Help with 1994 Bonneville - ignition coil

The Good Doctor

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Hi all.

Context: just replaced the entire engine in my Bonneville. After replacement, noticed that one of the ignition coils wasn't sparking or firing--or whatever it is they're supposed to do. How worried about this should I be? Does anyone have resources on ignition coil/ignition coil module troubleshooting? Any help appreciated, and happy to provide further info.
 

melsg5

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Not sure what you mean by how worried, if the coil doesnt work the engine wouldnt run!
Can you provide more details why you think one of the coils is not working?
Who replaced the engine you or a shop?
If a shop what information have they given you that leads you to believe a coil is not firing?
 

The Good Doctor

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Thanks for the response! More information, as requested:

Broke down while traveling and had the engine replaced by a mechanic. The car runs, but makes a funny noise when accelerating from idle/low speeds. Checked the ignition wires and found that one is not sparking (or whatever the technical term is). Other than it being a different wire, this video exactly describes my situation. Car also seems to have trouble attaining/maintaining high speeds (75mph+) especially on inclines...but this might be an unrelated issue or a nonissue.

I might as well ask: what--if anything--should I do to 'break in' this new (to me, anyway) engine? The mechanic told me to drive it like I normally would and that nothing needs to be done. But at the very least I think I want to get the oil changed--my receipt shows that the shop put in 5w20 whereas the specs call for 10w30.

Really appreciate the help.
 

melsg5

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He installed a used engine I assume not a new engine?
Use the oil that the oil cap states.
Do you have a check engine light on?
Google GM 3.8 coil check to see how to check a coil.
______________________________
 

The Good Doctor

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Right, installed a used engine.

Although they didn't mix oils, the oil the shop put in is not what is recommended on the oil cap. How worried about THAT should I be?

Check engine light did come on once, but did not run codes, and it hasn't come back on again--although problem persists.

Found what seems to be a good article and a promising video, but I don't have the tools (e.g., HEI spark tester) to make the test. So I suppose I'll have to get it/them somehow or take the car to someone who can test it.

But that's my question...since the car is moving, how worried should I be about this?
 

melsg5

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You invested I assume a large amount of money in the repair so I would put the correct oil in it.
You have a noise from an unknown source and have a performance issue, it should be checked in case it could lead to further problems/expense.
It is not clear what made you jump to testing coils and watching the first video which does not illustrate the proper way to test a coil and can actually cause further damage.
 

The Good Doctor

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I'm glad for the feedback on the video; I wouldn't otherwise know whether or not what is shown is actually correct.

I'll bring it to a mechanic as soon as I can, but that's part of the problem: I don't know how soon I can do so. I wanted to describe the symptoms here so I could try to gauge how serious it might be.

I'm pretty sure it is the ignition coil or module because nothing else seems to be out of the ordinary. (Even if the first video demonstrates improper technique, it does describe my situation.)

I appreciate the help... If you think of anything else I'd be glad to hear it, and I'll provide an update once I've taken it to a shop or otherwise have more info.
 
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