Airflow mode / LTFT histogram

[SiriusC1024]

5-15 minutes varied driving is all it takes. Make changes then repeat.

[dhirocz]

You called it. Wow. It looks like somehow I got 42lb injector data and 36 lb injectors. That explains a lot.

When I get to a stopping point today I’ll need to make some phone calls.

[dhirocz]

Ok so they’re 0280155868 injectors, listed as a Bosch or FAST 36 lb injector. At 4 bar, they’re 42lb.

I’m working on getting injector data so I can confirm what is in my tune is right or not.

[SiriusC1024]

Good luck finding FAST data.

I've got data for the Bosch P/N here at post #29:
https://forum.hptuners.com/showthrea...pository/page2

It's the offset table you have that made me question the data. The data above is quite a bit different than what is in your tune. Those offsets and SPA are contributing to the O2 switching problem, which started as OL-fault, you've been chasing. It's difficult to maintain control with bad data. OL-Fault means instability of the PI loop.

Stock Min Injector Pulse, so you need to put Transients>Min Fuel Milligrams to stock. .032 in a 2001 Z06 file.

Looking at the SPA you could probably get away with a 1.03 Min Pulse and Min Fuel Mg of .028.

[dhirocz]

I owe you a HUGE one. I ran it a few times in SD and again MAF. VE table was way out. Idles rock solid now.the changes I make stick and it tunes much nicer. It also runs much smoother.Ill have to retune but so far its been quick.

Wish I knew that stuff like that. I understand the basics but I guess you have to start somewhere.

What I don’t understand is why the injector data I got was so far off. The difference is night and day. Is this typical of these injectors or FIC?

I got MAF and VE near idle good enough that I should be able to run RAF logging in the morning and tighten the tune up over the next few days of work.

[SiriusC1024]

It's off because they have had different companies perform injector characterization, and they all do it differently. That file I linked is actual GM data that's been converted to Gen III.

Try increasing the switch rate a bit. Last log I looked at they seemed a little slow.

[dhirocz]

Well I’m going to pull MAF and VE back in over the next couple days, hit my RAF again and then go back to the 02’s. I’m sure they’re probably all out of whack now lol

With it being more stable, the good thing is it shouldn’t be nearly as much of a fight to pull them in.

After I clean it back up I’ll post the results.

One thing I did notice that changed… is it normal to be lean after flash? I notice if I start logging immediately after I flash it, it tends to be lean for a couple minutes. I’m assuming this is due to heat soak of the iat while I’m stopped making corrections.its usually about 5-7% and only lasts until I’ve been driving for a couple of minutes, and fades away.

It has me wanting to move the IAT even further away from the engine; it’s currently divorced from the MAF, in the ram air box near the filter.I don’t want to move it too far away though; I’m not trying to trick the ecm.

[SiriusC1024]

Is it the IAT doing it or fuel trims?

[dhirocz]

I'm thinking the IAT is changing fuel based on air density, thus creating an error since the air isn't really that hot, which is moving the trims.

As of right now I'm waiting to log until the car is at operating temp, and the IAT reads the same as ambient. I'm tempted to move the sensor outwards some more, maybe near where the fog light would have been, but somewhere shielded from water. It's current location provides much more stable IAT readings, but the back of the sensor is still apparently picking up engine compartment heat...just not quite as much.

Today I adjusted the RAF and pulled the MAF in some more, mostly in the lower half of the powerband. Tomorrow I will focus on the upper half when I'm on my way in to work, a good 45+ minutes. Hoping to do the same by revisiting VE again for a couple of days, then I get to revert back to the 02's. I see now they are all over the place again. Also will be addressing a startup flare and looking to add a tad bit of air to my TF...it returns sometimes too hard to idle and still comes in to idle occasionally too low and hunts (though not nearly as bad as before)

[SiriusC1024]

If you move the IAT make it match some sort of factory configuration. Then you can copy the complex temperature model values from that tune to yours.

[dhirocz]

So I've been getting this thing worked out. I had my idle AFR stability issue come back. And I have no idea what is causing it.

So the surge is still gone. the data that I do get is more consistent; however, I still have a problem with it deciding to go lean especially near idle. I'm attaching a log that shows this. At first I thought maybe it was my sensor, but the engine was definitely responding to this so I believe it to be genuine.

Before this I noticed I was going rich during deep decel, but I figured that just might be the tune needing correction since I dont normally run under 2875mhz.
The numbers were initially worse; this all started thanks to sitting in traffic on I95 for almost an hour due to wonderful holiday traffic accidents (yuck)
I was doing MAF tuning and this did not involve a shut down and restart.
Part of me wonders if cats can do this, but I figured I should ask here first.

12_20_23 lean.hpl
z06 12_20_23 #1 MAF.hpt

[SiriusC1024]

You're still tuning with the wideband. Try using the narrowbands. Interesting stuff on the matter going on here:
https://forum.hptuners.com/showthrea...nd-vs-Wideband

Get VE right. This will help steady the idle.

[dhirocz]

I’ll try to pull in the 02’s again tonight and log everything under about 4500 with the narrowbands.
I am still confused however, how the car can swing 20 percent lean at/near an idle in the same driving session. It’s not as bad as it once was with the IAT fiasco, but it’s still there.
Let me give this a shot and we will see how it goes.
If the wideband isn’t accurate near idle, then should I tune VE near idle the same way?

[dhirocz]

So I got the chance to play with her a little bit. Got the 02's swinging. Tightened up my switchpoints (didn't need much). I did some low end tuning of the MAF table with the narrowbands and it does indeed run better. I also checked VE and it was off.

....and before I could stop to upload the changes, it started leaning out again.

I did make a point to reset the trims each time.

I'm starting to think I have a bad fuel pump or something. It just slowly continues to lean out and I dont currently know why. This is evidenced in both the second MAF and VE LTFT tables and seems to happen after its been running at least 1/2 and hour. It's cold out, and the IAT's were in check, so unless I missed something in the tune, I dont know what else could cause this except a weak pump. Pump is stock, car has 65k on it. Both happened during cruise so I'm less inclined to think it's a volume issue and more just a failing pump, if it is indeed the pump. I would have to break out my gauge to test this theory. System runs at 14.5v, and the pump does have a hotwire kit on it.

12_21_23 lean MAF.hpl
12_21_23 lean VE.hpl

[SiriusC1024]

Have you tried starting over with factory O2 settings then adjusting as needed? Switching is still really slow.

[dhirocz]

Yes. Last time it was the error table that fixed that issue. I’m going to fool with it some more tomorrow after I dig out my FP gauge.

[SiriusC1024]

Ok. One quick thing to try would be the LT O2 settings I gave you.

[dhirocz]

Sorry, Christmas stuff has been slowing me down a bit. I did revert to those settings and it helped some, but it needed more changes to get the 02's to swing, and as you can see, still needs further refinement.

I'm planning on going out with a mechanical gauge and monitoring FP while it's doing this. Hopefully I can get this done tonight. Now that I'm thinking about it, the pump is running at 14.5 volts thanks to a hotwire kit combined with a big 3 upgrade, so I wouldn't be surprised if the pump is being a tad pissy due to temperature. Even though I have not proven or disproved the fuel pump as being the culprit, I'm considering upgrading it anyway, based on both age and my desire to supercharge it this coming year.

[dhirocz]

Found the problem. Intermittent fuel check valve leak. Car would start gurgling during prime at a 1/4 tank which accompanied the leanout. Best I could figure, the fuel temp would rise with less fuel which caused the check to start leaking. This was causing a drop in fuel pressure. If I was cruising on a full tank it wouldn’t do it. Sitting in traffic would also cause it. It was accompanied by gurgling and bubbling during prime. Parts on order.

[SiriusC1024]

Sweet. Glad to hear. Smooth sailing now you think?