sublute Posted November 28, 2007 Author Share Posted November 28, 2007 I tried real quickly to get a voltage from the harness to gnd and got no voltage. I will double check this now I know it should be the yellow lead. I have to go pick my daughter up from preschool, so I'll try to do this when we get back. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 I've got voltage (~12VDC)on the yellow lead of 1,2,3 and stopped , again 4 is really hard to reach. Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 I've got voltage (~12VDC)on the yellow lead of 1,2,3 and stopped , again 4 is really hard to reach.Good, and we can probably safely assume that #4 will also read the same. Do you have any resistors easily available? I'd like to load one of the injector connections (#2?) with a "dummy" (disconnect the injector); in order to keep the heat dissipation reasonable (in case switching to the off state isn't occuring), it should be about 1,000 ohms or so, 1/4 watt or higher dissipation. It could get somewhat warm, so keep it away from anything heat-sensitive. Measure the voltage from the resistor lead on the non-yellow injector wire to ground; on a scope, while cranking you should see a voltage of a bit less than 12 volts, dipping to under 1 volt every 500 milliseconds (1/2 second) or so for a bit less than 100 milliseconds duration. With a meter, the readings can be hard to interpret, as I mentioned previously. If you can do this and get usable info, repeat it at #1 (I'm particularly interested in the result at that location). If no resistor is available, the injectors could remain attached and the connectors back-probed. I'm not suggesting that as the first choice because the connectors don't lend themselves to doing that easily. This is admittedly "the long way around", but since simple things seem to check out, I'm trying to cover the less-simple (perhaps bordering on bizarre ). Quote Link to comment Share on other sites More sharing options...
Skip Posted November 28, 2007 Share Posted November 28, 2007 OB99W.. is it possible that the switching circuit pulling the non yellow wire to ground (Triac, SCR ect) is looking for an impedance (coil) and not pure resistance? Could a pure resistance hurt the board? Why not stick a straight pin through the wire and clip to it? Drop of silicone will fix the breech. Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 OB99W.. is it possible that the switching circuit pullingthe non yellow wire to ground (Triac, SCR ect) is looking for an impedance (coil) and not pure resistance? Could a pure resistance hurt the board? It shouldn't be a problem -- although an inductor will slow the initial current rise, it gets to be a fairly high value due to the low DC resistance of the coil (we're applying switched DC, not a higher-frequency AC signal where the impedance might be more of a factor); an inductor also produces a "kick-back" voltage on turn-off from which the ECU has to have protection. A 1,000 ohm resistor will only draw 13 milliamps max (assuming a fully charged battery), lower than the injector itself would draw, and produces no (discernable) kick at turn-off. Why not stick a straight pin through the wire and clip to it? Drop of silicone will fix the breech. I'm not particularly fond of doing that, because sometimes one or more wire strands get broken, and sometimes people don't properly seal the "breech". Still, if the other approach isn't easily accomplished, that will certainly work. Quote Link to comment Share on other sites More sharing options...
WAWalker Posted November 28, 2007 Share Posted November 28, 2007 You can "back probe" the fuel injector conectors with a safety pin easily and safetly. With the corrosion problems on the east coast I would not recommend probing the wire. PS Yes, ignition timing stays fixed @ 10 deg. during a crank-no start (fuel supply interupted). Appears that the advance happens @ ~400 RPM (not sure what the ECU uses to determine when engine is actually running, I would ASSume crankshaft speed). Not that this is relavant at the moment. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 I've got a 1k 10watt resistor here... I'll try it when I can get out there. Quote Link to comment Share on other sites More sharing options...
Skip Posted November 28, 2007 Share Posted November 28, 2007 good luck these guys have your bases covered I'll step out now as my suggs are all poor ones it seems. Sure hope you get it fixed. pin hole sealed with silicone - come on Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 OK, I scoped 1 and 2 injector and they look the same on the scope, a short dip consistant with your description. For kicks, I flashed the timing light at the scope and it looks like the wire is sparking just before the dip... It should dip just after, right? I'd have to do it again to be sure. Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 [...]I'll step out now as my suggs are all poor ones it seems.[...]I doubt anyone here really thinks that. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 All your help and input is good. I should slow the sweep down a little so I might be able to see clearer. I have to keep one eye on my daughter, though... Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 [...]For kicks, I flashed the timing light at the scope and it looks like the wire is sparking just before the dip... It should dip just after, right? I'd have to do it again to be sure.The spark should occur just after the "dip" (or "pulse", when the injector is open), assuming you're looking at the spark and injector pulse for the same cylinder in each case -- it certainly shouldn't be before it! But it might be hard to determine the relationship by visualizing the timing light flash. Since you've got a dual-trace scope, can you look at an injector on one channel, and at a corresponding igniter (coil primary) lead on the other. You should expect to see an injector pulse followed by a coil one, alternating with a coil pulse that has no preceding injector pulse (due to the wasted spark ignition). Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 [...] I have to keep one eye on my daughter, though...Or both eyes, if necessary. The car can wait a bit, I assume. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 I'm trying to find if the ignition primary lead 1 or 3 corresponds to what cylinders.... I would make sense if lead 1 fired 1-2 and 3 fired 3-4, but I'm not counting on that.... Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 [...]I would make sense if lead 1 fired 1-2 and 3 fired 3-4, but I'm not counting on that....I believe that's correct, but I understand your discomfort with assumption. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 According to Haynes I am right. 1 does 1-2 and 3 does 3-4 Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 I hooked up channel B (with no ground) to the ignitor output I get a good 12 volt deflection on the center lead (normal), but when connected to 1 or 3 and cranked to compare with the injector signal, I get no deflection. Should I be going between pin 2 and 1 as the ignitor should ground the constant 12vdc of pin 2 when it fires? Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 28, 2007 Share Posted November 28, 2007 I hooked up channel B (with no ground) to the ignitor output I get a good 12 volt deflection on the center lead (normal), but when connected to 1 or 3 and cranked to compare with the injector signal, I get no deflection. Should I suspect the ignitor? If the igniter was dead, you wouldn't have any spark at all, so I don't think the igniter deserves our attention right now. The igniter pulses the coil the same way the ECU pulses the injectors. That is, battery voltage is applied to the "high" end (common pin 2) of the primary, and the "low" end (pin 1 or 3) is switched to ground by the igniter. Therefore, if you are looking at pins 1 or 3 with the coil primary unplugged and no resistor connected from 1 (or 3) to 2, there'll be no voltage at those pins. I'd suggest connecting the coil, and back-probing pins 1 or 3, or use a resistor as you did with the injector. If you're already doing what I just suggested and have no pulsing voltage at the "low" pins, then we're moving into the "bizarre" area. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 28, 2007 Author Share Posted November 28, 2007 I back probed the low side of the coil between 1-2. I double checked to be sure I had contact with the probes (snipped leads of a diode). The battery is getting low, but I couldn't trace it on the scope when cranking. The output looked noisey??? I then put an analog VOM on it and the voltage was steady on .75 VDC and then peaking/pulsing at 1 volt when cranking. This doesn't sound right. I will try it again when the battery is charged. It is really taking a beating... Do you think the ignitor is not grounding properly, thus malfunctioning? Could the reading be because the battery is low? The spark I was seeing on the plugs might have been not so good? The coil steps up to what voltage? 1 volt would translate to ??? on the secondary? Enough to trigger the timing light, spark the plug weakly, but not to ovecome a fuel fouled plug??? I should check the ignitor ground? Quote Link to comment Share on other sites More sharing options...
subaru360 Posted November 29, 2007 Share Posted November 29, 2007 I back probed the low side of the coil between 1-2. I double checked to be sure I had contact with the probes (snipped leads of a diode). The battery is getting low, but I couldn't trace it on the scope when cranking. The output looked noisey??? I then put an analog VOM on it and the voltage was steady on .75 VDC and then peaking/pulsing at 1 volt when cranking. This doesn't sound right. I will try it again when the battery is charged. It is really taking a beating... Do you think the ignitor is not grounding properly, thus malfunctioning? Could the reading be because the battery is low? The spark I was seeing on the plugs might have been not so good? The coil steps up to what voltage? 1 volt would translate to ??? on the secondary? Enough to trigger the timing light, spark the plug weakly, but not to ovecome a fuel fouled plug??? I should check the ignitor ground? Platinum plugs foul really easy. I would recomend a fresh set of NGK standard plugs, crank it over with the plugs out to clear out the cylinders. (unhook the coil pack while doing this so you don't start a fire) Charge up the battery and see if it starts. It might just be fouled plugs and everyone is overthinking it. The timing of the injectors isn't going to make a difference at start or idle. If it has good spark at the right time and any fuel at all it'll at least try to start. A set of plugs should be like $10, it's worth a shot to me. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 29, 2007 Author Share Posted November 29, 2007 I'm going to test the signal from the ECU to the igniter first to follow this train of diagnosing the igniter and check the switching to the coil. Do you think that drying the plugs with compressed air and a 500 watt heat lamp was not enough to clear up the plugs? I also blew out the cylinders with compressed air. Putting the old ones in for a try was on the list to do, but I haven't gotten around to it yet. Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 29, 2007 Share Posted November 29, 2007 I back probed the low side of the coil between 1-2. I double checked to be sure I had contact with the probes (snipped leads of a diode). The battery is getting low, but I couldn't trace it on the scope when cranking. The output looked noisey???Unless the scope is isolated from the car's chassis ground (which it wouldn't be, if the other channel was connected to an injector and ground, as we previously discussed), I wouldn't connect a probe between terminals 1 and 2 (or 3 and 2), but rather 1 (or 3) and chassis ground. The igniter should pull pin 1 (3) low, then the pin should go high again. The period during which it's low is the dwell, similar to when points are closed in the Kettering ignition system. Like that older system, the coil fires at the end of the dwell period. If looking at two traces on a scope, the voltage at pin 1 (3) relative to ground should rise (indicating end of dwell, and firing of plug) just about at the end of the injector pulse. I then put an analog VOM on it and the voltage was steady on .75 VDC and then peaking/pulsing at 1 volt when cranking. This doesn't sound right. I will try it again when the battery is charged. It is really taking a beating...[...]No, that doesn't sound "right", but using a meter to measure pulses is difficult/misleading at best. Yes, charge the battery. Even if the engine cranks, too low a speed impedes starting, and below a certain voltage, the ECU can't operate correctly. Perhaps my comments about battery charge, etc., got lost in the length of this thread; see the last paragraph of my post #66. Do you think the ignitor is not grounding properly,[...]If you aren't getting even an occassional "cough" while trying to start, then weak spark is high on the list of suspects. Sure, the coil, igniter, etc., could cause a weak spark, but low battery voltage is a more common cause. Try to get enough charge on it so that during cranking it's at least 10V, preferably higher. Crank with the accelerator floored to clear excess fuel; that may seem counterintuitive, but there's an "unloader" function that's actuated that way. Quote Link to comment Share on other sites More sharing options...
sublute Posted November 29, 2007 Author Share Posted November 29, 2007 I'll scope CH B across 1 and the gnd. this morning. I'll let you know what it looks like. I am getting very slight coughs with turning over during all this. It might be because I'm having wishful thinking, but I seem to get more of a cough with an injector disconnected?? I'm doing more coughing than this car and so is my daughter. I'm off to the Dr. this morning because this is just not going away. ~3 wks!!!! Thanks so much for bearing with me on this. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted November 29, 2007 Share Posted November 29, 2007 (unhook the coil pack while doing this so you don't start a fire) hhhmmmm...i'm thinking i would just leave it hooked up..."just in case"! sublute, congratulations on staying task oriented and level headed through this, i'm not sure what i would be, but it wouldn't be good! Quote Link to comment Share on other sites More sharing options...
OB99W Posted November 29, 2007 Share Posted November 29, 2007 [...]Thanks so much for bearing with me on this.You're welcome. I hope you and your daughter get well soon. (And eventually, the same for the car .) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.