Ats - LTG KR

[CCrunner84]

I've been struggling with KR on this car for awhile now, how can I tell what is real and what is not? The stock tune on 93, and also modified slightly for E85, has the same results.

The quick pictures below are with a ZZP tune with slightly reduced timing to see if I could improve it any. What's confusing is I can do some pulls and see nothing on the scanner and other times see a bunch driving normally in town. :banged: What am I missing here? I've tried E85, reduced timing and also smoothed the timing tables, has anyone else had troubles with these?

E85 WOT NO KR
E85 WOT.PNG

E85 WOT KR
KR E85 WOT.PNG

E85 KR
KR E85.PNG

[ECaulk]

If you're running more ethanol you need to add timing. The LTG is similar to the LNF, for my current e47 tune I command 20* at WOT, you're barely hitting 9*.

Read a few of the LNF KR discussions, I'm assuming the ecu is similarly programmed so KR becomes a generic catch all for the ecu doesn't like something.

[CCrunner84]

I've gone through some, which led me to smooth some of the tables, including the Advance and cam tables, but didn't seem to make a noticeable difference. The un-modified ZZP tune has a bit more timing but the result is very similar. According to ZZP I should also be running a low-ash oil, I'll be trying this along with some more tune changes.

[T-Man]

I would lean it out and increase timing. Smoothness definitely helps but lack of timing and too much fuel is backwards type thinking with DI. This isn't a PFI motor.
I'd also take a look at all of your ignition timing modifiers too.

[MarkTucker]

You get anywhere on this?

Just from your screenshots that you attached in your original post. The first screenshot is showing 11.04 commanded afr, the second screenshot is showing 9.74 commanded afr. Both of those are are with a 58% of ethanol.

Do you have a log and tune that you can post up?

Did you have ZZP tune it for you and you are just tuning it more off of their tune?

Is ZZP still helping you with the tuning?

[CCrunner84]

Not really, but I haven't toyed with it again.

That's interesting that the AFR is changing so drastically, I never noticed this. I do see COT is enabled, but it's only set to 1.02, I'm also seeing some other PE modifiers.

This is a 'base' tune if you could call it that, I've sent them a few logs but haven't gotten any feedback as far as recommended changes. I'm going to hook up a wideband to get a better idea of what's going on this weekend.

[ECaulk]

The LTG doesnt have a wideband stock?

[CCrunner84]

The LTG doesnt have a wideband stock?

Nope, I really hoped it did like the LNF...

[lt1z350]

I have same issues on my car with a larger turbo lots of random knock. I have leaned it out a little but seeing 8 degrees knock I am weary to throw more timing at it. I dont have e85 but do have meth on it and run it aggressive enough I had to lean it out for it causing it to go rich. I run a 50% mix with it so to be sure it is helping cool the cylinder. I even tried 104 no lead and still had the same kr show up. I am also only around 9 degrees timing wot at 23 lbs. Whats weird is it shows the 4-8 degrees kr but isnt pulling the timing back for it at all. Check your logs see if the commanded timing is falling when showing the knock. I will say I know what it sounds like and never hear it spark knocking. I did when the car was stock and we first picked it up as the idiots at the dealer filled it with 87 to be cheap and that was the only time I ever heard it actually ping. I even check it with a bore scope to see if signs on the pistons and nothing really to speak of showing up but my pistons are about spotless on tops due to the meth spraying on them and keeping them very clean. I feel like I am giving up a lot of power with not being able to give it more timing. or at least feel safe about it. More guys with the lnf need to chime in and give their experience as I have done a lot of searching on it but nothing has me feeling goof about the kr even if it is a catch all and showing up for some other reason other then true knock.

[ECaulk]

If you're running an e50 blend you need to be at least commanding 18* of timing, if I remember later I'll grab a screen shot of my timing table and I'm running e45-e50 depending on the fill up.

There is a post around here from GMTech discussing the issues with direct injection and KR on the LNF, I never bookmarked it but I guess I should have.

[lt1z350]

If I could command and get away with that much timing the car would probably pick up another 50 hp. I can feel 2-4 degrees and it shows on the delivered torque pid. Maybe I should have explained different I have an aem methanol kit on the car and running the 50/50 blend that way. I am getting ready to put the sensors on the car so I can run pump e85 to go along with it. I did see some posts way back where guys with cobalts were adding 8-10 degrees timing when using a comparable kit. I just can't get away with it or feel I can't. It's funny my 1992 formula is a 383 v8 single t76 turbo setup and that car I don't even run a knock sensor on it as they are so lazy and just cost power on that car so I set timing of what feels good and of course back it down if I hear it ping at all. On the caddy I don't fell like u can get away with that kind of tuning even though a knock sensor is there to pull timing. I guess the difference of tearing up a car I drive when I want or tearing up my wife's daily driver that I play with to make more fun when I drive it. I am currently working on some timing and cam timing tables smoothing them out changing the columns out so more control in higher spark airmass where stock runs out at 1.36 I think and my car with the bigger turbo I have seen 2.0 g. Seems this has been a fight for all ecotec based engines for a while now and someone has to have some ways around it or we wouldn't see cars running 125 plus in the quarter mile with a 4 cyl. It wouldn't be possible with out being able to add timing in relation to the 20+ lbs of boost these cars are now running. Maybe some other guys that own earlier models will have something more to add on this as the caddys now are fighting this and next wil be the group that buys new camaros and decide to go 2.0t just to be able to run with a ss with the proper mods and have a much lighter and less expensive car.

[cobaltssoverbooster]

on stock setups with standard CA 91 pump i was commanding 16* advance at all in. (cobalt platform...kapa's were more like 14*)
If you blended fuels with ethanol, 9* is the equivalent of running negative ignition advance. Burn rate with blended E fuels is slowed down causing the cylinder pressure zone to shift. you need about double your current commanded ignition if your running anything E47 and above.

[CCrunner84]

on stock setups with standard CA 91 pump i was commanding 16* advance at all in. (cobalt platform...kapa's were more like 14*)
If you blended fuels with ethanol, 9* is the equivalent of running negative ignition advance. Burn rate with blended E fuels is slowed down causing the cylinder pressure zone to shift. you need about double your current commanded ignition if your running anything E47 and above.

I'll give this a try tonight via the Flex Fuel Spark table to see if notice an improvement, thanks for the input!

[lt1z350]

how about when using a methanol injection setup on the car same thing apply?

[ECaulk]

Yes you need to add extra timing for the methanol injection, that is the main reason for adding methanol or at least the main reason I would be adding methanol (but I'm lucky and have plenty of e85 around)

[lt1z350]

yea thats the main reason for the meth and the cleaning the valves and pistons is a good benefit due to the direct injection but seeing the knock or false knock I have been seeing I was weary to add too much on top of what I see now or are you basically saying it is causing more kr due to running the meth and not adding the correct timing to work with it? Back when I first installed it I had to pull a lot of fuel due to going rich but now with the bigger turbo I have add all that back and then some to get afr right again. I do run it on the rich side I guess as I am used to tuning old school stuff and 11.7 being safe so maybe the 12.0-11.7 I see is also too rich for this setup and causing issues? I am going to post up my current tune anyone that cares to comment I am all ears. I know there are a lot of guys on here that are very good with this setup so I have no issues showing where I sit and anyone that thinks they can just drop a tune from my setup and run it with out knowing all the details is just nuts.

[ECaulk]

I'll look at the file later, I haven't touched a LTG file, hopefully there is a stock one in the repository to compare too, unless you have your stock file you can upload.

For direct injection you should be around 12.5AFR (0.85 lambda) at the richest, and closer to 12.9AFR (0.88 lambda) will most likely net better results, for my LNF on pump I run 12.9AFR and on e47 I run 13.0AFR.

[lt1z350]

There is a couple stock ones in there but I will upload my stock one when get to laptop later as there is an early generation and second gen tune that are pretty different from the dealer and I am on the second one. They updated the tune and went to a colder plug. I went even further and went another stage colder as reading the other plug the tip was getting so hot it was rounding over so with the colder plug it looks much better.
Can too much fuel in these engines cause kr? So running 12.0 wot or any time in pe can be causing issues where as typical engine adding fuel normally cools the cylinder and gets rid of kr?

[CCrunner84]

I was always under the impression when running e85 it wasn't necessary to drop down to a colder plug, I'd be curious to hear what others suggest.

[lt1z350]

Pics of plugs a little rich but no signs of detonation at all. They are a very cold plug which helps but my last log shows 8,degrees at 4400 and always shows kr at 4400 even if no where else which is weird and up top was 6 degrees