Silverunner

The check engine light is showing its a code 71 for EGR system. I've replaced the EGR valve with another used one, checked all grounds that I could think of and checked for any vaccum leaks which I didn't find any. Check engine light still comes on.

The as reed valve does make a loud scratching sound, but I'm not sure if its supposed to though.

What else could be the problem for egr?
Thanks, Steven

Silverunner

Anyone have any ideas?

Guardian_Saint

http://i137.photobucket.com/albums/q.../IMG_01482.jpg

http://i137.photobucket.com/albums/q...j/IMG_0149.jpg

WillRadford

I just had a 71 code read in my 94 4runner 3.0 today and Im determining what to do. Im wondering what Guardian_Saint was doing in those pics on his post. Why are those yellow caps where the vaccume line should be?

95SlowRunner

Check your vacum lines first for any leaks, particularly if you have pulled your engine or done any work requiring removing those vacum lines. I had the same code from after rebuilding my engine in my '95. It turned out that I swapped two vacum lines around but luckly my '89 has a 3.0 as well so I had something to compare it to and was able to find the problem.

thook

I think he's suggesting bypassing the EGR in a subtle way. It's an option if it's legal in your state. There are plenty threads on it. I did it to both my 4rnrs. One of them, I didn't have much of a choice....limited by EGR valve funding.

^VooDoo^

Heres a way to test from the top of the egr system.
1st while the engine is idling using the hose going to the EGR dashpot, Suck on it, If the engine dies and you cant keep sucking air through it then the dashpot is good.
2nd the green vsv cellonoid over on the passenger fender is working ok, You can do a suck on test to see if its opening and closing right, I think the valve closes on a throttle decel.

If both of those are good then its the little black plastick disk thingy at teh front of the engine with all the hoses going into it. (It gets plugged with water and carbon sometimes)
Or the heat sensor has bad, Thats the one with the 2 wires coming out the side of the egr tube below the dashpot.

I think its the little black plastic thingy if the first 2 checks are good.

thook

Black plastic thingy....vacuum modulator...

jasonbrink

I went through this for a couple years and just drove it with the light on, right up until a few weeks ago when I had finally had enough of that orange glow. I had to fix the real culprit (of mine).
Mine didn't have the egr temp. sensor, being from NY. My vehicle had over 200k on it, I figured something must have worn out.
So, just like the DEALER does, I just threw parts at it. I replaced the vacuum modulator, which really wasn't working right. Light came back on after about 30 miles. I replaced the egr valve with a checked used one, the old one did seem to function correctly, I replaced it anyway-light came back on in a day. Christ, I went as far as getting a new TPS and fiddling with that for a week.
THEN-
I went through the FSM doing every egr test to find the problem. Everything was fine. I couldn't figure it out.
UNTIL I found a test I didn't try before. I'm not sure why I didn't. It was for the VSV. The VSV (vacuum switching valve) was the cause of my two year code 71. I felt sooo dumb. There is a test in the FSM for this, which I can post. I have all the PDF's from the toyota.com site. I spemt a whole day at work doing it! In fact I'll post all of the tests for future searches for "code 71"
Try all these tests and do yourself a favor & go to autozone (or whatever part store near you that loans tools & get a vacuum pump like this: http://www.autozone.com/in_our_store...acuum_pump.htm
It makes it so much easier on your lungs, plus you know you are pulling enough vacuum-you can be more positive of your testing. PLUS, it's free! (if you return it)
I'll find those pdf.s now

jasonbrink

Do all these tests& you should be able to find whatever is messed up- Here:
http://personal.utulsa.edu/~nathan-b...ne/19egrsy.pdf

Snorkeldepth

My Code 71 problem was a clogged EGR VSV. Pull off your VSV and take a look at it. The metal pipes that connect the vacum lines running over the front/top of the engine can corrode on the inside and when the corrosion breaks loose it clogs the VSV. I could see the clogged VSV port when I removed my VSV.

If you search "Code 71" you'll find my story and others as well.

Aging together

Having this exact problem and would like to follow your diagnostic path, but it's not in the link anymore. Still have it? THANKS!

scope103

http://web.archive.org/web/201003261...77exhaustg.pdf

Terrys87

iTrader: (1)

I do not have to deal with emissions test but I have never had to replace an EGR >>> Link. https://www.yotatech.com/forums/f199...l#post51647988

A good cleaning of the EGR of all of the carbon, vacuum lines cleared, Plenum cleaned, Pull the Throttle Body off of the Plenum and with a cloths hangar, flat blade screw driver and get all ports cleaned out and go to the car wash and use high pressure to get the rest of the carbon out. It takes me about 2 hours to get one tore down, cleaned up and put back together to clear the code. Never had one not to work when completed. Usually about 125k miles you need to clean all of the carbon out. Make sure all hoses are connected and routed correctly.

Aging together

Thank you scope103 ... EXACTLY what I needed. And now the dumbest question of the year: Test 5d says to connect port R directly to the intake manifold, but the diagram just shows the hose going down and doesn't show the connecting point. Where do I connect port R to?
THANKS!

scope103

You just want plain-ole unmoderated vacuum. The easiest place to get it is probably from the "air filter."

All three ports on the air filter are the same. They usually supply the PAIR, ADD, and the Fuel Pressure-up and AC idle-up VSVs, so you can safely disconnect them to run your tests..

Aging together

Hey scope103 - thanks so much for the tests and tips. Last question ... based on the tests it looks like the modulator, which is ironic because that's the ONLY part of the EGR system that has ever been replaced and it was done only a few thousand miles ago. But when I got to test 5e, where it's suppose to have high vacuum, it had very low. Plus when I did the test for the modulator inspection where I plug P and R and blow through Q, I could barely get air though there, and I play a brass instrument! So my last question is: when they say air should move freely, how hard does one need to push air through? Common sense tells me not as hard as I was but I figured I'd run it by you. Thanks again for all your help!

scope103

I have no idea. I've never run any of those tests; I'd be stuck using the same common sense you are using. And I've never blown on a horn!

If it helps at all, here's a little more expanded description of the operation of an EGR modulator: http://www.cygnusx1.net/Media/Supra/...taTech/h61.pdf

Aging together

SOLVED! And MANY thanks to scope103. I was ready to start pulling vacuum lines and moving this-and-that, but the tests you provided took me to exactly what I needed to look at for this code, and only what I needed to look at. After a whopping 10 minutes of following the tests you provided I found the problem ... turned out to in fact be the EGR vacuum modulator. The most difficult part of this fix is the price: one dealer wanted $120, but I found another dealer just a few miles away that sold it to me for $75 (its due for a smog check here in CA and I didn't want to take a chance on aftermarket). Literally 30 seconds to install and that annoying light is gone! When scope103 speaks, we should all listen! Thanks again!