ProLineDesigns

98 EX V6 2Dr 165K

CEL Insufficient EGR Flow.

Took off the manifold and cleaned the almost clogged EGR port and put everything back together as speced by the Service Bulletin. Took it on a test drive and the CEL came back on same code.

What is the next EGR system part I would look at? Maybe the EGR valve is bad?

Duane_in_Japan

YES, you will need hand pump vacuum pump to test the EGR diaphram and hoses, isnt there a solenoid in the system to allow vacuum to get to the EGR and more vacuum hoses, one of these should be the problem, including as you stated. Honda uses the MAP sensor to watch over the EGR vacuum, if the EGR does not open enough, since your ports are clean now, then the MAP will not see a vacuum loss due to an open EGR Valve and it reports to the computer to set a code, I do not believe you have a MAP problem, just an EGR System issue but which part, test and you will find it. When you pump up the EGR directly with engine running, the engine should die or almost die.

ProLineDesigns

What should be the range of results on the vaccum pump?

Or will the result be the engine dying out like you said? I assume if the engine dies out then it is not the EGR valve and something else in the system?

Thanks

Duane_in_Japan

If it does not hold the vacuum then the vacuum diaphram on the EGR valve assy is bad and the EGR valve is not opening. If the valve is opening and holding vacuum, say anywhere from 4 to 20 inches of vacuum and the engine does not die or at least stumble pretty bad then all or most of your EGR ports in the intake are clogged with carbon. Dont forget, there are other hoses and solenoids involved so test right at the EGR valve. Backing away from the EGR valve will be a hose going to a control solenoid, when this solenoid gets power (or a ground signal) from the computer, it opens its pintle allowing vacuum to be applied to the EGR valve and hose. Prior to the solenoid is its hose probably coming from the intake manifold.

I am not looking at a schematic to be sure that is all the pieces but maybe when you put things back together, there was a mistake but since you are getting the same code, you probably did a good job, you are going to have to monitor the power going to the solenoid with a voltmeter mounted where you can see it while driving, you may even need to "T" into the vacuum lines one at a time and monitor the vacuum to each hose before and after the solenoid to see if it is changing during EGR command.

As I mentioned Honda utilizes the MAP sensor to "SENSE" when the EGR is commanded on and if the vacuum does not change enough then a code is set, not hard to troubleshoot but if you need more help just ask, my explaination was simplified but I went to the Philippines for some R & R if you know what I mean so I have lots of e mails to help.