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That reminds me of a Peugeot I was asked to look at a few month ago with a suspected seized engine. The mechanic took the spark plugs out to see if relieving the compression would make it crank a little. If cranked a lot and sprayed 1.6 liters of fuel all over the workshop floor. They got me in to figure out why the cylinders were filling up with petrol. Turns out the ECU had developed a fault and was permanently switching on all 4 injectors as soon as the ignition was turned on.
 

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This is the best one.
Isuzu truck with injectors inside the rocker cover. Fuel line to injector not seated properly and filled the engine up with diesel. 100km/h and hydraulic lock. $58,000 later for engine alone.

 

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Discussion Starter #124
Now that I read the manual a little more closely the measurements between terminals 3 and 2 and 3 and 1 are for the two primary windings so should be the same at ~ 0.8 ohm. When I measure the resistance between the two output spark plug wire terminals on each coil I get the correct 10.3 K ohms. So looks like the coil is ok. Now I have to figure out why I don't have any spark when I used to. Still learning.
I'm quoting myself here - back to the current issue which is a new one as this used to work - no spark on any of the plugs. Checked the IGN and ECM fuses which are okay. Checked that the connector to the coil is providing 12V on one terminal to coil when ignition is on. Coil seems to ohm out ok according to the above. Is it possible for coil to still be bad if it ohms out okay?
 

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Yes I have found that but I am sure that's not whats causing your problem. It seems to be the grounding side which maybe thru an igniter? or directly thru the ECU. Autospark might know a bit more than me on that one.
 

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Just looking at a Mitsubishi wiring diagram which I think is the same as Hyundai back then and there is no igniter. The two coils are earthed individually thru the ECU so it's unlikely the ECU is at fault. Both coils do have a common power supply and a common earth. At this stage I would be try hot wiring each of these circuits and see if you get spark. Who knows you may have an intermittent power supply coming from the ignition switch.
 

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Is it possible for coil to still be bad if it ohms out okay?
Yes, that's a possibility. So we need to test the coil circuit to confirm that's what the problem is or rule it out. If the coil is getting from the circuit what it needs to fire but isn't producing a spark then that would be pretty good confirmation that the coil is bad.

The coil is just like every other electrical component on the car. It needs a power supply and a ground to make it work. You've checked the supply already, although you need to also check that the supply doesn't drop out during crank, as charlescrown suggests (remember battery voltage is approx 10V during crank). Once you confirm the supply is good during crank, check the two ground triggers. If they're also good then you can feel pretty confident that the coil has failed.
 

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If I am looking at the correct diagram (Mitsubishi Lancer hope it's the same) each coil has a transistor in the primary winding with the emitter going to earth. The coil would then fire when the base of the transistor is earthed thru the ECU. I would measure the primary current with the key on engine off and if that dosn't work (circuit design) I would see what the primary current is when cranking. You should see the meter fluctuating which would indicate that it is triggering the coils.
 

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Discussion Starter #129
Just looking at a Mitsubishi wiring diagram which I think is the same as Hyundai back then and there is no igniter. The two coils are earthed individually thru the ECU so it's unlikely the ECU is at fault. Both coils do have a common power supply and a common earth. At this stage I would be try hot wiring each of these circuits and see if you get spark. Who knows you may have an intermittent power supply coming from the ignition switch.
The coil has plastic caps covering 2 terminals on each coil pack. By hot wiring do you mean jumpering batt +12V to one of those terminals and grounding the other one and then checking that I get spark from that coil by cranking the engine? Sorry, electrical circuitry is not one of my strong points.
 

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If I am looking at the correct diagram
Your not.

charlescrown said:
each coil has a transistor in the primary winding with the emitter going to earth.
On Hyundai engines the coil driver transistor is inside the ECU.

charlescrown said:
The coil would then fire when the base of the transistor is earthed thru the ECU.
Not if the transistor's emitter is connected to ground it wouldn't. The transistor in that configuration must be an NPN transistor, so it would need a 'P'ositive signal on the base to switch the transistor on.

charlescrown said:
I would measure the primary current with the key on engine off and if that dosn't work (circuit design) I would see what the primary current is when cranking. You should see the meter fluctuating which would indicate that it is triggering the coils.
Before getting into all that I would just check to see if the coil is getting control signals from the ECU. If not there isn't much point to measuring the primary current.

rreitz said:
By hot wiring do you mean jumpering batt +12V to one of those terminals and grounding the other
You don't need to hot wire anything, and if you make a mistake doing that you'll damage the ECU. I would just check the inputs to the coil. If it is getting what it needs to fire but isn't producing a spark it's faulty.
 

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Discussion Starter #131
Ok here is what I did for the next test. Disconnected all spark plug wires from the coil. I made a 3 wire jumper between the coil male connector and the female connector in the wiring harness using paper clips bent to fit like clips on each of the spade terminals. Using the 12V test light grounded to the Batt negative terminal I verified that power is being supplied to the coil by touching the light tip to the paper clip on the power terminal. With key in run position there is ~ 11.8V on the power terminal. With key in crank position there is ~ 10.7V on the power terminal. Then verified that the light pulses when cranking on each of the signal lines. So far so good. So the coil is getting everything it needs. Next I attached a plug wire with old plug attached to #1 coil post. Crank engine and no spark. Tried on #3 post and no spark. Got a different spark plug wire and new plug and tried same test on terminals #1 and #3. No spark. Have you ever seen a failure mode where the coil ohms out okay but doesn't respond to the signal pulses? I could understand one coil failing but both at the same time? Can I conclude from the above that the coil is at fault or am I missing something else that I should try first? Thanks.
 

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How did you connect the test light when checking the signal pulses? The coil control signals are grounds so you want to move the test light clip to battery positive when testing those. The light should be off then blink during crank.

The other thing that I've mentioned before is the plugs on a wasted spark ignition are part of a series circuit, so I like to have spark plugs connected to both of the of the HT ports when checking for spark on that type of system. So that would be plugs on 1 & 4, 2 & 3.
 

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Discussion Starter #133
Well that was a good point about having two plugs attached. I also reversed the test light clip connection from neg to pos batt terminal as suggested. With the 2 plugs attached the light pulses on/offduring crank and both plugs now fire. Thanks for the reminder. So the hunt continues. I think I'm running out of things to check. New fuel pump, new CKS, coil and ECM appear to be functioning, Cam sensor appears to work at least with the crude wrench test to cycle between 5V and 0V (I'm still wondering if this could however be marginal), exhaust doesn't appear to be blocked since when I was able to coax it to start with starting fluid I went around to the tail pipe and exhaust was flowing out with no unusual noises, Idle air control valve rattles, new fuel filter, plugs get wet during crank. I think I'll put it all back together and see what happens.
 

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Discussion Starter #134
So I put it all back together, tightened up all the loose hoses that were removed to get at various parts, put the coil back on, wire brushed the plugs and put them back in, pushed in the fuel pump relay, connected the fuel pump power connector under the rear seat and inserted the key. It started right up. Let it run for 25 minutes, radiator fan came on/off two or 3 times ran a little longer then turned it off. That's the good news. The not so good news is that after I put the new fuel pump in a few days ago it didn't start however the plugs were wet. I checked the coil at that time by removing all 4 spark plugs, inserting them back in their cables, grounding all 4 to the block and cranking the starter. None of them fired. However today, without changing anything else since the last no start, it decided to start up all by itself and idle like it used to. So I still don't trust it and having it quit abruptly while moving in traffic is not a pleasant experience - especially for the folks behind me. Still wondering if there is some heat sensitive component still lurking somewhere. I'll play a little more with it in the driveway and maybe get my nerve up to go up the hill from my house. At least I can coast down if need be (have done that before). To be continued ...
 

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You have to remember that it's very unlikely that both coils could fail at the same time. The ECU has separate earths to trigger the coils so you need to looks elsewhere for a common thing to all cylinders. Anyway good to see it's running. Had to chuckle and think it's possessed with your statement that "it decided to start up all by itself and idle like it used to".
 

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Sounds like the engine tried to start then failed to start in the middle of it
Plugs were wet and no spark to start engine
There seems to be some sort of bad electrical connection somewhere??

Next time it doesn't want to start, try smacking the engine fuse box with the other end of a screwdriver
Just a guess.
 

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However today, without changing anything else since the last no start, it decided to start up.
You did change something though. You had the coil disconnected and you inserted your breakout leads to check the coil wiring. Before that there was no spark, and now there is. Whatever you moved while doing that would be worth moving again now with the engine is running to see if it will stumble or die again. Could there be a poor connection on the coil harness connector perhaps? Try giving that a good wiggle, twist and pull on it lightly to see if it has any effect. It definitely seems like there is a problem with the coil wiring and you have disturbed it when you done your tests.
 

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Discussion Starter #138
Next time it doesn't want to start, try smacking the engine fuse box with the other end of a screwdriver
Just a guess.
Actually I did pull the IGN and ECM fuses, checked them with an ohm meter and then reinserted them so who knows if that reseated something. However there was no corrosion around the pins.
 

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Discussion Starter #139 (Edited)
You did change something though. You had the coil disconnected and you inserted your breakout leads to check the coil wiring. Before that there was no spark, and now there is. Whatever you moved while doing that would be worth moving again now with the engine is running to see if it will stumble or die again. Could there be a poor connection on the coil harness connector perhaps? Try giving that a good wiggle, twist and pull on it lightly to see if it has any effect. It definitely seems like there is a problem with the coil wiring and you have disturbed it when you done your tests.
Your right, I should have said I didn't replace anything. I actually unbolted the coil and had it laying next to the engine because I couldn't get my breakout leads inserted with it installed. I also grounded the coil body to the engine with another wire then used the light to test what was happening on each of the leads. Tonight after work I will start it up (assuming the gremlin doesn't want to play games) and play with the connector to see what happens. I sure would like to find something solid before venturing out on the road again.
 

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Discussion Starter #140 (Edited)
Whatever you moved while doing that would be worth moving again now with the engine is running to see if it will stumble or die again. Could there be a poor connection on the coil harness connector perhaps? Try giving that a good wiggle, twist and pull on it lightly to see if it has any effect. It definitely seems like there is a problem with the coil wiring and you have disturbed it when you done your tests.
Bingo!:grin2: Got it started let it run a bit then opened the hood and pushed the coil wiring harness connector towards the firewall and the engine stumbled and stopped. Tried to start it and nothing but cranking. Pushed the coil connector and harness towards the front of the car and it started right up. Pushed the connector again and it stopped. Examined the male side of the connector on the coil side and the case is cracked on the bottom where it is supposed to have a slot that holds it firmly to a tab on the coil housing. The connector was floating on top of this tab but not secured. I can't believe you pinpointed this down to the exact connector! In all fairness, Charlescrown previously recommended a more general wiggle test in a previous post but I probably wiggled everything but the coil wire harness or maybe didn't push/pull like I did this time. I have a new coil on the way since the cracked housing is on the coil side however I will check the female side as well. New coil should be here Weds. After I put it on I will perform the wiggle test several more times to make sure and see if I can get the old coil connector to misbehave off the car using an Ohm meter while push/pulling on the connector. Will post with the results.
 
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