P0344, P0478, P0470, P1661 What to do.

[BigRedWeather]

I noticed a very slight unevenness in my engine and then pulled these codes

P0344 Camshaft Position Sensor Circuit Intermittent
P0478 Exhaust Pressure Control Valve High
P0470 Exhaust Pressure Sensor Malfunction

It seemed the PO344 could cause this. I drove it the next day and it ran smooth. Left work that day and it was rough as a cob - even stopped at a few stop lights. If I kept the tach up it ran pretty smooth. When into the stealer to get a CPS, came back out and it was running smooth agin, full power and I had done nothing to it.

I got home a pulled

P1661 Output Circuit Check Signal Low.
P0478 Exhaust Pressure Control Valve High
P0470 Exhaust Pressure Sensor Malfunction

the PO344 was no longer there. It seems these code must not really be telling me the truth. I'm not sure which one I should pay attention, which I should ignore and which one I should attack first. My scanner is a Snap-On MT2500 which I have had for a month and have much to learn about it.

Any guidance would be appreciated.


BigRedWeather

 

[OLDBULL8]

The EBP is mounted on the front middle of the engine with a tube running down to the exhaust. The tube can be plugged or partially plugged or could have rusted holes in it. Easy to remove and clean it or replace the tube. The sensor itself could be plugged, if you remove it and clean it, be very carefull as it has a diaphram in it and can be punctured easilly. The purpose of this is so the engine warms up faster. Pretty sure the EBP sensor controls the EBPV.

 

[wils2527]

I would have to agree 100% with OLDBULL8 try with the cheap and easy and clean the EBP tube clean. You can use some weed whacker line and brake clean to get all the soot out of the tube assembly.

Just hope that P1661 code goes away at some point during this.

 

[79jasper]

Some people say the EBP sensor controls some mapping tables.
The people that clean/replace the tube and sensor have seen mileage gains, so I would believe it.

You can also use an old speedometer cable to clean it.

 

[BigRedWeather]

This problem plagued me for a week. Some mornings I couldn't get the truck out of the garage it was running so rough. Another morning it was running real rough, but I could drive it and by the time I had gone 10 miles it was running smooth as silk. Then that evening, on the way home from work it also ran real smooth too. The next morning it was rough as a cob again. What could be causing all of that??!!

Finally it threw this code: P1283 "IPR Circuit Failure" for the very first time. After I had read forums for four hours and posted my symptoms on forums, for the first time I saw a casual reference to tightening the nut on the back of the Injection Pressure Regulator. I tightened that nut 3/4 of a turn ( it won't tighten very tight because it starts turning a collar). My problem was solved. I let it run for 3 days to be sure it wouldn't come-again/go-again and it didn't. Then put my original CPS back in the truck and it still ran smoothly.

It goes to show you that having a scanner is not a fail safe diagnostic tool. Certainly I have a lot to learn about using one, but even if you have a scanner you can go around the barn a few times to fix your truck.

Heat, or vibration or something must have been adjusting that nut on my IPR to cause my truck to run smooth at times, and very rough a while later. That nut moves the solenoid that opens and closes the valve in the IPR that regulates the pressure to the oil galley. The change to my IPR was very slight, but very significant.


BigRedWeather

 

[79jasper]

I need to tighten mine also.

I think with an AE scanner, you could look at the IPR readings and stuff. And command it to change.

 

[wils2527]

Interesting. Adding that to my bag of tricks. Good find!!!

 

[79jasper]

Did you remove anything to get to it?

From looking at mine, the fuel bowl, or FPR would have to come out at least.
Good thing I'll have mine back out to do new fuel lines and replace the leaky restriction sensor with a plug.