Well guys. I finally think that will be killing the misfire code. Let me start by saying that I went down the path that we all have...intake gaskets, fuel injectors, cps, pick up coil, tps, wires and rerouting -- it has been insane. That darn gum POS 0304 wouldn't go away. A couple of times, like after the intake gaskets, I thought I had it, but didnt I haven't had this much of a debachle with a motor since my I owned a 1994 Lumina Z34 DOHC 3.4 (if you are a real glutton for punishment, try one of those -- BTW if you have one, I know all the 'secrets' of that motor)

So here is what I was experiencing. It all makes sense now. Every morning I would fire up the van, and it would run good. The van would be OK until I turned it off. Say I would go to the store. I would come back out, start the van and it would studder. Then I would floor it and it would kick back to life. Then I would put it in drive and as soon as I would give it 1/4-1/2 throttle it would studder, miss and even backfire. I would get 0304 usually after this, but not everytime.

I finally accepted I needed professional help lol. I went to aquaitance's shop where he did a compression test and leak down test. Here is another funny thing that was really koockie. He first did the compression test and all my cylinders were at 120-130. Great right? So he does a leak down test when it was cold and found it was only 5%. Not bad you say...well he repositioned the CPS, and called me. He said "I think its OK, but you need to drive it for awhile. I have driven it some and only once the light came on, but I have driven it a few times now with no SES light."

I went to pick it up and just like before the SES light came on again on the way home. I went back to him and he performed another leakdown test. Now cylinder 4 was up to 20%! How could this be?
He started some more diagnostics. He thought maybe it was a valve, guide, spring etc. So he took the head off, found that one of the guides was shot and the exaust valve was toast.
So what caused this all to happen?
Any guesses????

well...



The head has a hairline crack in it...what a pisser

Two new heads and valve have been ordered. I won't get it back till tuesday. Ill check in with you all then.

Until then, happy motoring!

 

What casued the original problem to crack the head I don't know.

What has been happening since then is heat warpage. When you shut down the engine after the first start of the day the head cooled iratically which opened up the already cracked head leading to the stumbling problem upon restart. Once the engine cooled overnight the head crack came back together as if no crack at all.

 

Yes, I think you are spot on correct.

About the heads on the 3.9, I was alerted about the crack from the head shop here in Clearwater.
I am getting the newer designed aftermarket heads. The tech at the head shop said he sees this a lot. This issue is that the #4 and #6 exaust vavles are right next to each other. There isnt enough steel in the head between them. So over time, being subject to 500 degrees every day they crack. The new heads I am getting from Clearwater Head are updated. In the pics below you can clearly see the redesign, and the now updated extra steel between the exaust vavles.

Old head:



New Head:

 

Great looking new head!!

My compliments to your mechanic, he did a fine job tracking down a difficult problem. You reminded me that a leak down test is superior to a compression test. Something I had forgotten.

Thanks for the excellent posts,
Tar

 

OK, I'll be the one to ask - could you tell us how much the new heads cost?

 

They really aren't as much as you think they are:

http://www.ebay.com/itm/NEW-DODGE-DA...e3073b&vxp=mtr

These are the exact ones from the place that my friend got them from. (We live about 5 miles from this place)

I got my van back yesterday and I have to say there is are real difference in drivablility. The van starts quicker, idles much better, and the slight chugging and vibrations, which you think just are from an old engine, are gone.
My friend showed me the old head/valve that was the problem. You really couldn't see the crack, but the crack also causes the vavle not to seat correctly, hence the misfire. We could see this by putting the vavle in the seat. It was the problem
I have run the van 50 miles now and have gone through 5 starting cycles. No SES light.... Preliminary estimation - it is gone
I need to go another 50 miles to be sure, but it is looking really good.

So, the shop chargers for two new heads, new head/upper engine gaskets, and a boat load of diagnosis, was under 1500. I think he treated me fairly. For the money, it is just worth the piece of mind

 

Well, I'm certain this cracked head situation is my problem, too. I sure do like these Dodge B vans but I'm sick and tired of performing major surgery on every one I come to own. Wonder how much longer I can drive mine with a cracked head before there is a catastrophic failure?

Van has only 100K on it now, maybe I can go another 100K without taking the engine apart? If so I might just say "screw it" and live with it.

Things don't bother me now as much as they used to...

 

How much longer --- well that is really hard to say....

What eventually happens, the head shop told me also, is the valve will end up either warping or wearing out the guide. So in my uber speculation, probably 10k-25k miles after you deem you have a problem...
Good luck...
ALSO
I have gone 100 miles now -- No check engine light the van runs good.

 

Yeah, you solved your problem.

 

My check engine light comes on every now and then and goes off by itself and the performance of the van is always the same and the engine is there when I look under the hood and check so there is no tellin! LOL!