Every once in a while my Monte will throw the front bank too lean code, and the freeze frame data shows the short and long fuel trims at 20% and 16% almost constantly. I believe the code is thrown at startup, which can act up, but based on the fuel trims, should I get it tuned?

 

Do you have modifications? If your car is stock, and you are having such fuel trim issues, it's most likely something wrong with the car and not the tune.

Vacuum leak, bad oxygen sensor, leaking injector, etc.

 

X2 on the mod list. I know you had some pretty extensive threads about mods you wanted to do, just not sure how many you've already done.

TBH though, unless you've boosted it already, I think it would be pretty unlikely for a bunch of NA mods to be needing that much more fuel.

 

The mods I've actually done thus far are ZZP High Velocity Intake Insert, ZZP 1.0 PCM, ZZP CAI, and a chopped downpipe. The main o2 sensor is approximately 2-3 feet from open air.

 

Something is definitely wrong. A little intake and exhaust work isnt going to be moving 30% more air at idle.

Was it like that before the zzp pcm (wondering if the tune is jacked - wrong injectors programmed in, wrong maf or map programmed in, or something)? Is it like that under all conditions or just idle?

I'd be hesitant to drive it until its resolved as those fuel trims are maxed. If it's still running lean for whatever reason, it physically cant command any more fuel.

 

I honestly can't remember when it started throwing that code. Its been a few months at least, and no signs of serious damage that I can tell.
I just changed my spark plugs (NGK TR55's) and oil the other day, and took pictures of all the spark plugs. Lets see if they look off to you.
I'll order them front bank first, then rear.

1

3

5

2

4

6

 

What gap are those plugs at? That gap on #1 looks like it's well over .100", but maybe it's just an optical illusion.

 

I also checked the gap before tossing the plugs. They were gapped at ~.057 all within .001 of each other. I used a coin type tool, and I'm not actually sure at which point you take the measurement. Is it the middle of the electrode you take the measurement from, or one of the sides?

Another thing, I just wen't for a quick drive with my scan tool plugged in, and confirmed that the ECU only demands fuel at idle.

At startup

15% load cruising

20% load accelerating

Idling at a stop light

 

Definitely an optical illusion in the picture on those plug gaps, lol!

Good to hear the the fueling issue is only at idle. Do you still have your stock pcm? If so, it's a quick swap to flip them to see if it went away. Beyond that, I dunno. I'd think a vac leak big enough to request that much fueling would also be driving up the rpm. Any misfiring at idle only that goes away once you get rolling?

 

I definately still have the stock ECU, I'd just have to find where I put the thing.

As far as misfires at idle, I'm not a mechanic by any means, and haven't spent tons of time around misfiring cars. The one time my car personally had an issue of that degree was when the ICM died, and I was down two cylinders. I immidiately knew something was incredibly wrong, cause the whole car rocked side to side almost. But there aren't any other codes being set besides the front bank too lean one.

If it helps any, heres a video of some warm start sound clips.

Link

I'll also include this ride along video that has the more typical cold start which high idles for a bit.