nickhans

I have a 1991 Accord LX and i have had a bad EGR Valve for a few months and i noticed that my gas milage has gone down a little bit. I know I have a bad EGR valve because it does all that wierd revs when i start it up. And I also want to know how to clean them, i asked someone how to do it and they said Brake cleaner. well ive done my studies and there is a plastic part in it and it might eat away at it and my EGR would get worse. please help me if you can. thanks

P_Adams

The Egr, surprisingly, doesn't grossly effect gas milage. By the very nature of how it works, if it were to malfunction, we should see gas milage improvements (we're no longer injecting an inert gas into the Combustion Chamber (Diluting the charge))
I'm curious, even during the perscribed EGR function test, the RPM drops only 100 rpm. You might want to look at your IACM (Idle Air Control Motor) as your culprit. They can develope an internal vacume leak which can cause those wild idle speeds. Crud build-up in the Throttle Body can also cause it to 'hunt' when idling.

P

amckee

The plastic part you are refering to will not be in your line of fire when spraying out the EGR with brake cleaner. Do not spray it into the vacuum port. Thats where your diaphram is. You're wanting to clean the plunger, seat and the surrounding chamber. Make sure you have a new gasket. Once this is reinstalled, test it by applying vacuum to the valve. Your engine should stumble. The valve should also hold vacuum. If it doesn't stumble, your ports are clogged in the intake manifold. Your idle problem does, as P_Adams said, sound like a IAC valve or fast idle valve. Remove the IAC and clean it with choke or brake cleaner and make sure the screen is clean. The Fast idle valve has a thimble inside with a donut around it. Sometimes the donut gets loose and can be screwed back down. I have to disagree with P_Adams on a couple of points. Exhaust gas is by no means inert. It is, however, Oxygen depleated which does , as he states, dilute the charge, but in a way which makes the O2 sensor think the mixture is rich. The EGR doesn't reduce emissions by reburning the exhaust. It does so by lowering combustion temperatures and keeping them from being formed in as high a quantity in the first place. Lower combustion temps helps prevent predetination which is another cause of poor mileage due to inefficiant combustion. I gained 4 1/2 MPG by cleaning out my EGR system a couple of months ago.

P_Adams

Sorry. By inert I should point out I mean non-reactive. It will not burn, and by that condition controls combustion tempuratures.

P

nickhans

what does the IAC valve look like

nickhans

http://63.150.115.104/Commerce...0.jpg

Does it look like this

amckee

If thats not it its similar. Thats the side that mates with the plenum of course. From the front it looks like a little motor or solinoid.

SOHCMAN

That appears to be a fast idle valve, but it doesnlt look like my 5th gens. You should see something similar under the TB. The EGR valve is locatedto the left of where the intake manifold connects (depending on what model you are working on)

amckee

IAC will also have a wire pigtail connected to it. SOHCMAN is correct, that is a fitv. IAC has a screen between the valve and the plenum. It's on the left side of the plenum looking toward the firewall.