Intermittent spark related problem - need your help

[apeman69]

Sorry folks, this is a long one again!

For the last few weeks I've been having an intermittent problem that seems to happen with no specific determinable pattern whatsoever
It's happened in most gears, at all sorts of RPM, when booting it or tootling along, even sometimes when the car is started (from hot or cold): there is no regular or common driving condition when it appears and it's now getting on my nerves.

What happens:-
Car will sound like a Subaru (as if running on e.g. 4 cyls)
AFR will go very lean (up to mid 20s)
Power will reduce
A bit of spluttering
Sometimes the EML has come on until the fault has cleared or it has flashed on and off until the fault has cleared. It does not stay on when the fault has cleared and it doesn't come on every time the fault is present.
Sometimes the TCL off light will come on and remain on until the car is restarted, irrespective of the fault going away. TCL off does not always come on when the fault is present.
I've had EML briefly on on it's own, EML on with TCL off, TCL off on on it's own: every combination really.

These symptoms can last anything from a second up to, on one occasion, about 60 secs. Obviously when I can see it's running this lean it's a bit scary! The fault generally clears itself within a few seconds but can come and go numerous times through a short journey or not appear at all during a journey.

One day the fault was particularly frequent and problematic. I found a pinhole leak in the fuel supply pipe from my AFPR to the fuel rail so I replaced the pipe. I could see a drop of fuel leaking every 2-3 seconds. Nick Mann advised me to change this pipe a long time ago and I totally forgot about it. For the next 2 days the car ran great and I hoped that was the end of it.

Then the fault got more frequent and more intense.
I then changed the fuel filter (as I've been running the tank low for ages and I doubt the fuel filter had ever been changed). All 6 plugs were replaced with the same type NGK BKR7EIX iridium ones I've had in for the last 2 years. The ones that came out were a bit dirty but had no visible damage and didn't give me any concern about the plugs or anything else that their condition could point me to. These had done 20,000 miles or so and I've wanted to change them for a while and it was a good opportunity to have a look at other stuff that may be causing the problem.

Before changing the plugs I measured the resistance of 2 of the coils (perhaps... it isn't too clear to me how to do this properly and I can't work it out from the workshop manual) as a fault with these was also an option I considered. I measured the resistance from the spark plug connector on the coil to the spark plug lead connector on the coil. I hope this is the right way to measure the secondary resistance. I have no idea about the primary. Anyway I got a reading of 17.3 Kohm doing this on the 2 coils that can easily be removed with the engine cover off.
This seemed a bit high to me but as the 2 were consistent I took a gamble on the third being faulty (and having a different reading) so I bought one from Nutter John. When I got this I measured the resistance and got 9.7 Kohm. This confused me more but I now know, after looking at the workshop manual and assuming I am measuring it correctly, that at least 2 coils would appear to be out of spec (9-13 Kohm secondary resistance). I still don't know about the third coil as when changing the plugs I forgot to check it

When revving the car I could hear a hiss and, sure enough, had a small split in a vacuum pipe off the inlet manifold. Pipe changed and all dump valve, IC and boost pipes checked for tightness. No more hissing!

For the last 7 days the car has run without fault. Yesterday the fault returned when I started it from cold to move it from one work car park to another. My fuel puimp is hard-wired to the battery and I had a problem with one of the wires previously so, in the dark, I attempted to get the back seat out of the way and have a look. I couldn't easily access the area I wanted to so I just gave it a bang with my hand in frustration
Obviously this didn't make a difference to how the car was running: idling with an AFR of 20+
So, in the early hours of this morning, in near total darkness, I lifted the bonnet to have a poke around whilst the fault was present. I had noticed previously that the plug lead to coil pack connection seemed a bit looser that I'd like and that the Magnecor KV85 ignition leads were a bit tight fitting in terms of length so I proceeded to ensure that the lead connections to the coil packs were pushed all the way on. What a nice little shock (literally) I got from one of the leads/coils. I couldn't see any sparking in the darkness but there is electricity 'leaking' somewhere around one of the coils/leads, as my numbed fingers will atest!
I've just had a good look around in the daylight and changed one of the coils for the one I bought off Nutter John (the one I got the shock from).
I also noticed that there is a small hole in the insulator of two of the leads (one being the one I got a shock from). The hole on both leads was orientated downwards towards the block. I have twisted them so that the hole is now upwards... clutching at straws but my thinking is that it would make more sense to have them this way if the spark is grounding to the engine through this hole.

Now I'm at the stage where I think it's definitely spark-related.


QUESTIONS

Can anyone tell me, in idiot terms, how to measure the primary and secondary resistance of the coil packs. I've searched and still can't work it out. I know, from the workshop manuals, that the values should be: primary - 0.5 to 0.7 ohms; secondary - 9 to 13 Kohms.
If I'm measuring them correctly then the secondary resistance of at least 2 of my coils is way out of spec. It doesn't seem likely that the car would run as well as it does (most of the time) if this is the case?

From the photos I've attached do you think I need some new leads or will this not really cause any problem (I think I already know the answer to this one so has anybody got some good condition leads for sale?)
Lead1.jpg
lead2.jpg

The coil pack I put on today (9.7 Kohm according to my measurements) looks slightly different to the original ones on the car and the electrical connector was very tight to get on. Are there different types available or is it just a slight design change?
coil.jpg

[apeman69]

Can anyone advise me on the process of measuring the coil pack resistance?

For anyone using the Magnecor leads: check the condition of them as mine have been on the car for less than 3 years. They have a 10 year guarantee so I'll be getting in touch with them soon about this.

Sent from my Huge Brain using MyThumb (TM)

[Mark 4]

Can't help with the questions Alan but I do have a set of Magnecor leads about 10 months old if that's any help.

[Wodjno]

I would insulate the leads that are on there first by wrapping them with insulation tape. This will stop any arcing from the leads if there is any. Make sure the plugs onto the coil packs are fitting properly and that they click in place properly. If not use a small cable tie to secure them. And lastly replace each coil-pack, 1 at a time with the replacement 1. And see if the problem still happens each time.

I had the same issue at the Nurburgring and it was just 1 of the plugs working lose on the coil-pack. the clip had broken. A cable tie resolved the issue. The car sounded like the exhaust had been ripped open, or as you say like a Scoob..


Wodj

[Nick Mann]

Why does the AFR go lean? Is that a sign of unburnt fuel coming through the system?

[Wodjno]

Why does the AFR go lean? Is that a sign of unburnt fuel coming through the system?

That would be correct Nick. The fuel is mixed with the oxygen and as it is unburn't when it enters the exhaust. The Lamda sensor picks up more oxygen, thus reading lean.

[apeman69]

Thanks for the replies and for confirming I'm thinking on the right lines. Swapping each coil and seeing what happens could take me a long time as the fault seems to appear whenever it feels like. I'm thinking that a failing coil would just get worse and thus more frequent so perhaps there could be a dodgy connection somewhere. I'll check this out.
I've got another set of Magnecor leads now and will be putting these on this week so I can check stuff then.
I'd still appreciate any comments or info on coil pack resistance so I can decide whether to change at least another 1, maybe 2 while i've got it in bits for the second time in as many weeks..... eeek!
Thanks fellas.

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[pezza]

Ello Alan,

Just wondering what fault codes you received, if you managed to read them. I also have a similar intermittment issue, which does not have a effect on the feel of the car as you encountered. But on cruise under light throttle, the car will go lean from cruise to about 19 or 20 AFR for about 4 seconds and then engine management light may come on. At this point I lift off the gas and reapplying seems to resolve the issue. It hasn't happened more than once on a journey. (once every 3 - 4 weeks maybe)

I have swapped ignition leads from from standard to Mags plus done a plug change. I am running LPG alongside petrol and have encountered this on both fuels. I notice that you have upgraded your injectors. Mine are still standard.

The engine codes I receive are the multiple engine misfire ones but have evidence from my lpg ecu that it has loss of signal to injectors for a period of one second or so, so it could be a wiring issue somewhere.

It is definitely worth checking your codes when it happens as some of the misfire codes will specifiy a particular cyclinder as having a fault. I have found that switching the engine off after the code has cleared to code so if you have means of testing the code before power cycling the ECU then I would try this.

Cheers

Derek

[apeman69]

Cheers Derek. I've thought of seeing if I can get the error codes but I just don't know when it's going to happen and for how long so, until now, I've simply been caught unawares!
I've thought about fuel delivery and the possibility of fuel pump or injector faults but, given the state of the ignition leads and the secondary resistance readings from 2 of the coils I still think this thing is ignition-related.
I'll be changing the leads anyway, as they've got holes in the insulation, so I'm going to swap the coils around and have the replacement (thought to be good) one in the most inaccessible position. That way I can more easily test and swap the other suspect one (or two).
I'm sure I remember something about faulty ignition leads causing higher resistance in the secondary coil, which is what I'm seeing on the 2 coils that I could test the other day: both of which are connected to a lead with a hole in it.

[adaxo]

Ello Alan,

Just wondering what fault codes you received, if you managed to read them. I also have a similar intermittment issue, which does not have a effect on the feel of the car as you encountered. But on cruise under light throttle, the car will go lean from cruise to about 19 or 20 AFR for about 4 seconds and then engine management light may come on. At this point I lift off the gas and reapplying seems to resolve the issue. It hasn't happened more than once on a journey. (once every 3 - 4 weeks maybe)

Cheers

Derek

I will not help there guys but got exact the same thing happen to my car since manual conversion, I keep quiet about that mainly due to my English is well to bad to explain that properly and Derek's description fit just right.
I blame for this issue that may ECU need to be flashed with manual rom (maybe is still 'looking' for some signals from auto gbox or something), only one difference to Derek description it that I got that issue nearly always after some full throttle action, for example quick escape from junctions on full throttle and then keep steady speed around 70mph or overtaking, if I do the same maneuver on light throttle is not happen.
One more thing to add is that recently I change all conduit and find out that one wire supplying power to first coil from gbox side was in quiet sorry state with damaged insulation etc.

Hope we could find cure for this annoying issue.

[apeman69]

Adam, I think my problem is different from yours though the symptoms may be similar.
It can happen with my car at any time whatsoever it seems... it cannot be said that under these circumstances it will happen and under those it will not.
With yours it may be worthwhile asking those who have done a manual conversion if their cars have similar issues. I know that there will be a difference in tune and certainly vacuum pressure between the two so you should ensure that all the little bits and pieces surrounding the conversion have been done and handled appropriately.

With my problem it seems appropriate to note that the 2 coil packs that I have tested the secondary resistance of have both given me a reading of 17.3Kohm (workshop manual says 9-13Kohm). The ignition lead to each of these coils has a hole in the insulator, which I'm sure can lead to higher than normal secondary coil resistance (damage to coil). The third coil is untested and has a lead which looks good.
Since replacing one of the 17.3Kohm coils the fault has reduced noticably in terms of frequency and severity (at it's worse the car did not want to move forwards) but it is still there to a lesser degree and now feels like it did when I first noticed the fault. Perhaps one coil gave up altogether and another is giving up now. I still have the 'bad'' leads on at the moment and am not driving the car until I've changed these at least.
This makes me think that the 17.3Kohm coil must have been contributing to the fault, so I will source another 2 good coils and change the lot!
Perhaps the unknown-to-me degradation of the ignition leads has killed (or seriously injured) 2 of my coils. I will probably never know for sure but if the third coil (connected to a potentially 'good' lead) shows a resistance that is in spec then it would appear fair to assume that this is the case. Magnecor could be in for another e-mail!

[Davezj]

Alan,
I have a set of 3 Coils packs from my old vr4 that worked fine for me, you are more than welcome to borrow them to swap out yours for testing, so you can prove one way or the other if it is the coil packs.
As far as I know them are good coil packs, I will check the resistane of coil before I send them down just make sure I am not confusing the issue with slightly dodge part that have not caused me any problems past. Let me know exactly what measurement you are doing and I will repeat the measurement on mine.

[apeman69]

Cheers Dave, that's a very kind offer. I'm measuring resistance between the plug connector and lead connector of the coil. Multimeter set to 20000 ohms. Looking for 9-13 as the reading.
I'll pm you my address when I get in from work tonight.

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[Davezj]

Hi alan,
i have check my 3 available coil pack, and done a resistance check and the are all 17.45K Ohms.
which i thought was a bit odd,
so i check my Jap workshop manual and the translated version, and both of them say the VR4 coil packs should have a resistance of 15.3K - 20.7K Ohms so they are bang smak in the middle of where they shoudl be.
where did you get you resistance figures from of 9K-13K Ohms.

[apeman69]

Errr..... from the wrong freakin' manual: http://www.clubvr4.com/forum/showthr...ual-PDF-s-x-26
Now I think I've got one coil from a 2.5 N/A on the car (resistance in range of above spec AND it looks different, as shown in the last picture of post no. 1)
I can't understand how the car runs better with this (wrong?) coil on unless the one I took off was on it's way out. I'll be putting the old one back on.

Dave, if you can still send me the coils that would be great. I'll shove them on and see what happens I think, as my head hurts again!

[Davezj]

Yes I will send them Alan. I will test them on my car over the weekend, just to double check the good ness of them.

[pezza]

Fingers crossed mate.. hope you sort it.. I will need to work methodically to get to the bottom of the issue I am encountering..

[adaxo]

Just to clear things up, 2.5 6A13 n/a got distributor (no coils) 2.0 4G63 n/a got two coils similar to 6A13 TT (PDF manual from here 16-52, 16-54)

[Davezj]

(PDF manual from here 16-52, 16-54)

Adam what does the above mean.
do you mean in the jap manual which is downloadable from this site, in section 16, pages 52-54 you can find the information?

[adaxo]

Pdf manual available here on cvr4 part 16 (engine electric) pages 52-54, show how its done on 2.0 and v6 n/a, I'm referring to Alan suspicion of use coils from v6 n/a