EGR vacuum modulator question (1 Viewer)

[OhioFJ]

Greetings all.

I'm tracking down a vacuum leak that has developed in my '79/40. I was pulling a good 19-20 with idle at 650; this abruptly changed to a vacuum of about 15-16 and idle of ~1100. Check timing and valves - all ok.

Smoke test through the brake booster revealed a huge leak at the EGR j-pipe gasket, however I also noted smoke coming from underneath the EGR vacuum modulator cap - I assume this is not normal. Amazingly the manifold gasket seems ok.

The only emission FSM I have is for the '81 year and shows an EGR VM with three ports on the top of the cap. My modulator has only two ports on top labeled P,Q.

Questions:
- What is the test procedure for this vacuum modulator (two ports on top, one one the base)
- Is it a serviceable item at all? alternatives? I believe it is nla, but I can't make out the part#

Thanks for looking.

 

[fjc-man]

Is yours a federal or California emissions system? The testing is a little different.

 

[OhioFJ]

It’s federal

 

[fjc-man]

I sent you a pm.

 

[OhioFJ]

I assume this is not good

 

[AntFarm]

Here’s the section out of the 79-80 emissions manual to help you out. Easy test of the modulator.

 

[AntFarm]

However if I were in your shoes, this is a good time to consider a proper Desmog. You need to address the J-pipe anyway. Jim C is in your neck of the woods and is the Desmog guru. Look up My Desmog Thread over in the 60 section.

 

[OhioFJ]

Awesome, thank you both. Much appreciated.