Mechanics

ENGINE MISFIRE

1996 Pontiac Bonneville

Engine Performance problem
1996 Pontiac Bonneville 6 cyl Front Wheel Drive Automatic 200000 miles

engine misfires when ever it wants to. Mostly when hot and idling or damp weather. I sprayed coil packs and wires with water mist and saw some very fine line arcing but the engine was running just fine at this time. What might be going on with this thing!
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Bob r 007
March 20, 2008.




Did you pull off the wires at the coil and check for any signs of corrosion?

Are these random misfires?

How old are the wires.

Even minor arcing isn't good.

No cor. Just a grease substance on coil end of wire misfires seem to be more random than a sure circumstance I was told at time of purchase (4 months ago)that plugs and wires were changed

Tiny
Bob r 007
Mar 20, 2008.
Any loss of coolant on this?

These are common for intake manifold problems that will cause misfires. Generally they don't tend to be moisture related, but could be consistent with the hot motor.

Are they decent wires or cheapies?

Pull a plug and check gap or condition at all?

Holds all coolant wires seem thinner than some that I've seen is this common for this type of car or a good indication of cheapness! Yes my next step was going to be to check plugs and wire ends at plugs boots etc

Tiny
Bob r 007
Mar 20, 2008.
Usually there is a name brand on the wires. Have seen cheap ones fail.

Good news on the coolant!

What type intake manifold problems might exist on this engine to cause random misfire

Tiny
Bob r 007
Mar 20, 2008.
http://www.autoblog.com/2006/04/15/gm-to-handle-intake-manifold-gasket-problem-on-a-case-by-case-ba/

http://www.complaints.com/directory/2005/october/1/31.htm

A google search will give you more,

But in a nut shell, there is a coolant passage in the mainifold that gets eroded from heat and hydrolic pressure that corrodes an opening internally.

The plastic manifolds are a problem child, and have seen engines lock up because it can be that quick.

Happened to my Boss..twice LMAO!!!!!

(did I laugh out loud ?) :)

Wow sounds serious is there a test to verify such a problem
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Tiny
Bob r 007
Mar 20, 2008.
Compression test.

Pull the manifold off and evaluate it.

Symptoms include: Pull the plugs and look for coolant burning.
Loss of coolant.

PO300

Lets say that new plugs and new high quality wires are installed, compression is passable, coolant is full, and the same thing happens. What are some other alternatives

Tiny
Bob r 007
Mar 20, 2008.

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