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did a tune up, still a little miss/hesitation?


lothos

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I did new plugs and wires on the 1995 STS 4.6L with ACDelco parts.

Car ran absolutely great that night. Today after work I noticed a little bit of a miss at a stop light, and some hesitation. It cleared up when I ran errands tonight. Flooring it is great now, but every once in a while there is a miss and some sluggishness at the upper end up around 80mph.

I'm thinking there's a coil pack going bad now? They seem to be 14 years old. Would that be the suggested thing to check out next?

Thanks guys!

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

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I also need to replace my O2 sensors, I think they're original. Can't seem to remove the O2 sensor next to the firewall though. I have ACDelco O2 replacement sensors.

Could the O2 sensors have anything to do with this?

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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Have you changed the fuel filter? Almost sounds like a fuel-supply issue.

Before changing the coils, I'd start by wire-brushing all the towers on them, and making sure that the ground-strap and all the pin-connectors on the coil-pack "plate" are clean and well-connected.

I don't think 02 sensors would cause a miss, as they'll usually set codes as they're failing, and generally just lead to higher fuel consumption. I could be wrong.

Not that this solves any "real" issues, but I find my car runs considerably better when I clean the throttle body out of all the 'crud' that builds up around throttle plate, and then reset the PCM by disconnecting the battery, so the new air/fuel/idle parameters are re-learned. May want to try that too, as you just did a tune-up.

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Have you changed the fuel filter? Almost sounds like a fuel-supply issue.

Before changing the coils, I'd start by wire-brushing all the towers on them, and making sure that the ground-strap and all the pin-connectors on the coil-pack "plate" are clean and well-connected.

I don't think 02 sensors would cause a miss, as they'll usually set codes as they're failing, and generally just lead to higher fuel consumption. I could be wrong.

Not that this solves any "real" issues, but I find my car runs considerably better when I clean the throttle body out of all the 'crud' that builds up around throttle plate, and then reset the PCM by disconnecting the battery, so the new air/fuel/idle parameters are re-learned. May want to try that too, as you just did a tune-up.

I did replace the fuel filter about a year and a half ago with a Fram filter. Does that mean the fuel pump might be failing? I cleaned the throttle body out at about the same time, I suppose it's time to do that again.

I had another thread on here asking for advice because the car ran like crap when it was raining out, coil packs were suggested there. It hasn't rained yet since I did the plugs, so I'm not sure if that solved that particular problem or not.

I'm going to keep my eye on it and see how it does. Thanks for the reply BostonETC97

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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The towers on the coil packs looked good. I'll take my wire brush and clean them off, and clean the bottoms too and see if that clears it up.

I did have some symptoms before that sounded like a coil pack, and never looked into it. I'm really hoping it's a coil pack and not the fuel pump lol

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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I've been driving it for a couple days now since the tune up.

It feels like a plug to me. I think I'll focus on the coil packs at this point unless someone has another suggestion?

Also I have a multimeter and can measure the top of the coil packs. How do I get the leads inside the bottom of the coil packs? Is there a special pin or something that I should be using?

Thanks guys!

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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I've been driving it for a couple days now since the tune up.

It feels like a plug to me. I think I'll focus on the coil packs at this point unless someone has another suggestion?

Also I have a multimeter and can measure the top of the coil packs. How do I get the leads inside the bottom of the coil packs? Is there a special pin or something that I should be using?

Thanks guys!

I devised something to get into those slots, figure something out, we have a thread here on coil testing, not sure if I or JimD started it

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I've been driving it for a couple days now since the tune up.

It feels like a plug to me. I think I'll focus on the coil packs at this point unless someone has another suggestion?

Also I have a multimeter and can measure the top of the coil packs. How do I get the leads inside the bottom of the coil packs? Is there a special pin or something that I should be using?

Thanks guys!

I devised something to get into those slots, figure something out, we have a thread here on coil testing, not sure if I or JimD started it

I have the link to that thread at home. I'll check it out again.

I believe I've also seen some little adaptor things at Sears for multimeters, they were only a couple bucks if I remember right. Can't find them online but I'll check the store this weekend.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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I've been driving it for a couple days now since the tune up.

It feels like a plug to me. I think I'll focus on the coil packs at this point unless someone has another suggestion?

Also I have a multimeter and can measure the top of the coil packs. How do I get the leads inside the bottom of the coil packs? Is there a special pin or something that I should be using?

Thanks guys!

I devised something to get into those slots, figure something out, we have a thread here on coil testing, not sure if I or JimD started it

I have the link to that thread at home. I'll check it out again.

I believe I've also seen some little adaptor things at Sears for multimeters, they were only a couple bucks if I remember right. Can't find them online but I'll check the store this weekend.

I just remembered that I used crimp knife electrical connectors, I just crimped a wire on it and touched my ohm meter to them

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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before I did the plugs and wires, the car would run really rough when it was pouring rain outside. The day before I did the plugs and wires, the car actually stalled on me backing into a parking spot.

It's running much better now. Today it was pouring again outside and the car was just slightly rough after being smooth for a couple days now.

Does that sound like it could be the coil packs? That's kind of what I'm leaning towards right now.

I stopped at Sears for some of those cheap adaptor things to measure inside the slots on the bottom of the coil packs, and they clearanced them out. I'll have to check Northern Tool for something similar.

Am I on the right track here? Or could a fuel pump act up when it's wet outside also?

Thanks guys!

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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