cityofcaterpillars

I replaced the engine in my girlfiends 98 hatch. There is a misfire on cylinder 2 that appears to be electrical. We switched the plug, wire and dizzy and nothing. When you pull the wire from the plug while its running the engine will keep running where if you pull the wires from any of the other plugs the engine will stall.

Car runs fine when actually driving. It also seems to be better in park rather than drive.

Any help would be great. This is the first OBD2 and auto I have worked on.

mk378

Compression test.

If that is OK, switch the fuel injectors (switch cylinder 2 with 3 since those are 180 degrees apart in the firing order) and see if the problem moves.

Unplugging the spark wires with the engine on is not recommended, it can damage the coil. Unplug the fuel injectors one at a time instead.

cityofcaterpillars

Ill give that a shot this weekend. We were thinking it was a lack of spark because you can smell the fuel but I guess that doesn't mean that all the injectors are firing

rfmerrill

Check for leaks on the intake runner to that cylinder too. Misfire only at idle can be a vacuum leak.

edit: And you would still smell fuel if it was misfiring due to that

cityofcaterpillars

Did a compression test and it was 120 on all cylinders except cylinder 2. Cylinder 2 was at 30. So looks like we bought a junk engine

mk378

Could just be the valve adjustment. 120 on the other cylinders is not very good either though.

cityofcaterpillars

I'll check the valves. I'm gonna do another compression test again today just to double check the numbers. Any chance it could be a bad exhaust manifold gasket?

mk378

No, the manifold gaskets don't affect compression. You can even test compression on an engine with no manifolds installed. It's looking at the pressure inside the cylinder, which is held by the piston and rings, valves, and head gasket.

cityofcaterpillars

right. I thought that as soon as I hit reply

cityofcaterpillars

So I did a leak down test and I can't find any leaks at all. Compression is still crap. Any ideas would be great. I have no idea what is wrong with this engine. I have everything to rebuild the engine but I'd like to try everything I can first.

mk378

Turn the engine to TDC of cylinder 2 (the "TOP" on the cam pulley will be at 3 o'clock instead of at the top) and check that all 4 rocker arms on that cylinder are loose.

cityofcaterpillars

Forgot to add that cylinder 2 and 3 both have low compression.

a little more history about the engine. It was pulled from a buddies car and was running at that time. It did sit for a while. So really what could go bad while it was sitting?

adamhunsicker

Throw a cap full of oil into each cylinder then rerun the compression test. If compression comes up, it's bad rings.

If that doesn't help, do a leak down test. Be sure to listen at the tail pipe, throttle body (at wide open throttle), valve cover (take the oil cap off) and radiator (take the radiator cap off). Also pull the spark plugs from all 4 cylinders while doing this test and listen for air escaping at the adjacent spark plug holes. Remember when doing a leak down test you have to have the cylinder you're testing at top dead center of the compression stroke. I know it's a pain in the ***, but this test will 100% identify the problem area if done correctly.

cityofcaterpillars

I did do a leak down test. The crappy one I bought from harbor freight didn't work so I just used straight compressed air. I couldn't find any leaks. May have done the test wrong?

civic402lx

That dies not make any sense. You said cyl 2 & 3 have low comp numbers but your leak down test show no leak? Its going somewhere. Otherwuse it would not have low comp numbers.

cityofcaterpillars

The leak down tester wasn't working. Harbor Freight so go figure. Ended up being the rings. Engine is torn down not and being rebuilt