MAP drop or VE?

[LS ROB]

boundary maf only~vve1.1.hptVE vs FUEL TRIMS.pdfHiccup.pdfMAF - DETAILS.pdf

Unfortunately, guys I'm back to dealing with this hiccup. I was not able to attach the file due to it being 53 minutes long, so I attached some screenshots in hopes someone may be able to see something.

As for filters, I ATTEMPTED my hand at one. Still not sure on this but I'm using, ([50090.156] > 80) AND ([50090.156.avg(500)] > 80) AND ([50090.156.avg(-500)] > 80) for logging throttle under 80%

For this log, I'm MAF only and I changed my boundary back to 520 across the board as I went back through previous posts i've made and tried some of the suggestions. Please take a look and if there's enough information, let me know what you think.

Thanks!

[GHuggins]

Couldn't see accel pedal in those screenshots, so don't know if this will do anything for you, but you're welcome to try it.

[LS ROB]

Couldn't see accel pedal in those screenshots, so don't know if this will do anything for you, but you're welcome to try it.

Thanks Greg. I'll flash it tomorrow if I get a chance. Been tied up this evening and calling it a day. I do have a question for you though and it may seem like an odd question but from simple math; it seems like the amounts of timing that is pulled during each occurance, coincides with my UNDER & OVER SPARK TABLES. So, my question; is it actually possible to have an idle rpm overspeed WHILE in gear? The only scenario I can think of would be the BRAF being too high. But most times the throttle would hang if that was the case so, that makes me second guess myself here. I appreciate your help and i'll report back once I can test it out.

[GHuggins]

That is EXACTLY why I made the changes that I made. I suspected from what you were describing that it was going to idle mode. This will happen if you're barely touching the pedal. Problem is - there are also other tables that define this that aren't there, so have no idea if what I did for you will have any effect at all.....

The main things that will define this are your baro tables, torque model, braf too high causing low pedal (actually have taken 2 or 3 g/s out on some to fix this same problem in others, but those had overly sensitive min air tables to begin with), dfco tps settings and driver demand. Problem is - well there are all these other tables in the background that also define idle "startup flare rpm settings and so on" - these have really been kicking my arse on other gens as of late - that we don't have access to.

Like I said - don't know if those changes will help you any at all. BUT another work around - make the tune to where it requires more throttle to move (falsely bigger tb for instance) and it should cooperate. You can increase your baro tables or etc scaler / decrease dd values in the throttle tables up to a point and no this won't cause problems going down in values. Problem - you're possibly going to have to rework a lot of stuff again.

[LS ROB]

Hey Greg, reporting back on that tweak you did. The hiccup is still present and a little more pronounced. However, I immediately felt that the car was stonger from the coast to the stop sign in my subdivision. So, i had to try it. Instant tire fire. I Did get a log but of course it would probably be of no use since my curiosity got the best of me. I think i will try to work the vve table some with what you did to see if i can tame it some, as you have previously said i may need to do. I'm also going to get the car up in the air to inspect headers to see if i may have an exhaust leak that could be throwing off the o2's.

test1.hpl

[GHuggins]

Made some changes based off of the log for you Rob. Reworked the O2's as they seemed to be adding and pulling a lot of fuel for switching. Changed your baro table a slight bit more. Killed the overly aggressive throttle with idle - you'll still have throttle control, just not as aggressive. Dialed back throttle tables, Increased TB size - assume you have a 102?

The more power was the torque model changes - engine's probably been holding itself back a little - great as long as it doesn't cause other issues.

Should be dulled down ever so slightly with these and hopefully better for you.

[LS ROB]

Made some changes based off of the log for you Rob. Reworked the O2's as they seemed to be adding and pulling a lot of fuel for switching. Changed your baro table a slight bit more. Killed the overly aggressive throttle with idle - you'll still have throttle control, just not as aggressive. Dialed back throttle tables, Increased TB size - assume you have a 102?

The more power was the torque model changes - engine's probably been holding itself back a little - great as long as it doesn't cause other issues.

Should be dulled down ever so slightly with these and hopefully better for you.

thanks brother. ill check that out. i didn't get a chance to yesterday. we will see what she does.

[LS ROB]

fbody.hplboundary maf only_vve1.1-2.hpt

Reporting back on those changes Greg. The pedal feels better and whatever you did to those o2 sensors seems like it put them closer to the sweet spot. I think I should be able to dial in the VVE table pretty closely now. However, the hiccup is still there. This is the first log so I haven't tried to work the VVE yet. I am not too familiar with the DFCO stuff just yet but it seemed as if a good bit of timing was being pulled as I would come to a stop. Not sure exactly what caused it but, the car actually died once while coming to a stop. Have you ever seen the timing flutter like it does around the 5:07 mark? I'm logging TPS COMMANDED and as you can see its mostly steady @ 14.5-14.9. Is it possible the ecm may have an issue or does it seem like something that I just need to figure out? I purchased the ecm from Speartech. Are there any particular channels you suggest I log?

[GHuggins]

This should - "should" work around your remaining issues. Wondering now if your min air was just way too low from the get go after looking at some of my ls7 cammed tunes. If it starts "auto-driving" or having coast down issues then I can make some more changes to your dfco as I previously set it up to a really low setting to see if it was causing your problem and we can lower you min air just a touch at a time until it stops "self cruising", but that's only if the problem is present. Honestly not sure why it's doing what it's doing now as you're not changing your throttle at all and it's yanking timing, which is why I went to your min air table being pretty low - about half what your actual airflow is in that rpm zone. Also made changes to your drive idle correction tables, so if it does still yank timing it'll only be a degree or two and shouldn't be noticed.

[LS ROB]

Much appreciated Greg. It may be Friday before I am able to get some drive time in but ill report back with my results. Will logging Idle Desired tell me what my BRAF should be?

[GHuggins]

Not on a 4th gen. Adaptive idle will tell the most, but even then it's not 100% with cams. I use adaptive idle, commanded timing vs actual during a hot idle usually with a load like ac and go from there. Even then a lot of people will set it up over slightly to where adaptive will pull a degree or two.

[LS ROB]

Reporting back on this. This thing is still acting up. Is it possible for a pushrod to be tad long and hold the valve open creating a brief "lean" condition? I can see AFR spike to mid 15's when this happens. However, I have noticed that I can only "feel" it at steady state cruising. If I roll into the throttle or even lightly accelerating, I cannot "feel" it but can see it on the wideband. Could Transients be band-aiding it during transition so that it is not felt or felt very faintly?

morning.hpl

[GHuggins]

This one has your stock torque model and increases your tb airflow a little. Honestly I'm not seeing in the log why it's doing what's it doing now. It still looks like it's going back to idle for a brief second. You can try zeroing out prediction coefficients, but that may have adverse effects as well. It's just a cam, tb mod right? You can even try a stock VVE model just to see how it performs. If anything makes it worse go back the opposite way. Sorry can't be much more help than that at the moment. From what you're describing it almost even sounds like an occasional misfire?

[LS ROB]

This one has your stock torque model and increases your tb airflow a little. Honestly I'm not seeing in the log why it's doing what's it doing now. It still looks like it's going back to idle for a brief second. You can try zeroing out prediction coefficients, but that may have adverse effects as well. It's just a cam, tb mod right? You can even try a stock VVE model just to see how it performs. If anything makes it worse go back the opposite way. Sorry can't be much more help than that at the moment. From what you're describing it almost even sounds like an occasional misfire?

cam, tb heads have been milled .020. long tubes with msd intake. im currently logging idle and misfire channels. I took a drive logging misfire channels and nothing showed up on the cylinders but i logged misfire rpm and misfire ve which showed .02%. im not sure what that means but ill upload it to show you what i'm logging.

[LS ROB]

idle.hpl

idle log showing misfire channels. Greg, I really appreciate everything you have helped with brother. I'll keep at it and update if I get it figured out.

[LS ROB]

I had a little time to experiment today on this. I'm now thinking that this may be a mechanical issue. I switched the Wideband from bank 1 to bank 2. I turned the injectors off one at a time to see what effect it had on the engine. When I disabled cylinder injectors 1,6,8 & 3; there was not much difference in the way the engine acted and the wideband barely went to 16.xx. However, when I disabled the injectors for cylinders 2,4,5 & 7; the wideband went lean instantly up to 20.xx. Is this normal? Anyone have any experience diagnosing pushrods being a little long/short? Engine don't have any noise until it has been ran a while and at operating temp. Only then, is there slight valvetrain noise.


b2idle inj.disable.hpl

[blindsquirrel]

Check the pushrod length/lifter preload and get it over with so you can stop speculating about it.

[LS ROB]

Reporting back. Pushrods checked out so that's not an issue. I reviewed some of the changes that Greg made and some of the info he gave in this thread. I went back and did some tweaking on the timing tables, lowered BRAF some, fiddled with DFCO and coastdown. It seems to have helped a bit but I can still tell it's there. Definitely not as pronounced as it was. If nothing changes by tomorrow, I'm planning on getting some highway time in so I can verify VVE is still in decent shape after all the changes. I am still getting a lean condition but it's not pulling as much timing now. I will probably try to flip my intake tube to move the MAF location and see what effect that has, if any. Then change the DESIRED THROTTLE AREA axis type from VSS to RPM to see what that does. I have attached the log and tune in case someone sees something obvious.


log1.hplcurrent tune sparkdfcoscalarbraf.hpt

[LS ROB]

Got a chance to fiddle with this thing today. I moved the MAF farther away from the TB and the car wouldn't even start for some reason. Is MAF referenced on start up? If so, it may not have gotten a good reading in the new location. I was not able to move the MAF sensor closer to the TB due to mounting restrictions and limited intake tube couplings. However, it fired right up when I moved it back. When this hiccup happens, it coincides with the IDLE ADAPTIVE SPARK CONTROL tables. I'm now wondering if this is a VSS issue. My Speedo is correct on the dash (Dakota Digital) but the scanner is way off. Could a speed misreading cause the Adaptive Spark to kick in? And if so; what does the DESIRED THROTTLE AREA table do? Would changing it to read RPM instead of VSS help at all? I'm hesitant to try this due to the warning on the table below it. New log is attached. Was doing some NB tuning today and made some progress. Besides the issue I'm having, the car feels pretty good.

lc.hplcurrent tune nb vve1.1.hpt

[LS ROB]

Are there any adverse effects of zeroing out the IDLE ADAPTIVE SPARK CONTROL table?