Misfire Cylinder 4. Cant clear the code. Ideas?

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JMac101

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I have a 2001 Dodge Caravan 4 cylinder 2.4 L van. The check engine light came on, the code was P304 misfire cylinder 4. I changed the coil, plugs, wires, injectors, fuel rail, throttle position sensor, map sensor, cleaned the EGR and back preasure pipe out with carb cleaner. I also flushed the oil and changed the filter as well as the fuel rail wiring harness and I still have a cylinder 4 misfire. I think I may have a cracked head gasket but Im not sure. Upon startup the van starts up fine, runs and the check engine light blinks. The exhaust puffs out white smoke for 45 seconds and then goes to normal exhaust. I have no coolant leaks, no coolant in exhaust or coolant odor. Anyone have any idea what could be wrong or suggestions on how to fix it, maybe a suggestion on what to look for????
Also I have no heat at all.
Thanks
 
Compression test. I have a GM motor I worked on pass compression with flying colors with a bad head gasket, however, since it was just a slight one. It would also only leak into the cylinder while sitting, off, so it would miss when it was started for about 30-45 seconds or so.
Best test for a bad head gasket is one of the kits you put on the radiator to suck the air in the system through some dye. Thats how I finally determined what it was.
 
So I should compression test it. can do that, but how do I test the head gasket and how does it work?
 
is it extremely difficult to replace a a head gasket? is there a way I can repair a crack head gasket without removing it?
 
Had a vacuum leak at cylinder 4 intake port on a 2001 Altima 2.4, causing a cylinder 4 misfire at idle. Turns out it is a common problem because there is no bolt in the area that leaks and the intake gasket is just paper and blows out over time there. The replacement gasket is much more sturdy.

But the issue you are having seems tied to that smoke you are seeing at startup. Sometimes oil smoke looks white at cold start. You could have some oil getting in there (combustion chamber) when it's shut down, and then see smoke when it starts up. Any oil consumption? How often has the oil been changed?
 
i change my oil every 3000 or so miles. the last oil change went way over 4000 miles because I didnt get around to it. Now a crazy amount of oil comsumption. I had my oil changed 1800 miles ago and I had it filled almost to maximum when the shop did it and now 1800 miles later it is probably 3/4 of the way up the dip stick. I think that was just oil burnt from everyday driving.
 
How exactly did you determine you have no coolant leaks. I would do a cooling system pressure check to determine if you have any coolant leaks? That should tell you if the head gasket is bad.

They make something you can add to the radiator to repair head gasket leaks. It is certainly not the right way to fix it, but something to consider if it is a beater car, or something you don't want to invest the time and money in. If you decide to go that way, replace the radiator cap with a 7 pound cap to lower pressure in the cooling system. Clear the codes and keep your fingers crossed.
 
what should I do if it is oil getting in the chamber?
How can I stop it or correct it. If I had a leaky head gasket wouldnt I smell coolant or see leakage?
the coolant level is good and the van doesnt hid temps over the half way mark at all.
 
To compression test, you want to pull the relay for the fuel pump, then pull all the spark plugs.
Screw the tester into the hole, and hold the gas pedal to the floor while you crank it over 4-5 times. Take the reading and go to the next hole, again floorboard while cranking it over 4-5 times. Repeat for the other two. What you are looking for is how even they are. Usual spec is something like the engine is good if the lowest number is within 25% of the highest. So take the highest and multiply by .75 and thats your minimum.
 
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Originally Posted By: JMac101
7lb cap?


They make low pressure radiator caps, typically they are 7 lb caps. They help in situations where a radiator, head gasket, or heater core has a slight leak, and a person is using some kind of stop leak product instead of making the proper repair. They have gotten me out of a fix more than once over the last 3 1/2 decades. Less pressure builds up in the cooling system, the only downside is it lowers the boiling point of the water I think. But that was never the issue, it was a leak I was trying to stop in a beater.
 
I say look into why you might have oil getting into #4 cylinder. The oil consumption you now have is tied to this smoke at start up. Typically I have seen an issue with the oil in the top of the engine not being able to drain back down well in certain areas. The oil sits there for a long while, giving it time to seep down the valve stems and straight into the combustion chamber for a smokey start up later. When you pull out #4 spark plug, I would expect it to be wet with oil or have some oil related deposits on the electrodes.

How many miles on this engine?
 
oh i get it. Now I just got to figure out if it is a cracked head or oil comsumption. I dont see any leaks. Does pretty decent on gas mileage ( 20 mpg or so). every now and then i have loss of power. I would like to repair the car the way it should be repaired to keep it running, but if it is too far gone I can just give temp fixes and keep my fingers crossed that it will last until next year when I can buy another car. Id like to try and repair it the right way though if possible.
 
if spark plug 4 is oil covered what does that mean? is that normal or not normal? I can pull the plugs tomorrow and give you an update. what should i look for?
 
If a head gasket is leaking into a cylinder you will not see any leaks, you could have white smoke. It all depends on how bad the leak is, that is why I suggested the cooling system pressure test. It is easier to do than a compression test. I would do a compression test if I didn't find a coolant leak with the pressure tester.

Oil on a spark plug is a problem, if so do a dry and wet compression test. It could be as simple as a bad valve stem seal, or bad rings and valves.
 
Spark plug electrodes should be clean and dry. If oil is getting into the combustion chamber, the electrodes will have deposits- hard or soft, oily or somewhat wet with oil, depending if engine was shut off fully hot from being driven a distance or on the highway or just driven short distance and shut off relatively cold
 
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