Running lean on startup

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01-19-2022
HappySalesman

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Running lean on startup

So I just got the exhaust leaks fixed on my 02 Z28, and decided it was time I get my MAF and VE tables dialed in. I figured I'd start with the MAF since it seemed to be the easiest and quickest. For reference I'm using a TSP card-style MAF in a 102mm housing with a honeycomb on the inlet to help straighten the airflow.

I've noticed something though. Upon starting, my wideband is reading incredibly lean. At idle I've seen it peg at 16+ (which is the max it'll read). Looking at logs while driving around show it average something like 15.25 regardless of what AFR the car is commanding. At first I thought it was only because the car was cold, but it did it even after letting it sit for 20 minutes or so and the coolant was plenty hot. I figured it was just the MAF tables being off, but after five minutes or so the readings start to look more normal, and it stop pegging the wideband while idling.

Anyone have any ideas as to what could cause this? Did I miss something while setting up for MAF tuning? I've got the tune attached, as well as logs from the two drives I took a couple days ago.

Thanks!
01-19-2022
dhoagland

I'm assuming by idle air flow and MAP you have a cam?
What injectors are you running?

You might try adjusting the MAF against the logs and see if it starts correcting
01-19-2022
blindsquirrel

Does it run bad when cold, or do you just want to see different numbers on your gauge? If it's the latter you should maybe reconsider why you'd need to do that.
01-20-2022
HappySalesman

Quote:

Originally Posted by blindsquirrel

Does it run bad when cold, or do you just want to see different numbers on your gauge? If it's the latter you should maybe reconsider why you'd need to do that.

It runs fine when cold. I was more concerned with why it was reading very lean for the first 5-10 minutes when the PCM was commanding a more normal AFR. My first thought was that the MAF table was off, but then why would it suddenly change? Unless the MAF somehow isn't as accurate when cold?

Quote:

Originally Posted by dhoagland

I'm assuming by idle air flow and MAP you have a cam?
What injectors are you running?

You might try adjusting the MAF against the logs and see if it starts correcting

My apologies, I'm used to posting on LS1Tech where all of my mods are in my signature lol. The car has Heads, Cam, Intake and a full dual exhaust. 227/232. I'm running a set of FIC 42lb injectors.

Like I said above, my first thought was that the MAF table was off and that was why I was getting the lean readings, but after it switched back to normal it threw me off, and I wanted to make sure I wasn't going to start putting incorrect data in.