Random Cyl2 Misfire, Help! (gotta work tomorrow!)

[PCGUY112887]

Ok so I start my car after work today, SES is flashing and it's goin rough. Turn it off, turn it back on, doin the same thing. I'm like crap

Managed to drive it to autozone, where they pulled my code and told me I had a Cyl 2 misfire. Last time this happened it was about 5 months ago when I was at a friends house, went and started it up and it started to misfire. I didn't know what the problem was (nothing obvious) and it was 2am so I just slept there. In the morning I started it up and it ran totally fine so I checked coilpacks (gave correct OHM readings), and checked the wire and sparkplug (even got a new one), all looked fine. Threw in some injector cleaner to make sure it wasn't a dirty one and all was good.

So today it starts doing the same thing, on the same cylinder. I have't pulled any plugs or wires yet but i'm betting once again their going to be fine. I just ran Seafoam through the tank last fillup so an injector coulden't be dirty.

The guy at autozone said he wasn't sure but something similar on his blazer happened and he had a dirty EGR valve and he cleaned it and it was fine... I don't even know how to clean my EGR valve.

Please help I gotta go to work in the morning!

[tractorman]

I've never heard of a dirty EGR causing a miss.

There's no EASY fix here except luck. I'd cut out cylinders first and see which one it is. Then start swapping parts around and re-checking. When the miss follows the part, you've found your problem.

pull off coil wires one at a time, stick a paper clip in each one so it touches the outside of the metal connector, and sticks up when you snap the wire back on the coil. Ground a wire, and spark each of them clips while it's running- that'll cut out one cylinder at a time, and you can find where to start.

[geoffinbc]

Make sure your plugs are tight. Aluminum heads are notorious for allowing plugs to back out.

[PCGUY112887]

Ok well I checked some things out, tested resistance of the coilpacks (got 6.25 when set to 20k, and got like 6.11 and 6.07 on the others so I think that's fine).

Pulled the sparkplug and it was fine, wire looked fine. At autozone they pulled 2 codes, both being the same thing. I think it's because at one stoplight on the way home it stopped flashing for a bit and was smoother, then started again. This also leads me to believe that it may be the injector for Cyl 2 because of the way this happened before, and the fact that I ran fuel injector cleaner last tank and maybe it loosened some crap and now something is stuck in the injector.

Also in the service records for my car it shows it running rough, then them replacing Cyl 1 injector.

[PCGUY112887]

Wow fuel injectors aren't cheap.... $80 for the cheapest one.

Would Accel Performance; Fuel Injector: Stock Replacement; Flow Rate 21 Lb.; 6 Pc. work without having to modify anything? They come out to be about $40 each if you buy them all together, and why not go with the higher flowing ones if they work without having to change anything.

I think tomorrow i'm going to swap injector 2 and 4 or something and see if the misfire moves, if it does then just get all new injectors since the others goin out are probally right behind it. Can you even swap around injectors and they work the same? And isn't there someway to test the resistance on an injector? Rather make sure this is the problem before I get all-new injectors.

[turboD]

There's a condition that GM calls "fretting", a slight corrosion buildup on the injector connector terminals. If you disconnect the injector and reconnect it, the missfire will go away for a time, then return. The fix is easy, just paste dielectric grease in the injector terminals and reconnect. GM makes a great dielectric grease for electrical connector, pt no 12377900. Works on any terminal/connector, including bulkhead connectors.

[PCGUY112887]

Ok so I wasn't sure how to get the fuel rail off (relieved the pressure but didn't know how those 2 metal lines came out, probally with some tool) so I pulled the connector off each injector and checked em out, all were clean. So I took the mutli meter and got 12.5-12.7 ohms on all of them.

So does that mean that the injectors are fine and I ripped this upper off for nothing? What else could it be? Somehow a wire/coilpack gone bad? Something bigger? (like a gasket )

Edit - I noticed that the EGR gasket was REALLY bad, totally crushed, discolored, flaking apart and brittle to the touch. Is this normal or could this of somehow been leaking causing problems?

[heza]

take the injector to get it flow checked. that would be the simplest thing to do.

[PCGUY112887]

Well I just went ahead and put it back together and now it won't even start, kinda sounds like I have a vac leak (a while ago when I pulled my brake booster and tried to start it woulden't, then when i stopped tryin you heard a small "pop" of air I guess). It sounds like that, and I don't get how I could have a leak.

I guess it'll be towed to a shop tomorrow or something.

[NeonKnight]

just swap around an injector, taking off the fuel rail is not hard. you just unbolt it and it pops right out. the injectors sit on that rail, just make sure to coat the o rings of the injectors before you put them back in. Just take some of the oil off the oil cap, or use the dipstick and just recoat the ring.

swap around the injectors, if it moves then you know whats up. i did this on my brothers 2.0 4 cyl ford probe. thing was odd, it missed, stopped, missed, stopped. replaced all new plugs wires cap rotor etc... helped but still did it. lol

try it out man, dont pay the shop prices its a simple thing.

as for it not starting, the pop you heard... sure it was air and not a fuse or something?

recheck all vac lines.

[PCGUY112887]

I fiddled with all of the connections and it started, must have had something lose.

Also when I started it, it wasn't missing anymore. You can tell it's just a tad bit rough, but not enough to trigger a SES light. I'm going to attempt to have a shop run the car off some cleaner (since rigging up my own system will cost about as much as a shop will) and hopefully get the injectors nice and clean again. System is probally dirty since I do 100% city driving and if I replace fuel injectors I want to replace all 6, and attempting to clean is cheaper .

[geldartb]

Make sure your plugs are tight. Aluminum heads are notorious for allowing plugs to back out.

found that one out while i was rechecking the gap after my swap.

[IsaacHayes]

Fix the EGR gasket if you haven't. A vacuum leak will cause a rough running engine.

[Scott Crowe]

I've had this happen before on another car and it was indeed a dirty injector that Techron in the tank twice wouldn't cure. Fixed it by having the injectors professionally cleaned. Neat tool they used but very expensive, I ended up buying a kit I found on eBay that did the same thing but was a lot cheaper. I've also seen it advertised on the LS1.com website.

[jackal2000]

Fixed it by having the injectors professionally cleaned. Neat tool they used but very expensive

are you talking about a MOTORVAC?