2003 Jetta rough start in morning

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I've noticed over the past few months that during the first start of the day, in the morning, and only after it's been raining or is very humid, will the car run horribly until it warms up. It severely misfires and then after 15-20 minutes or so runs normal.

I changed the spark plugs but it hasn't helped. I'm thinking maybe the boots or coil need to be switched. My assumption is condensation is getting where it shouldn't and causing electrical firing issues. What do you guys think?

Thanks
 
Do you have a check engine light?
This could be several things going on with your Jetta from a vacuum leak to an electrical issue, maybe with the coil/boot/wire etc. or fuel related. Sounds to me as though there is a hair crack in one of the coilovers and the engines runs better as moisture evaporates.
 
yeah the cel blinks during misfires then stays on. I haven't checked it with an obd meter though, i assume it would just say misfire
 
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Originally Posted By: llmercll
I've noticed over the past few months that during the first start of the day, in the morning, and only after it's been raining or is very humid, will the car run horribly until it warms up. It severely misfires and then after 15-20 minutes or so runs normal.

I changed the spark plugs but it hasn't helped. I'm thinking maybe the boots or coil need to be switched. My assumption is condensation is getting where it shouldn't and causing electrical firing issues. What do you guys think?

Thanks


Misfires when damp definitely points to electrical. Had several vehicles with these symptoms, which cleared up with new plug wires (or on older vehicles, cap and rotor) or in one case, the coil pack had some sort of issue and needed to be replaced.
 
Originally Posted By: llmercll
yeah the cel blinks during misfires then stays on. I haven't checked it with an obd meter though, i assume it would just say misfire


A code reader may help you to determine which cylinder is misfiring and to narrow down the problem. If you don't have a code reader, you can take it to any number of auto parts stores and they'll do it for free.
 
A quick check would be to spray the plug wire boots on the coils with WD40, and if the misfire clears, change the wires. My Subaru gets a little persnickety sometimes when it's really damp, and a quick shot of WD on the coil clears any grouchiness right up.
 
Originally Posted By: skyactiv
Myself owning a VW, https://www.ecstuning.com has tons of VW OEM and aftermarket parts at the best prices.

They're ok for aftermarket stuff, but AutoHausAZ and GermanAutoParts beat them on price, shipping, and especially customer service - every time.
 
Originally Posted By: rooflessVW
Originally Posted By: skyactiv
Myself owning a VW, https://www.ecstuning.com has tons of VW OEM and aftermarket parts at the best prices.

They're ok for aftermarket stuff, but AutoHausAZ and GermanAutoParts beat them on price, shipping, and especially customer service - every time.


Good to know!
 
Having owned a 2004 VW Passat 1.8T for 14 years, I can speak about throwing parts at such a problem. DON'T.

Get the car scanned first. It might be a crank position sensor going out, but don't ASSUME.
 
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join VWVortex, maybe someone close with a VagCom diagnostic in their computer like i do. autozone will scan as well, + coil packs were an issue then, get a scan to identify which one. Ecs has great service but as always shop around as prices vary$$$
 
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