My EGR is throwing a code 71 and it doesn't really effect performance as much as it does the gas milage. My milage went from 18 or 19 to 13 or 14 and it has been getting worse. the code comes on about every month and half or so, then i reset it and it goes away for a while then it comes back on. I have noticed it coming on when it probably gets the hottest, like after going up a long hill, heavy traffic, or pulling a trailer. Is this the pyrometer in the egr or the EGR valve sticking?

Thanks

 

Code 71 can be a vaccum leak. Try replacing the vaccum hoses to the EGR valve. If that does not work, I think you test the EGR by putting a vaccum pump on the EGR. If the engine does not immediately runs rough, you have a bad EGR valve.

 

Did you ever find the problem? I am having the same problem with some rough idiling..

Thanks
Shannon

 

so code 71 is a vacuum leak? mine is throwing that code too

 

No its egr. I have noticed that it only turns on when the engine is really working hard or when i am off road. From what i learned from the service manual is that it opens when it gets to a certain temperature. mine does fine until i get on the freeway for more that 10 miles or when i am off road and not much air is flowing past it. This leads me to believe that it is stuck shut and i need a new EGR valve, i just haven't done anything about it yet.

 

Mine displays the same exact symptoms, however I took the valve off, cleaned it, and hooked it up to a vacuum pump. It actuated fine, and even let the carb cleaner through. (took a lot of black junk with it). So I don't think that is your problem. I have decided to ignore it.

 

Here is a link with the codes:
http://www.off-road.com/toyota/tech/codes/

Code 71 for the EGR could be a vacumn leak which is preventing the valve from opening or the switch from working due to a vacumn leak , the switch whether the Temp controlled vacumn switch or the temp controlled electrical switch could be causing the problem as well.
Also if you have the EGR with the Temp Sensor ....that could be bad and not telling the ECM the valve is open .
Could be alot of things depending on the layout which is why you need to use the Service Manual to check operation of these different controls and understand your model year layout and function so you know where to look .
Here is a 93 FSM online version :
http://personal.utulsa.edu/~nathan-buchanan/93fsm/

scroll down to get to the 3VZE if that is what you have , the 4 banger is first , and then under "engine" and then "emission control" , you will see that over the years several diff. types of control systems have been produced so you have to go through them and find yours and then you can see what controls and or switches what for the system you have , once you do that you can use the FSM to troubleshoot any of the controls whether temp/electrical , temp/vacumn or exhaust temp switched .
The other angle is to remove the EGR altogether which I am going to do on mine soon , then I do not have to worry about the booger anymore .

 

I failed to notice that you have a '94 , the 93 FSM I linked previously I believe would cover your motor but if not here is the link where you can go online and either download or use online the manual for your model and year :
http://www.ncttora.com/fsm/index.html
Sorry about that , I need to pay more attention.......

 

hey,

not to hijack the thread or anything...but thanks for that link..ive been looking forever for a link like that...

does anyone know if theres much difference btween a 91 truck and a 93....

 

Nothing too signicant to prevent you from using the '93 manual information, if that answers your question.

 

so it might not be the egr at all, but the vacuum switch that operates it?

 

Yes , it may be a vacumn issue , it could be a dirty throttle body which could result in a stopped up vacumn port , could be vacumn line has trash in it (blow them out with rubber safe cleaner or air) or could be one of many vacumn switches , temp controlled electrical switch or if you have the Temp Sensor (kinda like an O2 sensor) then that could be bad and not telling ECM that EGR is open , use the manual and find the system you have and then you can troubleshoot controls .

 

I saw in another thread that said that if you hook a vacuum pump to the egr valve and pump it and it runs rough then its is a vacuum issue not the egr valve. I did this today and pumped it once and the engine stumbled down a few hundred rpm and pumped it again and it almost died. So i think the egr is fine, but maybe it is a switch. I am not overly worried about it though.

 

I mean really, besides the annoying light, what is it hurting? I priced a new temp sensor (O2 thing) last night $145.00!!!!!!!!!!!!!! I'll live with the light.

 

god are you kidding? that is incredible! No wonder not much stuff goes wrong with toyotas. The parts are so freakin good/expensive.

Yeah if the light comes on i always check to make sure its just the egr valve, just in case. but yeah it has been on and off for a bout 6 months now.

 

By pass it, its a useless piece...

 

I'd like to, but can't find a good how-to. Know where one is? preferably with pics??

 

Well the downside to ignoring the O2 sensor is that is how your ECM controls the mixture under many different conditions , if the O2 is bad that needs to be replaced ...............EGR on the other hand if its not working and not stuck open then no problem really .

 

No, my O2 sensor is not out. The temperature sensor is basically a little O2 sensor. It does nothing more than open/close the egr valve to my knowledge. Correct me if I'm wrong anyone.

 

Nope your right , and they have a mod for that too , you replace the Temp Sensor with a resistor and it will stop the ECM from generating the code . Real cheap and easy to do if you want to stop that infernal light from blinking .
Actually the EGR will still open and close with the sensor bad , but the sensor will not tell the ECM when the EGR is open and then generate the code .
Thats why the resistor mod is nice , EGR still works just no code generated and no need to buy the sensor .