HELP! No spark cylinder 4-6 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

FNG · 11-30-2011, 04:50 AM

Help please, I have a 1997 Boxster 2.5L that I recently replaced the head gaskets on. I have reassembled everything but I have no spark on the left side of engine (cylinders 4-6). The engine will start and run (rough) but its only firing on the right side (cylinders 1-3). I am assuming that its an electrical problem but not sure if its a bad connection or a bad ground and I don't know where to start. Any help or advice would be greatly appreciated. Thanks Matt

Bigsmoothlee · 11-30-2011, 05:40 AM

How did you check for no spark?
It was running fine before right?
Here are some things to check

Is the ground strap connected to the valve cover?

Most ecus will cut spark to a cyl (or bank) if its misfiring badly enough to damage the cats ( which have an 8 year/80k warranty )

If you did the same thing I did, youll notice that after attempt, one exhaust bank will be cold, and the other will be warm. On the bank 4-6, the intake manifold will be warm by the head.

If thats the case, you set cyls 1 and 4 on on the compression cycle when you set the cam timing, instead of cyl1 on compression and cyl4 on overlap.

With the engine in the car, you can remove the valve cover for cyl 4-6. Loosen the cams, sprocket, chain and tensioner. Make sure the cam isnt pressing down on the lifters.

Rotate the engine 360deg. Thats just ONE revolution. Bolt the cam back in place,and set your timing again, put the cover on, and start the car back up.

FNG · 11-30-2011, 06:37 AM

I am going to give this a try and will let you know if it corrects the problem. I do belive I set the initial timing wrong, because the procedure that I followed had me set both sets of cams with cylinder 1 on tdc of the compression stroke. I thought that it sounded funny but don't know a great amount about these engine. Learning as I go. I will go to TDC compression stroke on cylinder 1 loosen cams on cylinders 4-6 and than rotate engine 360 degrees and than retighten. If there is anything I am forgetting please let me know, I will get back with you tomorrow to let you know if it worked. Thanks again for the help! Matt

FNG · 11-30-2011, 06:47 AM

Also do I need to reset the timing on the two cams as well before reinstalling them? thanks matt

Bigsmoothlee · 11-30-2011, 12:10 PM

Matt,
Dont even bother touching the other side. With the engine in the car, just pull off the valve cover on the passenger side, set the engine at TDC, remove the cams, turn the engine 360 deg ( just once ), and put the cams back in place. Obviously, you gotta give the engine two turns AFTER reassmbly to make sure the marks line up, just like any other car.