How to Test coil packs

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martinrkey
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How to Test coil packs

Postby martinrkey » Tue Dec 11, 2007 10:47 am

This is info for all the people that have problems during running (lack of power/ missfire) and also start up problems due to coil packs.

To save money and to save a costly trip to renault for diag. you can test each coil yourself for free this is totally cost free and will take around five mins.
1: Open bonnet, remove plastic cover over engine
2 you will see each coil pack held in by a 10mm nut, undo all nuts and keep safe so not to fall in engine.
3:Start engine, now pull out each coil one at a time, If you do this in the dark(makes it easer to see) and the coil packs are faulty you will see sparking around the middle of the coil just above the the rubber cup and near to the center where there is a metal piece. Also to chack each one is working ok place rubber cap end near to the engine mount and you should get a good arc, if not then its no good.

Each coil pack is around £40 buy and fit yourself as the way you removed them above.

Also a tip if you look at the coil pack and just above the rubber cup the plastic is turing yellowy then thats a good sign that they are arcing out at that place.

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BurntCarcus
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Postby BurntCarcus » Tue Dec 11, 2007 12:10 pm

Good post m8, had many of these things go on me, had to limp 26 miles home from work one day on 3 pots. Another thing you could do is start the engine and remove a coil one at a time. You will hear it drop to 2 pots if you pull out a good one(may even stall) and no change when you pull out the duff one, thats if it has gone completly and is only running on 3 pots to start with. I always had a spare under the floor :cool:
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AlexB
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Postby AlexB » Tue Dec 11, 2007 2:06 pm

martinrkey,

Running a coil without load is almost a guaranteed way of damaging it! Better use a smallneon lamp. Approach its glass tube to the coil and hold it by the wires. The working coil will cause the gas to glow. Get one of these:
https://en.wikipedia.org/wiki/Image:Neonowki.jpg
AlexB
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martinrkey
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Postby martinrkey » Wed Dec 12, 2007 10:05 am

By holding the neon lamp near the wires would only show that there is power going to the coil and not show if the coil is working correctly wouldnt it?? also by keeping the rubber end near to an earth ie the engine mount or head you will be releasing the load that way. But if its sparking in the middle of the coil then is knackerd anyways. I did say in my post to do one at a time that way the coil will only be under load for a few seconds (enough to see if working) so likely hood of damage will be to a minimal.

martinrkey
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Postby martinrkey » Wed Dec 12, 2007 10:11 am

BurntCarcus wrote:Good post m8, had many of these things go on me, had to limp 26 miles home from work one day on 3 pots. Another thing you could do is start the engine and remove a coil one at a time. You will hear it drop to 2 pots if you pull out a good one(may even stall) and no change when you pull out the duff one, thats if it has gone completly and is only running on 3 pots to start with. I always had a spare under the floor :cool:


Hi thanks, just trying to give a little advise to save money. Your idea is just as good but when i done that two of my coils had just enough life in them to still cause a spark, but when pulled out there was arcing all over the place in the middle and at rubber end. The next day they went down completly, Using both our ways will give a def outcome if coils work or not.

Hope this help people

AlexB
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Postby AlexB » Wed Dec 12, 2007 11:13 am

To cause a spark in dry air under the normal pressure you need 30kV per cm. The normal gap in a spark plug is just under 1 mm. The gap in wires when you pull out the coil can be more than 20mm. So, you are overloading the insulator significantly!

As for the neon lamp, it will only show high intensity electrostatic fields caused by working coils. A half-dead coil can be detected by comparison.

Another simple way is to remove the spark plugs and check their condition.
AlexB
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markren2004
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Postby markren2004 » Tue Dec 18, 2007 1:00 pm

the haynes manual has a method for testing them.
I'll dig it out tonight and have a look at what it says.

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72uoba
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Postby 72uoba » Tue Dec 18, 2007 1:29 pm

I was under the impression that doing this can cause serious damage to the ECU and is thus not recommended in modern cars.

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Postby markren2004 » Tue Dec 18, 2007 7:53 pm

markren2004 wrote:the haynes manual has a method for testing them.
I'll dig it out tonight and have a look at what it says.

ok, the haynes manual says to test coils / ignition system you need to remove the spark plug and reconnect it to the coil, so it's attached, but obviously outside of the engine.
Then earth the outside of the spark plug to the bodywork using a jump lead and then start the car...looking for a good spark.
It says if you just pull off coils it can cause serious damage to the coil and/or the ECU.

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Postby snowy » Wed Dec 19, 2007 10:11 pm

how many miles did your coils give you before they packed up?

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Postby yoshimi » Wed Dec 19, 2007 10:35 pm

I've had this problem too. Car's just back from Renault with a £160+ bill for diagnostic and coil replacement. Car is 6 weeks out of warranty. :evil:

markren2004
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Postby markren2004 » Thu Dec 20, 2007 8:47 am

yoshimi wrote:I've had this problem too. Car's just back from Renault with a £160+ bill for diagnostic and coil replacement. Car is 6 weeks out of warranty. :evil:

I read somewhere that renault extended warranty on coils to 4 yrs. don't know how true it is, but worth seeing if you can get your money back.

glenn47
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Postby glenn47 » Thu Dec 20, 2007 7:10 pm

I've got a 53 plate (Nov 2003). My coils packed up september this year. Renault garage replaced them free of charge saying the warranty on those coils had been extended to 4 years. I just got in. Might be worth a go.

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Postby Bumpy macaroon » Fri Feb 22, 2008 9:42 am

Have posted this on the toxic fume sticky, thought i would put it here aswell
wifes third coil just gone westward, third winter in row so same old procedure call ren assitance AA turn up told him it was a coil and then he did something i had not seen before,
usually they just plug the laptop into the car but this guy removed a metal casting off the front of the engine block between engine and radiator, held on with two bolts, this revealed the petrol injectors, with the car running he then disconnected one if the injectors electrical connections first one the car almost died (now firing on two pots), reconnect back to how it was and then disconnected the next, no change, which pointed at coil for third cylinder, change coil restart - fault gone,
seemed to me to be a very easy way for the home mechanic to diagnose a coil problem without causing possible damage to a serviceable coil have read somewhere that removing coils when running can cause them problems.
Oh and before I go the coil he put in has a brown top instead of grey when asked he told me they (the brown) are the new modification, the grey ones had had two or three changes to them over the years and before the grey there were black caps dont know if any of this makes sense but it may help someone
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Re:

Postby dwgendy » Sun Feb 01, 2009 5:11 pm

markren2004 wrote:
markren2004 wrote:the haynes manual has a method for testing them.
I'll dig it out tonight and have a look at what it says.

ok, the haynes manual says to test coils / ignition system you need to remove the spark plug and reconnect it to the coil, so it's attached, but obviously outside of the engine.
Then earth the outside of the spark plug to the bodywork using a jump lead and then start the car...looking for a good spark.
It says if you just pull off coils it can cause serious damage to the coil and/or the ECU.


How about that, the Renault dealer tested the coils infront of my eyes by earhting them to the engine to show me they were working properly!!! When is said that would damge them, he replied in a condescending manner saying "who told you that? that not true at all". I've been having problems with the car since then, car shakes and knoks on low speed and gentle gass pedal pressure. Anyone suggest anyhting?
Megane II sedan, 2005, 1.6, 16V, Steptronic.


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