420A Engine misfire don’t know what to do at this point

[estuardowrld]

Hey everyone i’m gonna keep this short. Basically i did an auto to manual swap everything ran perfect until i took on the freeway. Came back i got 6 codes 2 Misfires 4 Codes for each cylinder. Swapped out Plugs, Fuel filter, Wires, Ignition coil, Cam sensor Crank sensor, So once I erased the codes and drove it on the freeway the light came back on and it started flashing 3 times pause and flashed another 3 times. It seems to only happen when i take it to 4 or 5th gear is may be wrong.

 

[Justin DuBois]

Have you had the ECU checked for capacitor leakage?

 

[estuardowrld]

Yeah so i dirst tried it with the Original Auto Ecu my cat came with the light came on. Tried it with the manual one i got for the swap same thing. Don’t know if it’s cus my manifold is cracked could that cause the issue?

 

[Justin DuBois]

Posting the error codes from the ECUs might give some clues.
Someone on here might have done an auto to manual swap on a GS.

Justin

 

[estuardowrld]

P300-Random misfire detected
0301-Cylinder 1 Misfire
302–Cylinder 2 Misfire
303-Cylinder 3 misfire
304-Cylinder 4 misfire
300- Random misfire pending

 

[TerminalTalon]

I hope you kept the old stuff because it sounds like you loaded the parts cannon and fired.
Have you checked timing? Belt condition, confirmed timing marks, etc.
Something has to involve itself in all 4 misfiring.
Fuel
Timing
Sensors
If it wasn’t running bad before the swap it might be directly related to the missing sensors or something not quite right with everything involved.

 

[estuardowrld]

Well before the swap it already had those codes. But the transmission was bad so i went for the swap. I’m guessing the codes just stayed there. What other sensors could i be missing? The only thing i have touched is the fuel pump fuel injectors, And timing.

 

[TerminalTalon]

Can you erase the codes and see what pops back up?
Does it still have a EGR valve?
Lots of things can cause misfires but I can tell you from years of experience that part quality matters every time. I’ve chased customer complaints down to many new junk parts because the clear realization that if part “A” costs $300 but Amazon has it for $80 you’re getting f***ed.

 

[estuardowrld]

Yeah i’ve erased the codes 3 times already and it’s all the same codes. They activate every time i hop on the freeway. And yes it still has the EGR valve.

 

[estuardowrld]

I’m thinking of running an engine compression test today. But the thing is when i was driving on the highway with the CEL it started flashing

 

[Sirius1995]

Low compression can cause misfire codes, so can timing, or valvetrain issue, also depending what grade gas you use, you might have pre-ignition (aka ignition knock) happening, and knowing these engines knock sensors, they are not really good at doing their job so might either not lit CE light at all or just flash it, depends how quickly fuel trim fixes itself and what's the condition of o2 sensors, also clogged exhaust/cat might create too much back pressure to cause misfiring, id start with checking timing and compression, depending on dry compression test results, try to add a bit oil on the cylinder which has low compression and do a wet compression test, if it raises the result about to normal, you'll need new piston rings, if not, you have a leak somewhere, so do leak down test, you can also try to see if there's a small vacuum leak somewhere, those can cause all type of problems too and sometimes hard to spot

 

[Sirius1995]

Also wouldn't hurt to check cylinders and pistons with a borescope, sometimes just a small scoring in the cylinder walls can be enough, also I had one rather new Kia forte GT which had same issue, they had old gas in the tank and when it slushed in the tank when turning, it caused random misfiring

 

[estuardowrld]

Alright so i did a compression test all came back to 180. Here’s a new development the spark plugs i swapped 2 days ago brand new came out black. And the car smells like gas terribly. Also my manifold is cracked badly and whenever i start the car it smells like smog.

 

[estuardowrld]

Also i’m sure the car has some vaccum leaks. As when i bought the car a bunch of vaccum lines were ripped/torn.

 

[Sirius1995]

Sounds like you have a long road ahead, exhaust manifolds are always cracked on these, you can just put some jb weld there or get aftermarket header, if it's intake manifold, I assume your idle is also really high, I have couple oem intake manifolds if you need a new one..

What spark plugs do you use btw? Is it stock 420a?

Check vacuum line diagrams from here, you should find them easily

What comes to floded spark plugs, that could be stuck open injectors, you can measure resistance and see if it matches specs (also info is found easily from here), I also have couple sets of OEM injectors if you need any..

180psi sounds a good compression, check for cylinder wall scoring with bore scope and check your timing

 

[estuardowrld]

Okay sounds good seems like i narrowed down my options. Also i got some headers for my car and a CAI my buddy donated. Also i don’t know if this cold be an issue but my exhaust system is really rusted to the point the muffler and resonator fell off. How much for the Fuel injectors?

 

[Sirius1995]

Okay sounds good seems like i narrowed down my options. Also i got some headers for my car and a CAI my buddy donated. Also i don’t know if this cold be an issue but my exhaust system is really rusted to the point the muffler and resonator fell off. How much for the Fuel injectors?

You can probably get p0420 and such codes for leaking exhaust as it's worst..

$50+shipping, you can pm me about them to not get this off topic

 

[syndr0me]

It seems to only happen when i take it to 4 or 5th gear is may be wrong.

EDIT* Just saw your 420a. Not sure if the following still applies...


Like 5th gear cruising speed, under 3000rpm?

Sounds like one of these notorious ''P0300 after clutch job'' issues. Since you did an Auto to Manual swap.

Just food for thought.

https://www.dsmtuners.com/threads/multiple-cylinder-misfire-p0300.260269/

Seems to mostly boil down to excess vibration cause the crank sensor to freak out. Which is usually a why a quick cycle to ''from ON to ACC, back ON'' while coasting will temporarily relieve your issue... for a minute or two... sometimes seconds.

Try taking a look at your harmonic balancer while the car is idling. Is it wobbling a lot? Might give some clues.

Good luck!

 

[estuardowrld]

So i ended up narrowing it down. My car is either burning to much fuel or there is to much air into the engine. The car misfires even before the Manual swap. 50? For each injector or how much for all 4? Could a faulty fuel filter chase this too?

 

[DogWhistle]

Do you know if anyone has replaced the oem injectors? If your spark plugs are blackend, you're running too rich. If the injectors have been swapped to larger ones, you're dumping too much fuel into the combustion chamber.

A faulty (partially plugged) fuel filter would cause a lean condition (too little fuel), as would a cracked intake manifold.

Now that you've identified some problems, replace the vacuum lines and locate the intake manifold leak and go from there.

 

[estuardowrld]

To be honest i don’t know if they have. Ima double check on that right now too. My manifold is really cracked but i have some headers to replace it.

 

[Sirius1995]

To be honest i don’t know if they have. Ima double check on that right now too. My manifold is really cracked but i have some headers to replace it.

So what spark plugs you have in it right now?
Your issue could be just your spark plugs too, and $50 is for all 4oem injectors + shipping

Again, bore scope your cinders, attach pictures here of each cylinder and spark plug

Otherwise we can't help more really I afraid

 

[estuardowrld]

Okay I’ll PM about those injectors also i’m running ngk power copper gapped at .42. Where do i get a bio scope?

 

[99dsmer4g63]

If your exhaust manifold is cracked badly the o2 sensor will never read correctly.

I’m just assuming because you said your header is cracked to shit. The o2 sensor isn’t getting the correct reading and is throwing fuel at your car to try to get the o2 sensor to read correctly thus flooding your car.

Fix your exhaust first

-Daniel

 

[Sirius1995]

Okay I’ll PM about those injectors also i’m running ngk power copper gapped at .42. Where do i get a bio scope?

I would use brisks or champions with stock cap
You can find borescopes from Amazon or autozone