1998 s70 non-turbo COIL
the '98s have a distributor, so there's only one coil- it's on the strut tower and connects to the center of the distributor cap. If you have a misfire on #2, it's one of the following, in order of likelihood: bad plug, bad plug wire, bad injector, poor compression in that cylinder.
the '98s have a distributor, so there's only one coil- it's on the strut tower and connects to the center of the distributor cap. If you have a misfire on #2, it's one of the following, in order of likelihood: bad plug, bad plug wire, bad injector, poor compression in that cylinder.
You have to find out WHY it's poor compression. If you do a compression test and find a cylinder that's low, here's what you do:
Generally speaking, if there's nothing at all, you've got a hole somewhere... usually a valve, but sometimes, a piston. If compression is low, you can add a couple spoonfuls of oil the the problem cylinder, then run the test again, and see if compression improves a good bit. If it does, it's rings. If not, it's something else. To specifically figure out the problem, a leak- down test is in order. While you need an actual leak- down tester to determine the severity of the problem, you can often do without if all you want to find is the source of the leak, the compression drop is significant, and accuracy isn't important to you. Take your compression gauge's hose (if it's quick- connect) and screw it into the cylinder normally. set that cylinder on its compression stroke so that all valves are closed. then, connect compressed air to it, and you can find where it's leaking by listening for where the air is escaping. If it's escaping through the intake manifold, it's an intake valve leak. through the exhaust? exhaust valve. Through the dipstick? rings or a hole in a piston. Bubbles in the coolant? head gasket or cracked head/ block.
On the other hand, if you have low compression, you're going to have to pull the head to fix it, no matter what, so you COULD just do so and look at the condition of everything in there.
Generally speaking, if there's nothing at all, you've got a hole somewhere... usually a valve, but sometimes, a piston. If compression is low, you can add a couple spoonfuls of oil the the problem cylinder, then run the test again, and see if compression improves a good bit. If it does, it's rings. If not, it's something else. To specifically figure out the problem, a leak- down test is in order. While you need an actual leak- down tester to determine the severity of the problem, you can often do without if all you want to find is the source of the leak, the compression drop is significant, and accuracy isn't important to you. Take your compression gauge's hose (if it's quick- connect) and screw it into the cylinder normally. set that cylinder on its compression stroke so that all valves are closed. then, connect compressed air to it, and you can find where it's leaking by listening for where the air is escaping. If it's escaping through the intake manifold, it's an intake valve leak. through the exhaust? exhaust valve. Through the dipstick? rings or a hole in a piston. Bubbles in the coolant? head gasket or cracked head/ block.
On the other hand, if you have low compression, you're going to have to pull the head to fix it, no matter what, so you COULD just do so and look at the condition of everything in there.
Thread
Thread Starter
Forum
Replies
Last Post
Kim Gregory
Volvo S90 & V90
1
Feb 20, 2013 08:02 AM




