3800 lost two cylinders

b4black

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On my way home from work yesterday, sitting at a red light and engine starts running very rough and the service engine soon light starts flashing. Was running great up until that point So I limp the car back to work and park it. Throwing a code P0300, multiple misfires.


Using the Torque app, I can see the cylinders #2 and #4 are misfiring. I tried the following:

  1. swapped 3/6 coil with 2/5 and swapped another used coil with 1/4, no change
  2. Swapped #2 and #4 plug wires with new. No change. Triple checked to make sure they are routed to the correct cylinder.
  3. Pulled #4 spark plug. Looks good. Gap under 0.060". Replaced anyway with new plug gapped at 0.050". No change.
  4. Motor oil looks good. Coolant looks good and full. Engine did not overheat that I know off.
Any ideas on what happened and what to check next?
 

boostedguy05

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call it a 2533 v6 and drive it into the ground.

but ya, what he said.
 

b4black

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Just swapped #2 and #6 injectors. No change. 2 and 4 misfires still.
 

1quick

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I would try a compression test next.
I'd do that, if compression is good the only other thing I could think to check is the icm, not sure if that goes out completely or can drop just one coil pack signal, I had one over heating on a series 1 and it dropped all cylinders when it would happen, make sure there is dielectric grease on the back side of the coil packs
 

RICH17

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I lost soo many ICM's on my series 1 that I had to buy a spare and keep the tools handy. Fucking junk
 

b4black

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Thanks for the ideas. Im away for the weekend. Monday Ill check the compresion. I have a spare ICM as well.

I lined up a trailer, so can drag it home if needed.
 

bikrboy128

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toss an ICM on there, bet that will solve it. i've had plenty of SII ICMs fail on one coil only
 

b4black

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Update: Tried one of the inline spark test lights. The good and bad cylinders were lighting up the same.

Lifted the rear fuel rail, placed brown paper under the injectors, cranked the engine and the brown paper was wet. So the injectors were injecting.

Checked compression. Good and bad cylinders were the same.

Swapped the spare ICM - fixed. :)

Lesson learned - a bad ICM can take out two of six cylinders (on different coils!). Next time, I'm just swapping the ICM and three coils pairs all at once to start.
 

10sec

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It'nt that what more than a few people said to do first?
 

b4black

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It'nt that what more than a few people said to do first?
It was one of several suggestions. That's why I did it even though the spark tester showed all cylinders sparking. I listened. :bigthumb:
 

MonzaRacer

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On spark testers, get the cheap ones,,,

OEM sells them that you screw apart. Take two fasten together with two short custom cables give them at least 1/2-3/4 in gap and start it. If I'm or coil is ganked this will show it real quick. Another way is to get nice steel or aluminum box, 6 plugs, good used ok, heavy side cuts and 6 of the long 14 mm spark plug thread repair inserts. You make holes, screw them in , nip off ground straps, make it with ground cables and alligator clips, number them, run all wires to this and have someone crank it. I added a remote button, and when engine is out install a 4 wire trailer connector with covercap. One to S terminal, one to ground, one to power. And one left over for what ever you see fit. Then take simple mo.entary button and wire it to other end of plug. Thus making a perfect inspection connection. You can wire plugs for timing lights, starter buttons. Power and ground connections for testing. Just tips to make diagnostics easier and quicker.
 

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