Thread: 525i Head
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Old 03-09-2011, 02:28 AM
robertobaggio20 robertobaggio20 is offline
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Join Date: Oct 2009
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Rick, I have an idea. Before you install the intake manifold, and after everything else has been fixed up, please check for spark. This will ensure that everything that you've fixed up and connected actually works as planned, including the fuel injectors ( you should be able to smell the fuel through the open spark plugs' holes, do not fix up the spark plugs before you check for spark following your rebuild). Or of course, you can suspend the fuel rail slightly above the head with wire or rope cord or something, and you'll be able to see each injector literally firing the fuel charge in sequence. I suggest you test this first in this way before testing for spark, in order to minimise freak fires.

The method is ridiculously easy, as I discovered today on a hunch after watching a video on youtube. I was under the impression that the ignition coil would have to be compressed against the spark plug, by basically holding it down. While this can be done with an appropriately insulated hand, some may prefer not to touch the coil at all in any way due to the high voltages involved (20k-40k volts, can't remember which). However there's a far simpler way. First, remove one ignition coil. Make sure its connected to the wiring harness. Place it upside down on the engine, the shock towers, something...use a cloth or whatever to create a surface to do this. The ignition coil's rubber boot should be facing directly up (and not at any angle). Then, insert a spark plug into the boot and push it in. It will spring out a little but leave that. After that, connect 1 end of a jumper cable to the threaded portion of the spark plug, and the other end of the same jumper cable to a ground point such as a nut on the car's body. The weight of this jumper lead together with its own weight will pull the spark plug down onto the springs sufficiently to make contact with the conductor (the spring) in the spark plug boot. Then crank the engine for a few seconds.

If everything works ok, you should be able to see your spark. If there are no sparks, check your jumper cable's connections, make sure the spark plug is upright as best as you can manage it (together with the boot), and if necessary switch to a different spark plug. (needless to say, use known good plugs). If you still don't get spark, there's something wrong. With the intake manifold still not installed, it will be FAR easier for you to troubleshoot things.

If you see sparks, great. Test a different coil in the same manner. There's no need to test more than 2 coils to verify that everything is working as planned. Then, go for the final phase of your reinstallation.

This of course cannot really verify anything about timing except the most extreme scenarios, but it is a useful intermediate step that takes almost no time to do and could save you alot of trouble and stress in trying to troubleshoot something.


rgds,
Roberto

p.s. Hey bro.....did you clean out your fuel injectors? Backflushed them too? You can do this with a carb cleaner and around $5 in parts from a hardware store. Please search youtube and you'll find a great video on this.
p.

Last edited by robertobaggio20; 03-09-2011 at 06:43 AM. Reason: How to check for spark
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