I just changed the wires and plugs on my 94 buick regal 3.8. The wires are all connected correctly and the plugs are in tight, with the proper gap. However since I have changed them the car is idling pretty rough. It goes away as I drive, even at low speed, any ideas? (Also, It used to idle rough every once and a while, but is more persistent since I changed the plugs and wires.)
Why does my car idle rough after changing spark plugs/ wires?
check pcv valve. it may be hung up with its new found power and thighter vacuum. Shake it, if it ratles its good
Why does my car idle rough after changing spark plugs/ wires?
Were any of the plugs dropped or bumped?
The porcelain might have a hair-line crack.
you might have changed wire possitions
if it ran good b4 check gap of plugs as well check to c u didnt dross a wire these things happen were all human if this doesnt work if its 96 or newr its obd2 . hook it to a machine and read the codes.. hope this helps,
Take the plugs back out. The one that's misfiring will be wet and/or black. Double-check your firing order carefully (this is the most common problem), then re-install and make sure the wires are on tight at both ends. Then try again.
Good luck!
you might have damaged the porcelain on the plugs when you put them in,there real easy to break,its possible also that you might have got a set of plugs that aren't all that good,i have done this a few times,you may have to take them back out,and re-check the gap,and make sure they aren't damaged ,any cracking in the porcelain will cause one to mis -fire,if it got worse when you did the tune up is has to be something to do with it ,good luck with it.
I would say maybe a coincidence. Check the idle air control (iac) located near the throttle body. also see that the throttle body is clean. You might check the throttle position sensor (tps) also. As a lesser suspect would be the egr valve.
It can happen that you got some bad wires. The best way to check this is to park the car in the garage nose first or go outside at night and pop the hood and start the engine. If there is any arcing you will see it in the dark.
Some wires, it only takes one wire, will have a slight manufacturing flaw and will throw the spark to the path of least resistance which isn't the spark plug in this case.
They can replace them under warranty if this is the case.
You also need to be aware of a perfect replacement spark plug. Just because someone hands you a spark plug in a auto parts store does not mean it is the right plug. You need to eyeball every plug to make sure they are all identical to the ones you removed. Especially width, depth or height so it doesn't hit the piston or cross thread into the cylinder head.
If one plug isn't torqued properly (snug) you'll have a slight miss in that cylinder.
Make sure the plug wire boots are snug on the plugs, too. The little %26quot;clip%26quot; inside the wire boots are not all set at the same depth and can be adjusted so the boot covers most of the plug.
Also, if you get any of the anti-seize graphite compound on the boots or on the outside of the plug then the spark will pass the spark plug and go straight to the head. You'd have to pull the wire and plug one at a time and clean them off with clean rag and something like brake parts cleaner. There are two types of %26quot;grease%26quot; you use when changing the plugs. The anti-seize conducts electricity and should only go on the plug threads and the dielectric grease you put on the boots does not conduct electricity.
Good Luck!
Grab the wire rs by the and if you get a shock. That is a good please to start looking for your problem.A crack in the plug or the cap.It could be lose there.
