Faulty Coils? Misfire At High Rpm? Read This.

[Zahos]

This thread follows on from this other thread, where people were having problems on boost b/c of cracked coils. In most cases coils were not actually faulty themselves, but due to fatigue, or who knows what, had developed small cracks where the spark could jump from..... (I guess same principal as cracking the ceramic coating on a spark plug).

Anyhow, I said I was going to follow up on this issue by reporting the progress of my coils where I melted more plastic over the crack with a soldering iron, and also get them plastic welded, as I feared the melted plastic would not stick due to the fact that they are made differently, and that they didn't fuse together properly.

MELTING:

The plastic I melted on is showing signs that it is coming off (as expected), so don't bother trying this... seriously!

PLASTIC WELDING:

I took a spare set of coils I have to get plastic welded, and after testing the plastic, I was told they could not be welded! They said some plastics can't be done, and this is one of them!!!!

BUT.. he made a very good suggestion.

EPOXY GLUE:

If you look at the back of your coils (the tallest part), you will notice it is a clear / yellow type of plastic, unlike the rest of the coil. This in fact is simply made from an epoxy resin (like Selley's Araldite), and that's all it is! So rather than spending my money on welding that would have cost me a few $$$, he told me that spending $5 on some selley's Araldite would be by far the best option.

Simply clean the surface VERY WELL, and mix up some Araldite and slap it on - problem solved! And you shouldn't have to worry about it coming off!

Only thing is, you will need to give it about 48 hours to dry properly (maybe more), before you can put them back on.

Hope this helps a few of you out there.

Zahos

EDIT: Added a crappy pic of where to put glue (area in red)

Edited February 19, 2007 by Zahos

[benm]

I had another forum member tell me the araldite thing on Sunday.

http://www.selleys.com.au/content_306.htm

[benm]

Well i've tried this and so far it has given me noticable results.

About 2mths ago I taped all 6 coils which gave a noticable improvement. I then replaced #1 and #4 coils with 2nd hand standard coils and got another noticable improvement so obviously the 2 I pulled out were slightly faulty.

I spent the last 2 days covering these 2 coils with about a 2-3mm layer of araldite and fitted them today. I let the car warm up for 10mins and then took it for a quick burn and their was a noticable improvement so I left them in there. I had no hesitation and my car felt the quickest it has been in the last 3 or so months.

I've just started covering another 2 in araldite (very time consuming coz it takes about 3 days per coil to completely cover otherwise it just runs off and drips everywhere but where you want it). Hopefully by about wed-thu next week i'll be completely done.

I bought the twin-syringe 24ml "clear drying" araldite at bunnings for $13. Looks like im using around 6ml per/coil so i'll need to get another 24ml twin-syringe stick.

[Zahos]

Gee You used a fair bit then....

I could have gotten away with the tiny tubes you bu for $5...

Did you cover the entire coil?

I only covered the section at the front that is most prone to cracking.

I had the syringe from another job i did last year and I still haven't used half...

I did all 6, 3 times also putting a little on each time to avoid dripping...

I gave it about 1 hour between coats, and let them rest in different positions each time so the glue runs in the direction i want it to, also moulding it as it dries...

here's some pics I just took of mine...

[JaFF]

so will a few cracked coils cause hesitation?

I seem to have this problem. replaced the sparks and reset the ecu, fixed for a few mins then back to hesitating.

maybe i should check the coils,hmm. btw it seems to hesitate at like 5000rpm, maybe sooner, and then rev out fine to redline. is this what you guys were experiencing?

[benm]

I've been getting hesitation a lot below 5,000rpm as I never ever hit 5,000rpm during my daily driving.

[GTRgeoff]

Did anyone experience a tacho snapping all over the place on full throttle? I get an occasional miss but right through the rev range the tacho is crazy, then gets better when I lift off.

[JaFF]

well, I generally mean in 2nd. you know, sometime you'll just floor it all the way through to redline to get to 100. I only do this to make sure the car is running ok. for quite a while when doing this the car has felt a bit weak. the hesitation is really annoying. just cant work out the exact problem. The majority of it has developed since i installed an FMIC tho

[JAPCAB]

I replaced spark plugs with NGK BCPR6ES, and while i was changing them i taped up the coil pack stems; have i taped up the wrong thing? Should i be taping up/aradite'ing the black box things? Should i only tape them up if there are cracks or do it anyway? I was experiencing some missing aswell but since the new plugs and taping the stems it has dissapeared...

[Zahos]

- Even one cracked coil can cause a lot of hesitation!

- i was getting it between 4500 - 5500 rpm, and after that it was all good, it would rev out nicely...

- When i taped mine the problem went away, but after a week or two, came back b/c the tape shrunk on the coils, exposing parts of the crack once again

- I would be doing this to ALL of the coils, regardless of wheather there is a crack there or not, as it could crack soon anyhow as the others have....

[tang0]

you know that the 5 minute expoxy is pretty good ... means you could do all 6 coils, 3 times in about 2 hours ...

Gee You used a fair bit then....

I could have gotten away with the tiny tubes you bu for $5...

 

Did you cover the entire coil?

I only covered the section at the front that is most prone to cracking.

I had the syringe from another job i did last year and I still haven't used half...

 

I did all 6, 3 times also putting a little on each time to avoid dripping...

I gave it about 1 hour between coats, and let them rest in different positions each time so the glue runs in the direction i want it to, also moulding it as it dries...

 

here's some pics I just took of mine...

[benm]

It's sticks within 5mins but it doesn't dry enough to be able to do multiple layers or all 4 sides of each coil.

[nizmokid]

I will be trying this epoxy glue this week, as I am going to place a new turbo on the car and I don't want this popin to come back and as the weather has heated up the the tape must of shrunk or came loose and I have a little poping back, but nothing like before!.....epoxy here I come!

[nizmokid]

Zahos how did you clean up the coilpacks before you glued them up, did u sand or use prep wash?

[Zahos]

I just cleaned it up with thinners.

Dont use turps, b/c that has a bit of oil in it.

If you want to sand it down, go for it, but just dont wipe it with your bare fingers, use a clean cloth.

[nizmokid]

coils still going strong then?

[benm]

I finally finished aralditing all 6 coils yesterday and put them back in. Car hasn't driven this well in over 3mths

[nizmokid]

good to hear, can't wait to do mine now!

[WLD747]

i read in a zoom article where they used silicon to coat the coils and the boot. Would a spray on silicon be a better insulator?

cheers

ak

[nizmokid]

has anyone used Silicon to fix this problem????