1999 Tacoma 2.7L 4x4 EGR Problem

EGR code is coming up P0402, I have changed the EGR valve, and vacuum hoses. I cleared the code with the negative terminal, but truck still wants to hesitate/vibrate when going from 3rd, 4th to 5th, until you go above like 65 then it stops. I changed the catalytic converter because it was rattling inside like crazy. does any one know if the cat would of caused the code? i have been about 300 miles and it still hasn't come back, but iam pretty sure it will cause of the hesitation the truck has? Does anyone know what i should do to fix the hesitate/vibrate and does anyone know or have a link that shows hoe to clean the EGR ports?

 

"P0402 - Exhaust Gas Recirculation Flow Excessive Detected"

The EGR temp sensor detected that the EGR was allowing too much exhaust into the intake. This would be like a large vavuum leak, causing motor to run rough.

Did the P0402 come back, after it was cleared?

I would blame the EGR modulator. Very easy to replace. I think I have one in my spare parts box, from when I worked on my P0401 a few years ago.

 

I seen a video that there a filter in the EGR modulator, should i just clean it or replace it. And what do you mean your spare parts box? i am new to the forum. and yes it came back on after being cleared.

 

That is a cardboard box that I put usable spare parts in. Never can tell when I might need one of those parts. Since I do most of my own maintenance and repairs, I have one for each vehicle I own. When I replaced my EGR modulator years ago (it didn't solve the problem), I saved the old one since it is perfectly good. You should now have a perfectly good, slightly used, EGR valve sitting around somewhere that is a candidate for a 'spare parts box'.

BTW, the code I had was a P0401, not a P0402. I just corrected my earlier post.

 

so you dont think its the EGR modulator anymore? cause of the code that came up

 

It could also be the VSV for the EGR, which is the part that tells the EGR when to open or close. Is that what you meant by the EGR modulator, @tan4x4? Could also be a bad vacuum line between the VSV and EGR. Observe:

 

In my case (P0401 - insufficient EGR flow detected), the solution was to simply clean the scale off the tip of the EGR temp sensor. It was sending a faulty message to the computer. My truck always ran perfectly, so my situation was different than yours. So many people don't bother, or don't know how, to do any troubleshooting before throwing expensive parts at a problem. I'm shocked that the dealer mechanic suggested what he did. He should have known better, or just wanted to sell you a new part.

It helps to completely understand a system, for trouble-shooting. Otherwise, you are just guessing. Get a manual, do some studying, Googling and become better educated. I've been working on cars for 30 years, and have the benefit of a lot of experience (and have learned from mistakes, as well).

Check out this informative web-page:
http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c1528009266a

 

No, I meant the VACUUM modulator. The VSV is a Vacuum Switching Valve, but that is another possibility (but is difficult to get at in a 3RZ).

 

Gotcha. I am learning for two. I am a reformed 2nd gen owner and my BFF, who is the least mechanically-inclined human alive, has a 1st gen 2wd with a 2RZ. Should be the same for 3RZ and 2RZ, no?

 

can a melted CAT send a PO401 ???

recently, I am also getting a stubborn PO401 "insufficient EGR"
no other codes,
Tried clearing the code at least a half dozen times after trying everything, it continues to return after 60 miles
1998 3RZ 4x4 , 260,000 miles (with a 3rz prerunner motor out of a crashed 2001 with under 100,000, all the manifolds and engine controls swapped from the 1998 to the newer motor, done several years ago)
I checked and replaced (with known good used parts from crashed prerunner ) everything related to the EGR
I removed and checked the EGR pipe
I removed and checked the EGR temp. sensor / both sensors I have respond the same, OHM reading change properly as I apply a heat gun
Removed and checked EGR valves, they open easily with minor vacuum and snap back
Nice clean modulator
vacuum lines all tight, no leaks, routed correctly
I tested VSV off the motor with 12v power applied all OK

I do smell burning CATs all over town , there seems to be something in the gas around here that makes them melt (no not just mine) and I am not getting any lean codes but did have a misfire event recently that is now fixed,( had to limp 200 miles in a rainstorm with it sputtering) it triggered a misfire code only, I changed plugs and wires and cured it and then the PO 401 code popped up a few weeks later
I melted a CAT last year and replaced it with used one I had with under 100,000 miles from the crashed stock 2001 prerunner and vaguely remember getting a code that cleared after changing the CAT, but dont remember what the code was but it seemed to not make sense at the time , (I was expecting a rear O2 sensor code).
Thought I heard the CAT rattle again the other day and thought "here we go again"

I am wondering if it can have something to do with the CAT
like less backpressure ?
or exhaust stream too cool not allowing the EGR temp sensor to read flow ?
or rear 02 sensor not telling ECU to switch the VSV ?

 

When I got a 401 code, I solved it by cleaning the temp sensor. I removed it, scraped the accumulated gunk off with a knife, and replaced. Cheap and easy fix.

 

Yes I tried that , also tried swapping it with one with less mileage

 

If your CAT is blocked up, it will trigger such a code.

 

I would bet anything it's the VSV...had a p0402 code two weeks ago and thanks to this site I learned that many people have spent a lot of time and money replacinging other parts of the egr system only to have the 402 come back. It turned out to be the VSV for all that I read...I did that first and have driven 600 miles with no return code.

Edit: Didn't realize how old this post was...hope you got it handled

 

Did you check vacuum off of the EGR modulator? That was my P0401 code issue. With the engine running, disconnect the Q line and connect your vacuum gauge, rev the engine and you should get vacuum 15-20 or so. If you have no vacuum, attach your vacuum gauge to manifold ports where the P and R vacuum lines attach to. Check those for vacuum as you rev the engine. If you have vacuum there, it's the modulator. If you don't, then it's a clogged port. Turn off the engine and try blowing out the port with compressed air while opening the throttle slightly. Good luck!