So brain boxes...
I was going to post this on the DTA forum, but there is probably more expertise here, so here goes. Also before you ask i've checked the dwell setting with Sandy and it's fine. We think it's running about 10.6:1 compression, on a 270 inlet and 260 exhaust cam, makes about 200ish BHP and 150 ft lbs of torque.
I've been through about four/five coil packs in the past two years. The first one was high quality, the next two were s*ite, then last couple were good quality. The failures have all been identical. I use the standard Mi-16 champion (i think BCP7ET) plugs always.
Over the course of a few months the following symptoms gradually surface.
- Car takes ages to turn over and fire from cold.
- It struggles to pull itself off idle for at least 10 seconds after initially firing.
- The car audibly looses all its deep bark, and sounds hollow and tinny.
- It looses about fifty horsepower, it's massively down on power. (it wheel-spins in the dry in second with and LSD when it's on form)
What I really need to know, is what exactly is failing within the coilpack (106 wasted spark) to cause these symptoms.. is it the windings breaking down, or the ignitor integrated circuit. As then i can take remedial action to resolve.
As i understand it, both heat and vibration kill coil packs. Heat because the integrated circuit is silicone and doesn't like heat. Vibration because the resin used to hold the thing together has a habit of coming apart allowing the windings to not be as insulated as they would normally be. The third cause i understand is a misfire, the car runs pretty sweetly
Change the plugs, change the coil pack, and boom, it's back to it's monstrous old self.... then after a very short time it begins to imperceptibly degrade... the first start is the best. From then on it's a gradual decline. I have not given it a set of leads for perhaps a year, but this pattern doesn't seem to be affected by them.
The coil is currently mounted reasonably solidly to the right hand of my MI-16 engine via a little bracket, there is plenty of air around it, and it's over the gear box. So there is metal - metal contact from the head, to the bracket, to the bolts through and metal inserts in the pack. There is currently no vibration damping from the engine.
Initally the pack was mounted on some l brackets hovering to the side of the same location, and i didn't really have any issues. I may be answering my own question here. But.. I still need to understand what's failing in the coilpack or how to test it using the multimeter to find out.
Secondly, when the car is cold it's tidy to drive, when it warms up, it's not quite as nice, very light throttle loads are a bit kangeroo.. this is both in traffic and at cruising speeds around town. Now i was in the car when sandy ironed this out at the original mapping. He pulled a bit of ignition for very light loads. It seems when the car (or something electrical) is cold it's pretty happy, warm, not so happy.
The car spends... quite a bit of time sitting in london traffic whenever I escape from the big smoke to give it it's monthly spanking, so it does sit there heat soaking regularly. However the car doesn't overheat, doesn't even have the soundproofing on the underside of the bonnet. And standard cars run these for years without problems.
Edited by kyepan, 03 November 2015 - 05:18 PM.