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Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on October 19, 2008, 2:23 pm

With a little time on my hands yesterday I had a Renault Megane Scenic come in with the usual pencil coil failure. I quickly identified the cylinder by disconnecting the injectors one by one. Cylinder 1 (pulley end) was the culprit & I made the following captures on all cylinders.

This first image shows each cylinder igntion primaries versus current as the vehicle was presented to me. they are set out in cylinder order 1 & 2 Top row & 3 & 4 bottom row.......

This next one shows the result of replacing just the single faulty coil.......

Interesting how the grounding on cylinder 2 (red signal top image) is held totally to ground & the sparkline voltage is noticeably higher in that example. The lower image shows a grounding just the same as all the other cylinders & the sparkline voltage is lower??? I don't know why they aren't held to ground fully, but I have noticed the same thing on other cars too with apparently no ill effects.

The primary trace (in red) on misfiring cylinder appears to be normal with a good sparkline voltage & burn time, even though it had a total misfire. I suppose I must be seeing the event on opposing good cylinder. I haven't studied a wiring diagram yet to see if they share the same grounding trigger path.

Any thoughts anyone?

Cheers

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on October 20, 2008, 9:33 pm, in reply to "Renault Megane Scenic 1600 16V Pencil Coil Fault"

I love the way Scoping opens up areas for greater understanding & this is a good example of how it can lead you to the answers. Fortunately I had a Clio in today with the same kind of coil failure & it gave me a great opportunity to follow up on Saturdays research. Coupled with a study of a wiring diagram it all became a little clearer.

Here is the wiring diag..........

These coils are wired in "series" so that coils 1 & 4 are fired simultaneously & then coils 2 & 3 are also fired as a pair. This circuit arrangement also means that if there is a "break" in the circuit i.e. it goes open circuit, then the pair of coils will become inactive (rather like Christmas tree lights do

) I knew that these coils acted as a pair, but I had no idea how basic the circuit was. I carried out a few tests to confirm the actual layout of the circuit in real terms. On each coil, the upper terminal is the “feed in” & the lower terminal is the one that is switched. Here is a photo that hopefully makes it more clear......

On the Clio I tested today, I noticed the exact same effect that I saw on Saturday & now having studied the wiring diagram it makes sense. Coils 3 & 4 are not directly switched to ground, but instead the circuit continues through the other coils 1 & 2 respectively. This explains why the grounding on coil 2 is full & coil 3 is only partial.

The problem with this explanation is, that it means that my previous scope examples must be wrong.

. In my first post, the "good" example after the fix, should display a fully grounded primary capture on cylinders 1 & 2. The thing is, I am very methodical about how I scope & save my files & I still have a niggling doubt that I have missed something. Only Time will tell, as I test a few more as they come in.

The Clio today looked like this…....

Cylinder 1 = Blue
Cylinder 4 = Red

Cylinder 2 = Blue
Cylinder 3 = Red

I hope I haven't confused anyone too much

Cheers for now

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Steve Nicholas <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5547' width='330' height='300' border=0 style='border:none;'> on October 20, 2008, 9:59 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Stephen Nicholas

Thanks for posting this Dave.

I like the animated GIF pictures - novel!

Regards,

Steve

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on October 20, 2008, 10:24 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Thanks Steve.

But did you learn anything from them? I enjoy putting these animations & posts together, as it helps it all sink in (for me as much as anything). But I would hate to think that folks just see them as fascinating cartoons!

A moving waveform draws you in a bit more than a static image. After all a single capture can be a little misleading sometimes.

It can also be a little risky, doing your learning in public!

Cheers for now

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Sean Connelly <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5507' width='330' height='300' border=0 style='border:none;'> on October 21, 2008, 9:36 am, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Hi Dave,

Very interesting and well documented post.

Where were you attaching your scope probes and were they actual scope probes with individual earths?

I can't explain your first set of traces but the ones in your second probe look correct except have you got the cylinders/coils swapped round? Shouldn't the top coil in the pairs (1&2) show the primary above the 0V as its got the resistance (and therefore voltage drop) of the second coil to be included in its trace, where as the second coils in the pairs (4&3) are closer to ground (though same current flowing through both). Though you will never get 0V as you will always have the voltage drop across the junction of the coil driver (0.6V?) in there...

I guess it depends how each scope channel was earthed....but must admit my head is starting to hurt now trying to figure it out ;-)

Cheers

Sean

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Bryan Smith <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5330' width='330' height='300' border=0 style='border:none;'> on October 21, 2008, 11:00 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Bryan Smith

Nice captures Dave. I currently use a Sykes Smart which is about 6 years old. I can post saved captures but everytime I see a Pico capture on here I take another look at the brochures and have decided that one will be my next investment. Incidently, everytime I have replaced one of these coils, which have been quite a few, I have fitted Beru (someone may tell me that they are oe anyway

) and so far none have failed a second time. The way I diagnose them (and again someone will probably tell me its wrong) is to remove the screws and just lift each coil gently so that you can here the arcing and the one that is faulty will be silent. I am very careful not to move the coil away too far to avoid any spikes.
Regards, Bryan.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by tony bickers <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on October 21, 2008, 11:33 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Tony Bickers

Interested to know whether you only replace one coil or the whole set? my experience with these horrible piles of french rubbish is that if you replace only the coil that is faulty over the next few weeks you will have the customer through the doors another 3 times to replace the rest,I only ever replace these as a set and tell the customer of the consequences of wrecked cat through petrol poisoning whenever I see one. Even Renault dealers replace these things singularly and I have had them in a few weeks later with another coil gone down. Last bill I saw from a dealer they charged 85 quid for a clip read plus VAT.Bryan, I keep these on the shelf and the latest version make is Valeo with a brown top.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by lee mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 12:00 am, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Lee Mackintosh

I think the Valeo ones are £27 and the Beru ones are £17 +vat from GSF. I've only ever fitted Beru ones and never had a problem yet.

Most of the time i advise customer to fit a complete set but rarely does that happen.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Tony Ludford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5539' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 8:05 am, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Tony Ludford

I think the original OE supplier for these were BERU, but Renault wanted them cheaper, so along came Sagem....

We fit them in pairs 1&4, 2&3 to prevent any repeat call-outs. Seems to work well, without charging for 4. (Give them the other good one as a spare, and if one of the others fails, they have one to fit, as a temp. without spending a fortune).

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Peter Warman <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=Peter+Warman' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 8:10 am, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Peter Warman - Administrator

I can confirm that

I have a customer with an 05 Clio, she rang last Friday with a misfire she was due in Monday but called the AA out first thing as she was a bit worried about driving it, they replaced 2 coils

The AA have replaced 2 coils twice and i have replaced all 4 once

Peter

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 1:52 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Peter Mutlow

Hi Bryan. The quickest and perhaps safest way of testing these coils without firing up picoscope is attaching a plug lead between coil pack and plug left in situ and then attach timing light to plug lead and watch the flashes (or lack of them). I always advise buying four but so far advice not accepted. Not had any comebacks with after market stuff nor another trip to replace the others.

Regards

Pete M

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Tony Ludford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5539' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 5:03 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Tony Ludford

What is she doing with it Peter?
Using it as a boat?

or is it valeted regularly?

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 9:45 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Hi Sean

The captures that display a full grounding were taken with the probe positioned at the lower terminal on the coils nearest (in the photo)

These two coils are the ones that are earthed directly by the PCM. The coils furthest away (gearbox end) are the ones with the direct feeds & their earth path has to go via the other coil in the circuit before the PCM switches it.

I must admit that my post is confused further by me, quoting cylinder numbers in a conventional way, rather than the odd way that the French do it.

I always offer the advice that a set of coils is preferable, but the decision is theirs. So long as they understand that repeated visits to the workshop, will give rise to further diagnostic costs, I am not worried how many they choose to have

.

Cheers for now

Dave

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by tony bickers <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on October 22, 2008, 11:33 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Tony Bickers

Hi Dave,

Your pics show blue top coils, is this before or after repair? I have latest level coils from Renault on the shelf, and they are brown top Valeo, I enforce my earlier post , if you do not replace all the coils the thing will be back through your doors, seen it too many times and every time it comes in I do an emmission test because a downed coil is going to kill the cat !

Never used aftermarket coils on these and don't think I ever will with all the documented and recorded faults with these components, if a duff set of spark plugs can play these up, what would a coil do !!

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on October 23, 2008, 7:05 am, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Hi Tony

I am pretty sure that the injectors are shut down when the PCM decides which cylinder is misfiring. I have done many many of these & as you do, I perform an emissions test & have never seen a failed cat as a result. Fords however

Their catalysts must be made to such a low standard I think.

The car that cam in on Tuesday had been in previously for a single coil, but that was 18 months ago, so the customer is not jumping up & down, but I know where you are coming from.

Cheers now

Dave

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Bryan Smith <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5330' width='330' height='300' border=0 style='border:none;'> on October 23, 2008, 12:07 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Bryan Smith

Hi Tony,
I do much the same as others have said and advise all four then let them make their own mind up. I will still not fit genuine though. If Beru are good enough for other VM's then they should be good enough for Renault. And as mentioned, they are the cheapest branded type and seem to be more reliable. I had one customer who had two full sets from Renault at huge expense and even though he came to me four times in two years he was more than happy. I do the same as others and check the catalyst everytime with no problems so far. I think most people come in as soon as it starts to misfire.
Regards, Bryan.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Shaun Dale <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2719' width='330' height='300' border=0 style='border:none;'> on October 28, 2008, 2:33 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

I have kept some known good secondhand coils when I have replaced sets. First thing I do is stick a scanner on and see if there are any misfire codes logged (bearing in mind that No 1 is the gearbox end). Then I fit a known good coil to confirm it, then I get a new one in.
On several occasions I have had No1 or No2 plug wells full of rusty water but have never found out how it gets there, I think it may be rain water run off from the scuttle but I am not sure.
On one occasion very recently one coil (No2) was badly water damaged and still working but No3 was the faulty one. I wonder if water temporarily shorting No2 out caused No3 to be damaged, the pair were replaced.
Shaun

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Jim watson <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5178' width='330' height='300' border=0 style='border:none;'> on October 28, 2008, 4:45 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

You also find the earlier ones had no "O" ring on them but later ones do.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Steve Gittins. <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1086' width='330' height='300' border=0 style='border:none;'> on November 26, 2008, 4:12 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Just a quick question which is slightly off on a tangent but I am after some help and have searched without success. Ive recently tried checking the ignition coil primary trace on a few different cars with varying success. Can anyone tell me if I'm doing something wrong. On some training courses ive used a Pico scope (which is excellent) and had no problems but (until I can get some money together for a Pico) I personally use a small handheld unit the same as this http://www.autodiagnos.com/en/products/autoscope/

The most recent car was a Renault Megane (with the troublesome pencil coils). When I connected the scope I get a missfire on that cylinder but do get a reasonable scope trace????? The car before which is a Datsun 280ZX Just stops as soon as I connect the scope??? I wonder if the scope is not suitable??? Maybe there's a breakdown in the coil signal due to the scope??? can anyone give me any pointers/advise or tell me what im doing wrong??? I have connected the Negative to the battery Negative and the Positive to the Coil, I cant see as its possible to do anything wrong here, Can anyone confirm?.

Many Thanks.
Steve.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Tony Ludford <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5539' width='330' height='300' border=0 style='border:none;'> on November 26, 2008, 10:22 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Tony Ludford

Try putting the leads, one to the Battery positive, and other to the coil switching circuit.
(I may be wrong though,as I use a multi-meter not a scope for switching tests)

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on November 27, 2008, 11:20 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Hi Steve

Dont be too disillusioned when you cant identify a failing coil on a Renault. Even with Pico, it can be hard (if not impossible) to clearly identify the offending coil. This is due to the fact that they are wired in series (as discussed previously)

I cant offer any advise as to your Datsun question though. I am sure that the more experienced guys will have something useful to offer though. Just a thought..... You havent got an option to measure amps on that tool have you? make sure your settings are correct

Cheers

Dave

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by Steve Gittins <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1086' width='330' height='300' border=0 style='border:none;'> on November 28, 2008, 9:47 am, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Hi Dave. Ive got the hang of (we'll sort of) the trace and what you should or should not be seeing. The problem I'm having is that when I connect the scope to a coil it seems to introduce a random misfire with a primary trace that has some occasional hash that seems loosely related to the misfire. As soon as I disconnect the tool the misfire stops. I cant decide if the misfire is on the cylinder I'm testing or the other cylinder thats in series with the one I'm testing. Any ideas???? I don't think its anything I'm doing but could well be wrong. Is it possible it could be the scope??? Anyone any idea's???

Cheers.
Steve.

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by george brockis <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1046' width='330' height='300' border=0 style='border:none;'> on November 28, 2008, 12:05 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

I had a faulty scope lead on my pico ,brand new out of the packet, dead short. luckily it only blew the fuse on this 406,gave me a worrying few minutes till i found the fuse as i thought i killed it . Try it with another lead as the scope should not affect it.
GEORGE

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by UKAT5354 <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5354' width='330' height='300' border=0 style='border:none;'> on November 30, 2008, 8:25 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"
Gwyn Williams

Hi Steve, so my little Interro is not so obsolete after all!! Quite a shock to see that AD are flogging them. Interro are a Californian Company which was taken over by Omnitec a few years ago. This very good scope was the USAs "Tool of the Year" in the early nineties.More can be read about it on Omnitecs American website. As for your problem with coils, you need to use the resistive O2 lead which should have been included with the tool. If not, try Ad to buy the lead.You will have to set the probe to read O2, otherwise the oscilloscope trace will be too small. You are correct in thinking that you are causing the misfire, indeed, if you were working on a single coil conventional distributer system, the engine would have stopped as soon as you touched the probe on the negative terminal. Any more info required, just ask, regards, Gwyn

Re: Renault Megane Scenic 1600 16V Pencil Coil Fault

Posted by UKAT1086 <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1086' width='330' height='300' border=0 style='border:none;'> on December 1, 2008, 1:29 pm, in reply to "Re: Renault Megane Scenic 1600 16V Pencil Coil Fault"

Excellent. Thankyou Gwyn. Its actually an interro that I have. I had guess it was some sort of lack of resistance but had no idea thats what the O2 lead was. There was a small device used in the lead on the Pico which I guess would be the same thing. I'll give it a try.

Thankyou.
Steve.

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