Odd rough sound at idle...possible misfire?

[Spartanzz]

Ok so not too long ago i had a misfire code i ran some injection cleaner through my gas tank and the code stopped coming back...But, while sitting at a light you can hear a rough sound every now and then. There isn't a real pattern to it it almost seems kinda random. any thoughts?

 

[machinegunsquid]

Re: Odd rough sound at idol...possible misfire?

Need more info than just "a rough sound every now and then"

Easiest way to check where it's coming from is to listen around, and try to pinpoint it.

Grab a long screwdriver, or a breaker bar, or something long and metal, and set the handle against your ear, and the other end against various engine parts. Where ever it sounds loudest/clearest is going to be your source.

 

[Vegas_Matt]

Re: Odd rough sound at idol...possible misfire?

idk this is very unspecific. might be pinging? maybe a pulley?

 

[Spartanzz]

Ok sorry guys for not being very descriptive was kinda half asleep while typing that lol. But, first off the sound seems the most apparent while in gear at a red light or stopped if its in park or neutral its very hard to hear and iv tried to pinpoint it but very hard too do so when i can get a general view of where its coming from...As of right now there is a pending Misfire Cylinder 3 code being put out. Tomorrow i plan to have a friend sit in the car with it in gear holding the break to see if i can fine where its coming from. And iv also replaced the S/C coupler so figured id get that out of the way first off. Also tomorrow we are going to take off the fuel rail and clean out the injector, figured it couldnt hurt. But any suggestions as to go about trying to find out what it is are always appreciated.

 

[machinegunsquid]

Quick tip before removing the injectors..Make damn sure you clean out all the sand/dirt/gunk around them, or it can fall into the cylinder. Compressed air works great.

You can take the S/C belt off, to eliminate the s/c, and all the pulleys required to run it. I had a bad tensioner before, and it sounded terrible.

A few good listening spots are: on the fuel rails, on the LIM, on the sides of the heads, and the block around the transmission.

Make sure to keep something covering the injector holes too, that way nothing drops down in there. Check all your o-rings for damage also.

 

[Spartanzz]

Ok thanks a lot for the info ill jeopardy you all updated when we start the work

 

[Coolride]

I worked as a tech for GM in the 90's, and we replaced plug wires more than anything else for cylinder misses. What you can do without a scope, is take a 12volt test light probe $5, and ground the clamp on ground somewhere, and jab the pointy edge in the plug wires one at a time, at the coil pack . Jab right thru the rubber boots on the plug wires, it'll kill one cylinder at a time, until the one it doesn't effect, and that's your missing cylinder. It then could be the plug,wire, or injector. Mostly the wires from my experience though, plugs usually last longer than the wires from what I've seen.

 

[Spartanzz]

Well the thing about the wires is i switched them (switched the 3 with the 6, which is the same coil pack) and it still gave the cylinder 3 code. But, what i did today was swap the coil pack that has 3 and 6 on it with one of the others then cleared the codes. So now im just playing the waiting game on it and the other things is im trying to get an evap leak code gone so i can get an emissions test done on this thing...so got some things to work out.