changed spark plugs... now slow off the line.

[dfellars77]

Hi, I am a bit of a Porsche Newb, but made my first attempt at changing the spark plugs last night. I installed Bosche +2 and even though it was a pain, everything seemed to go smoothly. Unfortunatley, now she is a little slow off the line and requires a bit more gas to get rolling. There is a slight knock from the drivers side and my thought that I did not get one of the wires attached properly. Does that sound right? I also replaced the air filter at the same time and it was a bit tight going, but it ran fine after installing the air filter.

thanks for the help!

[Tool Pants]

I can only guess.

Are you getting a misfire? If so then one or more of the electrical connectors to the coils are not seated. I have changed the plugs on several Boxstirs and this has happened to me.

So now when I do a plug change I change 3 on one side and then start the car. If it runs ok then I do the other side. That way if there is a misfire after a 6 plug change I do not have to go back and check all 6 connectors, just 3.

If you have a misfire then pull back the rubber boot on the connector and make sure the connector is fully seated.

[boggtown]

I just changed my plugs saturday and all went well so you can get lucky, lol. I would either guess something didnt get seated as toolpants suggests or maybe its the plugs themselves, who knows. Thats why I went with factory beru plugs.

[dfellars77]

checked the plugs wires and they are all attached correctly. This is my girlfriends car and has not had much in the way of TLC. When I pulled the air filter there were leaves and 3 cigarette butts in there and it is overdue for an oil change and coolant flush. I've been driving it all day and it is idling better and the knock appears less. Is it possible that the combination of new air filter and sparks plugs was a bit of a shock to the system and it will take a little longer for the computer to catch up?

[Loren]

Go back and look at the insulators on the coil packs. My guess is that one of more is cracked.

[secretagent214]

I changed my spark plugs a month or so ago and had basically the same problem. One of the connectors between the boot and wire wasn't tight. Of course, it's a pain to to figure out which one of 6 it is in such a confined work area. I ended up just pulling off one wire at a time, starting the engine and checking to see if there was a change, then plugging that wire back in. If I felt a change, it meant that that plug was firing. When I found one that made no change when I pulled it off, I worked a little harder to make sure it seated when plugging it back in. I started it up, and all was fine. If that doesn't fix it, at least you'll know for sure which plug isn't firing and can take a closer look at it.

It's a bit easier to test misfires on my old Plymouth Neon. All the plug wires are right up front on top of the engine. The Boxster is still worth the trade offs :)

Edited July 6, 2007 by secretagent214

[dfellars77]

Thanks for the advice everyone. I check the wires and boots but my mechanic is going to lift it for me and just double check. After driving it for about 20 miles the engine seemed to smooth out a bit more and I wonder if the engine was just shocked by the new plugs and air filter after not having much TLC over the past few years. I also installed a K&N Air filter which I decided to replace with a stock filter as soon as it arrives. I hope that will make a difference.