Testing and EGR Valve?

Now that I've gotten my motor to idle correctly, I'm gonna have to put back on the EGR valve. I know it will probably run better and cleaner with it off but thanks to the CARB bastards I'll have to leave it on (at least for testing).

So I've tested my valve off the car with a mityvac like vacuum pump. The diaphram does not move at all and no vacuum is held. Is the valve bad or is there something else that needs to happen before the vacuum will hold? i.e. does there need to be pressure on the exhaust side first?

Thanks

P.S. If it is indeed bad, does anyone have an EGR valve they want to get rid of??

its bad just bolt it on unless its stuck open it will not affect how it runs

98XJeep said:

its bad just bolt it on unless its stuck open it will not affect how it runs

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That would be great if the inspector doesn't pull off the hose and check with his own vacuum pump like they sometimes do... blasted smog check...

its not tested in mo. except in jeff city and i think that is just a talipipe test i could be wrong though

98XJeep said:

its not tested in mo. except in jeff city and i think that is just a talipipe test i could be wrong though

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Believe me, CA is annoyingly stringent about their smog checks. It's all the buffoons in the Air Resources Board that blame motorists for pollution not created by motorists.

why dosent somebody make a big air treatment plant like they do for water,sewer and other waste mgt? just a thought.

I didn't know they tested EGR valves.....just as long as the emissions were within spec and stuff (exhaust snif), and the gas cap test.

I cant say for sure on a 4.0 but every rig I yanked the egr or disabled ended in running like crap and pinging, these were all carbed engines and didnt include different manifolds and carbs/jetting changes, 318`s ,360,350`s. The FI system is calibrated to run with an amount of returned exhaust gasses. You should be able to move the pintle of the valve in and out unless its frozen, also are you sure you put enough vac to open it or check it? its designed to open at high vacume,cruise,little throttle,say 12+ inches vac.
If you had idle issues with it installed Id say the seat or plunger is burned or leaking and not seating allowing a vacume leak at idle basically and giving you a rough and low idle chocking it with exhaust.

Blaine B. said:

I didn't know they tested EGR valves.....just as long as the emissions were within spec and stuff (exhaust snif), and the gas cap test.

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Only some of the nit picky stations will do it. I had a time when they tested an EGR on one of my other cars.

dyna said:

You should be able to move the pintle of the valve in and out unless its frozen, also are you sure you put enough vac to open it or check it? its designed to open at high vacume,cruise,little throttle,say 12+ inches vac.

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My vacuum pump can make more vacuum than an engine can. When I tried to apply vacuum to the valve, it didn't even resist, it simply acted like there was nothing attached to the pump. The pintle moves freely by hand, its just that vacuum doesn't move it. I thought I read that it needed exhaust backpressure to work or maybe that was the transducer thingy which I don't have.

BTW, this is an 87 4.0L Renix.

Some of the EGR valves Ive messed with needed a large volume of vacume pulling on the diaphram, The mighty vac didnt work on some I thought were bad myself. Dunno, hopefully its good and it saves ya some $$$

SuperRA said:

My vacuum pump can make more vacuum than an engine can. When I tried to apply vacuum to the valve, it didn't even resist, it simply acted like there was nothing attached to the pump. The pintle moves freely by hand, its just that vacuum doesn't move it. I thought I read that it needed exhaust backpressure to work or maybe that was the transducer thingy which I don't have.

BTW, this is an 87 4.0L Renix.

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Put your finger over the end of the mighty vac hose. If you can pull and hold a vacuum with your finger on the end of the hose, the Mighty vac is good and the EGR is bad with a perforated diaphram that is not servicable.

If it isn't too late, you should know that the original EGR valve used on the 87, which is a single piece valve, WILL NOT operate from a vacuum pump even it it's good. It has a valve in the diaphragm that closes only under back pressure from the exhaust. In other words, a good one will leak vacuum!

Later two piece valves, with a separate modulator (or whatever that part is called....) have a solid diaphragm as far as I know, and should be testable with a vacuum pump.