 23, 2003 Yeah, the things I've wondered about before, Len would pull off the car and it would start right up. The Diz is triggering the injectors, but the ign wont tell the coil to fire, hmm. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 23, 2003 Author Share Posted April 23, 2003 I will test the diz again to make sure I'm getting both pulses, in the meanwhile though can I fix this with an aftermarket spark box with adjustable timing map? I dont know if the ECU would like it, and/or if the spark box needs the transistor or not. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 23, 2003 Share Posted April 23, 2003 I will test the diz again to make sure I'm getting both pulses' date=' in the meanwhile though can I fix this with an aftermarket spark box with adjustable timing map? I dont know if the ECU would like it, and/or if the spark box needs the transistor or not.[/quote'] The "spark box" will not use the transistor. It should be able to drive the coil directly, unlike the low level the ECU can put out. How will you time it, and how will you advance it? You would need a Megaspark perhaps, with an advance curve built in, or an early Z dizzy with a mechanical and vacuum advance. I doubt the ECU will mind though, that may be a good option if you indeed burned out the ECU ignition driver. Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 23, 2003 Author Share Posted April 23, 2003 Its either this or I'm going to have to ignore the car for awhile and start messing with the Camaro, and probably just buy an aftermarket computer setup to get the thing running, the guesswork is just crippling me. The spark boxes I've seen usually accept either of 3 ways for timing, crank trigger or optical is all I remember off the top of my head. I will continue to look into this then, there is a unit with an adjustable curve that I was interested in awhile back... I have seen the statement that an HEI "wont work with a turbo ECU" so I wasn't sure if the computer needs to see something from the transistor or what. or an early Z dizzy with a mechanical and vacuum advance That sounds "easy" other than the computer needing it for the injector timing Quote Link to comment Share on other sites More sharing options...
Mudge Posted April 23, 2003 Author Share Posted April 23, 2003 http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=4329&prmenbr=361 Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 23, 2003 Share Posted April 23, 2003 or an early Z dizzy with a mechanical and vacuum advance That sounds "easy" other than the computer needing it for the injector timing No, the computer really couldn't care less - the injector timing is based only on the crank angle sensor. The ignition timing is based off the same reference - they are separate systems. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 23, 2003 Share Posted April 23, 2003 http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=4329&prmenbr=361 That looks like a nice little unit, and the price is not bad either... Quote Link to comment Share on other sites More sharing options...
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