1999 Ford Ranger starts, dies immediately P0401

[Uncle Porkchop]

So, here's what's going on. About a month ago I began having trouble starting my truck. Sometimes, I crank and crank and crank until it finally starts up. Sometimes it starts, but then immediately dies. Today it cranked and then died immediately five tries in a row before I was able to get it running.
I had the IAC valve replaced two weeks ago, obviously didn't solve anything. Whether related or not, I get a P0401 error code.
Also, don't know if this helps or not, but a lot of the time I can punch the accelerator right before it dies and it starts and revs right up. Once started, I don't notice any major problems.
Forgot to mention, MAF sensor is nice and clean.

 

[Black_Splash]

How many miles on it? Maybe needs new spark plugs?

"edit" I've read that this is a sensor issue, but my tuck would never stay started when the plugs went bad.

 

[snake]

Just going strictly off memory, a code P0401 is EGR flow insufficient. Most of the time it is the DPFE sensor that will throw the code, but in your case I'll bet the EGR is funked up causing the driveability issue. You can research it online, but I think you can test the EGR by pulling a vacuum on it at idle, and the engine will die when the vac is applied. Sounds like yours may be stuck open though...

One more thing, next time it does this, check the schrader valve on the fuel rail for pressure. If you don't have any, check the fuel pump relay. Kind of common problem and usually intermittent.

 

[adsm08]

Just going strictly off memory, a code P0401 is EGR flow insufficient. Most of the time it is the DPFE sensor that will throw the code, but in your case I'll bet the EGR is funked up causing the driveability issue.

Snake, you are so close there that it is almost painful.

A plugged up DPFE will throw a 401 code. It will also request more EGR flow until it either sees what it wants or it kills the engine.

I"ll bet the DPEF is bad. Ford even has a TSB out for pretty much every vehicle 98 and up that says if you get a P0401, replace the DPFE before any other diagnostics are done.

In this case, I'd still at least check the EGR valve, but I'm betting the sensor is your root cause.

 

[disciplerocks]

I'd be surprised if the egr is actually causing the issue. Awaiting results.

 

[snake]

Snake, you are so close there that it is almost painful.

A plugged up DPFE will throw a 401 code. It will also request more EGR flow until it either sees what it wants or it kills the engine.

I"ll bet the DPEF is bad. Ford even has a TSB out for pretty much every vehicle 98 and up that says if you get a P0401, replace the DPFE before any other diagnostics are done.

In this case, I'd still at least check the EGR valve, but I'm betting the sensor is your root cause.

Yep, seen a lot of them bad, but never bad enough to kill the engine- yet. Thanks for the input!

 

[disciplerocks]

x2 on the DPFE being a POS. They never last long.

 

[adsm08]

I'd be surprised if the egr is actually causing the issue. Awaiting results.

As I was thinking about this more on my drive home today, I came to that same conclusion. If the EGR valve being stuck/plugged was the source of the insufficient flow code then it would genuinely be a low flow condition, which wouldn't kill the engine.

Yep, seen a lot of them bad, but never bad enough to kill the engine- yet. Thanks for the input!

I have. They don't usually get that bad before throwing a code and getting fixed, but it does happen. Usually only if the owner ignores the light and puts off repairs, but sometimes a piece of crap just plugs the downstream pipe.

x2 on the DPFE being a POS. They never last long.

It's not that the sensors are crap. They have to be sensitive just by the nature of the job they do, but unfortunately they live in a very harsh and hostile environment.

If they are built to be more robust and last longer they probably wouldn't do their job that well.