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Discussion Starter · #1 ·
Having a bit of trouble diagnosing my p0304 code. Let's start by listing what I've done so far. New head gasket( put everything back right and torque to specs), new ac delco spark plugs, new wires, swapped injector cylinder 4 with another cylinder, swapped coils, passed compression test( got 200psi all cylinders), new intake manifold gasket and valve cover gasket, oil change. Car struggles to turn on and when it does it shakes and acceleration has no power. Any ideas??
 

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Guessing you did allready but...


Did you pull out #4 plug for inspection?

Could have cracked the porcelain and not see it....

Did you try using a different wire?




Sent from AutoGuide.com App
 

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Discussion Starter · #3 ·
Yup I checked them and took it further by swapping it with another spark plug. Still get p0304. Also deleted my catalytic. Wires were switched as well.
 

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go have all the codes cleared, then rescanned. mine was just doing this and the injector was bad. i swapped it with cyl 3 to see if the code jumped and it didnt bc it was still showing the old code so i ended up spending hundreds on a list of new parts to only still have the misfire. finally when i had it read again, they cleared everything 1st then read it and the code finally jumped to cyl 3 so i knew the injector was bad. i spent about $1000 in parts total and all it was was a bad injector that had recently been changed. guess it was a faulty injector.
 

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Discussion Starter · #5 ·
Yes code was cleared after changing something each time. Would get a p0300 pending then the computer narrows it down to p0304 after a few minutes. Maybe a bad ICM?
 

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goin broke but n style
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Dont forget just because you have a new part does not mean it is good

go over everything again.
 

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UENVYME
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I'm having the SAME problem... I have replaced these parts..

Ignition Control Module
Wires
Plugs
Fuel Filter
Fuel Pump
Camshaft Position Sensor
Crankshaft Position Sensor
Intake Manifold Gasket
Intake to Throttle body gasket
Ohm'ed out all 4 injectors, came out good
Vacuum check good
Fuel pressure good
I have spark at #4

So the odd problem is, I can drive it if I feather the gas... (drove to have a fresh oil change) it still misses, and drives like shit, but I can... SO when I pull the wire, it has spark (while motor is running) but the is no change in the stumble with #4 wire removed (engine gets worse when I remove 1,2, & 3). I am also getting the same "Random Misfire" and "#4 Misfire". I am thinking it could be...

1) Out of timing, need to check the timing chain and gears
2) Need to have a CASE Relearn done since I replaced the Camshaft sensor
3) I have a gremlin and need to either change the motor or sell the pos...

Been chasing this for 3 months now....
 

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It's "Neanderthal"
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Check the compression, and while you're at it examine the #4 sparkplug, like is it oil fouled or wet with gas or dry and clean, etc. But you need to at least check the compression because you hear the spark but it's not firing, so it's either fuel or compression. If the cam was out of phase all of the cylinders would have the same symptom.
 

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UENVYME
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359 Posts
If the timing was off all the cylinder would act the same?

I went out and played with some wires (dunno where I read but someone had said they has a broken wire on the injector) and found my #4 plug wasn't "fully seated" (apparently from when I removed the intake manifold) plugged it back up... made a WORLD of difference at idle...and I was actually able to drive it to the store (with a VERY lgith foot...) however when under load (driving) it is still getting a random/multiple cylinder misfire... I'm wonder if all I need now is a case relearn since I changed out both the crank and cam shaft position sensors?.... Anybody?
 

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It's "Neanderthal"
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Yes, all cylinders would have the same problem. Did you think that the timing chain only works the #4 cylinder? Looks like you found the problem anyway, no fuel to #4.
 

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UENVYME
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359 Posts
Like I said, I reseated the connector for #4, and it seems to run better (I actually drove it to class today) but it is still missing, I'm still getting random/multiple cyl misfire, and I can hear it misfiring... I am wondering if I need to have a CASE relearn since I changed the cam and crank shaft sensors....

And I have no clue how the timing chain works, in fact I no crap about motors. lol, I was an Aircraft Electrician for 8 years, I have been an Intelligence Analyst and Infantrymen for the past 5, I don't know squat about motors lol. Give me a stereo, subs amp, more batteries, anything will wiring, I am good, but a lawnmower in from of me that won't crank... Im screwed lol
 

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UENVYME
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359 Posts
Here is what fixed my "Random/Multiple Cylinder Misfire" on my 2.2... I wasn't able to "narrow it down to ONE part" but here is my "little story (Might be a little lengthy)

Alright, an update on the truck... First off, know what the hell you need, whats wrong, and what could CAUSE the problem you are facing, BEFORE going to a dealership to have "diagnosed". (This might be a little lengthy)
I originally scheduled the appointment to have a "CASE Relearn" completed (for $100 which is NECESSARY after removing, installing, or replacing the Crank Shaft Position Sensor), but was talked into just having a diagnosis done first ($100) and if a relearn was needed it would be done... So I scheduled it for 10 am today. Walk in and I am asked "Who is your appointment with"... "Um, I dunno, I just ave one at 10 to have my truck looked at." "I was told the diagnosis would be done by 12 is that still correct" "Hahaha, no, I don't know who told you that" "OK, well, whatever I have another truck." So my awesome mom (Annette Wiseman Vaughan) comes, picks me up, and takes me home. (Thank you).
Fast forward a couple hours and I call from school to "check on my truck". I talk to a gentleman who was fairly nice and when he came back I was told "They are waiting on an estimate on how much it will cost to fix what they found wrong and they will call you" "OK, sssooooo what did they find?" "Who I am not sure" "OK thanks"
About an hour later I finally get a call from "Roger". He tells me that "there are multiple things, like the intake air sensor" to which I stopped him and said "the Intake Air TEMPERATURE sensor?" "Yes" "OK, that has nothing to do with my misfire" "Well, this that and the other. It would be easier if you came and talked to the tech" "OK see you soon"
Get there, and eventually get taken back to the service area to speak with apparently the guy in charge of the shop, who was just watching/overlooking what another tech was doing. He goes on to tell me about a leak coming from the intake manifold. I told him I know what he is talking about, I heard it too and haven't been able to pin point it even though I pulled the manifold off and replaced the gasket. He tells me the connector on the IAT sensor has corrosion and when he played with the connector it started to run better, I said OK, he asked if I had changed the Manifold Absolute Pressure Sensor, I said no, "but what did you find that is causing the misfire?" silence, stuttering which is when I was told he didn't actually work on it. I said, "Ok, did you do a CASE Relearn? Because I removed and replaced the Crankshaft Position Sensor and a relearn is NECESSARY. "No, we didn't, in fact I didn't even know that's something that it needed". "Um, OK, well THAT is ORIGINALLY WHY I brought my truck here, and even if you DID find all these other errors, I HAVE to have a relearn. I Don't care if you're going to charge me another $100, I need that done. SO how is the truck running now? Any better"... "Oh, no, it's still running pretty rough but OK sir we'll get the relearn done for ya" We are led out of the shop by "Roger" and sit and wait in their waiting room.
Of course my mom is pissed "You are NOT paying another $100, you originally brought it in for that care relearn thing" "Case mom" lol. So maybe not more than 15 minutes, my truck comes around the corner. The guy walks in, hands me my keys and says "here you go sir, and we aren't going to charge you." I said ok and hop'ed in. I start it "Hmmm... sounds better...." Start driving "wow, it's driving MUCH better..."
On the way home, I stopped at O'rileys and Autozone and picked up a MAP Sensor, IAT Sensor and Idle Control Valve. Got home, installed those parts... Wow... I can actually drive this thing now... holy crap, it idle's amazingly, if I "floor it" there is a "little" bit of skipping, but wow, I can actually drive this thing now... so happy...
So in the end, I have changed JUST ABOUT every sensor on the motor, fuel filter, fuel pump, Ignition Control Module, Coil, Wires, Plugs, Intake Manifold Gasket, Throttle body to intake manifold gasket, Idler Pulley... and probably more and it is finally running great... Still have a small leak around the intake manifold that I need to investigate and probably just need a new manifold... but I am able to drive my truck FINALLY!!!
 

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Headbanger Boogie
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1,788 Posts
Got to love them rapists at the dealerships. Luckily you just got a relearn and diagnosis. Good to hear your trucks running better. I think my map sensor on my 56 mm TB isnt working properly myself. I've always had a bit of high idle and can be a tad bit rough.
 
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