Cylinder #4 misfire!

So my truck started shuddering when i started it up after lunch. It was fine on the way to lunch but now its not firing right. I got up to speed and the Cel started flashing which means the cylinder isn't working at all. Crawled my way back to work and scanned it... P0304 code cylinder 4 misfire.

Now i need to get home today and the shop won't be.able to look at it till next week. Can i drive it or do i.risk snapping a rod??

 

Generally thats a fouled plug...grab a new plug and change it out. Its just gonna run like ass...I wouldnt think you'd snap a rod. If a plug dont cure it, it might be a coil??
Plug is a 2.00 fix... youll be able to tell instantly if she's fixed.

 

my brother has a '02 4cyl. that developed the same symptoms. he keep on driving it while trying to diagnose the problems. the misfire would jump from cyl. 1 to 4 randomly and the engine shaking got worse over time.

at the time the motor had like 245k miles so our last assumption was that it had a burnt valve. finally he had a mechanic friend look at it and he came to the same conclusion. at this point, instead of just replacing the valve, my brother decided to just rebuild the motor so the heads went off to the machine shop.

it purrs like a kitten now and it seems to have more pep. hopefully, your situation isn't like his. you can start with replacing the plugs. swap the coils around and see if the misfiring moves to another cyl.

 

Changed plug 4 and it sounds better already.

 

Drove it and its still rough. Cel came back on and started flashing again. Code still reads cylinder 4 misfire... fuck!!!!

 

plug wires? did the plug look fouled when you replaced it?

 

it is your ignition coil for that cylinder. i had this same problem replace the coil yourself and save alot of $$$

 

If it is misfires too long, you'll burn a valve and bend it.
and lose compression

old motor read like

168-49-169-168




Easy check is swap coilpacks around, clear code, drive it.
Scan codes, if it jumps a cylinder, it's 100% a coilpack.

Also, look into flowing your injectors..mine old 2RZ was missing because of coilpack plus also injectors weren't flowing correctly...there like $15-30 each to have them rebuilt with new baskets, o-rings and flowed.

 

Thanks guys. Anyone have a write up for replacing the coils?

 

unbolt, rebolt.

 

I've never done coils. Where are they

 

LOL, if you can do spark plugs, swapping coils is cake. it should looks similar to this pic. unplug the harness and swap 4 to 1 and 1 to 4. reset everything and drive it around and scan for codes when the light comes back on. if it misfires in cyl.1 then its the coil, but if it still misfires in cyl.4 then you can rule out the coil.

 

Ok, so when you say swap 4 to 1 and 1 to 4, you mean you take out the coil and put it in the other and vice versa? Also i thought 3 coils were on the left of the engine and 3 plugs were on the right of the engine?

5 6
3 4
1 2
Front

So how do i swap 1 to 4 if #4 doesnt have a coil?? Or am i swapping the wires?

 

He was referring to a 4 cylinder, the 4 cylinders have coilpacks..1 coilpack runs 2 cylinders.

You have individual coil's.
Take 4 and put it where 3 is on opposite bank.
Clear code, drive, when code pops back up..scan it..see if it says bank 1 cylinder 3 or whatever

 

So basically swap 3 and 4, but leave the plugs in?

 

yeah lol..your testing the coils..it has nothing to do with the plugs.
Just make sure your plugs are gapped and within normal condition of plugs(not fouled, etc)

 

if the light is flashing that means you could do harm to the catalytic converter from raw gas being feed to it

 

True..but it will take ALOT..I drove on a misfire for a LONG time..because mine stumped me..I tried so many different things..then I finally checked compression and took valve cover off..and realized why.
Mine still passed smog though after I fixed it.
So it can ruin cat but it's gonna be dumping ALOT of fuel and for a long period of time.

 

Okay, so before i go ahead and start pulling things off and swapping them i need to be %100 clear of what im doing. Couple things dont quite make sense:

1. If im swapping #3 coil into #4 hole and vice versa, how does it get power if the harness is unplugged?

2. #4 plug gets power from #1 coil, so wouldnt it be easier if i just swapped #2 and #3 plugs?

 

i don't know much about 5VZs..my bad. didn't notice how it was setup..so it's the same idea as 1-4, 2-3 on the 4 cylinders..i apologize for confusion

just swap cylinder 4 coil to any other coil that is a seperate circuit, that's all you needa know..then clear the code.