FIXED Troubleshooting misfire *Winterbeater*

FieroAlex

FieroAlex

Legacy Member
FIXED

Hey guys, this one has me stumped.

The car is a 2002 Hyundai Elantra

My winter beater started acting up on the 24th and hasn't really worked since. The car had a very rough idle on that day and would stumble when driven. It happened totally out of nowhere. I quickly parked the car when this started happening, I barely made it out of my parking lot anyways.

The car did not generate any codes although it was running very rough.

I checked for spark and I checked for fuel which all seemed fine. I checked the resistance for each injector and it was within factory specs. I also checked the ignition cables even though they are only a year old, they are also fine.

At this point I started changing and checking.

I put 4 brand new plugs, nothing changed.
I changed the coil packs, the car did seem to run better but it still had a rough idle and stumbled when driven.

At this point I let it idle for a while and I went for a small drive which finally gave me a flashing cell (Misfire).. Turns out it was misfire on Cyl. #2

I changed the fuel rail with the 4 injectors thinking that I probably had gummed up injectors. Now the car idles better overall but it's still sputtering and it still misfires.

So to recap

Misfire Cyl 2

New Plugs
Changed the coil packs
Changed the Fuel Rail with the injectors

Still stumbles and misfires.

Any other suggestions before I get into the compression check?
 
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Update:

Checked spark plug gap.. it's alright .040
Checked compression 230 230 230 240 so that's acceptable too..

I'm gonna go out and see if I can clean the MAF?
 
Have you changed the plug wires? Are you getting spark on cylinder 2?

I just chased down a misfire on my Subaru.. New OEM plug wires that were 1.5 years old, faulty wire on cylinder 3...
 
I did check for spark and I could clearly see the spark however I don't know if it's good spark.

I'll see if I can swing by the junk yard and pickup a second cable for testing.
 
If not that start looking for a vac leak.. most likely intake gasket. You can always unplug the maf sensor and drive around. The car doesn't need the maf to run
 
It was freezing outside today but I went to have a little look around. I couldn't find a vacuum leak but I'll try to pursue that option hopefully tomorrow.

The car doesn't have a MAF so I couldn't clean it. I did clean the MAP sensor however It didn't have any effect.

I had also read that the problem could be a leak at the intake gasket. I tried to see it but I couldn't see much since it's a pretty grimy area, I sprayed some sensor cleaner around the area hoping to see if there would be an RPM change or some bubbling from the gasket area but I couldn't see anything.

I couldn't get my hands on another ignition cable, I tried to switch them around but because of their lengths I can't. I did however check for spark again, and it clearly does work however when I remove the cable from cyl 2 while running there clearly isn't a difference in operating condition so that's definitely the problematic cylinder.

Anyone know where I can find a Noid light to test for injector signal?
 
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update.. just about froze my @$$ off this morning.. the good news is the car started but it's still running on 3cyl.

I made a custom Noid light with a small test light, I am able to confirm that the injector is getting the pulse signal
.
After staring at the fuel rail for several minutes I noticed that the injectors looked off so I took apart the rail again and fixed the way the injectors were sitting. It still misfires on #2

I took the fuel rail apart again and changed the #2 injector for one of the injectors on the first fuel rail and I'm still misfiring on #2

Tomorrow the junk yard re-opens. I'll go pickup another ignition cable for cyl #2 and hope that it fixes the problem. I did test the current cable and there doesn't seem to be any current leaks and it is delivering a spark but who knows.

I'm just about to give up on it. I'm not sure how to check the intake gasket, the only trick I found online was to spray the area with carb/sensor cleaner and see if the idle changes or if the cleaner bubbles but it did none of that.

The car does run much smoother than it did last week, even when driving. I don't get any codes besides the misfire cyl 2 codes. I cannot get it to misfire at idle or while revving in neutral it will only misfire under load.
 
I had similar problems and a bad wire insulatation right before the coilpack was the culprit.
 
FieroAlex said:
update.. just about froze my @$$ off this morning.. the good news is the car started but it's still running on 3cyl.

I made a custom Noid light with a small test light, I am able to confirm that the injector is getting the pulse signal
.
After staring at the fuel rail for several minutes I noticed that the injectors looked off so I took apart the rail again and fixed the way the injectors were sitting. It still misfires on #2

I took the fuel rail apart again and changed the #2 injector for one of the injectors on the first fuel rail and I'm still misfiring on #2

Tomorrow the junk yard re-opens. I'll go pickup another ignition cable for cyl #2 and hope that it fixes the problem. I did test the current cable and there doesn't seem to be any current leaks and it is delivering a spark but who knows.

I'm just about to give up on it. I'm not sure how to check the intake gasket, the only trick I found online was to spray the area with carb/sensor cleaner and see if the idle changes or if the cleaner bubbles but it did none of that.

The car does run much smoother than it did last week, even when driving. I don't get any codes besides the misfire cyl 2 codes. I cannot get it to misfire at idle or while revving in neutral it will only misfire under load.
Click to expand...

Swap your cyl 2 cablewith cyl 4 and reset the code. Also, take at look at your plug. Maybe you have some ''vert de Gris'' on plug 2
 
It's Fixed guys.. and I feel like a freaking noob.

I did have spark and the part of the cable that I checked was perfectly fine however Gregster was right, the base of the stalk, the part that gets inserted into the cylinder head had a micro crack under the rubber at the base. The wire would behave totally fine outside of the engine and I wouldn't get any jumping spark however once inserted into the head the spark jumped onto the cylinder walls instead of onto the plug.

I swear I checked that cable a good 5 times but not once did I think of checking the base of the stalk around the rubber. Shows that I've been out of the garage for over 10 years, I'm loosing some of my spark. :(

I got a free cable at the junk yard, I installed it and the car was fixed right away.

Thankfully I bought all my parts aside for the brand new plugs at Kenny's.. all in all I spent $30 for the new plugs, fuel rail, coil pack and wire. Decent enough but the week of downtime was killer.

Thanks for your help
 
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