stumble and a pop. egr AND vcv? (1 Viewer)

[TheGeorge]

so i have read through the whole classic stumble bit and planned to check out my egr valve after i r/r the j pipe i ordered shows up.

i also have the popping sound on occasional startups coming from the passenger side/dash/speaker area followed by a sulpher smell. search has led me to believe this is the VCV valve or one of the check valves amongst the tubing.

my question to the emission gurus is whether or not the stumble could be related to just the vacuum check valve itself? does that make sense? should i chase after that first (read: after j pipe, before tackling egr)? or just suck it up and check out both? any suggestions for a plan of attck?

thanks once again.
g
87 fj60

 

[hank14]

I don't think the VCV will cause the stumble. Do you have an emissions Factory Service Manual to test the VCV? If not, I can post directions later.

Try bypassing the EGR valve by plugging the vacuum line going into the top of it. If that doesn't improve your performance, it is unlikely to be the EGR valve.

 

[TheGeorge]

I don't think the VCV will cause the stumble. Do you have an emissions Factory Service Manual to test the VCV? If not, I can post directions later.

Try bypassing the EGR valve by plugging the vacuum line going into the top of it. If that doesn't improve your performance, it is unlikely to be the EGR valve.

hi hank.
no, i do not have the manual. getting a full FSM set is on the list of things to do, but it will be a while. if you could post instructions, that would be great.

thanks for the reply,
g

 

[2mbb]

the pop and smell in side the cabin is either last nights burrito's or the distributor cap vent. The distributor cap is vented from a filter mounted to the fire wall behind the dash box and vacuum is pulled thorugh the cap when the truck is running. There should be two vacuum tubes connected to your distributor cap and an VCV that clips on the underside of the air cleaner.

 

[hank14]

hi hank.
no, i do not have the manual. getting a full FSM set is on the list of things to do, but it will be a while. if you could post instructions, that would be great.

thanks for the reply,
g

You're welcome.

Here's a thread for some info:

https://forum.ih8mud.com/60-series-wagons/212377-poof-sound-coming-oder-under-dash.html

Here's the instructions for testing the VCV from page 3-9 of the FSM Emissions Manual:

Check VCV by blowing air into pipe.

A. Apply vacuum above 70 mmHg to pipe S (see the little letter labels on the VCV). You can use a syringe, vacuum pump, or negative lung pressure on a hose attached to pipe S to create vacuum.

B. While maintaining vacuum on S, blow air into pipe Y and check that air comes out of pipe Z.

C. Stop the applied vacuum to S.

D. Blow air into pipe Y and check that air does not come out of pipe Z.

If problem is found replace VCV.

I'll bet it is not working.

Hope this helps.

There is a separate description of testing the EGR valve as well. Maybe 2mbb can post the scanned forms.

 

[TheGeorge]

You're welcome.

Here's the instructions for testing the VCV from page 3-9 of the FSM Emissions Manual...

Maybe 2mbb can post the scanned forms.

hank,
thank you very much for taking the time to post that for me (and others i am sure). i will check it out and report back.


cheers,
g

 

[Trapper50cal]

what he said

 

[TheGeorge]

what he said

is that what was wrong with yours, trapper? i have yet to find a moment to check it out.

thanks,
g

 

[Trapper50cal]

I haven't checked my vcv on the dizzyside yet...I routed it correctly I think. It has only popped twice since the desmog so I'm waiting to see if it will do it again...a used one at $OR is 33 bucks and the new ones are 70 so wait and see for me