1999 Oldsmobile Aurora 9 plug wires on a V8?

Tiny
SECRITNINJA
  • MEMBER
  • 1999 OLDSMOBILE AURORA
  • 4.0L
  • AUTOMATIC
  • 133,000 MILES
1999 olds Aurora and lately its been very sluggish when accelerating, rpms have been dropping ever so slightly and its been terrible on gas. I pop the hood tonight and noticed there is a loose "plug" wire on the back side of the manifold. The thing is all 8 wires are plugged in to the plugs on the front of the manifold as well as into the coil pack on the back. So what is this 9th wire? I've pulled on it to be sure its not just sitting there and its certainly plugged into something on the other end. Its too dark and too involved to go any further tonight, but please somebody tell me what this wire is. The loose end I can see looks exactly like a plug wire
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Friday, September 5th, 2014 AT 7:44 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Based on your description, it sounds like one of the plug wires has come of the coil. Check that first and let me know what you find. Also, this would kill power and fuel mileage.
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Friday, September 5th, 2014 AT 8:26 PM
Tiny
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I just verified all 8 wires are connected to the coil pack. All 4 are connected to the plugs on the front of the manifold. As far as I can tell by feeling around all 4 are connected at the rear of the manifold too. I've just discovered the mystery wire is indeed a plug wire cause I've found both ends but can't get it out of the wire holder now. Also my gas gauge is going crazy now. It quickly shoots up and down by between 1/4 and 3/4 of a tank span. So now I'm super confused. I'll pull it apart in the morning to make sure all wires are connected on the rear of manifold but wouldn't it be missing really bad and constantly if that were the case? At a slow to moderate acceleration or if going up hill it'll stutter really bad but if I put more gas to it then it settles out and drives fine. I also don't have this problem once I get up to hwy speed only at slow to moderate acceleration. Also no check engine light. Can I still get the trouble codes if the check engine light isnt on? Anyway I'll dive further in tomorrow but thank you very much for your reply.
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Friday, September 5th, 2014 AT 9:15 PM
Tiny
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If you can, take a picture of the wire you see and upload it for me. Let me know what you find.
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Sunday, September 7th, 2014 AT 8:25 PM
Tiny
SECRITNINJA
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So figured out the extra wire I found was just that. Extra. The guy I had Change the plugs left one of the old ones loose but on the clip. The plugs on back of manifold and wire are a real pain to get to. I've verified all plugs and wires are good. Fuel filter is new. Compression test was good. Fuel sending unit ohms were good. Still no check engine light but was able to get an intermittent cylinder 1 miss fire code. Everything has checked out tho(plugs, Gaps, and wires). So now I'm thinking maybe the #1 coil is dropping out or maybe injector? I'll replace the coil this weekend cause their cheap enough, but how do I test/check an injector? Thanks a lot for all your help so far.
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Monday, September 8th, 2014 AT 8:00 PM
Tiny
JACOBANDNICKOLAS
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You can test if it is getting power by using a noid light.
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Tuesday, September 9th, 2014 AT 5:00 AM

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