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Simple spark plug change now a cylinder is not firing??

6K views 15 replies 6 participants last post by  95wave 
#1 ·
Changed my plugs on a 2007 s50 t5 and now it sounds like 4 cylinders are firing. Took all coil packs odd and on again with no luck. Any clue what I may have done?
 
#2 ·
You didn't pull on the harness wires to unplug the coil packs did you. The insulation can get brittle from the heat. The ECU should tell you what coil is not working although it's not really a good idea to run fuel and no spark. Did you get any codes? If you did swap the coil that's not firing with another cyl. If the misfire doesn't move you have a wire or connection problem.
 
#3 ·
Also ensure your gap is correct if you bought sparkplugs that were not pregapped. If all 5 were working and now one is not, it is either wiring issue, your gap is off, or your gap was smaller with the older plugs so the coil could handle it but now that it's correct the coil cannot.
 
#4 ·
+1. It's always the simple stuff.
 
#5 · (Edited)
They were pre-gapped Volvo plugs from ipd, I believe they were all .30... I guess I need to pull them all and recheck, should I squeeze them down a little to .27-.28?

Just checked the ones I removed and they are .38... Really confused now!

Can I drive my car 20 feet into my garage to get out of the rain or do I chance damaging something?
 
#6 ·
If you are worried about damage, and are looking for an ideal solution, try to push it in neutral into the garage.

However, I don't think you'll have an issue getting into your garage to escape the ran in a 20 ft. line. The problem with a misfire is that now you have raw fuel getting into your exhaust and to your converter; which could damage it. For the short amount of time, you should be okay!
 
#8 ·
I used pre-gapped NGK's. Did you happen to accidentally drop one of the coil packs while working with them? They're sensitive to drop and shock. Is it throwing a Check Engine Light at all? At least if you could narrow it down to one cylinder life would be easier for troubleshooting. :)
 
#9 ·
Did any of the boots unattach themselves from the coil packs at all when you were pulling them out by chance?
 
#12 ·
The simplest method for most applications, is pull each pack one at a time and see which one DOESN'T make a difference in the sound of the engine while running. That will tell you which on is not firing.

If it's like mine, that won't do you any good, because my coil packs were weak but didn't have a problem at idle, only at about 30% throttle.
 
#13 ·
1.Also take a look at the Firing Order - I believe it is Possible to switch 2 of the Units If the Routing is changed some .. ( Mixed Up ) and Grounds
2. Make sure when You tightened down everything is Nice and straight so You don't stress a Coil Pack and Damage It . ( Light Tq. ) on those .
 
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