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Old 08-18-2008, 09:00 AM   #1 (permalink)
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Default ignition coil questions

Trying to troubleshoot a stalling problem I had last week and I am running tests on the coil. Test 3 between the battery positive & the coil negative with key off should be 0, but I'm getting full battery of 12.44. With ignition on should still be 0, but now I get .11. When cranking it increases to .25.

Manual does not say what this means. Am I looking at a bad coil, amp, or grounding issue?

If it is the coil, is the Bosch coil the best option or something else? Cheap Napa coil?

And if it is the amp, what do you think of the Toddco setup?
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Old 08-18-2008, 02:34 PM   #2 (permalink)
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More info...

With the amplifier unplugged from the coil I still get the same readings.
Installed new coil and I still get the same readings.
The other wires to the coil are from the ignition switch right? So am I looking at a switch problem or something else???
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Old 08-18-2008, 02:47 PM   #3 (permalink)
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It basically means that your wiring has been tampered with. Should have no voltage to the coil when the ignition is off. You need to check wiring diagrams and work out what is working in reverse.
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Old 08-18-2008, 03:57 PM   #4 (permalink)
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More info...
With the amplifier unplugged from the coil I still get the same readings.
Installed new coil and I still get the same readings.
The other wires to the coil are from the ignition switch right? So am I looking at a switch problem or something else???
Hi Kevin,

You are on the logical track. Stay focused. P76rangie means well..but you can go through his proposed wiring saga later. Right now, you want to get your car started. Power to the coil (ignition off or on) is not something that normally prevents running...at least for your last few years.

Your swap in of another coil was wise. The extra expense is negligible and returnable for refund, a no price to pay to avoid testing frustration. I am assuming you tried to start the car with it in.

First..some basics...I have assumed you tested for spark and/or fuel pressure?

If you have confirmed no spark, I would now over to the amplifier. Do you have a 45DML8 distributor. If so their amplifiers fail if you simply stare at them in the wrong way.

There is a new, MUCH cheaper and more reliable aftermarket replacement than the original. I just recommended one to a US friend. It comes from Rovers North, their part no. PLI024. It comes with a wiring loom that will make it work with either the 3 or 2 pin distributors.

James
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Old 08-18-2008, 06:37 PM   #5 (permalink)
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Thanks for the responses Ian & James.

I was not completely clear in my original post. Here's the whole story as to why I was checking the coil.

The Rover starts & runs. I was doing a test drive last weekend since she has been laid up for sometime. When I was going down the highway about 10 miles from filling up, she stalled 3 times. Total loss of power. No hesitation or warning... just died at 60mph. Restarted fine the first two times. The third time she would just crank over & not catch. AAA towed her home.

Initially I thought fuel related since I had just filled up and she was driving fine all morning around town. Clogged filter or blocked breather perhaps. But after I got home I investigated more. After messing with the coil and all the connections, she started up like normally.

Ran tests on the coil and it all checked out except for the power going to the coil with the ignition off. Also found the wires from the amplifier to the coil had been burned by the exhaust manifold. Repaired them (which might have been the initial problem causing the stall). I did not do a visual check for spark since she runs & I did not have a helper. Installed new coil with same results, but she sounds better than before.

Will check the wiring at the ignition switch tomorrow.
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Old 08-18-2008, 11:14 PM   #6 (permalink)
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The Rover starts & runs. I was doing a test drive last weekend since she has been laid up for sometime. When I was going down the highway about 10 miles from filling up, she stalled 3 times. Total loss of power. No hesitation or warning... just died at 60mph. Restarted fine the first two times.

After messing with the coil and all the connections, she started up like normally.

..found the wires from the amplifier to the coil had been burned by the exhaust manifold. Repaired them (which might have been the initial problem causing the stall).
Well done.

The symptoms you describe are characteristic of an anomaly with issue with amplifer module. I agree, you might have already have cured the starting/running issue when you sorted its wiring. If it does reappear, I can post a dealer testing procedure for coil, amplifier and distributor.

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Will check the wiring at the ignition switch tomorrow.
Ignition switched power is white. The switch feeds many components through a spreading network of white wires so it is unlikely that you will much to help you at the switch itself. A better start would be the fuse box.

James
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Old 08-19-2008, 12:13 PM   #7 (permalink)
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This is so odd. Been pocking around with fuses, relays, & ignition switch but did not find anything. Re-ran the test. Still getting battery power with the ignition off. Get the same readings with everything connected, amp disconnected/ignition connected, and amp connected/ignition disconnected. Only time I get zero is with everything disconnected.

This does not make any sense to me. The only thing I can think of now is a ground problem or a bad multimeter. Any other suggestions????
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Old 08-19-2008, 04:23 PM   #8 (permalink)
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This is so odd. Been pocking around with fuses, relays, & ignition switch but did not find anything. Re-ran the test. Still getting battery power with the ignition off. Get the same readings with everything connected, amp disconnected/ignition connected, and amp connected/ignition disconnected. Only time I get zero is with everything disconnected.
You have yet to confirm the year, model and country your vehicle was made for. It would help if you also noted the model number on the distributor. From some of your description, I am guess it is a 35DLM8 with the amplifer on the body. Can you confirm?

I presume you have a wiring diagram. If you look at it you will likely see that the amplifier and coil are powered by the same white wire. It feeds the amplifier and the coil. That explains all the readings you have seen.

You have two unrelated directions to take. I. You can continue with the ignition problem and test the coil, amplifier and the distributer fully if you want to. OR 2. you can change tack and see if you can find why the white wire is giving you a battery feed rather than an ignition switch feed.

Take your pick.

James
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Old 08-20-2008, 05:39 AM   #9 (permalink)
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you can change tack and see if you can find why the white wire is giving you a battery feed rather than an ignition switch feed.
Hi Kevin,

James means well but is yet to learn how to read.

James, He has stated that the test he is doing is running the positive lead of the multimeter to the BATTERY. He is then running the earth wire to the negative side of the coil. It seems that this is a test listed in a manual. It would appear that this test is suppose to show no voltage on the multimeter as it should not be getting earthed. But he is getting a voltage reading and therefore the negative side of the coil is earthed.
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Old 08-20-2008, 06:44 AM   #10 (permalink)
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Originally Posted by Kevin88RRC View Post
Test 3 between the battery positive & the coil negative with key off should be 0, but I'm getting full battery of 12.44. With ignition on should still be 0, but now I get .11. When cranking it increases to .25.
First off, Kevin, I think nothing is wrong with the readings you see.
A long time ago, I recall a thread where someone was attempting the test you are doing and it was pointed out that the Manual is wrong. This should not be shocking, just a reminder not to believe everything you read.

If you connect the VOM between the Bat.+, and almost anything on the truck, you'll get some reading, depending on the resistance to ground your neg VOM lead is connected to.
The simple truth is, that when you are running, shut the key off, and the engine stops, you have broken the voltage path from the battery, and are no longer getting + voltage to the ign. circuit, and life is good.

If it's of any reassurance, I have tried to replicate what you did, and also show voltage. I am not remotely troubled that I see this ( if it's only because I have more experience with electrical systems, than the proofreaders of whomever writes Land Rover manuals) I'm not suggesting that you even bother, but were you to unscrew the amplifier from the distributor, you would see your meter go to zero, because the amplifier gets a ground from the heatsink plate on the back of it.
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Old 08-20-2008, 06:59 AM   #11 (permalink)
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Thanks Terry. It's annoying knowing that parts of the shop manual can be wrong. After having the high speed stalls (which I hope was caused by the burnt wires to the amp), I just wanted to make sure it did not happen again.
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Old 08-20-2008, 07:43 AM   #12 (permalink)
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The 'mystique' from using the term "electronic" scares people into believeing there is some black magic going on here. The facts are much more simple.
If you had a conventional set of points, in a conventional old distributor, and you melted the insulation on the single wire from the coil to the distributor, and the exposed conductor began to intermitantly ground to the manifold, you would get a stalling out situation, because you no longer had high tension spark.

It's no different with electronic, breakerless ignition.
The circuit inside the amplifier should be of no consequence to us, but all it is is a device which does the switching, just like the points did in a conventional distributor, but because the pickup coil is only that, it just makes a circuit within the amp to switch the coil. I am of the opinion that it's really a poor choice of words, describing it as an amp, it's really an electronic switch, whose on and off characteristics are sharply defined, like points, but without the arcing and variability of ever changing gaps that mechanical points have.
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Old 08-20-2008, 05:10 PM   #13 (permalink)
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Hi Kevin,

James means well but is yet to learn how to read.

James, He has stated that the test he is doing is running the positive lead of the multimeter to the BATTERY. He is then running the earth wire to the negative side of the coil. It seems that this is a test listed in a manual. It would appear that this test is suppose to show no voltage on the multimeter as it should not be getting earthed. But he is getting a voltage reading and therefore the negative side of the coil is earthed.
P7rangie! You're back! You HAVE been missed. I see you haven't changed.

Let's look together (hand in hand) at where Kevin was. He tested power and "Gets the same readings with everything connected, amp is connected/ignition connected, and amp connected/ignition disconnected."

Now I want to proceed with you very slowly with this. Assuming power from the same source branches to both the ampflier and the coil separately, here are some tough questions for you to answer;

1. If you leave all the wires to coil and amplifier connected, will you still have power to the coil?

2. Now, (here is the biggie!..prepare yourself) If you pull the wire to the amplifier, will you still have power to the coil?

If you got this far correctly. You will see why Terry and I noted that there is nothing wrong in the readings Kevin saw in his "tests". His concern for his multimeter is unwarranted.

The problem of power with ignition off is simple. Someone, sometime in this vehicle's history has provided a battery feed to the coil, somewhere in his wiring, either in addition to the ignition feed or instead of it. It is NOT a major issue in itself but it is curious and may indicate the existence of back feeds in the fuse box.

If you think he can cure that problem at the coil or its earth..I think you should go for it!

James
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Old 08-21-2008, 01:57 AM   #14 (permalink)
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You're back! You HAVE been missed. I see you haven't changed.
I go into this site twice a day. There just hasn't been anything I have felt the need to comment on. It is just that some people want to have a go at you rather than deal with the issue. So I responded.
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Old 05-09-2009, 05:01 AM   #15 (permalink)
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Hello to all u land rover nuts out there I have a problem with my disco and wondered if any one has had similar that they could throw some light my way I drove to the store and all was fine on way home the car just died no power backfired lots and max speed was approx 5 mph it was as though the leads had been swapped.

I have checked fuel pump all ok replaced dist cap leads plugs still ran rough got 2 experts mobile mechanics they scratched their head and walked away one charged me $30 to tell me he could not fix it.

replaced module on dizzy now no spark so the only thing i got left is the coil any suggestions guys
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