EGR Valve sticking

toyota
corolla

#1

A. How do I remove the egr valve on a 1992 Toyota Corola DX? It is close to the firewall and I cannot see the bolts (if any).

B. Can I clean it out? I was told that they don’t break but just start sticking when dirty.


#2

I’m not familiar with the process on this particular model but some EGR valves can be a pain in the neck to service.

That being said, whoever told you they don’t break is wrong. They certainly can fail if the diaphragm inside ruptures.

There are also several other parts involved in the EGR operation (time switch, temp switch, modulator, etc.) so you should really get a manual and follow the diagnostic procedures rather than resort to parts replacing which may or may not fix the problem.

Just being curious, but what are the symptoms that lead you to believe the EGR is bad?


#3

When it is connected the car will not idle.


#4

It is not normal for the egr to cause a non idle condition. You probably have a different issue. Does the car idle at cold start? Does it not idle at all ever? Why do you think it is the egr?


#5

It should always be closed at idle. There should be no signal (vacuum or electric) to open it. The ONLY time it opens is at high-vacuum cruising speed…At idle or when accelerating, it should be closed. If it is open at idle, the engine WILL run very rough and stall…

Are you subject to emissions testing?


#6

When the EGR valve is disconnected the car runs perfectly. When I connect it the car will run but very very rough and runs worst while at idle.


#7

Disconnect it for a few days and report back with the results. The CEL might come on, but we can cure that…


#8

Yes I have to have a smog test within the next few weeks


#9

Is the valve vacuum or electrically operated? The VALVE seems to be working fine. It’s the control circuit that is opening it when it’s not supposed to…


#10

Well there are like 1/8" hoses that connect to it. If I disconnect the hoses then it runs great.


#11

Right. The problem is at the other end of those hoses…


#12

http://www.partsgeek.com/mmparts/egr_valve/toyota/corolla.html
If you click on the link above that is what I think it looks like.


#13

Sorry the link opened to the page not the image. The link below opens to the 1992 Toyota Corrola EGR image

http://k9space.com/files/92toyota-egr-valve.jpg


#14

Or between them at the EGR Valve


#15

An EGR that is open at idle will cause the engine to idle very roughly or not at all. Based on the additional info this sounds like an EGR control problem rather than a failing EGR.

I had considered suggesting the proverbial BB fix but since smog is coming up that idea can be written off.


#16

What if the diaphram of the EGR valve is broken and thereby leaving the valve open. Would that not cause the problem with the idle?
I have plugged the connecting hoses to the EGR Valve with screws and the car runs perfect.


#17

What is the CEL? I have been running it with it disconnected. The car runs fine without the EGR valve.


#18

As I stated, I’m not that familiar with how this particular one is set up but normally a ruptured diaphragm in an EGR valve will cause it to close and never open. In a nutshell it sounds like straight manifold vacuum is being applied at an idle when it should not be. Many EGRs work off of ported vaccum (meaning the vacuum source is above the throttle plate rather than the intake itself) but some work in reverse.

With a length of vacuum hose you could try a homebrew test on the EGR. Plug the hose onto the EGR vacuum nipples, suck the air out, and close off the hose with the tip of the tongue; much like one might do with a soda straw. Note if this holds vacuum. A hand held vacuum pump is easier and more professional but this method works. You should be able to determine if a diaphragm is ruptured or not.
With the engine idling (and depending) you should hear the engine stumble when you suck on the hose and revert back to normal when you don’t. If this occurs the EGR is likely good and the problem is elsewhere.

You might also consider checking with a local library reference section about EGR system diagnosis. Some libraries carry a selection of auto repair manuals and if it’s anything like the one here they will not allow anyone to check them out but they have a copy machine and do allow people to run off copies of needed info.
If you have to purchase a service manual for this info consider something other than Chiltons. Chiltons soft covers are a horrible source of information.


#19

Thank you very helpful