Shake or Shutter...

[1duffman]

I have a shake or shutter at up into the lower 60 mph area. 30 mph is in town driving in my town so I see a lot of it, though it is very pronounced then and 50 and 55mph and during WOT acceleration. When I am at cruise a go to WOT it seem like its stumbling over itself, as though there is to much or to little air or fuel. I have looked all over the forum for this issue in an automatic, but only find similar issues pertaining to manuals. I am not sure where to look to log this. I have thought throttle cracker and follower but am not sure if I'm even looking in the correct area, or what I'm supposed to do with the information I get. I have attached a log and tune. I'm still trying to learn this thing so you'll see I have a lot of parameters logging and should probably be logging others instead of some. My tune isn't the greatest either but being a newb I feel as though I'm on the right track. Any hints and help you can give me would be well appreciated.

As a side note you'll see in my tune I have activated DCFO and Power Enrichment thresholds. I had to take a long trip and was more worried about mpg and passing/merging then logging proper values.

Also in this log you'll see the insane amounts of knock I have and my need to tune spark... I just can't figure it out and I'm not sure why. I feel like a dummy. I consistently run 92 so I know I need to work on my timing. Like I said ANY hints and help would be WELL appreciated!!!

Thank you in advance


2002 Denali XL
LQ4 Bored .030 over
862 Heads... I know, I know haha
Howards version of GMs ASA cam
No Cats, true duals w/ Flowmaster Super44's

[bigredtruck]

Hi 1DUFF. I am new to this tuning too so I will tell you what I saw looking at your logs. First thing I see is you are really rich, LTFT AND STFT are high negative in the lower portions.Half way through your log i see you go close to full throttle and you get 3 degrees of KR but your only commanding 14.68 and your lc-2 is showing 14.77 which is to lean. Again I am learning to so hopefully someone with more knowledge can chime in.

[1duffman]

Denali Tune 5-20-2017 VE.hptDenali 5-28-2017.hplDenali 5-28-2017 2.hpl

[dermotw]

Your KR comes in at slightly odd places, and you have relatively little advance anyway... where did the KR table come from? -I mean this;

Capture.JPG

Thats (similar to someone else I just saw on this forum) got much lower values than e.g. my 99 TA would have as standard;
Capture.JPG

Or e.g. a 2002 Camaro, standard;

Capture.JPG

[1duffman]

That is actually a stock table. I haven't touched it, I've played with my main spark table, that's about it. As far as knock goes the only thing I've touched is burst knock.

[dermotw]

Burst knock is only really going to affect it if you stamp on the throttle, its predicted kr, the ecu "guesses" when there might be knock (i.e. when throttle opens suddenly at low rpm) and reduces the timing before it even happens. (or thats the idea anyway), generally it doesn't do much... you can log it, but I doubt its affecting you.

However this is not likely to be your actual issue...

Your tune in general looks ok actually (imho...) nothing is miles off, except the KR settings maybe a bit odd. It is very rich at startup, but then perhaps it was cold where you are.. I also saw that your KR decay is set to 0 across the board, that means that if you get any KR, it won't go away (as seen in your logs, it just flatlines on and on...). More typically it decays to 0 in absence of knock, and the table looks like this (this is mine, compare with yours);

Capture.JPG

Could be that it is GMs idea to not decay the KR, though it does in other vehicles I've seen? But you can change this if you want, remember that you can always put it back!

[1duffman]

Awesome!!! I didn't know about the KR decay rate. I will have to try that and see how it turns out. What value would you suggest i start with? Maybe I'll try .001 at a time and see what happens.
After I zeroed out the burst knock vs RPM, I eliminated probably about 50% of my knock. Tryin to tune out actual knock, I actually have to run 92 all the time. I tried 87 for a short while and it would knock any time I touched the pedal. So I started with 92 and she's been happier ever since.