grabbem88

I was comfortable and didn’t want to go downstairs but here they are

grabbem88

Easy guy I’m slowly making changes by only what I’ve read and searched but I see there is more to it than timing and ve tables which obviously didn’t help.

grabbem88

I’ve made 10 tunes today so a little discouraged I am.

grabbem88

I was double checking log. Since it was easier to replicate and put cruise on this all happens with 5-13% tps. But I doubt if anything can changed there

ULTM8Z

At that low of a TPS, and with that cam, you may be getting manifold pressure fluctuations that are triggering unnecessary delta-MAP AE events, which could be what's driving your AFR's down to ~13:1. Delta-MAP can get triggered without a change in throttle if the manifold pressure fluctuates enough to cross the minimum threshold to engage Delta-MAP AE.

Look for the table AE Delta MAP enable threshold vs TPS.

At 0% and 12.5% TPS, try raising the map values to 5kPa and see if the issue goes away. This will also cause the AE delta-MAP to come in a little later during deliberate throttle changes so you may get some hesitation in other areas during throttle changes, but you can cover that with some additional AE delta-TPS AE.

So, if need be, go to Accelerator Enrichment vs Delta-TPS... for 0, 3.1, and possibly 6.3% TPS values, you can bump them up by say, .05 at a time to cover the AE Delta-MAP.

Yeah, there's a lot more than VE and timing in tuning.

ULTM8Z

I couldn't find the injector offset data for those p/n's unfortunately...

What format are your logs in? .csv? I can take a look at them if you want...

ultm8z@yahoo.com

grabbem88

So I turned up the closed loop coolant minimum to 210*. Car has no surge/miss just a lug or two but stock it did this so I’m confused why I can’t get it to run in closed loop.
this has been going on since the first tune
so I thought maybe it was on my end and everything was replaced. Wasted money there again all because a tuner put in my head it was my motor. (2800 miles btw)

ULTM8Z

So I took a look at your data...

I filtered it for 2000-2500 rpm and 0-15% TPS. I then plotted injector pulse width vs time (see below)... For such throttle light cruising, I wouldn't expect such it to be jumping around that much or have such a large average inj PW.

Looking at your bin, you've taken out quite a bit of fuel from the VE tables.

But Like I said, try increasing the delta MAP threshold for engaging the delta-MAP AE... at 0% and 12.5%, just as a test, put it to like 5 kPa. See if that calms things down a bit.

grabbem88

Thanks I appreciate this and I’ll put it back to closed loop but for 180 instead of 122

grabbem88

Like this?

ULTM8Z

Yep.

BTW, when you said you "changed everything", what exactly is new now?

Also, what's the pedigree on those injectors?

grabbem88

o2’s was latest Bosch for GM plug wires are Taylor otvc instead of Bosch but most were new when I first built this motor in August.

What pedigree?? 30lb Bosch lol

ULTM8Z

I mean did you buy the injectors new? Used?

BTW, Bosch O2 sensors have a reputation for not being the greatest in terms of quality... On the thirdgen.org forums, we always tend to go with AC Delco.

grabbem88

they were taken out of my friends car that made way more hp than me so maybe had 5k miles on them

reputation or not the Bosch to ac delco made zero improvement being that I use heated anyways I never had a failure but they are gm now

but like I said early by putting car in open loop and car runs perfect pretty much clarifies it’s my tune

ULTM8Z

One other thing you can play around with is the rich/lean thresholds for the O2 sensor. I actually moved mine 200 mV richer across the board. With the stock threshold settings, under moderate acceleration (not hard enough to get into power enrichment, such that the ECM is still in closed loop), the ECM would continually pull my AFR back to around 15:1. That may be good for mileage but not performance. I have my thresholds set now such that during part throttle cruise or light accelration, I get the 14.5 to 15:1. But during moderate acceleration, I'm into the 13.5:1 range, BUTthe key is that the BLMs are still hovering around 128, because I told the ECM to consider ~700 mV to be the target O2 voltage under high load, not the 450 mV in the stock calibration. Which gives much better part throttle driveabiity and a smoother transition into power enrichment when I get to WOT.

If I simply richened up the VE, the ECM would compare the exhaust results against the stock O2 threshold, then start pulling fuel back out, and my BLMs would start dropping, which is what was happening orginally before I moved the O2 thresholds.

Basically you're telling the ECM that the car wants to run a little richer without it trimming the fuel back to the stoichometric 14.7. Could also help your closed loop calm down a little.

So for instance on your O2 threshold tables..

Picture 1 below is the stock settings.

Picture 2 below would be if I wanted to move the O2 swing point 100 mV richer across the board. Note that I added in some tolerance on the upper and lower thresholds. For some reason GM gave no tolerance window on DA3. I try to run about 50 mV tolerance on either side of the nominal value to set my upper and lower thresholds.

Note that in this example I'm adding the same amount to both injector banks, but you can actually tune each bank individually by looking at the BLM's on each bank. Ideally they should be the same, but often that's not the case.

You can also change the O2 thresholds more for the higher airflow values... i.e., higher load on the engine, you can dial in a richer mixture in closed loop. GM already does that to some extent, but with heavily modified engine like yours, you may even want to exaggerate that further.

Who knows, for lower airflows, your radical cam may be throwing so much unburnt O2 out the exhaust, that you may want to dial the O2 thresholds down to lower values so as to essentially tell the ECM to expect that.

But yeah, you can play around with these values and see if that helps. You can play with VE all you want, but the ECM will always be trying to trim the fueling to be in line with these threshold values. So in fact, if you start playing with these thresholds, you may want to go back to stock VE tables and start again. First dial in the different thresholds until you get the car behaving the way you want, then see where your BLMs end up and then adjust the VE tables to get back to 128.