It's been almost 5 years since I've had an MIL (401 EGR Code Revisited) (2 Viewers)

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After replacing the power steering pump and hose a couple days ago, I was greeted with an MIL during a WOT test drive :rolleyes:

PO401 (Insufficient EGR Flow)

Cleared it a few times, but it always came back after a 3rd cycle, so sumthin was definitely kaput :meh:

Checked the EGR Valve and it tested fine.

Checked the modulator and although it passed the FSM's test fine, it didn't hold pressure when I blew into the bottom port (still not sure why the FSM doesn't have this test listed as it's more straight forward)


Here's a link to my original EGR thread that has since been closed:

https://forum.ih8mud.com/80-series-...er-dreaded-401-thread-few-diag-questions.html

New modulator came in today and although the old one still looked new on the outside, after cracking it open, you could clearly see the diaphragm torn :doh:

secondEGRmodulator1.jpg

secondEGRmodulator2.jpg

secondEGRmodulator3.jpg

secondEGRmodulator4.jpg

secondEGRmodulator5.jpg



Didn't bother checking the VSV, but so far, no more MIL, even after 4 drive cycles :cool:
 

94SRUNNER

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Another great write-up Snake.

In your EGR trouble shooting did you ever pull your EGR temp sensor? If so, how did it look?
 

94SRUNNER

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I only ask because when I had P0401, the culprit was the EGR temp senor, not that it was bad, but that it was so caked with carbon it was not working correctly. I cleaned it with a brass brush, re-installed and no more P0401.
 
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Well, I figure I'd update this thread since I got another 401 code this morning (first one since November 2012)

Checked the EGR Valve and it works as it should.

Then I tried pulling the modulator for a pressure test and found the bottom port had melted :eek:

EGRmodulator2014one.jpg

EGRmodulator2014two.jpg



I'm guessing perhaps the bottom hose came loose and hot exhaust gases just kept blowing on the bottom of the modulator until it just melted the port away :doh:

I did put a zip tie on the end of the hose (still there actually), but I'll be using a squeeze clamp when the new one comes in tomorrow :hmm:

For now, I plugged the end of the lower hose with a rivet to keep it from burning anything else :meh:

EGRmodulator2014three.jpg
 
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Isn't there any way of bypassing this mess until inspection time comes around again. Something easy to reverse?

Also, does "insufficient flow" harm anything? Like fuel efficiency or the engine itself?
 
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Isn't there any way of bypassing this mess until inspection time comes around again. Something easy to reverse?

Also, does "insufficient flow" harm anything? Like fuel efficiency or the engine itself?


In many other cars, it will, but the EGR system on the 1FZ was basically an add-on and there's plenty guys here running them either with a non-functional system or the system completely removed without issues.

That being said, I wouldn't want to bypass it anyways since I'm a bit OCD when it comes to MIL's and keeping her running tip top at all times :meh:

Also, I don't have to deal with emissions since my rig and other toys are registered in FL ;)

Hell, my other cars have flamethrowers installed, but they're still fit for the road down here :smokin:
 
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Isn't there any way of bypassing this mess until inspection time comes around again. Something easy to reverse?

Also, does "insufficient flow" harm anything? Like fuel efficiency or the engine itself?
People really don't understand what a EGR does. A proper working EGR does NOT hurt performance. It does help MPG.

Full throttle the EGR closes so it does not limit power in any way.
Steady cruise you only need a portion of the engine power to maintain speed. What happens is they lean out the fuel and so you don't burn valves you recycle some exhaust gas to displace some Oxygen and you end up back at your stoic 14.7:1 fuel mixture.
 
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And for the uninformed, in this instance MIL is not refering to "Mother in law"

Just thought I would clear that up :)

LOL

It can be just as irritating :eek:

In the biz, the more commonly used term is "Malfunction Indicator Lamp" (MIL)

Mainly because not all cars have a "Check Engine Light" (some have "Service Engine Soon" or an image of an engine with a slash through it, etc., etc.)
 

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