EGR Part II - link to pics

I didn't see my previous reply to my EGR and emission's test show up in the forum, so I am sending again.

Thanks for the previous info., Phil.

I took it all apart again this morning. To me, it doesn't look like the massive clogging I expected if the EGR were the source of my NOx emission error. If any experts could please look at the digital snaps I took and give me an opinion, I would appreciate it. Here is the link. There are three pictures on this page that are about 60K each. They pop up at once, so please wait about 20 seconds for them to download if you are on dial-up.

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I did really soak and drain the EGR chamber a few times with throttle-body cleaner. I don't know if it helped but it didn't seem like I felt any clogs "around the bend" in the chamber.

The port on the TB was not clogged any more than the other three ports shown in the pictures (I could not get the camera in position for a decent shot). It looked clear as far as I could see and feel. I shot TB cleaner in it and it did not backflow/ fill up.

My spark plugs have 63k on them. The car idles fairly smoothly and accelerates just fine. Old plugs wouldn't really affect NOx that much, would they?

The EGR modulator seemed to function as the book said it should when blowing air through it. I used compressed air to blow out the filter material.

Unless I unclogged things with the TB cleaning fluid, I don't think anything has been solved and hate to waste my 1 free re-inspection. Any thoughts would be appreciated.

Thanks in advance, Doug

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I'm a part time mechanic and used to have a california smog license but let it lapse. When testing Nox failures I first check EGR valve. I get vacuum pump and pump up 20 inches vacuum to EGR valve. It should hold vacuum. If not replace it. Then with engine idling pump up 20 inches on EGR. Engine should run bad or die. This means passages from exhaust and to intake manifold are open. Also when you are pumping up EGR you can put your fingers in holes in EGR and feel it open (careful might be hot). It that part of EGR tests oK then I tee in a vacuum gauge to EGR valve. Then I put car in park turn on engine and rev throttle. I should see vacuum on gauge (usually at least 10 inches or more of vacuum. If no vacuum check vacuum system. First 2 ported vacuum sources to modulator valve. Pull off one ported vacuum source at throttle and put vacuum gauge there. Rev engine and you should see strong vacuum. Do the same for other vacuum line at throttle which feeds modulator. Modulator has 2 vacuum sources and and exhaust tube coming in to its bottom. It works as follows as you open throttle vacuum goes to one ported line to modulator. If there is enough exhaust pressure (engine load) the modulator will pass this vacuum to EGR. As you open throttle wider it will cause vacuum on other ported line to modulator but this one will pass through modulator regardless of wether there is enough exhaust pressure or not. Some later Toyotas have a vacuum solenoid to bleed off EGR vacuum. If you have one of these the computer might disable EGR. You can plug this line and run previous tests and if these tests are good then you can assume computer is disabling EGR for some reason. But I have never had to go there. The catalytic converter is the other NOX reducer. You must make sure it is being fed properly with a rich mixture. On your smog check there should be very little oxygen left because a good engine might generate 2% oxygen but the oxidizing part of the catalytic converter uses this up in oxydizing HC (gas vapor) and CO (carbon monoxide caused by burning rich mixture in combustion chamber). the reducing part of cat (the part that takes care of Nox must be fed a slightly rich mixture, it need CO to reduce Nox. This is usually taken care of by a properly cycling feedback system as shown by a cycling oxygen sensor, cycling rich and lean. But sometimes the oxygen sensor gets out of calibration or the car is not in feedback or is lean so Nox reduction cannot occur. Usually testing, replacement of oxygen sensor has fixed a number of Nox failures. If the catalytic converter is being fed a proper mixture then the only thing that could cause nox failure is the cat itself, the reducing part is bad and cat replacement will fix that. Engine high temperatures, advanced timing or carbon in cylinders also could contribute to Nox, but they check timing during smogcheck and temp and carbon are not considered that big a change in Nox so can usually be ignored. Hope this helps, you might want to find a good mechanic who knows how to test these systems for a reasonable price.

Reply to
Edmechanic

Thanks for taking the time to write such a detailed post! Although I don't suffer this problem if I do, I have a much better understanding.

Thanks again! (and please visit often :).

Reply to
Jay

Ed, thanks for the great response!

Doug

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