View Single Post
Old 08-07-2006, 10:37 PM   #51
LetItSnow
Scooby Specialist
 
Member#: 38222
Join Date: Jun 2003
Chapter/Region: Tri-State
Location: Cicero, NY
Vehicle:
'10 &'12 Foresters
another Miata convert

Default

EXPERIMENT 2:

I'll admit, I came up short of understanding Sean's suggested comments, so I took them at face value and forged ahead. I was a little reluctant to put the 2.2k resistors any ol' place, but it had to be done. I decided to start in the easiest place in my setup - between the weatherproof plugs.

I figured since I was doing a second experiment, my test harness could use a little butchering, kind of like Buster, the Mythbusters' test dummy. I replaced the stripped areas with blade connectors to allow anything in my electronic armada to be plugged inline with our trouble zone. (Quick review: The test harness includes Ign1, Ign2, and MAP, either in/in/out or out/out/in, depending on where it's jacked in.) Using these new blades, I placed the resistors between the SMT6 and the coilpack, on the Ign1 and Ign2 output lines.

The experiment encompassed these steps:
1) Made sure the car started and ran before the experiment (a control for good science)
2) Plugged in the test harness
3) Measured the voltage between the PP6 and the resistor - 7.62v
4) Measured the voltage across the resistor - 4.54v
5) Measured the voltage after the resistor - 2.80v
6) Tried to start the car - it ran!

Granted, 2.80 + 4.54 != 7.62, but a quarter volt's tolerance isn't too far off, considering the crude setup.

I consider this to be a serious advance in the search for the coilpack burnout solution. With just a pair of resistors, the voltage has dropped ~4.5v, and the car still runs. 2.8v is close to the (assumed) 2.5v threshold of spark, so a higher resistance is in order for the next test.

To further aid in my testing, I've recently scored an oscilloscope from eBay, which will be here in a few days. After I see if the thing works, I'll check out the values of the signal to the coil while the engine is running. I think that if I can find an appropriate resistance, the 1.0-3.4 volt window can be found, and the nightmare will be over.

...or not. Stay tuned.

EDIT: The 1.0-3.4 volt window I was searching for does not match my findings with the oscilloscope. It can be said that some of my information in this post has been proven erroneous, so make sure you collect the information in the experiments that follow! (8/24/06)
* Registered users of the site do not see these ads.

Last edited by LetItSnow; 08-24-2006 at 11:55 AM.
LetItSnow is offline   Reply With Quote