EGR circuit... Cleaned it, still CEL. Now what?

Also, have you contacted a dealership, see if there's warranty extension, @BZzap! 's suggestion? Maybe feel them out on this.

 

I used (CRC's) MAF sensor cleaner on the MAP sensor (seemed close enough lol). MAF sensor cleaner is I think synonomous with sensitive electronic parts cleaner, and the MAP sensor looked pretty robust. The MAF sensor by comparison does look very fragile.

I first used isopropyl alcohol, then, leary about that, recleaned it (and the MAF sensor) with the MAF sensor cleaner.

You had P0401 before diving in, so likely not due to something you've done, it's something that persists.

Low hanging fruit item you can start with, might determine if the valve is ok, is check the resistances and voltages, per page 2444 (orig page number, per the Repair Manual) of the pdf I posted above. This at least doesn't require techstream. A screen grab:



Next steps, procure Techstream, and maybe a salvage EGR valve, say from EBay?

 

That's an idea. There's a guy put a 4th gen engine in his third gen: none of the EGR connection to engine boltings between exhaust and intake work, so the whole egr circuit just bridges that full distance, and he's saying it's very stiff, no issues. Still I think what you've done is good, that one nut is the royal pain, won't be missed.

IIRC, it was a German member, something like Christian Cool, was one of the first reporting gunk/carbon build-up in the intakes and so forth. The voice crying in the wilderness, lol.

 

So I just did the same does it take a while for the Cell to go out?

 

Going to bring this back alive... I posted another thread. (and a small hijack).

I replaced EGR valve and cooler and cleaned the intake off car. I'm getting the stutter at low power. If I disconnect the EGR, it seems to go away. Any ideas for me?

 

Is the new EGR valve same part number as the old? There was a revision, and the new one might need some Techstream intervention. That's been discussed here, but not sure if there was any solid answers.

Also, how many miles on it, and was this the first EGR cleaning? If the EGR is left long enough, the head gaskets fail, and no amount of cleaning will undo that.

Addendum: see from your other posting:

Yeah it could well be head gasket going. EGR (and intake) cleaning is best done by 100K miles (or sooner). Left this long, head gasket may be leaking, and the EGR cleaning, while worthwhile, will not undo that. How's engine coolant level in the reservoir, stable?

Try leak-down test and/or boroscope inspection of the combustion chambers.

 

I got the EGR cooler and valve from ROCK Auto as they had the best price. I do have the old one which is probably still good, I just had that CEL pop up and didn't feel like dealing with everything since it was all out. What would techstream show or do in this instance if it were different? Flash an update or something? There were no major indications that the head gasket is bad. Coolant level was solid. Only reason I did everything was to do the maintenance it probably hadn't seen in quite some time. Everything was blasted with carb Cleaner and in sure my O2 sensor paid for that. Probably need to change that soon. Do you think taking it out on the highway and flogging it a bit would clear anything or should I pull the intake again? Never really had to deal with an EGR like this. Seems a bit much for a little engine.

Thanks, Mendel.

 

I think the new style valve is slightly longer, requires cutting back electrical conduit insulation a bit, so it can reach the socket on the valve. If you didn’t have any problems with the conduit reach, could be you got the older style.

the part no is visible when installed, albeit kinda upside down and on there. This is mine, the old style:

 

Any update on this post? I replaced my cooler and valve, and cleaned the intake manifold twice. Each time it runs good for about 40 mile then I have an inconsistent rough idle and the p0401 code. Could it be the the MAP sensor?


Below is a photo of the map pressure at idle (though there was no rough idle at that exact moment)

 

"MAP" of 19.8 inHg?

I get the feeling this scan tool takes the perfectly good absolute pressure from the car, and converts it to manifold gauge pressure (which should be negative, being below atmospheric) and then shows that, without the minus sign, using inHg.

I'm not sure I've ever seen a scan tool go to quite that much trouble to complexify the data. (I'll stick my neck out and guess this scan tool does not contain a barometer, and is just doing the absolute-to-gauge conversion by subtracting some fixed number that somebody's barometer has probably shown recently, somewhere on the planet.)

If I'm right about what the scan tool is doing, you should be able to see that 19.8 figure go down some, at times when the MAP reading goes up, like when you put some load on the engine, or open the EGR valve some with the active test.

By itself, at normal idle, −19.8 inHg is a perfectly believable MGP.

There could be more than one thing going on. P0401 is an insufficient EGR flow code, something you'd get if that MAP reading doesn't rise (or your "MGP" reading doesn't fall) by the right amount when the EGR valve is opened.

But I haven't heard many cases of noticeable rough running being traced to insufficient EGR flow. You can definitely notice roughness if you get too much, or if it is delivered unevenly to the four cylinders.

So it would be interesting to see what your EGR flow monitor test result is, and also what your pressure reading does when you open the valve a dozen steps or so, if your scan tool has the ability to do that.

 

EGRs fail...can be tested.. had one fail electronically on 2020 Altima...used scan tool.
..U dun good