iWare

So, I've been having some problems with my 94 the last few months, lots of random stalling and sputtering and I did a compression test today and I did the whole oil in the cylinders test as well and didn't get any change but now when I start it up it's running aweful.
It sounds like it was mis firing so that was the first thing I checked, then double checked and it's correct. To make it clear, the engine sounds, feels, and smells like a badly running two stroke. Additionally after a few minutes letting it idle there came a horrible sulfur smell coming from the engine.
Could the oil I put in the cylinder be causing this, or do I need to be looking for something else?

littleredXJ

Double check all your ignition wires and make sure you hooked them back up properly. Also pull the plugs again and make sure you didn't cross thread or strip anything. That or you may have yanked our broken a wire on the harness when you were doing all the other work.

VTJeep

check the plugs themselves for any oil or contaminants on them. also that sulfer thing makes me think bad cat. and i think a bad cat can cause a rough running engine, i think...

get it on a code reader. even if theres no CEL, that doesnt mean there isnt something stored in there.

iWare

I double checked all the wires, plugs, etc and haven't found anything so far.
Earlier today the engine was running fine, before the compression test so I'm guessing that it had something to do with the test but I cant figure it out what.

Oh and another thing to add is that the engine is roughest around 1500 rpm, then at around 2k it smooths out a bit but it's still not quite like normal. The noise and vibration seems a lot like misfiring, but i've tripple checked the order of the wires and it's correct.

JCKustoms

Sounds like you might have broke a spark plug wire (pulled to hard on the wire itself, or...???)
Pull each plug wire off (one at a time) and run the engine. With one of them pulled listen for a difference in sound...do each one until you find which one "doesn't" change. Then that should be the one with a bad wire or spark plug or...

iWare

Thanks JC, I'll check those in the morning.
Also I was wondering, one of the things I've noticed is that it does smell like it's running rich. I'm wondering if some of the oil I had in the cylinders might have gotten onto the O2 sensor and be causing the rich condition causing the rough running.

JCKustoms

If that's the case you need to reset your computer.

tjwalker

The oil you introduced would burn off.

If this symptom started immediately after the compression test, you either have a faulty spark plug OR you have a plug wire problem.

You can verify the resistance of plug wires with a simple multimeter if you have one.

Otherwise, it might be time to spring for a new set of quality plug wires.

phoenix901223

something similair happened to me when I replaced cap/rotor, turns out I messed up the order, played with the wires and ran good as new.

iWare

I checked all the plug wires, all read out around 5 kOhms, one was a little higher at 8. All the spark plugs seem ok, they do need to be replaced soon but none of them seem any worse than when I pulled them before.

iWare

Heres a quick clip i took of the engine running to see if it will help with the diagnosis.

It's hard to hear but under throttle the engine gets rougher and shakes the whole body until around 2k rpm when it starts to smooth out.

tiwvr1

Open the hood when it gets dark out and run it. Look for spark arcing. If you you need to replace plugs soon, just replace them. Also even a small tear in the insulation of any of the wires will cause this.

Now, on a side note, this could be your previous issue esculating. Wierd things have happened before. Once had a chevy truck come into work for a oil change, did the oil change, truck wouldnt start. The starter was bad. Of course he blamed us, tried to make us pay for it, and then filed a complaint. Just saying,there is the possibilty that something finally broke totally unrelated to the compression test.

iWare

Thats what I've been thinking as well, especially since I'm running out of things that could have been affected during the test.
I'm thinking that the rough running is being caused by a really rich mixture, after running it smells like someone poured fuel all over the engine. The first thing that jumps to mind would be the O2 sensors, Is there any way to test them? Any other possible culprits?

Aaron N.S.

have you tried running some seafoam or injector cleaner through the system to remove any gunk in the system?