EGR problems

[Masterd]

Hey guys,

Im having an EGR problem and I'm hoping y'all can help.

LONG story short, my truck appears to be opening the EGR valve too soon. What happens is at about 1000 to 1500 rpm, it seems like the EGR is opening too soon, causing the engine to lope like it has a cam in it. Also, the hoses coming off the EGR tube start to hiss while its doing this.

Some info: Unplugging the vacuum hose from the EGR obviously eliminates the problem, but it also eliminates the hiss sound coming from the DPFE hoses. I threw the parts cannon at it so it has a new DPFE + hoses as well as a new EVR solenoid.

Codes were a 332, 335, 336 and a 157. All EGR codes and a MAF code. With the MAF unplugged, the problem also ceases, but Im thinking that's because the computer wont use EGR without a MAF signal.

Any help is great!

-Doug

 

[Centaurious]

First if you replaced the DPFE sensor make sure it is the Wells/Airtek made unit. I got mine at Autozone, it's metal like the factory unit and has been re-engineered for better performance and lifespan. Second the silicone hoses from the EGR pipe to the DPFE sensor shouldn't hiss, they just read a pressure differential, no air flow. Check the EGR pipe for cracks, especially in the bellows area. Check the vacuum solenoids for cracked hoses or cracked fittings and for vacuum lines that have fallen off.

 

[Masterd]

Well this O2 connector might have definitely been causing the computer to have a fit.

 

[Centaurious]

CARNAC THE MAGNIFICENT Says "I see a new O2 connector in your future."

Let us know if this fixes your original problem.

 

[MrQ]

Second the silicone hoses from the EGR pipe to the DPFE sensor shouldn't hiss, they just read a pressure differential, no air flow.

Correction, they do make an exhaust noise when cracked or disconnected. Pressure differential requires something to create that pressure, thus air displacement from exhaust gasses.

2nd the O2 sensor, that would definitely cause an issue.

 

[Masterd]

Well I ripped the upper intake off and put a new pigtail on that O2 wiring. Bolted everything back on and it runs really well now.

Problem: it still throws a 332 and a 335, and sputters under light throttle in or out of gear. BUT, it was fine at first after resetting the computer and replacing the o2 pigtail, and then sorta just came back.

Whats the recommended DPFE for this engine? Ive got the "upgraded" black plastic one with the D connector on it.

 

[MrQ]

Maybe you need to replace the EGR? Those vacuum diaphragms can go bad.

 

[massacre]

You can test the diaphragm with a hand vacuum pump like the mityvac

 

[Masterd]

I ran a vacuum line to the valve directly and it does function. I had the valve off of it when I took the upper intake off and it appears to hold mouth vacuum just fine. With the engine running I sucked on it and it ran rough.

Drove it to work today, and it's doing the same thing. Feather the throttle at 1000 to 1500 rpm and it gets choppy and the actual tone of the engine changes. I may have to T-pin the dpfe connector and start chasing voltages, as the 335 code is KOEO and the book says that's EGR Sensor voltage higher or lower than expected.

 

[Masterd]

Something more to add. Unplugging the DPFE connector and running a KOEO test yielded a 327 code, which is obvious because the DPFE is unplugged and also the magic 111 code. I think I'm on the right track here.