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2005 Malibu (Classic, fleet version) with 2.2 L Ecotec four-cylinder engine fails to start. It turns over, and scattered weak pops indicate that there’s rudimentary combustion going on, but it does not catch.

I’ve pulled the plugs, there was spark, but very weak. Plugs were in very bad condition — fouled up, with electrode eaten away — seems like no one bothered to change them in 120 000 miles. I’ve replaced the plugs, but I’ve found that spark still remained strangely weak, not the bright blue one I would expect. Anyhow, that did not help. Also, there are no plug wires, as there is resistor pack and rubber boots with contacts are all attached together as one unit on top of the engine. Is there way to test if the unit delivers proper voltage?

I’d never worked on GM car before, so I am not sure where to start. As fuel system is concerned, the fuel pump activates, and there is some pressure in the line, as the fuel port on the injector rail squirts fuel when pressed with a screwdriver. I am not sure if check engine light appeared before it happened, but right now all I can see is that it stays on when the motor is being cranked. From the experience with my cars, it should go away once the engine is rotating, as crank sensor is activated.

I’ve got around to test MIL codes, and it did not throw any, nor were any saved, and all systems checked out okay. Crank sensor (or its wiring) is my primary suspect (Although, it should have thrown the codes, shouldn’t it?), but I want to see what other common problems could cause this condition, and what else I should look into.

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Where is the coil pack? Or do you have a coil per cylinder? –  Mark Johnson Aug 19 '13 at 20:46
    
@MarkJohnson That is what the unit looks like: [image](i.ebayimg.com/00/s/OTYwWDEyODA=/…. The plastic housing incorporates plug boots on the bottom, and pack on top (with aluminium heatsink). –  theUg Aug 20 '13 at 7:54
    
Maybe a bad coil pack or ignition control module? A little forum surfing turns up a hint of a recall on one or both of those. Diagnostics: easyautodiagnostics.com/gm_2200_coilpack/… –  Mark Johnson Aug 20 '13 at 17:07
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If you figure it out, don't forget to post an answer. –  Mark Johnson Aug 23 '13 at 0:01
    
possible duplicate of How do I troubleshoot a vehicle that won't start? –  BigHomie Sep 20 '13 at 15:55

1 Answer 1

When trouble shooting a cranks but won't run condition it comes down to three things

Fuel, Fire, or Mechanical

  • Fuel - Spray either or starting fluid into the air intake while trying to crank the vehicle. You may have fuel pressure but not enough, this will rule out a fuel problem. If it runs you have a fuel problem if it doesn't you don't.
  • Fire - Check to see if you have spark. In your case you do, if it will jump the spark plug gap it's generally enough to run the engine. You can use a spark tester that tests for adequate spark.
  • Mechanical - The engine has a mechanical problem that prevents the engine from running. For example a blown head gasket, broken timing belt or chain, or it's jumped time.

In your case I suspect a mechanical problem. Check the compression, also if you have a lab scope check the waveform on the crank sensor, if not you could try a crank sensor. It takes about an hour and requires removal of the starter to gain access.

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The issue could be the timing chain. It is still intact, but slacking (possibly plastic guide or tensioners broke). It is an interference engine, and I wonder if that was enough to throw the timing off, but not enough to damage the valves. It spins smoothly, for what it's worth. –  theUg Sep 29 '13 at 19:17

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