LatitudeDancer

Cleaned my MAF a couple months ago:
https://chevroletforum.com/forum/tah...1-p0174-40809/

Worked well. Outside temps got back to the 90+ range and when accelerating slowly (load or no load) while kind of keeping things bogged down (not allowing a down shift), you could feel a power drop out/miss until higher RPMs (2,000+).

Over time got the P0171 code again so just assumed I got the MAF mostly clean but not perfect. I replaced the MAF and am giving it a few days to see if I can get the same power loss acceleration feel with the new one.

In the mean time, I did get a P1404 code eventually as well. Can a dirty MAF send a P1404 code? I read somewhere basically yes, because the MAF tells the EGR what to do.

in2pro

try disconnecting the EGR ( you will probably get a code) but it should stop it form operating long enough for you to see if it affects performance... but I'm wondering if your cats are clogged....

EinST

As for P1404, it is when the EGR valve is commanded closed but the pintle position sensor says otherwise. I don't see the connection to the MAF. A chunk of carbon is probably blocking the valve from closing fully.

LatitudeDancer

Pulled the EGR valve off. It had some carbon on it but nothing note worthy. Went to put it on and found a couple of carbon pieces about the size of mouse poop or larger and figure it could have been that. Large enough to get jammed in the plunger if being forced that way but not big enough to pass.

Sucked them out of the block with a vacuum cleaner, screwed it back together, and the light went off. We'll see if it stays that way. Will post back if it's something else, if not...