Author Topic: Misfire on cylinder #4 (Read 3065 times)

silverUURX · « **on:** May 15, 2015, 06:43:20 am »

Started my 13' sti up this am and she sounded rough and shaky… got the car out of the garage and made it 100m down the road before it threw a code. Cobb access port says cylinder 4 misfire. So i cleared the code and re-started the car. still feels rough and shaky. I just fuelled up last night with husky 94 as I always do. I'm hoping its a horrible tank of gas…. Anyone else seen something like this?

I have about 41000kms on the car and have been running cobb stage 2+ 93 for about 5000kms.

funk32 · « **Reply #1 on:** May 15, 2015, 07:58:13 am »

for a starters, misfires will not just disappear if you reset the ECU. This is a bad practice and I am not sure why it is everyones first go to when these cars have an issue like this.

what mods do you have?

things that can be checked

make sure the connection to the coil pack in seated
clean the maf sensor
check for leaks or smell of fuel
check spark plugs
check for vac leaks
if you really think it is ittshay gas swap the map to 91 ACN and that will pull the timing down.
and if all that looks good, time for compression and leak down tests

silverUURX · « **Reply #2 on:** May 15, 2015, 08:08:17 am »

Thanks for the response. As for mods just cobb stage 2+ bolt ons, so AP, sf intake and cobb down pipe.

started her up again and she sounds normal. not shaky or rough at all… drove around the block nicely and it seemed fine….

Ill go through what i can to look for leaks but probably going to head down to vex and see if they have an opinion too. Just for my own peace of mind.

Blue_Subie · « **Reply #3 on:** May 15, 2015, 11:17:38 am »

Recently got a flashing check engine light and it mentioned a misfire as well. After checking a lot of what funk32 mentioned (I just got my gaskets done so no leaks) all I had to do was change the spark plug wires...

silverUURX · « **Reply #4 on:** July 08, 2015, 04:26:10 pm »

coil pack was to blame. put a new one in and its been good.

RedndWhite · « **Reply #5 on:** July 09, 2015, 10:19:16 pm »

So I've ran into a similar issue; P0301, P0303. Misfire on Cyl 1 and 3.

- MAF sensor has been checked and cleaned, it's good.
- Had a spare coilpack sitting around, which I used there, and it's good.
- Spark plugs are brand new as of 5000 km ago... Haven't pulled one out to check the condition.
-- Bosch Platinum 4418

Seems bizarre to me, when I'm at idle, it doesn't idle right. The Tach is reading low, like sub 250, while the Dashcommand is reading 600, which is normal. The entire engine lugs and is visibly moving (that may just be bad bushings) but it moves the car around too. There also sounds like something struggling around cyl 4, while cyl 1 and 3 sound fine.

However, when I high idle it to 1500, the engine light goes away, everything smooths back out to normal, and it seems good to me.

I used the oxy at work on a very low psi and slowly moved it around the vac lines to see if there was any surges, didn't see or feel anything.

Could it be the fuel filter is clogged? At idle, the fuel pump isn't getting enough demand to push the fuel through, but when I idle it higher, it has that demand and pushes the fuel through?

This also happened *immediately* after filling up.

Noise and video of engine shaking.

silverUURX · « **Reply #6 on:** July 10, 2015, 08:01:36 am »

take it down to Vex. I'm sure they can fix you up in no time.

RedndWhite · « **Reply #7 on:** July 10, 2015, 08:57:56 am »

Quote from: silverUURX on July 10, 2015, 08:01:36 am

take it down to Vex. I'm sure they can fix you up in no time.

Not particularly the answer that I'm looking for. Given that Vex is at least a 2 hour drive one way, I'm not trailering it, towing it, or driving it, nor am I wanting to pay for labour on something that should be simple to diagnose and repair.

LilDrunkenSmurf · « **Reply #8 on:** July 10, 2015, 08:58:42 am »

Sell it and buy a Honda.

RedndWhite · « **Reply #9 on:** July 10, 2015, 09:01:44 am »

Quote from: LilDrunkenSmurf on July 10, 2015, 08:58:42 am

Sell it and buy a Honda.

>.< I drove a Honda to work today; dislike everything about it asides from the working air conditioning.

snackers · « **Reply #10 on:** July 10, 2015, 09:25:12 am »

Quote from: RedndWhite on July 09, 2015, 10:19:16 pm

- Spark plugs are brand new as of 5000 km ago... Haven't pulled one out to check the condition.

Pull the plugs. Make sure they're clean.
Check the plug wires. Specifically the ends.
I just did my plugs, and when I pulled one connector off, the wire completely seperated from the end. Rust.

Fuel could be a problem, but I have no idea how to diagnose that. Since you're getting misfire on cylinders that are on the same side of the engine, it might be a fuel rail clog?
But I would check spark first. Make sure your plugs/wires are actually getting power.

seat safety switch · « **Reply #11 on:** July 10, 2015, 09:42:02 am »

If it's the original coil pack and plug wires, those plug wires are long past dead.

If you have fast hands you can always pull a spark plug, leave it in the plug wire and see if it sparks when you put it near the frame and idle the car.

RedndWhite · « **Reply #12 on:** July 10, 2015, 10:47:07 am »

Quote from: snackers on July 10, 2015, 09:25:12 am

Pull the plugs. Make sure they're clean.
Check the plug wires. Specifically the ends.
I just did my plugs, and when I pulled one connector off, the wire completely seperated from the end. Rust.

Fuel could be a problem, but I have no idea how to diagnose that. Since you're getting misfire on cylinders that are on the same side of the engine, it might be a fuel rail clog?
But I would check spark first. Make sure your plugs/wires are actually getting power.

Okay, while I replaced the coil pack, I checked the wires, and they looked fine, no rust, seemed solid in the boot. I didn't test continuity in them, however, so they could be screwed. I haven't changed the fuel filters in 60k km, so I don't think it would hurt to replace those while I'm at it.

Quote from: seat safety switch on July 10, 2015, 09:42:02 am

If it's the original coil pack and plug wires, those plug wires are long past dead.

If you have fast hands you can always pull a spark plug, leave it in the plug wire and see if it sparks when you put it near the frame and idle the car.

Yeah, I don't have fast hands.

The big confusing part about this is the engine smoothing out and the CEL disappear after revving the engine a little bit. And when I let off the gas, it will stall.

Valkyrie · « **Reply #13 on:** July 28, 2015, 08:36:45 am »

Could be bad injectors. Had a 1 and 3 misfire on my 05. Did the usual air and spark check. Swapped coil packs out and plugs and solved the number 1 but the number 3 remained. After all that I pulled the number 3 injector and changed it with a new one and issue went away hasn't returned. They're a pain to switch out but I'd look there next before suspecting a clogged fuel line or rail.