Installed 2.4 LE5 in place of 2.2 LE8 now Idle/surging issue

I just did a new install with an 07 2.4 LE5 engine. It's now installed with a new tune into an 09 HHR (original engine was flex fuel 2.2 vvt LE8). I used the wiring harness from the 09 & everything converted over nicely. The only major change was that I had to solder the old style throttle body connector onto the 09 harness. Exhaust system is the larger 2.5" diameter now.

For a tune I basically copied & pasted most of the 07 tune into the 09 ECM, although I wanted to keep flex fuel so I copied the flex-fuel related tables from a 2010 2.4. I'm using the maf sensor with the original intake from the 09, but the MAF calibration table was identical between both.

Engine is running great at higher engine speeds but at idle or slow speeds it's doing some major surging. When I unplug the maf sensor the surging issue goes away. Can someone take a look at my tune & two logs (maf plugged in & maf unplugged) to see what might be wrong?

Thanks!

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verify throttle area scalar. right now its set to about a 60mm throttle body.
double check idle settings by tuning braf with russ k method.
then i would check the idle over and under speed adjustments.

right now your log never settles the rpm down to commanded when in closed loop so i think you have a braf error.
maf trims are pretty much on point so if air model is on point but it hangs then its usually an airflow model issue.

have you done any braf tuning?

ETC area scalar is a copy-paste from the 07 2.4 tune file (actually the whole airflow tab is completely the same). I'm using the same throttle body & intake manifold, only difference is that I have to use the HHR plastic airbox, but it bolted up perfectly onto the throttle body. I didn't measure the exterior diameter, but it looked to me like they were identical, only that the 2.2 throttle body had a smaller interior diameter.

That russ k method looks interesting, I will be checking it out if I can't figure anything else out.

Interesting. I keep getting stuck on that Maf being on point. I'm sure you air leak checked

how goes this JR?

Still having the problem but i've got an idea i'm going with here. I was also getting some engine codes, they've all been taken care of except for P1400 (Cold Start Emission Reduction Control) which i'm wondering if it could be related to the O2 sensors. They're from the 07 Cobalt so they might be the wrong ones for the Vehicle.

Interesting

Circling back to this one again. Issue doesn't seem to be related to the O2 sensors at all as i've got the proper ones in & no change. I just did up a new tune based off of a oem 07 cobalt 2.4 tune.

The vehicle still surges during idle when stopped and in gear, but the problem I really wanna solve is the 2800 RPM idle speed in park & neutral.

Vehicle default idle seems to be around 2800 RPM after I start it. It'll sometimes stay at 1500, but usually will creep up to 2800 after a few seconds. When i'm driving around town, I don't have to press the throttle and i'll be cruising around at say 1500 to 2000 RPM, then when I shift to neutral or park will be up at 2800 RPM. I don't even know where to start to get this fixed. I added a few idle related PID's (Idle desired RPM etc.)

Anyways i'm uploading a log that demonstrates a warm start & usual increase to 2800 RPM idle, along with the associated tune.

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You are sure there are no vacuum leaks? Injector seals good?

Would that cause a high idle? I just did another test & unplugged the MAF...still has a really high idle, although it no longer surges, so I suppose that's good.

I'm gonna post a log with the MAF unplugged when I get home.

if you have injector cups those have been known to be bad and/or the seals on those. any air leaks post tb are going to cause high idle.

so I finally got around to taking the intake manifold off. Inspected the manifold for cracks (engine was in an accident) but everything looks fine. I replaced the gaskets. Also took the injectors off & installed new cups & gaskets there. Absolutely no change, so i'm really sure it isn't any kind of a vacuum leak.

I tried running with maf & map plugged in, just maf, and just map. All three are giving me the high-idle issue. Here's a log with the map & maf plugged in. look at the end where I stop & put it in park...idle is absolutely crazy. Any thoughts on what this could be?

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I'm following this closely as I am also putting a 2.4 LE5 into an HHR. Had my ecm done by Flagship 1. Started right up and I believe it did surge somewhat maybe once at first but air filter box isn't done yet and currently open header exhaust with missing cat and second O2 not even deleted yet. The rest of the exhaust isn't done yet either and it's still up on jack stands with no wheels - so it might be a week before I can even test drive it.
I do not believe it is surging at idle continuously however. After a brief warm up it smoothes right out. I can post the current tune if you want but I have to wait another day because I'm waiting for a long enough USB wire to arrive so I can hook it up to the desktop workstation in the shop... I can't even read it yet.

in the idle ignition base value map, try reducing the max ignition value in the 2000-2800 rpm by 0.24-0.28 g/cyl range down to a maximum of 20*. try to smooth around it by a small amount and see if that helps bring the surge down some.
for some reason you have excessive airflow at idle. your reading 10 g/s and should be closer to 3g/s at the slower target idle speed setting. your riding heavily on the idle adaptive advance for idle, its pegged at -10 which means you never reduced enough ignition to stay down at the lower rpm.

i notice in your log that the ecu ran negative ignition yet it still always increased rpm. to me it feels like there is an airflow issue. the tps actual is always ~7% higher than tps desired position and the pedal shows a constant 0%. this should all be red flag information. meaning testing of desired tps are, base flow, and other idle settings may need to be tested in order to sort out the airflow error.

is there a way to perform a tps unit position re-learn?