Engine Shakes Violently and A Sweet Boxer Exhaust Note

[darkside]

A little backstory: In January, I realized that my exhaust was leaking. Louder than stock, yet it was bearable, passed inspection, and haven't been pulled over for it. I figured nothing of it as I was getting rid of my 240 soon.

Low and behold, I still have the car. A few days ago, I started up my car and it sounded like I had a boxer engine. The exhaust note was exactly similar to a WRX/STi. Realizing I haven't done the coveted EJ25V7 swap in my car, I figure something has gone awry. I opened my hood to see my engine shaking violently back and forth, along with my entire exhaust. I figured it might be my cat is busted and it is now pushing air back into my engine. However, my CEL has not come on.

I haven't had time to bring it to my mechanic, as he is on vacation and I am fairly useless diagnosing problems with my own car. So I turn to the forums. Any advice/suggestions (outside of making my car into a special effect in a Michael Bay movie...which I am so tempted to do at this point)

[MELLO*SOS]

Exhaust sounds like WRX + Engine shaking == MISS

One or more of your plugs (and/or less commonly, injectors) are not firing.

Inspect and diagnose:
spark plugs - First off, with the car idling, pull each spark plug wire off from the plug ONE AT A TIME. Right when you pull it off the engine should drop rpm and sound even worse. If so thats great that plug was firing, put the wire back on and move on to the next plug. If the engine RPM does NOT drop and the engine sounds identical, you've found the bad cylinder... Remove your plug and inspect - does the electrode end look good? Not broken off? Not fouled up with black soot? Replace em all at the same time, it's probably been a while anyways.. Obviously..

plug wires - Wires/Boots torn? Corroded? Not making good contact? $20 to $50 for a set at AZ, I'd test them before replacing..

cap - Cap terminals get corroded pretty easily, check it out. You can clean with some emery paper if needed or just replace, stupid cheap.

rotor - The rotor will also get corroded. Clean with emery paper.. Or replace, they are stupid cheap at AZ.

injectors - unplug each one, one at a time, while the engine is idleing. Should cause rpm to drop on each, if the rpm does not change when u unplug then that injector may not be firing properly.

I'm guessing one of your plug wires is loose, or a bad plug..

You'll have this fixed in no time!

[Okinawandrifter87]

Yup you def have a miss. Happened to me as well.

[MELLO*SOS]

Yah this happens all the time, if you don't know what shaking motor and wrx sound indicates then you might not know how to test/find/fix the problem.. Well I am feeling helpful so I updated my post with a little task to find the culprit. Hope it helps, pass it forward...

[darkside]

Thanks Mello, I really do appreciate it.

[boost86]

This happened to me a couple months ago. It really freaked me out, too. One of my spark plug wires popped off the distributor. Check your ignition, it should solve the problem.

[S-Nation S13]

lol thats what happened to me ..my problem was that the o rings on my injectors broke hehe

[BlitzRPS13]

Mine did the same thing randomly... it was a weak coilpack. Unclipped them one by one and #4 made no change.. replaced it and unclipped it.. and made a change in idle when pulled.. so far so good.

[lazysk8er2]

yea i have the same problem currently but it comes on and off. i know its in cylinder 1 but its wierd cuz ill unplug the injector clip and itll sometimes dip in rpm and sometimes not. then when i remove the coilpack itll do it only sometimes. im guessing they are both bad. so yea scope out what everyone else said.


it could also be a bad ground or your arcing in the engine bay.

[BlitzRPS13]

yea i have the same problem currently but it comes on and off. i know its in cylinder 1 but its wierd cuz ill unplug the injector clip and itll sometimes dip in rpm and sometimes not. then when i remove the coilpack itll do it only sometimes. im guessing they are both bad. so yea scope out what everyone else said.


it could also be a bad ground or your arcing in the engine bay.


Run a can of fuel injector cleaner through it yet? That or replace that injector and that coilpack.. should run great after... aslong as your wiring is alll good... aka coilpack harness ground.. mine looked like shit.