I have had a EGR problem with my 4Runner ever since I got it 4 years ago (no joke). To put it simple, If I have the EGR hooked up and fuctioning correctly I have a lean stumble at light throttle steady speed. If I give a little more throttle the EGR closes and all is well untill it opens again. I have no codes when it is like this.

If I unplug the vacum line from the EGR valve so that it always remains closed the truck runs PERFECT but I get a code 71 which is due to the EGR temp sensor staying cold. I am getting sick of the engine light being on and I want to fix it.

I am 100% positive that all the vacum lines are routed correctly. I have replaced the EGR modulator and verified the VSV is fuctioning correctly. I have tested the EGR valve by the method in toyota service manual. Apply vacum to the EGR valve at idle and bam, engine dies.

So as long as the vacum line is hooked up everything is "fuction correctly" but the engine runs like crap.

If I unhook it runs like a dream and I get a check engine light. Go figure

I am lost on what to do. I am a very good mechanic but this one has me stumped.

I have replaced fuel filter, tested fuel pressure under driving conditions, cleaned injectors, new TPS, plugs, wires, cap, rotor, compression test you name it I have tested it.

The ONLY thing I can think is maybe the spring in the EGR valve has lost its tension so the EGR is opening too far or too soon, allowing too much exhaust gas to enter the intake. Toyota does not give any specs on how much vacum should be required to open the valve, so as far as I know, the only way to check this would be a new valve. But at 170 bucks its an expensive guess. Any advise on what else to check before I buy a new valve.

 

try blocking off the egr to see what happens. block off the port between the egr and the intake and the plug the vaccum line. if that makes it run better than replace everything on the egr system. thats what i had to do on my 84 supra.

 

Unplugging the EGR valve makes it stay closed all the time. So it is basicly doing just what you said. The EGR is blocking all the flow when in the closed position.

 

Bypass it with a equivalent resistor so the ECU thinks it's hooked up.

 

just closing it is not a full diagnosis. the diaphram in the valve could also be leaking and still cause a problem or a miss. thats what happened to me. blocking it off will tell you if thats the case.

 

I did this today. I got 15ohm resister from radio shack and cleared the codes. I took a 25 mile trip today on the highway and no engine light and its running great. Im thinking about ditching all the EGR stuff on that side of the truck. This should make it way easier to get to the rear spark plug.

 

I was just wondering if you've still been A-OK without the EGR system? Im thinking about ditching mine too....

 

+1, particularly since it's all laid out on the bench right now...

 

I'd love to know how and where to put this resistor as your symptoms are my symptoms.

 

Have you checked your vacuum hoses? I replaced mine out of similar irritation, and my stumbeling and rough idel dissapeared. My EGR valve diaphram was full of brown ooze and frozen from carbon. The hoses might have been too. I think that clogged hoses causes alot of these kinds of problems. Also, if your EGR is causing problems, your intake throttle body flap may not be closing all the way. The TPS would read that and cause issues. I dont know about the 3.0, but the 4cyl EGR tube enters the rear of intake plenum, then, through the plenum the EGR tube extends to push the gasses directly behind the throttle body. That area gets very dirty and gets coated in carbon.
So I say check your throttle body to see if it coses, and replace the vacuum hoses, one at time. Take air to the metal cacuum tubes to clean them out.

 

Well.. Nearly four years later. How the 3vz hold without your EGR sys?

-Further adjustments required?
-Premature gasket failures?
-Heat issues?

As of tonight my EGR must go or be replaced.