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Ignition miss under load


KHE

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My '97 STS has started to miss under load - when travelling up hills or at cruising speed. I figured it was either plugs or plug wires but the plugs were replaced prior to me purchasing the car. When I Timeserted the engine last year, the plugs were fine - the platinum pads were intact. Last night, I started the engine and observed the plug wires... There were sparks arcing between adjacent wires in several places near the coils. So, it sounds like a new set of ignition wires are in order right? I then checked the wires on the '96 and they exhibited the same condition but that car has no driveability issues. Wierd....

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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My money is on the wires. Sounds a lot like mine after the fuel rail recall. Wires cured it. Got the best price and fast shipping from Rockauto.

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My favorite way to observe arcing and sparking with failing plug wires is to have someone you really trust brake-torque the engine while you spray the wires with a water mist. Spray the coil towers too just in case the coils got banged when the engine was removed and replaced.

You can expect to see a muted glow or corona if the area is totally dark (complete absence of any light source); that is normal under higher voltage conditions (high engine load).

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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My favorite way to observe arcing and sparking with failing plug wires is to have someone you really trust brake-torque the engine while you spray the wires with a water mist. Spray the coil towers too just in case the coils got banged when the engine was removed and replaced.

You can expect to see a muted glow or corona if the area is totally dark (complete absence of any light source); that is normal under higher voltage conditions (high engine load).

Mine has been missing recently and yesterday after dark I raised the hood, started it, sprayed a water mist and revved it ( I revved it without load from under the hood). The spark plug wires looked like the Milky Way while on your back staring at the sky at midnite in the middle of New Mexico. I think that perhaps indicates it's time to replace ...

;)

PS, it passed the California smog test the day before yesterday with flying colors, and I would like to move to New Mexico!

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Kevin, look into each end of the plug wire and see if you can see the core burned out of the wire. You could check the wires with an ohm meter also to see if you have one way out of range of the others or it might show no connection and the spark is jumping the gap. You would also see more sparking of a bad wire because the wire will search for a ground, as having to jump a gap seriously raises the resistence shown to the current.

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Thanks for the suggestions - pretty much confirms my initial thoughts that the wires are due for replacement. I'll test the resistance of a few of the wires in the morning just to see but I think it needs a set of wires since they are arcing. I did see the corona glow when I inspected them as it was totally dark in the garage - but several of the wires were arcing near the coils.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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  • 2 weeks later...

I installed a new set of plug wires - the arcing is gone but there is still something not quite right. The engine seems to intermittently cut out under light cruising (55-60 MPH) and the tach fluctuates about 100 RPMs. It is most noticable when travelling uphill.

I'm going to hook up the fuel pressure gage next...

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I bought Magnacore Red wires from www.ultrarev.com/home.php and am very happy with them. They are a bit of an upgrade from stock. The same wires made a big difference in my Corvette performance - much more crisp in the mid range.

Scott

1996 El Dorado

2006 STS

2000 Corvette

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