Help With Making 4L80e TCC Unlock Easier
 

I'm getting some low RPM, high load knock and it seems to me it's because the TCC is locked up and lugging the engine. I don't get any appreciable knock elsewhere nor at high RPM high load. This did get a little worse with the E70 or so I'm running now as compared to 93 and I know the timing is more aggressive due to that but it did it with 93 as well and even my stock truck with GM factory tune does it. I've lowered the timing a little in the problem area but I really just think the factory apply and release points are in a poor place.

What I want to do, at least to start, is get it to unlock anytime it's in 4th gear and more than 30% throttle is applied. The settings in HPTuners for this are confusing to me and seem counterintuitive.

I've tried going to: Transmission -> Auto TCC-> Apply/Release Speed, "Normal" and "Cruise" "Release TPS" and adjusting the 4th gear release % down to 30% all the way up through 72mph. It didn't seem to do anything when I tested it on the way in to work this morning.

I then messed with the apply/release speeds under Normal/Normal and Normal/Cruise by first leaving the apply alone and only changing the release MPH which didn't work as I thought it would and then also changing the apply MPH in the same ratio as the release. That worked even worse, applying it at strange (to me) places.

Would someone be so kind as to point me to what I need to change in the settings or to a thread or how to on TCC tuning? Thanks!

post the tune

Whoops. See attached. The attached is the latest and I made some changes last night using the BearCat tool. It improved things by showing my how to raise the RPM at which the converter will lock; however, it's not really what I want. I really want it to release on a throttle input % or torque amount if possible. If it's not, my next recouse will be to remove a little more timing from the High Octane spark table in that area and then remove most of the timing from the Flex spark in the same place. That will probably fix the knock, but not the drivability.

Also, my previous settings were at the bottom of this thread:

https://ls1tech.com/forums/pcm-diagn...ngee-cord.html

ETA: In the log attached, which is my latest, I just noticed more KR in other areas. I have increased the Ethanol percentage so I am going to have to remove some timing. It doesn't seem like I'm getting flex advance though. Maybe I'm reading it wrong.

First of all, you minimum converter locked table is fucked. You are slipping your converter clutch like crazy. Go 100 max, 90 or 95 min. Hell that alone might solve your issue. The way its set now, you should lock at part throttle 60 mph, and if you coast down it will hold lock to approx 57. Thats awfully high IMO, Ive had good luck locking in the mid 40s, and releasing in the high 30s. Of course my car is lighter then stock and geared well. Is there something about your combo of parts that doesnt allow this? I could easily get the rpms under 1500 with no bucking or surging with a 230 cam.

You're timing isnt overly aggressive by any means.

Thanks for your help!
This is my first time tuning, so it's possible that a lot of stuff that I didn't notice is FUBAR.

The converter clutch table is stock. I'll try your fix and see how it responds to that on my way home tonight. Hopefully that will do the trick.

I made my locking over 1700 RPM (IIRC) to try to alleviate this issue. It's using the BearCat tool parameters. If changing the minimum locked table works I can set it back closer to stock.

As far as my combo. My build information is in the post that I linked above. This is in a 3/4 ton regular cab truck:

I've built all kinds of stuff but this is my first forced induction build and my first time tuning. I like to jump in with both feet. :cool:

Ok since my turbo combo is new I cant give a ton of info, however during my initial testing driveability was the same or maybe better then my old HC LS1 combo. It doesnt seem to mind lower rpm cruising with a 5.3, 218/218 cam, 78/75 turbo, 4l80e, 3.73 gear and 3100lbs. Are you monitoring AFR? Are you sure fueling is correct during the lower rpms?

Yes, I have the AEM wideband hooked up to the interface and you can see the EQ Error graph in my log. My VE is pretty close in the areas that I've adjusted and drive in but it's off in areas that aren't readily street tuned. It's a work in progress. The truck actually drives exceptionally well with the only drivability problem at the moment being lugging with the TCC locked. At WOT it goes like hell (for a truck) and pulls like a train. The KR get a little worse with E70 and decreasing temperatures here but I'm near commanded AFR. Maybe I have to tweak the stoichometry a little to richen up the mix with alcohol?

I cant see everything in your log due to our scanner setups are different. But some glaring things are, you held 4th gear to mid 20 mphs. I should have caught that, with your heavy truck you are not going to want that going down that low, thats a definite bog. You have 4th apply till at 23-31 mph in the lower throttle range, i would match the 0-44% throttle to say 35 mph 4>3, and 3>4 upshift 37mph 0-19%. That should solve your issue. Im seeing this at trans>auto shift speed>part throttle shift>Normal>Shift speed vs TPS. Make sure youre converter lock speeds are above the 3>4 apply mphs. I would also disable shift lock.

I didn't realize that you couldn't see what I see when you open my log. Seems kind of inconvenient that the settings don't go with it?

Actually I don't feel that I have any big issues at low speed. It just unlocks or downshifts as soon as I touch the throttle at lower speeds. The issue is most prevalent at 45mph or higher, especially when going up a hill. It also only seems to happen when TCC is locked. For sure, that's the only time it's noticeable.

If I'm going up a long hill, it will never unlock the TCC unless I really get into it and it wants to downshift anyway or if I completely let off the throttle and then hit it again. It doesn't seem to want to "naturally" unlock like I imagine it should. Does that make sense? It's like it's not smart enough to disengage when it should or rather I'm not smart enough to know how to tell it to do so. Haha.

It should be releasing at anything under 57mph in 4th, and 43 in 3rd. You need to verify if you are in these parameters when its happening, then raise the mph limits to get above your problem issue. Saying "Im bogging at 45 mph when locked" means youre in 3rd gear. Raise the release speed to 50 if thats the case.

Here is a pic of mine. I don't lock in third, seems there is no use to do that.

Yeah you can get rid of the 3rd lockup completely if you wish

I am logging and checking what it's doing. That's what confused me in the first place. I tried telling it to unlock at a TPS % by changing the "Release TPS" to 30% and it didn't work. I don't have any idea what the "Release TPS" table is even supposed to do if it doesn't make the TCC release at a certain TPS %. I mean, WTF? It seems counterintuitive.

Here's the changes I've made so far based on both of your suggestions. We will see how it shapes up this evening. I didn't want to go full monty on the duty cycle just yet. Some things I found said it might be too harsh, so I used your recommended setting on one side and interpolated it to the 50% setting others recommended on the other side. Looks good anyway, like it's "meant to be". haha.

https://cimg1.ibsrv.net/gimg/ls1tech...38a90db04d.png

The other thing I want to work on later is that my 1-2 shift is ohhhh so sexy, but the 2-3 is :wrist: But one thing at a time right.

Thanks for your ideas!

Setting duty cycle min up to 90/95 helps prevent slipping. Slipping is bad for the converter clutch. The reason they design slip into it is so the average person doesnt "feel" lockup. Im not sure i understand this as you typically feel the shifting to a degree, whats essentially one more "gear" (rpm drop). I prefer moderate to firm shifts, upping to 90+ will give the converter clutch a positive engagement for performance and feel, which is what most prefer in the modified world.

GM probably just didn't want people complaining about their transmissions constantly shifting in and out of "5th gear" and confusing their stealership techs. ;)

I'm not opposed to going all the way up to 95, just figured I'd try a lower amount to see how it feels first. I also don't entirely know how my HD2 kit modifies pressures and thought it might be a little different.

Alright,

It definitely felt better when "lugging" with the firmer minimum duty settings so I'll probably increase them some more. It still is showing KR when locked, even sometimes when cruising at a steady speed. The funny thing is that when I was going up a long hill, TCC locked I heard the engine pinging quite a bit but it didn't show a speck of KR. The time shows about 5:15:33 in the log when I start going up the hill. Weird. Sounded like my old SBC's when I got a crappy lot of gas.

I still wish it would just unlock at a certain TPS% though. It would be nice if it just unlocked while pulling the hill.

A long time ago, several tuners on the internet came to the conclusion that audible knock was outside of the knock sensors detection range, as they are designed to stop the knock before it becomes audible, attuned to frequencies the original engineers found to be associated with the most common forms of engine knock it would encounter in regular service.

I am not sure about that, but I have noticed the same trend in Nissan and Toyota knock sensors; that is, audible pinging does not show up in the ECU as knock, whereas it would show knock if I had a bad tank of gas and couldn't hear anything.

Heck it may be as simple as a bad tank of gas.

I went for a drive this morning. After firming up the TCC minimum DC almost to your first suggestion, 01ssreda4, I really like the way it feels. You were absolutely right about it slipping before. I did back them off slightly just for personal preference on the feel of it locking in as it kind of bounced when too firm like shifting a manual and not doing a good job timing the clutch and throttle. I didn't back it off too far that I feel any slipping though. It now just feels like a 5th gear.

So, :usa: to 01ssreda4. Thanks!

I've also firmed up my 2-3 a little.

Now the bad news. Still knocking in the 1800-2200 RPM area with the converter locked and loading it. I've decided to reduce timing there again and see what happens. I'll let you guys know if it improves. If not, my next recourse is to start diluting the E with 93 octane and seeing if things improve. That might help me narrow it down on whether it's fuel related.

Thanks Guys! I really appreciate the help. It's hard navigating through all the B.S. to train yourself to tune and a little help here and there sure helps a lot.