ThomasJ

Hello, Im have been having a problem with my 4Runner ever since I got it three years ago. It will hesitate and miss out at light throttle. If I take off from a stop light and press the gas it wont really accellerate untill I get past quarter throttle or so. And at half to full throttle you can feel the power surging off and on as if it were getting sudden burst of fuel and air. I was double checking all the vacuum lines and discovered that if you pull the vacuum line off the egr valve the problem goes away. So I just started driving without the egr hooked up and it runs good. But, I get a code 71 due to the egr temp sensor being cold because the egr stays shut all the time. If it did not have a temp sensor for the egr I would just leave it unhooked. But the engine light is starting to annoy me as much as the stumble did.

I have had it to the dealer and they want to just start throwing parts at it to see what fixes it. Obviously you all know toyota parts are not cheap so I want to try to find the problem before I start playing a guessing game with my money.

Anybody had any problems like this? Its a 3.0 auto with 145K. Head gaskets were done at 120K and the problem was there before that also. The valvetrain is noisy but not any worse than any other runner ive heard. Gas milage is right around 10MPG in town and 14MPG on the highway. There are no other codes besides the 71. If I leave the egr hooked up it does not have any codes but runs like crap

Thanks for any help you guys can provide.

callmej75

My guess would be the egr valve or maybe one of the egr tobes are clogged.

ThomasJ

The problem im having is with the egr hooked up and functioning. If the tubes were clogged there would not be difference if the egr valve was hooked up or not, (there would be no flow). If I hook up the egr the tubes get extremely hot and the code 71 goes away. Indicating that the exhaust gas is flowing through the egr system as it should. The problem is this exhaust gas being present in the air/fuel mixture is causing the engine to miss and stumble. I just dont know why. Thanks for your reply.

callmej75

Do you have an exhaust gas temp sensor? If so it threads into the side of the egr valve and has a wire harness and a plug coming off of it.

ThomasJ

Yes, I do. This is what causes the code 71 when the egr is unhooked. When its unhooked this sensor and all the tubing stays cold.

Ironmike4x4

Good job TomasJ, I like it when people use the "eliminate and isolate" diagnostics. I would say you have a bad EGR valve is what it sounds like to me. I don't know what year model 4Runner you have but if it's acessible then I would take the EGR valve off and look inside to see if it's clogged up... also check the runner that goes into the intake itself to see if it's clogged as well.

eric-the-red

Sounds like you're getting too much egr at the wrong time. The amount of egr is controlled by the egr vacuum modulator. On the 3.0 that's a small round part near the front of the engine, passenger side, with 3 hoses. It has a filter inside which could be clogged, or some of the vacuum hoses could be leaking or connected wrong.

I don't really know a lot about the system, but if you're going to throw parts at it that would be someplace to start.

Have a look at this article, it might explain better.
http://www.autoshop101.com/forms/h61.pdf

toyguy1986

I concur, If you have a EGR modulator it more than likely is the problem as this tells the EGR when to open and close.

toyguy1986

Almost forgot but if the 3.0 is like the 22R running without the EGR working properly will cause high combustion temps and could lead to the HG failing.

callmej75

one way to test the egr valve is to take the vacuum line that comes off the modulator to the egr, leave it connected to the egr valve, and start the engine and suck on the vacuum line. if the motor almost dies or does die then the valve is working properly. could be the egr temp sensor on the side. does not sense different temps and therefore overheat. just my opinion.

spainobain1234

My EGR valve is RATTLING and I just Dont know what to do. I start it, and it makes a rattling noise.

crazy4runner

Bro that sound like you need to get a new EGR, never hurt to try..,

dustrider

you can check the opration of the EGR valve by removing it, then confirm that flow is completly shut through the ports. Then have your girlfriend suck on the vacuum opening valve line . It should open easily with a small amount of vacuum , when the vacuum is released it should snap back, If it returns slowly when the vacuum relases , or does not seal off the port it needs replaced

also check that the VSV is operating

stay away from the stealership unless you have a new car under warranty, millions of dollars to throw around, wear white shorts and will call for a limo to get picked up while the dealer service department fiddle fumble stumbles around for days picking there nose and flicking boogers at your motor

Cbar

I have what I think is an EGR issue. My engine is missing when at a stop light. I can see small but noticeable misses every 20 seconds or so. When I return to driving it is fine and nothing happens out of the ordinary. I also see a dip in my idle when shifting into neutral. I see it dip very low then recover to a higher rpm, dips to 400 and returns to 750 or so. I have no clue if that is normal. I am new to these engines so any advice would be helpful.

tantacoma

ThomasJ,
From your symptoms, and get-around, it sounds like your EGR valve is working properly and the temp sensor is working. Sot it must be the modulator. You should be able to find one of those at a local picknpull yard for cheap. Try that. Easy to remove and replace. Just be sure the vacuum lines are hooked up right.

On my 2.7L Tacoma, there is also a VSV in the EGR system. Not sure about your 3.0L.

Cbar

Thank you! Just a quick newbie question, how do you know the EGR is working properly? What makes the modulator a thought? What does it do? sorry for the dumb questions. Also, I have the 22RE. 1994 DLX 4x4.

tantacoma

Cbar,
FYI, I was addressing the issue of the original poster, not yours, or the other thread 'hijacker' .

As far as testing the EGR valve itself, thats easy. Its either completely closed (no gas recirc.) or open (gas being recyc.) . If it is stuck open, that creates a large vacuum leak, and the idle would be rough, or wouldn't idle at all. If it is stuck closed, then the EGR would never recirc the exhaust gas under any condition, and would not affect the idle.

To test if it is not stuck (freely opens and closes), just start up the motor, disconnect the vacuum line going to the valve (at the modulator, not the valve), and suck on it. If that creates a rough idle, then the valve is working properly.

Cbar

Thank you for the help. I will go take my "hijacking" self and test my EGR.

cativokane

My 95 3VZE had exact issues. All EGR system components were working fine. Last thing I did was recheck the vacuum lines and that was the problem. Switched lines. Corrected that and it runs smooth, no more rough idle surging.
Thanks