Update - Misfire Cylinder 4 (P0304) Steady light

[JMac101]

I still have a check engine light. Stays steady while driving highway speeds. Blinks while in park, at an idle or driving below 35mph. The van will run rough when cold or while warming up, but once it has ran for about an hour or so or has been taken on a couple short trips, I still have the light but it runs while with very minimal vibration but the light is still there.
I have tried replacing: plugs, wires, coil pack, oil & filter,fuel injectors, fuel rail, fuel rail wiring harness, MAP sensor, cleaned out the EGR (think it might be shot. Stock with 137,000 miles), throttle position sensor, valve cover gasket and spark plug tube seals, transmission fluid and filter, engine coolant flushed.
I know the parts changed where over kill but I figured while narrowing it down I might as well replace what I can while Im working on it.
Even after all of this I have a check engine light solid and still blinks in idle or at low speeds. I still have a (P0304) code and a pending P0304 code on my code scanner.
Does anyone think a burnt out oxygen sensor could cause something like this? maybe I burnt my cat converter out? I have a feeling it is the EGR because I was told it stays closed at idle but while driving at higher speeds and RPMS it should open and release. COuld it be choking out the nearest cylinder with back preasure?
I was told to compression test the motor, as well as preasure test the fuel line. I plan on doing this when I get paid on Friday if I have extra cash.
Any tips, suggestions, past experiences, advice, anything would be helpful. Thanks in advance guys and girls and sorry for writing a novel, but it was my dads van and Id like to keep it going as long as possible as he passed away in June.

 

[Trav]

Check for a vacuum leak in a hose,manifold etc.
Try giving the EGR valve a rap with a plastic hammer.It may not be seating 100%.
O2 sensors would set a different code and a plugged cat would cause other issues not just a single misfire code.

A vacuum gauge and a vacuum pump could be beneficial in diagnosing this one.

 

[The_Cams]

I'd concentrate my efforts on the #4 cylinder if this misfire isn't bouncing around. Use a vacuum gauge (cheap) to check for vacuum leaks. Re-check #4 plug, #4 wire(make sure OEM), wire routing, #4 coil, #4 fuel injector and seal. Compression check is helpful.

 

[jmc94gsx]

Regarding the EGR, often the valves stick, you can clean these all you want but it's not the real issue. EGR problems are associated with misfires so this may be something to look over a second time. I dealt with this same thing last year and sounds kind of familiar.

Did you experience a rough idle? Did you try pressing in the valve with your thumbs after you pulled it? If yes did it promptly retreat or did it stick? If it didn't your options are either replace it, or, lubricate it with a cap full of oil followed by pressing it repeatedly until the valve's stem no longer sticks. This is a bandaid fix, it saved me some dollars, but you may have to repeat this again 8 months from now.
Misfire #4----what cylinder is the EGR closest too?

 

[JMac101]

EGR closest to cylinder 4. Mounted on the lower right side of cylinder 4 on the oil crank case. The other side is mounted right above cylinder 4 in the air intake manifold.

 

[JMac101]

How much would a vaccum gauge cost?
Is it the same as a compression gauge?

 

[bdcardinal]

What is the application? on OBD2 a blinking CEL indicates a misfire that is causing cat damage.

 

[JTK]

EGR normally wouldn't come into play at idle anyway. Not too familiar with a 2001 Caravan 2.4L, but on engines like the 3.8L V6 in a Ford Windstar, EGR is jetted to each of the 6 intake runners. If several jets plug, more EGR gas is forced to the jets that are still flowing. This leads to misfires on those cylinders from the oxygen starvation. O-ring leaks on some upper intake manifolds can also leak air at hi vac situations like idle.

Joel

 

[JMac101]

at idle the check engine light blinks like crazy and also at speeds below 35mph. anything above it is steady.
How many people think it could be the EGR????

 

[JMac101]

once warmed up I have minor idle with a blinking light in park and low speed but a steady light at highway speeds. Dont think it is an O Ring in upper intake. Maybe the EGR is shot. Who knows?

 

[JTK]

JMac, if the pintle is stuck on the EGR valve itself and the valve won't seat, it's a possiblity that's your problem @ idle. A *flashing* CEL indicates a random/multiple cylinder misfire (P0300). AFAIK, that's the only thing a flashing CEL represents. Once steady that P0304 might set. How are your ignition wires, especially the one to #4?? Could also be a fuel injector issue to that cyl. Maybe read the #4 sparkplug for starters.

Joel

 

[jmc94gsx]

On my mazda it gave two codes p0401 (insufficient egr flow) and p0300 (random/ multiple cylinder misfire detected. It also had rough start ups and idles, but it was intermitent due to a sticking valve. I relubed the EGR pintle twice and it hasn't given me problems since August of last year. So yes I will likely say your EGR is bad. ON mine the electronic parts were fine, but the valve itself aged and was failing.
Sometimes the EGR is fed back into a specific intake manifold runner, so some cylinders are affected more that others. That is why I asked for the placement.