LSJ refuses to idle smoothly when using MAF

[eronq9]

Alright so I have been dealing with this problem ever since I have had this car, I have tried 3 TB, 2 MAFs, 2 MAPs, and all that and the car literally refuses to idle smoothly, its reasonable with the ac off or if the outside temperatures are below 70deg Fahrenheit, but when it gets into the summer months the car will not do it. I have tried cranking up the ETC scalar, helps for about 2 days then the car "relearns" a bad idle again. Keep raising ETC scalar, keeps temporarily helping until the car starts to feel weird because of the other things the ETC scalar is changing.

Soooo still trying to figure out whats causing the issue to begin with, as far as I can tell it has nothing to do with fueling or tune. I can change idle timing just changes what rpm it starts to go wacky at. The only way to get the car to idle perfectly in any weather or AC on or off is to turn off the MAF completely by setting MAF fail high to 0Hz and setting MIL on first error. When on VE exclusively, the car idles smoother than brand new. With dynamic blending set at 3600rpm car idles bad, and even worse MAF only. I have replaced and cleaned the MAF without help, I don't understand why the PCM decides to increase the Throttle Position until it idles bad on dynamic, but VE only it finds a beautiful idle. I am guessing theres possibly a post MAF, pre manifold leak? So the single PCV hose there could be letting unmetered air in, but still not sure why that would cause the computer to increase TPS.

Here is a picture of Dynamic Enabled. I mapped timing, TPS, RPM, and the airflows
Bad idle.JPG

Here is VE ONLY
good idle.JPG

For some reason VE only it finds an idle at 3% less of a TPS than with the MAF enabled.

I would run VE only if I was not running off the VE table in terms of MAP kPa at 4000rpm
Plus MAF only is better for WOT.
MAF only just makes it worse.

[AP83]

I ran into a similar issue both with the M62 and the S256, it wound up being the EVAP both times.

No evap = smooth MAF.

[eronq9]

I ran into a similar issue both with the M62 and the S256, it wound up being the EVAP both times.

No evap = smooth MAF.

Yeah i thought that, but even open loop maf with evap isnt smooth.

Did you plug off the TB?

I am thinking it has to be some sort of turbulence or unmetered air throwing it off.

It idles sooooo good VE only i die a little inside when i turn MAF back on lol

[AP83]

Everything is plugged.

The EVAP solenoid isn't designed to take boost, and once you blow it out internally, it doesn't close all the way when it's supposed to and becomes an unmetered air leak.

[eronq9]

Everything is plugged.

The EVAP solenoid isn't designed to take boost, and once you blow it out internally, it doesn't close all the way when it's supposed to and becomes an unmetered air leak.

Well on a supercharged setup the EVAP doesn't take boost, but i may try plugging it to give it a shot.

[eronq9]

So on my way to class this morning, car idled fine and even did ok with the AC on.

I am almost thinking something gets hot and doesn't seal as well, going to look into it soon, but when the engine bay is still relatively cold it idles just fine.

[eronq9]

Okay even with EVAP plugged it still won't idle smoothly, if I unplug the maf it will idle perfectly after setting the MIL.

Idle timing stays basically at -5deg all the time with maf enabled and AC on at idle.

I guess it's time for a new PCM, don't really know what else to try, when the maf is on the computer is set on increasing throttle position when it should be removing it.

I have never seen this issue o the other lsjs I have messed with, they all idle fine.