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Discussion Starter #1
I am throwing P0303 Cylinder 3 Misfire. I have had new plugs and wires and gapped them down to .30. The only thing I haven't done is swap injectors, do you guys think that could be the problem? Thanks
 

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mjwilson said:
I am throwing P0303 Cylinder 3 Misfire. I have had new plugs and wires and gapped them down to .30. The only thing I haven't done is swap injectors, do you guys think that could be the problem? Thanks
What kind of coil pack do you have??? IF its the msd thats probably your problem. Lots of people have trouble with those and the stocker is better. Its definately not your injectors.
 

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Discussion Starter #3
bump

I did have the MSD Coil pack, but I just switched back to stock and it didn't change the code. And I did reset the battery to clear the code.
 

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Yes swap injectors and see if the code follows the injector. You pretty much eliminated the wires, plugs, coil pack. If after the injector swap and you still have the code in the same cylinder, do a compression test. Might be something internal. Ring, valve, busted piston etc.
 

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no, a cylinder misfire is where there is not enough spark coming from the spark plug and the cylinder. SO when giving in acceleration fast or stomping on the gas your car would to backfire and cause this to buck. Change your spark plugs first then see if it help, if not get new wires also. Your car is fine, this will cost no more then 60 bucks unless you get name brand plugs and wires.
 

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Discussion Starter #10
misfire

thanks for the help guys....I just installed new plugs today now I just have to pull the code up and see if it is still coming up.
 

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mjwilson said:
I did have the MSD Coil pack, but I just switched back to stock and it didn't change the code. And I did reset the battery to clear the code.
Well I just had this problem (p0304), here is what I replaced

-plugs
-plug wires
-coil pack (stock)
-injectors
-fuel rail
-TPS sensor AND new plug
-cleaned out throttle body

And NONE of it helped. I finally figured out that my intake manifold gasket had busted, (I heard a LOUD whistle coming from it). When I took it apart, the gasket had ripped right around the 4th cylinder, hence the p0304 code. I replaced it with a $2.20 gasket from the dealer, and it runs perfect. I spent almost $300.00 trying to figure it out, when all I really needed to spend was $2.20. Its just an option.
 

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Same problem, but I found the loose intake bolt before any damage was done to the gasket. It was throwing the p304 code. Tightened the bolts to specs, and haven't had a problem since.
 

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cjsmuscle said:
Same problem, but I found the loose intake bolt before any damage was done to the gasket. It was throwing the p304 code. Tightened the bolts to specs, and haven't had a problem since.
:readclose:thumbsup:
When I went to take of the manifold, I couldn't believe how loose the bolts were.
 

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TPS Wiring= Problem

I have seen this a couple of times before, and 80% of the time it is the Wire Loom For the TPS- - - - not the TPS its-self!! Turn the car on, open the hood, and rev the engine lightly with the throttle linkage right behind the throttle body. This will cause the engine to torque back and fourth making and breaking the connection of the wires in this harness if they have broke. While accelerating or reving the engine the TPS is loosing its signal and causing the misfire code. I have replaced two coil packs and many sets of wires trying to find the problem and this was the cause on two different cars. I know that there are other problems that it may be but I would take it to the dealership and get them to replace the wire loom to the TPS if this has not been done before. There is a replacement kit for this, do a search and get one ordered! Later
 

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Go step by step.

1. Swap the number 3 plug with the number 2 plug. See if the code chases.

2. If not swap the #3 wire with the #2 Wire and see once again.

3. Swap injectors and see one again.

4. Do a compression test.

5. Do a vacume test at idle.

It is highly unlikely that it is the coil. If it is a stock coil that is. The plug adjacent on the coil would be missing as well. The coil fires two plugs at a time. One is a waste spark that is fired at the exhuast stroke of one piston and the other is fired on the power stroke of the other piston at the same time. Hense if lets say cylinder #3 is missing and on the coil cylinder #2 , which if memory serves is right accross from it, would miss as well. Becuase that portion of the coil is producing weak spark.

If memory serves, #1 and #4 use the top portion of the coil, and #2 and #3 use the lower portion of the coil.

If you replaced the plugs with original equipment plugs, one of the plugs could be bad. I have been burned at work because of this.

I use to own a 2004 Neon SXT and it was missing at Idle on the number 3 cylinder i verified that it wasnt the wires, plugs, coil, or injectors. I later came to the conclusion that one of the valve springs was weak and causing a loss of compression intermitently. This was causing the slight miss. But i doubt that is your problem. However, anything is possible.

** One other thing, depending on what year your Srt-4 is, it might be pcm related as well. I think it is 2003 or 2004 that the pcm can be flash programmed that fixes the mis fire. Something to do with when the engine is cold it runs to rich and fouls the plugs out. But only the dealership can do this mind you.
 

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Discussion Starter #20
update

finally swapped injectors a couple days ago from cylinder 3 to cylinder 4. After doing that I threw a cylinder 4 misfire. I will be replacing it asap. thanks for everyones help.
 
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