Knock retard at cruise

[JLF1977]

So, I've got a 2011 Buick Lucerne 3.9 that I've started playing with. I'm still familiarizing myself with the HPT software, as it's a bit different than what I'm used to. I've gotten the transmission pretty much where I want it to be as far as shift points and all that. Now that I'm starting to alter timing and fuel, I'm running in to some things that don't make a lot of sense to me. I have a timing table with just 1* of added timing, and stock fueling, as related to AFRs. PE values are increased a little, though I don't think they need to be. I will attach two logs. The long one is on a tune that the only thing different from the posted tune is the speed of the PE. What you'll see in the long log is tons of KR...all at cruise. For reference, the gas in the tank is 93 octane. Spark plugs and wires are new in this car, as is the air filter. Less than 1,000 miles on those items. I have the front oxygen sensor to change, but haven't gotten to it yet, what with another issue I had to address. I'm just kind of curious what I'm missing here. I shouldn't need 93 octane to pull KR out of a stock timing table. For the record, and I do not have a log for this, when it was dead stock, there was no KR in it at all. I'm tempted to simply revert spark and fuel back to factory, and go from there...again. Any input on these? Thanks.


P.S.: The long log has to be a Google Drive link. It is too large to upload.
https://drive.google.com/file/d/1KXn...usp=drive_link

[SiriusC1024]

Watch timing in scanner and compare to the tune. Something should stand out.

Spark adders in Spark>Advance>Fuel are still active. I don't think you've accounted for them.

It also looks like you've been playing around with the variable cam angles. VCP Spark doesn't match the changes you've made.

Easiest thing is to zero out the fuel and vcp adders when developing a new table. EGR spark is suspicious, given the state of related DTC's.

[JLF1977]

I see those numbers, and that would make sense, as that's about what I'm seeing. Thank you. I don't think I messed with cam angles...at least not on purpose. LOL. Definitely still in the learning stages of this bit of software, and I definitely don't understand how that table works. Thanks for the input here...I appreciate it.

[SiriusC1024]

Really? That spike in VCP is usually accompanied by wild-looking cam angles in the same zone. The cams are used to provide EGR function and ish-Atkinson cycle there. Oh I see it's there. Idk how I missed it. Intake camshaft High. I must've clicked Med right next to it without noticing. Try the Med table ramp in the High. Flatten VCP. Less mpg but more responsiveness.

[JLF1977]

I'm going to look at the stock table versus what's in it now, and make sure, but I haven't knowingly touched it. I did get reset the VCP table to 2*, and went for a drive, and had nearly no KR. Only in the higher gram/cyl cells was there any, and it was...2*. So, that tells me a little bit. I kept it at 2* so that I knew which cells had been modified. Under WOT, I have NO KR, and I'm happy about that. I leaned it out at cruise some, since the idea for me here really is to gain mileage on the highway. This is my first VVT car to tune, and my first time with HPT. I used DHP PT on a L67 powered W-Body Cutlass Supreme a while back. I had that nailed down pretty nice. This is WAY different! Again, your help is very beneficial. I thought I had seen some tutorials for everything on this? But, I'm not finding them now. Was I imagining things, or do these exist?

[SiriusC1024]

Nah I don't think you touched cam angles. Again, my mistake.

If you flatline VCP it will help a lot to do like I mentioned with the cam angles. The Med angle map is good for performance because it gets better volumetric efficiency by as rpm increases.

EQ ratio is way way too rich. Try 1.18-1.2 not 1.6. Lower the throttle thresholds. If you look in the log you can see PE isn't being commanded where it needs to be. KR is happening here. Cut it in half. EQ ratio and throttle adjustments will probably get rid of the high cylair KR.

Disable Spark>Retard>Burst Knock Retard by zeroing out the multiplier tables.

Full throttle shift rpm can probably come up. Part throttle shift map isn't making sense.

[JLF1977]

Sorry for the delay in responding to this. I'll look at those tables. Believe it or not, WOT shifts happen at some 6,300rpm. I'm a little nervous taking it up there on a stock cam & valve train. I keep the part throttle with high shift points to keep from lugging the engine around town, and further, with the 4T65-E having its fourth gear shaft troubles, keeping out of fourth gear around town just seems like a good idea. I did this in my L67 powered Cutlass Supreme with good results. That car had 6,700rpm shift points. The revised tune does have the EQ brought down to 1.2. When you talk about lowering the throttle thresholds...is that the minimum MAP enable in the Power Enrich tab, and using a lower number?

Once again...thank you.

[SiriusC1024]

Oh I see. It's setup backward where rpm threshold is met before speed, making speed dictate WOT shift. Both conditions have to be satisfied. It's better to reduce the speed WOT shift points so that you can command based on rpm.

For the EQ settings I mean Fuel>Power Enrich>Throttle. Min MAP is ok at 70kPa.

[JLF1977]

Ah, I see. I'll play around with that, then. OK, that's what I suspected you'd meant. I think I set it at 50kPa...will see if higher works better this afternoon. Thank you again, sir. One of these times, I'll post up another current tune revision and a log so you can see changes.

[SiriusC1024]

You had it at 70kPa in the tune IIRC. What I'm trying to say is if you look at the log, PE isn't being commanded when MAP is met. This is because of throttle settings. 96kPa at load with no PE is going to cause KR.

[JLF1977]

Oh, I see. This is definitely all a learning curve for me. Thanks for the explanation...and patience2. I promise, I'll get it. From what I remember in using the DHP software back in the day, PE and AE were all set by throttle percentages. I think that is one thing that throws me the most. I'm trying to follow how to read kPa vs TP% vs KR vs anything else related.

Is this the Fuel --> PE --> Throttle --> Hot table? The software talks about a "Cold" tab, but I don't have that. From 2,000rpm on up, it's at 50% TPS to enable PE.

PE TP.jpg

[SiriusC1024]

It's no problem. Look here. 92kPa with 41% throttle. No PE because of throttle percentage. KR.
kr pe.png

Highlight the Hot enable table and multiply the values by 0.5.

Put enrichment ramp at 1.000.

Min Map at 80 kPa would probably be better. Don't want PE to occur that often.

[JLF1977]

Alright. I did get those changes made...trying to keep a log of these changes, within reason, so I can learn how this stuff works. If I like what I see, I'll post the current tune and a log so you can see what I'm seeing. I'll flash before I go to work in the morning, and get some data from it.

[SiriusC1024]

It'll be a good start. Looking forward to your results.

[JLF1977]

So, at cruise, we're getting there. I'm understanding what to look for and how to read the scans now. Learning how to look at stuff and where to find the tables I need. I'm going to attach what is currently in the PCM and a log from in town. Couple things throw me for a loop. So, I have the AFRs lean at light throttle with the intention of helping highway gas mileage. I did this before in my L67 Cutlass, and had very good results with it. But, as I watch the log (thanks for posting that screen shot a few posts back...that's when it clicked how to put data together), what I'm noticing is that even when TP% increases, it doesn't command a richer AFR per the throttle opening. You can figure out pretty quick that causes some issues with KR. I've gotta be missing something pretty simple, but I'd have thought that the AFR table would be it, but that doesn't appear to be the case.

Here is what's in the PCM and an in town log from it.

[SiriusC1024]

Hmm yep. Open a ticket with HPT to define the power enrichment cold table. They're pretty good about that kind of stuff.

Changing stoichiometric AFR doesn't do what you're wanting. The narrowbands will force stoichiometric regardless of what you set. Changing that value like you did throws off airflow calcs, as can be seen in the log. This makes cylinder airflow report incorrectly, so spark maps and torques are all wrong.

The only way to make it run lean is to force OL.

You can get a little bit leaner by changing O2 switchpoints to something like 412mV during idle and cruise, but have to make sure the behavior of the narrowband switching isn't affected.

I see you didn't put the med cam table in the high. Try it

[JLF1977]

Yeah, I didn't mess with that, since I hadn't understood what you meant with that. Now, I do...and I'll do that. I'll also get ahold of HPT on this to get the table you're referring to. So...am I better off putting the AFR table that I've messed with back to the factory table?

[SiriusC1024]

Absolutely. Use VCM Scanner>Vehicle Controls & Special Functions to clear those LTFT's based on erroneous data.

[JLF1977]

You got it. I made those other changes and have already flashed it in. I'll reset the fuel trims before work in the morning. Will see how this all plays out!

[JLF1977]

So, I'm starting to get a little happier with driveability...but now...I can't find my MAF table! LOL I've been through EVERYTHING, and not seeing what I'm after.