how to check the egr vacuum modulator
msrdude
never mentioned it. Just apply vacuum to the bottom port and if it
doesn't hold vacuum, then the membrane/diaphram is broken inside. Is
that true?
I tried to do that, and the result is: It does not hold vacuum. If i
cover ports p,q,r and the port inside the air filter area, then it
will hold vacuum. It looks like you need to cover the ports in order
to check the bottom port, but i could be wrong. Can anyone tell me if
the modulator is good or not?
Ray O
"msrdude" <kim...@gmail.com> wrote in message
news:32f1ef38-4255-40b7...@z8g2000prd.googlegroups.com...
With the modulator installed on the engine, disconnect vacuum hoses from p
and r and disconnect q from the EGR valve. Plug p and r with your fingers
and blow into q. Air should flow from the air filter side freely.
Start the engine, and maintain 2,500 RPM. Repeat the above test. There
should be a strong resistance to air flow.
The modulator is probably good since they do not fail very often. I think a
more likely problem is a crack in one of the thermal vacuum switching valves
(TVSV).or vacuum switching valve (VSV).
By the way, what model, model year, engine on the vehicle?
--
Ray O
(correct punctuation to reply)
msrdude
How would you check the thermal vacuum switching valve?
Ray O
> its a 95 corolla with 1.8 l engine.
>
> How would you check the thermal vacuum switching valve?
With the engine coolant below 99 degrees Fahrenheit, blow air into the upper
port - air should not flow out of the lower port.
Disconnect the vacuum hose between the modulator and EGR valve, and using a
3-way union, connect a vacuum gauge. Start the engine, rev to 2,500 RPM,
and check to see that there is no vacuum.
Warm up the engine so that the engine coolant temperature is above 133
degrees Fahrenheit, blow air into the upper port - air should flow out of
the lower port.
Reconnect the vacuum hoses, and with the engine warmed up at 2,500 RPM, the
gauge should indicate low vacuum.
Inspect the TVSV for cracks.
Disconnect the vacuum hose from the R port of the modulator and connect the
R port directly to the intake manifold with another hose. The vacuum gauge
should indicate high vacuum at 2,500 RPM and the engine should start to run
roughly.
msrdude
both work fine.
I kind of confirmed that my egr vacuum modulator is broken. I
mentioned earlier that when I applied vacuum to the bottom port of egr
modulator, it did not hold any vacuum at all, it goes out from the
ports, and can only be held if I covered all of the ports with my
fingers. I checked out my dads car, its a 96 camry, its the same year
and make, but different model but i do not think it makes any
difference because it should all work the same. Anyways, i applied
vacuum to the bottom port, and it held vacuum!, but slowly, the gauge
went down. I think my dad needs a new modulator but not now because
its a small leak and it should not harm the car or the egr emissions
yet.