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My car runs like !@#! when it's wet outside


lothos

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My car runs like junk when it's wet outside. It stormed this morning and the ground was still wet when I went to work. When I turned on the car and left it in park, the RPMs were high. After a minute or two, they would drop real low, and almost immediately go back up again. After another minute, the RPMs would drop again and immediately rise again.

Putting the car into gear, it runs rough and acceleration is slow and sluggish. The car shakes a little bit sitting at stoplights, the rpm's bounce up and down. One stoplight I had to hold the brakes down hard because the car was trying to take off on me while the rpm's bounced. Putting it in neutral at the light seems to make the rpm's rise and it's smoother than leaving it in drive. Still acts like it did in the first paragraph.

After maybe fifteen minutes it seems like the car dries out. It idles like normal, the power is back.

I'm at a loss here, and this is pretty annoying. Obviously something is getting wet and causing this, but I'm not sure what or where to start looking. I'm not getting any codes and I've never really experienced fixing anything like this before.

Any help or pointers / tips / suggestions would be greatly appreciated!

Thanks!

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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Bad Ignition wires, start the car in the dark with the beauty cover off and spritz the wires with a spray bottle with water in it and see what you see. Check the wires

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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Thanks BBF!!

That's a good suggestion. I'm going to try to take the day off tomorrow, since we've been slow at work, and do my front brakes. Going to spend the day tomorrow checking out this problem as well.

I did replace the plugs and wires about 15k miles ago with ACDelco. Unfortunetly they came with dielectric grease and I followed the directions and installed the grease as well. Found out on the forum here that I shouldn't have done that. It might be time to check the wires, I remember reading that dielectric grease isn't needed and around 15k miles it starts to show issues. I wasn't even thinking about that since I did it recently but will look into it.

I think there's a ground on the block down near the tranny too, I've cleaned most my grounds but not that one. So I'm going to look into that tomorrow while the car is up on jack stands.

Any other suggestions for things to look into would be greatly appreciated. I have the FSM and I also have a digital multimeter. So I can follow directions in the FSM but I don't have any clue where to start troubleshooting this one! :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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Well, they say that using grease with them can cause a misfire, why them came with grease is beyond me.

Check your coils closely, something is a problem when its damp out, maybe a wire is leaning up against metal. Look carefully for burn marks, spray them with water, the guru used to recommend that

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 will check out your suggestions, thanks!

Quick question about the coil packs. I grabbed a couple out of a junked 1996 STS and rockauto says they're compatible.

How can I test it with my multimeter, the leads aren't small enough to fit in the (secondary?) coil in the bottom.

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 will check out your suggestions, thanks!

Quick question about the coil packs. I grabbed a couple out of a junked 1996 STS and rockauto says they're compatible.

How can I test it with my multimeter, the leads aren't small enough to fit in the (secondary?) coil in the bottom.

We have a thread someplace that we created for COIL testing and norms

You will need to use something to slip into the secondary, like a knife connector or such. I will try to link you to the COIL testing thread

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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Here is the thread that JimD started on coil testing:

http://caddyinfo.ipbhost.com/index.php?showtopic=16967

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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Don't overlook the common problems. Make sure that the coil terminals are clean. I have had a couple of terminals corrode for no reason that I can figure out. Caused a misfire, which was worse on wet days. I just pulled the spark plug wire at the coil, brass wire brushed them bright and shiny, cleaned the wire end with a small brush, and the engine ran fine.

Worth a try if you haven't tried this yet. Price is right.

-George

Drive'em like you own 'em. - ....................04 DTS............................

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When everything is dried up, and you finish your mechanical tests, and all is OK, I would also suggest spraying your electrical componants down with WD40. I am not saying this will fix your current problem, but having a thin coating of this both inhibits rust, and forms a moisture barrier on your electrical componants.

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