Too Rich at Low Load

[lpmagruder]

For those of you that have done your own tuning, did you have to lean it out considerably in closed loop at idle and low load? I'm trying to figure out if I have an issue, or just need to address this in my tune.

I'm still running largely the factory ROM, only thing I've done so far is remove the irrelevant CELs. Nothing too far from stock, my MAF tube is the Cobb one which is same diameter as factory. The only major difference from the donor car I can think of is the very short and open exhaust.

On open loop it feels fine, but idling and low load it's crazy rich, you can tell by the smell and black soot. Hesitating and minor stumbling too. The narrowband agrees, my long term fuel trims are pegged at 25% lean, and it's throwing a "Too Rich" code. I believe 25% is as far as it'll go.

Tried two MAFs, one verified working on a WRX. Haven't tried swapping the front O2 sensor but since it's acknowledging it's rich and pulling all the fuel it can and still throwing the code, I don't think it's that.

[Bob_n_Cincy]

For those of you that have done your own tuning, did you have to lean it out considerably in closed loop at idle and low load? I'm trying to figure out if I have an issue, or just need to address this in my tune.

I'm still running largely the factory ROM, only thing I've done so far is remove the irrelevant CELs. Nothing too far from stock, my MAF tube is the Cobb one which is same diameter as factory. The only major difference from the donor car I can think of is the very short and open exhaust.

On open loop it feels fine, but idling and low load it's crazy rich, you can tell by the smell and black soot. Hesitating and minor stumbling too. The narrowband agrees, my long term fuel trims are pegged at 25% lean, and it's throwing a "Too Rich" code. I believe 25% is as far as it'll go.

Tried two MAFs, one verified working on a WRX. Haven't tried swapping the front O2 sensor but since it's acknowledging it's rich and pulling all the fuel it can and still throwing the code, I don't think it's that.

My car is similar to yours except I have a OEM air cleaner.
Below is a quick snap shot of my data while Idling in close loop mode. See if your numbers agree.
bobs idle.jpg

[lpmagruder]

I'll check today!

Do you have a pic of how you fit your oem airbox?

I still have it and kinda prefer to use it over the cone filter I have, but I got a little frustrated trying to package it.

[Bob_n_Cincy]

I'll check today!

Do you have a pic of how you fit your oem airbox?

I still have it and kinda prefer to use it over the cone filter I have, but I got a little frustrated trying to package it.

I used 2 air box lids sandwiched together. This allowed me to snorkle the air intake hose out the side vent. The air in the engine compartment is hot.
airbox.jpg

[lpmagruder]

Oh nice, I didn't realize 2 would fit together. I have 2, one from an 03 and 1 from an 07, I'll try that.

I dust hooked up my laptop and got it to about the coolant temp you were at. Didn't bother logging, all the values were right near yours.

[Bob_n_Cincy]

Oh nice, I didn't realize 2 would fit together. I have 2, one from an 03 and 1 from an 07, I'll try that.

I dust hooked up my laptop and got it to about the coolant temp you were at. Didn't bother logging, all the values were right near yours.

It didn't fit together, I had to add a filler plate
top.jpg

[lpmagruder]

I'm sorta thinking I have a stuck injector. Nothing concrete, but if I prime the pump a few times then start it, I get a whole lot of unburned fuel coming out initially.

With the MAF being probably good (one came straight off a WRX running just fine, and both are logging about the same) and I'm pretty sure any leak letting unmetered air would only cause lean conditions when the manifold is in vacuum, I'm not sure what else to poke at. I have some spare injectors and they're not too terrible to get to so I may just throw some parts at it and see what happens.

[lpmagruder]

I was tearing into it the last few days, wanted to pressure test before I started messing with injectors. I couldn't get more than ~4psi into the manifold without the evap stuff on the front passenger side making some funky noises. I had "abandoned" that system and capped the hose under the fuel pressure/return so I thought it was all sealed, but it seemed weird that they weren't holding manifold pressure.

So, I yanked both of them, machined a few little plugs to cover the pre-turbo and manifold connections, and disabled the 2 CELs that created. I'll probably eventually use the barb on the manifold for a boost gauge, that looks like a super convenient location.

Screenshot 2023-10-10 204633.jpg

Reset ECU, drove about 40 miles today and it seemed fine. I didn't feel it stumble like it had been. It's still pulling a significant amount of fuel at low load, but it seems to be within the range the ECU is happy with:

romraiderLTV_20231010-195728.png

I'm pretty green with ECU tuning. I did a little bit on my 03 back in college, but I have also blown up a motor in it since then and reverted to a stock map :-) Do these values look concerning? I'm thinking about checking this table periodically and eventually modifying base fueling to get it closer to 0. Also waiting for my wideband in the mail to check that the stock narrowband is reading right.