EGR Valve Question

[DBMaster]

This is one of those "answer only if you have the part in hand and know for sure" questions. I don't want to throw any more money away trying to fix the "Code 12" issue if there isn't anything really wrong. I had the EGR valve out yesterday because I figured that the gasket is cheap enough and it wouldn't hurt to clean it and get a closer look at it.

I already replaced the EGR solenoid and CVC valve with NEW parts because the diagnosis lead me there first.

Anyway, I noted that the EGR valve will open all the way and hold vacuum. It was not really all that dirty, either.

Now, here's the big question. Should the EGR operate smoothly all the way to the full open position, or is it normal for there to be a "detent" or "sticking" position about 2/3 of the way to full open. I cleaned the thing thoroughly and put dry teflon on the shaft and the detent can still be felt. When I connected my manual vacuum pump I could give it a little vacuum and it would open 2/3, give it a little more and then it would open all the way. If the detent is an abnormal condition then I think I found my check engine issue. I rarely get the light when I am on the highway. I either get it in town when I am not very far from the house, or I don't get it at all.

If you have a good valve laying around this detent can be felt when you push up manually on the diaphragm with your finger as well. Thank you for your patience and help, folks.

[shepherd79]

try this,
try to pump the vacuum pump, see what the pressure you have to pull to pass that detent. the normal vacuum pull with the engine running is 20psi. if it takes more than that you may want to get new valve.

[DBMaster]

It takes less than 15in (I assume you mean in vacuum since that is what the gauge reads), but the CVC valve limits vacuum to the EGR to about 8in. My analog gauge is not precise enough to tell me exactly when it passes the detent. I figured if anyone had a known good valve off the engine they could see if theirs had a detent. There may be a local auto parts place that would get the vale in for me so I could check a new one. I have no problem spending the $140 if it would actually fix the problem.

It is very strange to think of any engine "computer" as antiquated, but ours are. The newer ones will tell you (with the aid of a diagnostic machine) exactly what the "EGR system" problem is. This is very annoying!

[Robs89LXi]

Not 100% sure, but no, I don't think there should be a detent. It should be smooth all the way through. Find a pick-a-part junkyard nearby, swap out with what you have and test it. Should be a pretty cheap way to tell.

[DBMaster]

So far, my search at local wrecking yards has yielded nothing. It is getting harder to find these older Hondas around here for some reason. Since the Grand Prairie yards were a bust I can always try Haltom City or Jacksboro.

[Robs89LXi]

If those don't work out for you, let me know. I go by the pull-your-own-part type junkyards pretty frequently, and there are several 3G's around, so I'll be glad to grab one for you.

[DBMaster]

I am just interested in knowing about the operational question. If you don't mind pulling one just to see how it operates that would be great. At this point if I actually have to replace the valve I would like to go with a new one.

[Robs89LXi]

Well, heck. Just go by a Honda dealer and look at one in the parts dept. A service rep. ought to be able to answer your questions too.

[Kabuki]

Nope, I'm SURE that it should not have a detent. The range of motion should be nice and fluid, with no hangups.

[DBMaster]

Thank you for that. I guess I will take a chance and go ahead and order the thing.

[DBMaster]

Well, Honda fans, here is the update. I received the new EGR valve from Majestic Honda (just FYI it DOES NOt come with a gasket). It moved smoothly through the whole range of lift. After replacing the valve the check engine light is not coming back on.

I think there is an interesting lesson here. Just because the EGR kills the engine and holds vacuum it does not mean that all is well. My faulty diagnosis led me to spend and extra $180 on the EGR solenoid and CVC valve. To be fair to myself, though, I read numerous tech tips online that said that the EGR and lift sensor were components that almost never went bad. Also, my mechanic who spent 25 years at a Honda dealership said he rarely had to replace an EGR. On the ones prior to 1989 the air chamber had an internal brass filter that would frequently clog. I guess that's why in 89 they switched to one that is simply a hollow plastic canister.

After explaining to him what I had done in my diagnosis he said, "You're the man. You have already done everything I would do. Please let me know what you did when you get it fixed."

Believe it or not, the pre-OBD "computers" in our cars are not all that sophisticated. The newer ones (when hooked to a diagnostic machine) will tell you WHICH part of the EGR system is having problems. I guess not all new automotive technology is evil. :)

Thank you for all your help and suggestions, especially Rob.

TTFN