CA Smog problems EGR (1 Viewer)

[Bob Lacey]

Hi FZJ80 1997 trying to get through CA smog.
Smog test shows no problem with emissions- very clean- but check engine light on.
OBD2 code shows problem as being the exhaust gas recirculation and recommended replacing :
EGR 25620-66011
modulator 25870-66011
vacuum valve 90910-12079
all done with genuine parts and check engine light still on and OBD2 code still shows same problem.
All the vacuum hoses seem to be OK.
wondering if anyone had experienced the same problem any imput would be greatly appreciated.
Bob

 

[Travis 76]

Did you get the code erased and it came back?
Check for air flow through the small vacuum pipe that goes through the manifold, you can bypass it if it is clogged. Check all the steel pipes as they can rust from the inside. Check the ports in the throttle body, make sure they are clear. Also the passage in the intake manifold behind the egr may be clogged. Make sure you drive enough after computer reset before smog check if they scan the computer.

 

[Pin_Head]

So what was the actual code? Replacing those parts doesn’t necessarily guarantee it won’t fail again. P0401 insufficient flow is often due to a clogged passage way in the intake manifold.

 

[Bob Lacey]

Travis Pin head

Thanks for your responses
code 401
I had smog station make a diagnosis which read as follows:
PO401 EGR insufficient flow .Checked Scan Data Tested EGR valve good, Checked EGR passages good. Found no vacuum to EGR valve. Found vacuum switching valve not functioning, Verified proper signal to switching valve.
Also found vacuum modulator later not holding vacuum. Recommend replacing vacuum modular and EGR vacuum switching valve .

Based on the above I replaced the 3 components as mentioned in my initial post.

 

[cahill]

Probably is the clogged passage in the intake manifold as already stated. It is a bit of a pain to take the intake manifold off to clean it but that is the only way to clean it that I know of.

 

[JcrewLC]

Did you check the monitors and maybe you just need to drive enough miles to clear it? Mine had that. I drove it enough miles before clearing the light. Drove it again for like 20 miles and CEL never came back. So I took it to get smogged and it passed.

 

[Pin_Head]

The clogged intake passage is often due to the deposition of tar because of high blow by in a high mileage engine with poor oil control. You want to take a hard look at your mileage and blow by before you sink a lot of money in a fix that will re-occcur in a short time.

 

[Bob Lacey]

Thank you all for your imput
I did drive 50 miles to reset but code 401 still shows up so I will check all of your suggestions clean out ports ,throttle body etc
and report back
Bob

 

[Outsane]

Mine was fixed by cleaning out the copper tube ports near the throttle body.

Very small drill bit, don't drop it.. ask @NLXTACY

 

[effjay80]

Here's the link that was my road to clarity after long term CEL and failing CO emissions. After throttle body and manifold cleaning replaced EGR/Modulator, VSV, and all the vacuum hoses and all clear now. Only toxic emissions remaining are from my dog in the passenger seat and thankfully no CEL sensor inside for that.

P0401 Defeated - with pics

I started to throw a dreaded P0401 code that was constant, and recurring immediately after clearing. I have the FSM, and read God knows how many EGR and P0401 threads - More than enough burn my eyeballs and confuse the hell out of me, so I decided to dive in. Preparation - I had decided to...

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