Yet another "bug" to sort out but may be worth investigating. It sounds like this van is all to hell but I think once I get all the bugs sorted out, it's going to be a good vehicle.

The OBD II is storing two codes related to the fuel evaporative system. Usually it's just one code.

I've got a code reader but have also been using one of those OBD-II Bluetooth devices that plugs into the port under the dash and links up to my phone. I'm at work and my van is in the parking lot but I tried pulling the stored codes up on my phone but it won't show anything unless it's linked up to my van. I can't remember right off hand what the codes are but they are pertaining to the fuel evaporative system. There are two of these codes stored but they are the same thing. I can post these tomorrow. I apologize.

I can clear the codes but the CEL comes right back which I realize is normal.

Here is what's weird. The first time the CEL kicked on was after straight piping the cat converter so I thought it was bank 2 telling me the converter has failed. Yeah I now but I wanted to know if any of these issues is due to the converter before laying down a bunch of cash on a new one and it didn't fix the problem. I don't have an inspection system where I live so it's not like I need this device to pass.

However the ECU is not storing any codes (bank 1, bank 2) related to the converter! Seems like a weird coincidence. How could removing the cat converter have anything do with the fuel evaporative system?

I mentioned at times that the engine acts like it's running out of fuel after a heat soak. When this occurs and it's not everytime, I start the engine (30 minutes to an hour later) and it will start up fine but make it maybe 100 to 200 feet then just start loosing power and popping and cracking like it's a lean condition. Then either hold the throttle to the floor for a few seconds until the problem goes away or just shut the engine off and restart it. If I am just running errands around town and restart the vehicle within 10 minutes or even when stone cold, it doesn't do this.

I'm starting to wonder if these evap codes and this issue are related. I was going to trace down the vaccum lines from the gas tank to the charcoal canister then to the engine.

I was wanting to know where does the vacuum line from the charcoal canister connect to on the engine? I'm assuming it connects to a port on the intake manifold. Which cylinder would that be near?

I'm curious if this hose is cracked or is not connected. If it is could this cause an extremely lean condition after a hot soak? Seems like there is a purge valve or something else in the system between the charcoal canister and engine. If there is a leak somewhere, maybe when this device opens, it's allowing unmetered air to enter the engine. Then shuts off. These evap systems seem to vary from make to make and I have never really studied them to know how they actually work. I know the charcoal canister stores fumes and it released into the engine. That's all I know.

I found this info on a 2002 Dakota. I read it but I'm going to read it a few more times to understand how this purge valve works.

https://www.justanswer.com/dodge/5u7...ota-check.html

I'm just speculating here.

And these OBD-II codes can be baffling at times. Such as I drive around with the gas cap off my 2003 Subaru and it will never throw an evap code. It should but it doesn't.

 

post the codes, model year and engine size.

 

2001 Ram 1500 , 3.9 liter.

PO455 Large evap leak detected
PO442 Small evap leak detected
PO301 Cylinder missfire detected

Just from what I've read, I wonder if when this Purge valve between the charcoal canister and engine opens it's causing a high amount of unmetered air to enter the engine causing this loss of power and the popping and cracking.

I'm going to try to trace down these hoses and see if I can find a loose or cracked hose.

 

Check all the lines for the EVAP system. They tend to dry rot, and crack. Not always obvious.

 

Check to make sure the gas cap is on tight.

 

If I can't find anything wrong, can I just cap off the port on the engine ? Wherever that is. I guess I'll just have to trace it down from the pump. I'm thinking it's a 1/2" size hose so that would create quite a vacuum leak.

Unplug this pump/valve and see if the stalling issue goes away?

TN has no inspection system so I can deal with the CEL.

Gas cap seems to be tight and sealing but if there was something faulty in the EVAP system, would this cause this stalling problem, 200 feet after starting the engine on a hot start?

The van never does this when cold or just driving down the road. It's like something is introducing a large vacuum leak at a specific time.

 

I think the evap system waits till the engine is at least somewhat warm before venting the canister... So, if you have a big enough leak, yeah, I could see it causing a stall.

 

Gas caps are inexpensive and whether it looks or seems to seal good, it probably is time to replace. My 99 van had thrown an evap code couple years ago and replaced the gas cap... no more code, worth a shot.

The other thing is if you haven't gotten under your van and felt or seen those lines attached to your evap canister, I'd suggest you do...
Not sure where you are but here in California it's not to tough to get at the bracket and get a good look at the canister and rubber lines.
My lines had cracks and were disintegrating, luckily was able to cut them back enough for good rubber and clamp. Won't last forever but has bought me 3-4 years so far.
As I recall there are some vacuum lines n rubber elbows under the battery area that you should check also. Some of these connectors you look at at you'd think (no way this is the problem) but a closer look reveals it really is

 

FYI, the P0455 does not clear on it's own right away, you have to clear the codes with a scantool

 

Update:

So I pulled the air cleaner off and started looking for vacuum hoses. I found one on the front side of the intake manifold just below the throttle body. From the back of the engine, it would be at the 1 o'clock position. I traced this line back to this device:




This is not from my van. This is from a Dodge truck I found on this forum. But I can tell you it's on the driver's side near the wheel well on a RAM van.

Then from this device to another hose (or two) onto the charcoal canister.

I'm not sure if this is the purge valve or leak detection pump. There is an additional device on the charcoal canister and yet another box adjacent to it.

I can't find any loose or cracked hoses in this setup. I pull this hose off the intake manifold with the engine running and I could hear a huge vacuum leak. But it did not stall the engine. It may just be that the engine was still cold and the rich mixture was compensating for the false air entering the engine.

Just to see if this had any effect, I disconnected this hose and capped the port off on the intake manifold.

It's too soon to tell but so far I've started the engine a couple of times after it has sat for more than 30 minutes and it has yet to act like it's running out of gas/back firing out of the exhaust.

Perhaps when the ECU opens this purge valve or kicks this vaccum pump on and the engine is warmed up, the engine is not running as rich as it would be when it's cold so the extra air strangles the engine. Just my theory. I need to do some more research on how this system functions. I may be way off course.