Rough idle, no power (yes, I searched)

[downbyfive]

I did a search on this, but I'm not sure if other people's rough idle problems are quite like mine, so I'll ask...

1991 240SX, 94k miles, stock

So I was sitting at a stoplight tonight, idleing at about 700, when all of the sudden, the rpm's dropped to like 3-400 and the car just started shaking like it was going to stall out, but it stayed running. Well, pulling away, power was reduced drastically, most notably at the low end. When I let it sit and idle at home, it stays around 600, but the engine is bouncing back and forth like crazy and causing the whole car to sort of shake back and forth, and the the engine noise is muted, without the normal valve noises. Any idea what the problem may be? It seems maybe different from the others because it started doing it all of the sudden, while the car was just idling...

[Mr.Sandman]

dude, check all your spark plugs, make sure all four pistons are firing...i had the same problems with my 91 coupe. thats what it sounds like, if not, still a problem pm..ill help you out.

[SlidnSideways]

I agree. Just sounds like you may not be firing on one plug.

--Tim--

[downbyfive]

Well, I changed all the plugs (probably needed it anyway) and no dice...How do I make sure all the connections are firing?

[SlidnSideways]

It could be a wire thats shot or something. Try to pull all of the wires one by one and hold a pair of needlenose to the end that hooks on to the plug. MAKE SURE THEY HAVE RUBBER HANDLES. Have a friend crank the car for ya and check to see if the wire arcs a spark to the tip of the needlenose.

[downbyfive]

Well, I pulled the wires one by one and discovered it was the 3rd cylinder that was not firing....but after changing the plug wires, it's still doing the same thing. I checked the distributor, and nothing looked gummed up or even dirty. Could it be a bad injector?

[Mr.Sandman]

Could it be a bad injector?

thats your next check, take it into shop. Unless you know someone with knowledge, if you know what i mean.lol

[Florida240sx]

How is that his next step?If he isn't getting spark then no need to check the injector...

[fatboy]

have the car running. with everything hooked up. tkae a screw driver and listen to the a good injector. it should have a pretty loud click sound. listen to your dead number 3 cylinder now. if you dont hear the click, you have injector problems. whether its your injector or harness problem is to be determined. you can switch injectors with a good one. if the misfire switches cylinders, you have a bad injector. for extra insurance, ohm down the injector. if its an open circuit, you have a stuck injector

[180fan]

Or try unplugging the injector while it's off. If the the situation gets worse when you pull a plug, then it's not that plug and move onto the next plug. When you find pulling the plug on one injector doesn't change your situation, you've found your culprit injector if that's the case. Personally I like to wiggle the harness to the injector around first before going to pulling plugs.

[downbyfive]

It was the injector. I tested the harness and the injector was getting power, but when I pulled the harness off the injector while the car was running, the rpm's didn't change. So I put in a new injector (took about five minutes) and it purrs like a kitten....Thanks for your replies...