Dreaded CEL code 71
 

Ok I got the code 71
Broke out the FSM and checking my EGR temp sensor.
Im good at lower temps but I'm out of spec by a little at higer temps.
Question is how critical is this ?

Did you pull the sensor and clean it ?, sometimes they get carbon build up on them and they don`t clean right.

Also, make sure that the tube that runs along the passenger side of the plenum is clean of debris/gook. ALSO make sure your EGR valve is operating correctly, and clean it as well. The temp sensor seems to usually be fine, its just that its not getting the correct EGR flow either from the clogged passages or non operating EGR valve.

Actually if you look closely --- I think that the spot that the temp sensor is in is a blind hole. I didn't have time to add to this earlier, but I had the EGR off last night and it seems to function but I couldn't check the vacuum. I used that as an excuse to go pick up a new Mity Vac hand pump.
just to check i put a 13kohm resistor in place of the sensor. So far other than the same erratic idle it seems to be good -- No return of the code. I suspect that the EGR is not functioning. No open - no temp change -- get the code

Just for info I tested the temp sensor in a calibrated temp well. I would think in most cases that if the sensor was actually bad it would read OPEN

Well last night it was still bugging me about the EGR not operating, so I broke out the new Mityvac and checked it out. It works great with no bleed-down. I went back to the manual and started reading again. The only other suggestion was to check for Vacuum leaks.
I lifted, tested and pulled and I did hear a hiss on occasion. at almost 11:30 last night I found an Autozone open and bought a chunk of Vacuum line.
Drove it in to work this morning and it runs better no CEL so far..... I still have a cold/ hot idle issue but it's not terrible.

Update
After all the work I did last week I still got the code 71. I went back to the FSM and dug deeper. I found a total of 3 vacuum leaks. Tested all the stuff related to the EGR (VSV / EGR ) tested not running .. running I think I have narrowed it down to the vacuum modulator. It tests bad according to the FSM ...Now I just need to find a new one.

I did find that this issue is very common on these Toyotas. If you are having issues contact me I might be able to help.

Just curious, where did you find your vacuum leaks?

The most simple way to check if EGR is working is to just apply vacuum to the hose that goes on top of the EGR. If your truck runs like crap, its operating, and your problem lies in the VSV or modulator. If it doesn't run like crap, then its your EGR valve, or passage.

What did you do this weekend on your truck?

Baja Runner
The major leak was a larger vac line going I think to the antilock modulator.
it had a leak on the bottom of the hose just before the hard line. the 2 others were both just linesthat had come loose???
And Razed is correct-- the system is somewhat complex and all inter-related. Coolant temp, vacuum, modulator valve, VSV, EGR temp sense. all have to be correct so it will work.
What i did to check that it worked was this----
Pulled vacuum directly to EGR watched the stem move and made sure no leak down.
Then tried to pull vac on the "Q" line from the modulator while not running. It would not pull vac- (which should be correct -VSV vented)
Then started it up and brought up tp operating temp. Tried to pull vac on "Q" line again and engine stumbled. That is correct according to FSM.
I did find one of the vac lines on the other side of modulator -- running to the throttle body was plugged. checked the modulator according to FSM and it fails
So --- there ya go

I chased down a code 71 on my 22re. Went through the diagnosing steps listed in the FSM & chased the problem down to the EGR vacuum modulator. One of the only mechanics I trust, Jim Wilson at Wilson Automotive here in Flagstaff, suggested that I carefully pop off the cover on the modulator and clean the filter inside. The filter is very small, about 1 inch in diameter & 1/4 inch thick, and I was able to clean it with compressed air. Pulled the ECU fuse for 30 seconds, and the CEL has stayed off for several weeks now.

Just figured I pass this along, it saved me a lot of money!