Rough idle when ambient temp hot

Craziest intermittent problem I’ve been trying to find without a CEL.

It started out slow and I would get a quick engine stutter when I am under load
Week or so later I went in with a scanner to look at an airbag code and I found a pending code “p0401 insufficient egr flow” but it never came up on my dash (CEL bulb is working not burnt out)
Some time later the stutters started happening more frequently and started doing it at idle
Some more time later the CEL finally threw the code as confirmed and then just disappeared next day on its own.
Problem progressed and got worse and worse and CEL didn’t come back on.
I replaced the VSV and the vacuum modulator and nothing.
Recently I noticed that at colder temperatures (roughly 50F) the problem doesn’t exists but when it gets warmer in the mid 70F and hotter it gets worse and more frequent.

No CEL lights and it’s getting worse idk what it is ‍♂️

-Ive cleaned the egr valve and put new gaskets
-Replaced the VSV
-Replaced Vacuum Modulator
-ran it and checked Fuel trims and they where within 10%, they where like 3-5% (positive)
-cleaned MAF just cause

 

Engine?

 

Have you removed the EGR pipe and cleaned the crud out of it ?
If not, take it off and let it soak submerged in parts cleaner to soften the build up before digging the crud out.

 

is the throttle body an easy to clean diy and would it make a difference?
Presumably we are talking the 2.7 here since the 3.4 doesn’t have egr ?

 

2.7l

 

Doing that now I’ll let you know, otherwise so far all egr components have been clean like someone already came thru before me, I’ve had this truck for a little under half a year with 130k miles

 

Yeah I wanted to get to that I’ll let you know how it goes

 

Hey so I got it out and it’s clean as a whistle but noticed the gasket was cracked and black lines coming from the center of the opening which I’m guessing is the exhaust gas leaking out, I found a 02 sensor gasket on Amazon delivered next day but I’m wondering if I can use the O2 sensor gasket for the egr?

 

Amazon has the EGR gaskets also.
But you do you

 

So I cleaned the throttle body and put in new gaskets, changed the egr valve itself and new gaskets, still driving like crap, please someone help me before I unload my gun into this truck

 

Thanks for the opportunity to follow along!

You are chasing a rough idle? In some other thread I read about motor mounts and transmission mounts causing a rough idle— helped that guy

- that might be worth looking into?

 

It’s not that, I did pull out the vacuum hose on the fuel pressure regulator and smelled like fuel, I’m pretty sure it’s not suppose to smell like fuel, so I replaced the fuel regulator but the problem still exists, does it need to be bled or something I have todo to get the air out of the system?

 

I dont know what your mechanical experience is or how big your tool box is but a basic mechanical check of the motor is required first. This is to eliminate what it isn’t as opposed to what it is. Check valve clearances first and examine the lobes on the cams, look for a difference in lob heights and profiles, if there is an issue, it will be obvious. While doing this you can run a compression leak down test, not a compression test, a leak down test. If she passes all of these tests then we move onto ignition, both primary and secondary. If she would throw a code, even a pending code would help. The fuel trims are right where they are supposed to be so I dont think you are having a fuel pressure or injector issue. Check the spark plugs and the boots. You want to look inside the boot for any traces of spark leakage. This is usually indicated by a white powdery track that will go from the wire nipple to the boot base where it hits the spark plug hex. With your fingernail scratch the porcelain on the plug to check for cracks that you cant see, the spark will follow this crack to the base. Plugs are cheap so unless you just put them in and they are Denso you should be fine.

 

Il be looking into the spark plugs and coils, can you look at this as see if something’s wrong? D=drive P=Park

 

First off, you are logging a wideband O2 sensor...I didn't even know we had those in these trucks. Learned something new everyday I guess.

Second, I've seen worse fuel trims than that but what are your trims with load? You need to log the data and put it into a csv file then chart it in excel. You can then see how the trims behave in driving operations.

Third, sounds like you have some sort of vacuum leak to me. Sounds like you're getting more air than is metered by the MAF thus the hesitation.

 

Oh yeah, make sure your MAF and O2 sensors are working. Clean the MAF if you haven't in a while.

 

Oh and did I forget to mention this is a California emissions vehicle? I’m guessing that is the problem I’m having with finding the problem, maf I cleaned recently

 

It’s misfiring when cold and hot? Edit: maybe pop the #4 coil out and see if the tip is dry or covered in oil. If it’s wet, I’ll guess you need a new valve cover gasket and spark plug tube seals. Good luck!

 

Misfires When it is hot, hotter it gets worse it gets, sitting letting it warm up gets worse, if I’m cruising on the freeway 80mph its less

 

are you using any coolant?