With vacuum connected, the EGR moves when I give it gas. Not a lot (don't know if that's normal), and it doesn't return to it's idle position immediately afterward (not sure if that's normal, either).

When I plugged the EGR and dizzy lines, the bogging down after throttle did not happen. I connected just the dizzy line and tried again; no bogging.

It seems the EGR is the problem then, no?

 

Yes, it looks like the EGR could be *a* problem... some of them use not only vacuum but also exhaust backpressure to operate but I forget which years use what, and I have experience only with the 100% vacuum-operated variant.

Regardless, it looks like you've identified at least one culprit... if it were mine, I would remove the EGR and clean it out, it's likely sticking due to carbon build-up. Judicious use of carb cleaner and maybe some mechanical scraping might help it, you should be able to operate it by attaching and then sucking on a vacuum hose, see if you can get it to easily move its full length.

The EGR valve allows an amount of exhaust gases to be recirculated back into the combustion chambers during certain conditions - one of which is NOT at idle. So, if you're feeding exhaust gasses back into the air/fuel mixture at idle, you're leaning out the resulting mixture and bad things can happen.

But yor idle speed(s) still concern me, I have questions about your choke's operation, etc. so this may not be the only thing requiring attention.

But, begin with cleaning out and unsticking the EGR valve and see how it reacts to that... correctly identifying *which* EGR valve you have is something of a chore, the parts catalog wants the engine's Calibration Code to locate the correct part. You might do best by googling the Engineering ID number on the thing (e.g. E4TE 9D475-BA or some such).

 

The choke and idle speed thing was my dumb fault - I had the operation of the adjustment screws backward. I forgot the up screw was idle and the lower screw was high idle. This isn't the first time I've had to mess with those so I feel especially stupid for forgetting.

I've corrected that and it now idles a good bit lower than it was in the video, and does so smoothly after some adjusting on the mixture screw (that one is hard to mess up. go me).

This EGR is brand new, a BWD from Advance. I just took it off and noticed some sludge in one of the holes of the "plate" the valve bolts to, so I cleaned it out.

Sucking on a hose attached to valve didn't make anything happen (the jokes write themselves) aside from a nice buzz for a moment. The diaphragm didn't move at all.

 

Remember that some of these valves use more than just vacuum to do their jobs, this could be one of them. Maybe one of the other guys who know more about this stuff offhand will chime in, or maybe you can find it in the archives here (or elsewhere via Google).

This next part makes me wonder:

In my experience with vacuum-only valves, they close pretty instantly upon lowering of the RPM.... which is another thing that makes me question the installation of your vacuum hoses, if all the thermally-activated doodads (valves) are in place and operating as they should, yadda yadda yadda.

I really wish you had a tachometer....

 

If it were me I'd remove the EGR and install a plate across the opening to see if the problem goes away. It can be temporary or permanent.

 

I'm even more profoundly dumb than I thought. When I went to get a new EGR valve, I got the cheapest one Advance said would fit my truck.

It was a replacement for "OE No. E0TE-A1A, A2A"

I still have my stock EGR, which I cleaned off to reveal as one of these:


This would explain the new one simply not doing it's job, wouldn't it?

 

Hey! That description is reserved for ME!!!

Oh, I dunno.....

Yes, I'm opening this one up big-time, but....

Clean up your old one then suck on it, see if you can get it to perform.

If you can get it cleaned up to where it looks like it might be operational again, put it back on and see what happens.

 

The old one is entirely clapped out. It whistles when you move air through it and pushing on the plunger/rod in the back will get it stuck in the pushed position. Trashed.

Of course the replacements for this part run 30-50 dollars more expensive than the incorrect one. Oh well, I'm just happy to have narrowed down at least one major aspect of this mess.

Thanks for all of your help and patience, Chris. If a new, PROPER valve doesn't fix the problem I'm sure I'll be posting about it.

 

No prob, boss is out today + it's Friday and a slow day at work, I need something to do.

If it sticks, I wonder if carb cleaner would dissolve some of the carbon buildup and un-stick it..

 

I'll give it a shot, but I'm not gonna pray for a miracle. Thankfully I found a direct replacement for 40 bucks online. Definitely better than the $85 Advanced wants for THE SAME EXACT PART FROM THE SAME MANUFACTURER