95 4Runner egr problems

ThomasJ · 08-25-2005, 07:27 PM

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.

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callmej75 · 08-25-2005, 07:36 PM

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

ThomasJ · 08-25-2005, 07:57 PM

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 · 08-25-2005, 08:01 PM

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 · 08-25-2005, 08:10 PM

Quote:

Originally Posted by 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.

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 · 08-25-2005, 08:22 PM

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 · 08-26-2005, 09:14 AM

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 · 08-26-2005, 09:27 AM

Quote:

Originally Posted by 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

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 · 08-26-2005, 09:30 AM

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 · 08-26-2005, 10:39 AM

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.

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08-25-2005, 07:36 PM	#2 (permalink)
callmej75 Contributing Member Join Date: Feb 2004 Posts: 2,932	My guess would be the egr valve or maybe one of the egr tobes are clogged.

08-25-2005, 07:57 PM	#3 (permalink)
ThomasJ Registered User Join Date: Aug 2005 Location: Lafayette IN Posts: 230	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.

08-25-2005, 08:01 PM	#4 (permalink)
callmej75 Contributing Member Join Date: Feb 2004 Posts: 2,932	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.

08-26-2005, 09:14 AM	#7 (permalink)
eric-the-red Contributing Member Join Date: Oct 2003 Location: Port Coquitlam, BC Posts: 2,493	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

08-26-2005, 09:30 AM	#9 (permalink)
toyguy1986 Registered User Join Date: Jul 2005 Posts: 56	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.

08-26-2005, 10:39 AM	#10 (permalink)
callmej75 Contributing Member Join Date: Feb 2004 Posts: 2,932	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.