holsky

Hey guys,

Im new to the forum, and new to toyotas and I just picked up a 94 4runner v6 w/197K, it sat for 2 years with bad water pump/blown head gasket. Well I took it to my mechanic and he fixed it. It ran great for a day and then the check engine light came on. So I went out and bought a haynes manual for the truck and checked the code and its 71...egr valve.

Ive searched and looked around on here and on other toyota forums but cant seem to get the right answer on how to go about fixing it or just completely ripping it out.

Its really sluggish, takes me forever to get up to 65 on the interstate, idles alittle hight around 1100-1300 rpms. And the gas milage seems low from what ive been seeing with other members milage.

Ive seen on here that some people have competely taken it out and put a 15ohm resistor on the temp sensor to think that its reading the right temp so you dont have a check engine light. I kinda also wonder if my cat is clogged and making it harder for the exhaust gases go through and pushing back up in the egr valve and making it stay open.

But Im just trying to figure out what the best way is to go about fixing it. I really hate to buy the temp sensor and the egr valve and it not fix it. I hate trial and error games with emission controls because it always seems that you throw too much money into it for nothing.

But any help would be appreicated. I just want to get it fixed so its running good.

Thanks.
Austin

Baja Toy

Whenever you get a 71 code, a few things could be wrong. The best thing to do is to check the EGR valve itself and EGR modulator. Note that the modulator can opened and clean if it is not too clogged with deposits. There is a procedure on how to do this.
If both items are good, check each one of the vaccum lines leading to the EGR and modulator. Make sure you blow air at one end and that it comes out at the other end including the metal vaccum lines. The metal lines are notorious for collecting corrosion inside preventing the air from circulating. If the lines are OK, proceed to check the VSV. There is also a procedure on how to test it. Check this link for more info:http://personal.utulsa.edu/~nathan-b...77exhaustg.pdf

TNRabbit

Unplug the vacuum hose to the EGR control valve & see if anything changes:



Also, it sounds like you may have TPS issues, and possibly a vacuum leak. There's probably more than one issue here...

holsky

Hmm... mine doesnt idle that rough at all if the egr is hooked up. If i unplugg it, it doesnt seem to make too much of a difference but a slight ticking noise.

Thanks for the help guys and the links, im going to look at it more tonight and see what i can do. And take it out and try to clean it.

Also how do you guys feel about taking the cat off? Its almost got 200K on it and i bet that thing is completely clogged. Or does the vehicle need it to create enough back pressure for the truck to run?

Thanks,
Austin

holsky

Ok with looking around on here, i have found a few pictures of vacuum line routes. I noticed that there were a few of the lines mixed up. So i fixed them according to the pictures. Now I did find two hoses that were not connected to anything.

Here a picture of what i found to help me out but where is the number 17630 located? Its pictured right below the egr valve. Those two hoses that arent hooked up go to that (as far as i can tell).

Well i found it and hooked up the lines. Ill see if makes a difference.

TNRabbit

17630 goes to the power steering pump. It idles up the engine when you turn the steering so the drain doesn't drop your idle down too far (completely unnecessary; I removed mine when it failed--plus they cost like $200 from the dealer!). You can safely block those off if necessary.

holsky

Well it drove great last night coming home from work. No check engine light yet, hopefully it doesn't come back on. It has the power now and doesn't hesitate. But what does these trucks idle at when running at normal temps? Mines around 1000 still.

TNRabbit

S/B 800 rpm +/- 50 rpm.

Have you adjusted with the idle screw, on the front of the Plenum/Throttle Body as you're looking at it directly in front of the truck? (flat head, recessed, to the left of the Throttle Body opening)?

holsky

No I havent, but my check engine light came back on today and the truck ran like crap again... (same code 71) and I noticed that the egr temp sensor wasnt hot. It should be correct.? Is it basicly like an o2 sensor? Does it burn off any of the exhaust gasses or anything like that?

But I kinda wonder if there isnt more vacuum lines not in the right spot, so if anyone could help me out and take some pictures of the vacuum lines with the numbers and where they go that would be awesome. Like I said last night I found a few pictures of them and I know about 3-5 of them were routed wrong.

Tomorrow im still going to get my cat taken off, and i think i might try to take off the egr system and get that resistor and see what happens. With the resistor, do you just stick it in the egr temp sensor plug?

But thanks alot for your guys help. I really appreciate it!

Thanks,
Austin

invader

I just got done dealing with code 71 earlier this week.

First,check out the EGR valve itself.

Connect a vacuum line, (either with a vacuum pump or connect a line from one of the vacuum ports on the intake manifold), directly to the EGR valve while idling. It should kill the motor, (or at least make is run extremely ruff). If not, you EGR valve is not working. If it does then read on.

Next, make sure you have vacuum to the vacuum modulator. Tee the vacuum gage into the line at both inlets to the vacuum modulator. There should be vacuum at both inlet ports of the vacuum modulator.

Then take the vacuum gage and tee it into the vacuum line to the EGR valve. Rev up the engine to at least 3500 rpm and you should get some sort of vacuum reading. With the motor cold it should be low vacuum. With the motor hot it should be higher vacuum.

This is where I found my problem. I had no vacuum getting to my EGR valve so it was not opening. It turned out to be the vacuum modulator. The modulator was getting vacuum but was not turning it on to the EGR valve.

When my head gasket blew, it pushed water into the bottom of the vacuum modulator and that is what killed the modulator.

Replaced the modulator and no more CEL.

Hope this helps,

Invader

holsky

EDIT:::: ALRIGHT IM GOING TO SAY THAT NONE OF MY EGR STUFF WORKS, BECAUSE I UNHOOKED ALL OF THE VACUUM LINES ON THE EGR AND ON THE EGR MODULATOR AND THE TRUCK IDLE DIDNT CHANGE...

OK thanks for the help man... I know if i take off the vacuum line on the top of the egr valve the motor doesnt change.

Here is what ive got right now.

#1 and #4 goes to the blue plug
#5 and #2 goes to the brown plug
#6 and #3 goes to the green plug
#* goes to a blue circle filter mounted on the passenger side engine bay

Here are some pictures of where these are going.

In the first picture the hoses are reading #1 to the left with the orange thing, top #*, and to the right #2
In the second picture the hoses are reading #4,#5,#3,#6

Are these correct??

Baja Toy

Even if they are correct, that doesn't mean each component is working correctly. There is no way around it, you need to check each component as indicated and you need to check each vacuum line to make sure they are free flowing.
I could be wrong, but I remember that only disconnecting the big vacuum lines or applying vacuum to the EGR make the motor stall.

holsky

Yeah i totally agree with you but if the vacuum lines are wrong, its going to make somthing else malfunction. So thats why im trying to see if they are in the correct spot or not. Because a few of them were in the wrong spot...

Kiroshu

Does the engine have a hesitation upon accel? Does it idle rough or run terrible cold? This a possible egr problem to where the egr is opening at the wrong times and way to early. The only time the egr opens or at least it is supose to open at highway speeds. Only at highway speeds if it opens any other time it causes drive ability probs. Possible Tps if its not egr. Since the truck has so many miles. Most yota trucks egr valves go out at about 200k so just disconnect the vac line to and cap it off. It won't hurt it. if you got block off plates take it off and leave it off it won't hurt and will make it run better anyway. Unless you wanna buy a new one. If its not egr start checking your tps and or look for vac leaks. Oh and taking off the cat may help performance alittle if it is indeed clogged it will cause some hesitation so i;;d say take it off and gut it anyway. Its up too you. Alot of vehciles go 300K 400K with the original cats.

holsky

The truck does hesitate under acceleration... But it runs great when cold, and idles good alittle high at 1000 when warmed up. I really hate to buy a new one, bc im sure if i do get one it wont be that and it will be the modulator or the egr temp sensor and i looked at the prices of them and its about 350 bucks and i hate to do that when you can just take them off and it wont effect anything. Thanks for your help, I am going to try to take the egr system off tomorrow and put that resistor in the temp sensor plug and see how it runs. I mean it does run good but like i said there is that hesitation and it takes me forever to get up to speed on the on ramp. It ran great last night going home from work when i reset the cel, but it kicked back on again today coming to work.

But i did notice it does run alot better then before once i switched around those vacuum lines that were wrong. I think as soon as i get that cat off and take the egr system off I think it will run a lot better then it did. I mean its not going to hurt me what so ever to take that stuff off.

Thanks,
Austin

Kiroshu

Cool let us know if it fixes it or an more details.

holsky

Update:::

So today I went and got my new tires put on, then headed to the exhaust shop... I got my exhaust leak fixed and had them cut out my cat. It
didn't look bad at all, it looked like it has been replaced.. So I kinda have been wanting to get a flowmaster on it so they told me they could do it and I got all that done and have 2 1/4 inch pipe now and it sounds fantastic.

Then I headed back home and took all of the vacuum lines off the egr system and blaocked off all of the wholes and put that resistor in the plug and the cel has yet to come on and the truck runs fantastic!!! I had to turn the idle down alittle but other than that I'm very happy with it. I think once I get some extra time I'm going to make me some block off plates so I can go ahead and take the rest of the stuff off!

Thanks a lot for your help guys!!
Austin

Kiroshu

Cool glad you got it together. Good job.