Perhaps the valve needs to be 'exercised' several times in efforts to loosen it up. No telling how long it had been sitting on a shelf???

 

Oh, I tried it before I finished hooking it all up... I put the sensor on, and a spare vacuum line, and put a little vacuum on it to watch it move. It was very free and smooth.

Today, it was stuck about 1/8" open, but would still move with significantly more vacuum, and make 'plop' sound when it finally turned loose. Definitely not like when it was fresh from the box 3 or 4 days ago.

I just got back from the parts store, and the guy didn't even question it - he looked at the plunger on the bottom, and said "yeah, this happens all the time." I asked if I could get credit toward a better one, and he said that the one I had was the best one they offer. Soooo... he issued a credit receipt, and a replacement will be there in the morning. Of course they wouldn't have one in stock!

I'll tell you what - this is driving me nuts! Between doubting whether I have a clue and defective parts throwing me for a loop, I can't take it anymore!

 

That just pisses me off, getting bad parts from the store. It sure screws up your whole train of thought on fixing the truck. So your sensor is fine and was telling you the new EGR was bad, and naturally you (and I) would think it was the sensor. Take the sensor back and demand your money back, it was their bad part that made you buy it in the first place.

 

It does **** me off, but it made me happy that there were no questions asked about exchanging for another valve. No hassle, no partial refund, no issues at all.

If they'd have given me a bunch of hassle, I would have gotten ugly and made demands and called them a few choice words.

Now if the replacement is the real deal, life will be good.

 

The 2nd new EGR valve is on, and no codes (so far). I may not get to drive too much over the weekend, but we'll see how it goes.

On a side note (I now wish I'd done these separately)... Before I got elbows deep in this EGR thing, I bought a set of spark plugs and wires. I put the plugs in, and the old ones were well used but no ugly stuff that would lead me to think there were internal issues. I ran out of daylight, and forgot about the wires. I found those in the garage today too, and put them on (while checking the timing order just to be sure).

What prompted me to remember the wires was another recent post about wire routing causing issues. I also tried to make sure that I didn't bring any issues of that nature about. The old wires looked like the factory originals, so I'm sure they were overdue (2 of them had worn through the insulation!)

So, at this point, the truck is running smooth, no codes, and in regards to another post about the ticking sound - it's just barely there now?

 

I got the chance to drive the truck around tonight for awhile, and guess what? It started chugging again, drove like crap all the way back home, and when I checked codes, got the old 33!

The valve moves - under my own suction, and when the engine asks for it to. I watched it with my own eyes... even after the codes came up, with the engine running I could see it open with a rise in rpm. It did have the plunger up higher on the shaft again, so I pulled it off and it appears to be fully closed even though the plunger looks odd?

I even checked vacuum at all connections tracing back from the valve to the manifold... all good.

I don't know where to turn from here - could the 2nd new EGR valve be bad too? Could it be something else?

 

Hmm, exhaust gas should have next to no oxygen - so am puzzled why the engine RPMs increased as the EGR valve opened - unless there is a leak in the valve supply tubing coming off the exhaust - allowing the valve to pull in fresh air instead of exhaust gas.

An unmetered source of air might possibly cause the problems you're experiencing - causing the engine to run leaner than it should for those conditions.

Still doesn't explain why the computer is throwing codes for EGR position???

 

Maybe I didn't word that right - when I opened the throttle body by hand to increase rpm (while standing in front of the truck where I could see inside the egr valve), the valve would open.

I have the valve off once again... it moves, but it's rough (like it's needing some lube, or wasn't machined well). And with the rubber plunger not seated at the bottom of the shaft, I have to wonder if it's really closed when it feels like it closes or not.

Could/would the rubber slide up the shaft?
Should I try to lube the shaft with some wd-40 or silicon to free it up?
Should I just take it back and try to get it replaced again?
Could the computer be messed up, giving/asking for wrong info?
Last but not least - should I be looking at something else (catalytic converter, O2 sensor, etc.) and assume that the valve is good?

 

I'll take your questions one at a time.

I'm not sure if the rubber would slide up the shaft, but I suppose it's possible. Do you still have the pld one you dissected? You could look at it to see if the rubber would be able to do that.

You can try to lube it but it wouldn't last long with the exhaust baking it.

With it moving rough I would take it back but after 2 bad parts I think I would get my money back and go somewhere else, maybe even to the dealer for a Motorcraft part.

I've never seen a computer mess up in that way. If you want to test the function of the computer, pull the MAP vacuum and/or other sensors while the truck is running and see if codes are stored for the components you unplug.

I still think that this nightmarish problem should be corrected before suspecting anything else. There isn't anything else this code can be associated with, except a wiring problem to the sensor or from the sensor to the computer. The computer supplies the sensor with both positive and negative in addition to recieving the signal from the sensor.

 

I wondered about the wiring - the chilton manual explains how to test it, but doesn't give any clues about which wire is which. Any clues as to which of those 3 wires are which would be much appreciated.

I've been looking at the valve this morning. I'm thinking some crazy things here... When I first put the sensor on this latest valve, it didn't fit down all the way. The pintle on the sensor had to compress just a bit before the sensor would seat. That didn't seem quite right.

Even if the valve is completely seated (which I 'think' it is), wouldn't that tell the computer that it's partially open if the sensor is retracted a bit? Seems like it would always be out of sync and unable to get the air/fuel mix right.

By this point, I've got a pretty large assortment of gaskets for this thing. I'm gonna try today with a 2nd gasket between the sensor and valve. I put it together that way, and it took up about the right amout of slack. The pintle didn't have to move to seat the sensor, and I have good vacuum in the valve. Putting vacuum on the valve, I don't hear a click like there would be if there was a space between the two parts. At this point, I have nothing to loose.

In the mean time, does anyone know which wires are which on the sensor?

And by the way, many thanks once again for all of the help and guidance along the way on this!