I have a 2000 Volvo s40 which I recent
I recently purchased. The car was was driving fine except it would shake and lag under hard acceleration. After searching the internet I determined that I have bad coils.

I replaced the coils and bought Volvo spark plugs and now the car won't start. It cranks but it won't turn over. I took the new plugs out and they were soaked with gasoline. I tried putting the the old plugs and coils back in and the car started once. But it idled rough and back fired.

Any ideas what I should try next?

 

When you put the new coils back in carefully check the electrical connectors. Unfortunately there is room for each wire to back out of the connector as you snap it into place on the coil. The fix is to carefully push each wire so that the female wire end slips over the male coil pin. I used needle nose pliers and gently seated each wire.

If that doesn't work then pull one of the spark plug wires connected to one of the coils. Grab an old spark plug and a helper to crank the car. Place the old spark plug into the spark plug wire and hold it against the engine. Make sure your hands are gripping the rubber part of the spark plug holder or you will get a nice shock. Now have your helper crank the engine to see if the spark plug sparks.

If no spark then I'd look at the under hood fuse panel to see if you blew a fuse.

 

I tested the wires on cylinder 1 and 2; they both sparked. I assume cylinders 3 and 4 are sparking since they are connected to 1 and 2?

I also checked every fuse under the hood and they all look good.

Is it possible that something happened to my computer since the battery was disconnected?

 

I forgot to mention that I know that I'm getting fuel to the engine. Whenever I pull the spark plugs out they are soaked with gas.

 

Have you tried opening the throttle all the way and cranking to clear the fuel?

 

Ok I did get it to start. But it idled very rough. There was also smoke coming from under engine.

 

When you tested the plug did you notice the color of the spark? It should be bright "electric" blue. A white or yellow spark could mean the plug wire has too much resistance or the plug has too large a gap.

Also, with the car idling, pull one of the spark plug wires to see if the roughness gets worse or stays the same.

I'm just wondering if you have bad spark plug wires . I've seen the spark plug boot leak so much it would throw a spark to the head. You could not see it because it's down inside that long tube under the rubber 90* elbow. But once you lifted it off the plug while the engine was running you could hear the "pop pop pop" as the spark jumped to the head. Did you replace the wires with the coils?

 

I'm getting a white spark. I've tried every combination of new/old coils and plugs. They all spark white. The Volvo plugs are gapped at .028 the manual says that it's supposed to be .03. The old ones were close to .04!

It's also worth noting that the new coil isn't oem. It's from advance auto.

When I do get the car to start it backfires. I didn't have the issue before, it would idle smoothly. I do have the spark plug wires in the right configuration. 1 & 3, 2 & 4.

 

I found the problem. The wires are suppossed to be 1 & 4, 2 & 3