Borrowing a Timing Light

[IoN6]

It would depend on which side of the valve the vacuum is being applied to. IE You could pull a vacuum in the direction that would OPEN the valve at lower levels. What does it do if you pull as high of a vacuum as you can? Does the time it holds increase or decrease?

I try to not use the shotgun approach to replacing parts, but I do understand the hair loss of troubleshooting these issues. The EGR valve, when I bought a new one for my '93 however many years ago was almost $400. Not a tremendous amount of money but enough that I would possibly ignore the path you are going down, for now. Especially when there are far cheaper things to shotgun your money at. IMO anyway.

It looks like you have some new vac lines to the EGR, did you replace everything "inside" the intake clamshell? How is your intake tube from the airbox to throttle body? How does it run >3000rpm? Will it keep pulling or does it feel almost like it runs into a brick wall?

 

[SanchaLover]

If the EGR is stalling the vehicle when vacuum is applied to it, then per the FSM it is functioning as intended. Remember, in normal operation the vacuum is always being renewed by the engine, so the EGR is not meant to hold a static amount of vacuum. The FSM does not specify your test as a way to test the EGR valve.

But if you're pulling your hair out and at the point of throwing parts at it, then theoretically I would say you are right and the EGR valve diaphragm should not lose vacuum, so replacing it with a new one wouldn't be totally uncalled for.

But what do I know; I'm dealing with my own emissions issues as well right now that I can't figure out. Lol.

That's what I was thinking. Taking everything said on the internet with a grain of salt, I've read on Mud and elsewhere that the EGR valve should hold a vacuum without leaking. Here is an example (under "Alternate EGR valve tests").

And if you were wondering, I have no hair left to pull out.

 

[SanchaLover]

It would depend on which side of the valve the vacuum is being applied to. IE You could pull a vacuum in the direction that would OPEN the valve at lower levels. What does it do if you pull as high of a vacuum as you can? Does the time it holds increase or decrease?

I try to not use the shotgun approach to replacing parts, but I do understand the hair loss of troubleshooting these issues. The EGR valve, when I bought a new one for my '93 however many years ago was almost $400. Not a tremendous amount of money but enough that I would possibly ignore the path you are going down, for now. Especially when there are far cheaper things to shotgun your money at. IMO anyway.

It looks like you have some new vac lines to the EGR, did you replace everything "inside" the intake clamshell? How is your intake tube from the airbox to throttle body? How does it run >3000rpm? Will it keep pulling or does it feel almost like it runs into a brick wall?

If I pull more vacuum, the time it holds increases. It loses vacuum fairly consistently, but maybe slightly slower at lower levels of vacuum.

PO must have replaced them at some point (I've only had the truck since December). I just ordered new vac lines that I plan to install over the weekend. The ones under the clamshell look to be in the same condition as the ones up top, but I haven't removed the intake manifold so I can't be certain. I'm trying to avoid removing the intake manifold if possible, but that's soon to come if I don't get it sorted out.

Intake tube looks brand new. No cracking or fading of any kind. After my second failed test, I installed an OEM air filter, which replaced a K&N oily filter.

I haven't noticed any issues above 3000rpm, but I will check next time I'm in it. If I did have a loss of power, what could that indicate?

Thanks!

 

[SanchaLover]

It would depend on which side of the valve the vacuum is being applied to. IE You could pull a vacuum in the direction that would OPEN the valve at lower levels. What does it do if you pull as high of a vacuum as you can? Does the time it holds increase or decrease?

I try to not use the shotgun approach to replacing parts, but I do understand the hair loss of troubleshooting these issues. The EGR valve, when I bought a new one for my '93 however many years ago was almost $400. Not a tremendous amount of money but enough that I would possibly ignore the path you are going down, for now. Especially when there are far cheaper things to shotgun your money at. IMO anyway.

It looks like you have some new vac lines to the EGR, did you replace everything "inside" the intake clamshell? How is your intake tube from the airbox to throttle body? How does it run >3000rpm? Will it keep pulling or does it feel almost like it runs into a brick wall?

I took videos applying vacuum to the EGR. One video is pulling from DS and the other is pulling from PS. I can't figure out how to attach them to this post but I can email them if it would help. Again, thanks for all the input I really appreciate it.

 

[Crash]

If I pull more vacuum, the time it holds increases. It loses vacuum fairly consistently, but maybe slightly slower at lower levels of vacuum.

PO must have replaced them at some point (I've only had the truck since December). I just ordered new vac lines that I plan to install over the weekend. The ones under the clamshell look to be in the same condition as the ones up top, but I haven't removed the intake manifold so I can't be certain. I'm trying to avoid removing the intake manifold if possible, but that's soon to come if I don't get it sorted out.

Intake tube looks brand new. No cracking or fading of any kind. After my second failed test, I installed an OEM air filter, which replaced a K&N oily filter.

I haven't noticed any issues above 3000rpm, but I will check next time I'm in it. If I did have a loss of power, what could that indicate?

Thanks!

In my experience K&N filters simply don’t work as well as OEM. Ran that aftermarket filter on my 62 in the early aughts and switched back to stock after finding evidence of oily dust in the intake tubes post AFM. Don’t see that now.

 

[IoN6]

If I pull more vacuum, the time it holds increases. It loses vacuum fairly consistently, but maybe slightly slower at lower levels of vacuum.

PO must have replaced them at some point (I've only had the truck since December). I just ordered new vac lines that I plan to install over the weekend. The ones under the clamshell look to be in the same condition as the ones up top, but I haven't removed the intake manifold so I can't be certain. I'm trying to avoid removing the intake manifold if possible, but that's soon to come if I don't get it sorted out.

Intake tube looks brand new. No cracking or fading of any kind. After my second failed test, I installed an OEM air filter, which replaced a K&N oily filter.

I haven't noticed any issues above 3000rpm, but I will check next time I'm in it. If I did have a loss of power, what could that indicate?

Thanks!

I had a problem where the fuel pump was not kicking into "high" (>3000rpm) and while it would still kinda pull it felt like I instantly was 2000lbs heavier.

The OBDI vehicles, while simpler, are pretty tedious to troubleshoot. Pulling the top half of the intake plenum is not too intense and is really the only way to get to the VSV's or check any/all of the vacuum lines hidden inside. The likelihood of it previously torn into is nearly 100% IMO, with that in mind I would track and trace all of the lines to make sure they were reconnected where they are supposed to go.

 

[SanchaLover]

I had a problem where the fuel pump was not kicking into "high" (>3000rpm) and while it would still kinda pull it felt like I instantly was 2000lbs heavier.

The OBDI vehicles, while simpler, are pretty tedious to troubleshoot. Pulling the top half of the intake plenum is not too intense and is really the only way to get to the VSV's or check any/all of the vacuum lines hidden inside. The likelihood of it previously torn into is nearly 100% IMO, with that in mind I would track and trace all of the lines to make sure they were reconnected where they are supposed to go.

I haven't experienced that but I will check for it.

I've been reading through the FSM and watching/reading others' experiences so that may be next on the list.

 

[IoN6]

It was not noticeable until I went through all of my struggles...