Bear with me...

When running 93 octane unleaded, I very rarely ever saw even a blip of minimal KR on an HPTuners datalog.
Since switching to E-85, I've not seen any hint of KR, ever.
Heck, accidentally sprayed a 150 shot with 41 degrees of timing when I first converted to flex fuel, and didn't get any KR...lol

Ran at bracket race Saturday, roughly 50 degrees out (@ warmest)
Negative DA all day
81% + Ethanol content
Heat soaked, idle IAT's roughly 100 degrees, cooling to 68 degrees or so by end of pass
Coolant, mid 180's steady
60# injectors, max IDC of 55% or so, dual intank pumps, 340lph engine/255 nitrous off of WOT switched relay

I double entered, (2 different classes) so got 4 time runs instead of 2
First 2 time run passes, 12.10 and 12.07, both @ 113mph, N/A
Datalogs looked great, aside from needing a slight 1-2 shift tweak, which I made...
Datalogged and saved all remaining runs, but didn't look at them until today

3rd pass, also a time run, decided to eff with my buddy (11.30 car), and sprayed a 150 shot, through 1st gear, then let off, let him catch me, then sprayed again... 11.17@121

4th, through 7th pass, car was 1 to 2/10ths slower than 1st two passes, and I attributed it to weather change...

Instead, found what slowed car down was immediate 4 degree retard at WOT, straight line and steady, until releasing throttle...every pass, and even every burnout, for runs 4 through 7...

No CEL.

Convinced I have either a (shorted or open circuit) knock sensor harness, since it immediately goes to the 4 degree max, on the MAXIMUM KNOCK RETARD vs. RPM (PE) table.

My Naturally Aspirated Lambda readings were steady, and plenty safe, at .81-.83 Lambda (7.90-8.00 AFR), and my one Nitrous pass was plenty safe, at .70-.74 Lambda (6.83-7.22 AFR), which is where the car likes to be, on or off the juice...

This will be the 2nd time that the Knock Sensors maxed out the retard, and I think I am going to simply turn them OFF...

I attached some screenshots below, showing the KR reading on the datalogs
Run 1, zero retard
N2O run, a slight, and quick blip of .2 degrees retard, probably registering before the LNC-2000 did it's job of retarding for nitrous.
Screen shot of Burnout, also showing KR
and Run 3, NA, with 4 degrees KR (Don't mind the throttle blip at the end of the KR reading. This was a bracket race, so whomped the throttle there at the end...


My "GUESS" is that the nitrous pass...my 1st with the too tall for 26" tires, 4.11's, got something LOOSE, or out of alignment, causing the KR readings...or I simply have a bad pair of sensors again...

Any feedback, opinions, suggestions, advice, I'm all ears...




RUN 1 N/A, no KR



Next run...N2O pass, no KR



BURNOUT BOX, 4 degrees KR, on and off the throttle...




NEXT RUN, NO NITROUS, 4 degrees of KR, mimic-ing throttle position

 

Yes when it throws a code for the knock sensors it will default to the max retard specified in that table at WOT. If you've already replaced them and the PCM still doesn't like them about the only thing you can do at that point is to just disable those codes. Also disabling those codes does not disable the knock sensors and they can still pull timing, etc.

 

Thanks for reply NicD.
So, if I say screw it, and decide to ZERO OUT the table, it will NOT (i.e; can't) retard at all, correct?

​​​​​​​

 

Have you pulled any plugs?

 

Hi Rel,

Correct. It will still retard the timing, but by 0 degrees. In other words, no timing retard. 0 out the tables and you're good to go.
Just understand the potential consequences of this, as I'm sure you're well aware.

Which is why Brandon is asking if you've checked your plugs (all of them).

 

I'm asking because I have never sprayed on E, but isn't that a **** ton of timing?

Again, I'm not trying to start ****, just asking.

 

Not yet, I have not. Car was idling and running great all 7 passes. As well as yesterday when I dropped it off the trailer and took a quick blast around the block. Just didnt look at and review the last 5 logs until this morning at work, and that's when I saw the KR. The KR is showing up naturally aspirated, after the one nitrous pass... I had other commitments after work today, so havent touched the car yet.

Gotcha. FWIW, back in April I think it was, I was getting Burst Knock of the maximum 8 degrees. Turned that off and "problem KR" disappeared 100%. In fact never have really had any notable KR until this past Saturday.

Lots of people from what I have seen/read, are not retarding any timing at all with E85.
Heres what I did...
My (93 octane gasoline) total timing at WOT, for best ET/MPH, and on chassis dyno, was 28*.
On E-85, it has run best numbers with 31* total.
The Flex Fuel Spark Adder settings adds a ton of timing down low, and I left that alone, which really woke up low end.
At high MAP/WOT, I simply left the 3 or 4* added, but subtracted it off of my main spark table...
That makes sure the commanded total timing of 31* is never passed.

As for the E-85 nitrous only timing retard, the LNC-2000 takes out 5-7*, depending on the jetting I choose to run.

On or off nitrous, running straight flex fuel, I am only commanding 3* higher than it was on 93 octane gas.

BTW, I normally only use the nitrous for a little blip, if needed, at the end if the track to nose out whomever I am bracket racing.

I do, however, make full nitrous passes with anywhere from 100-200 hp jetting, quite often on the street and at the occasional test and tune.

N20 details:
Nitrous Outlet 400hp wet 92mm plate kit
Nitrous Outlet bottle warmer
-6 feed line
Dual intank pumps, 60# injectors
Nitrous Express MaximizerEZ progressive controller
Push button nitrous enable, with 0 delay when bracket racing
WOT switch with .5 to 1 second delay when running nitrous passes

 

So on E the box is still pulling timing back?

That makes more sense. I thought you were running a straight 31 degrees on spray with E.

 

Yes. The LNC-2000 subtracts timing as soon as the nitrous is engaged...anywhere from 0-15 degrees. I used to take 6 or 7 out for a 150 shot. And 11-12 for a 200. Niw take 4 or 6 usually and that's it.

 

Just to clarify...
I never got a MIL for the knock sensors or anything else.

Plugs actually look great. Were you thinking a melted one may have caused the instant 4* of KR?

The reason I don't believe it is "real" knock is because on the 4 logs it is there, it is instantly there and mimics the throttle. As soon as I go WOT, it is 4* kr. Soon as I let off, zero kr... There is no erraticness or buildup to the 4 degrees...just instant kr with WOT but no nitrous and on straight E85.

I also have realized that I forgot to mention that I have a Trick Chassis 9" rear and I did a gear swap 3 days before racing. Gear swap on a 9" rear in these cars is a pita and I found it easier to remove Y pipe, and of course also removed my chassis mount torque arm.

 

That. Or, really just signs of detonation in general.

 

That would be stupid of them, E85 burns pretty quickly and if you don't retard the timing on ethanol it may not knock but it's certainly on the wrong side of the timing curve that's for sure and will beat the engine up. General rule of thumb, always pull timing for nitrous.


Eventually it would have, just because the check engine light wasn't lit doesn't mean it wasn't a pending code. If you ever see a static amount of knock retard like that it's guaranteed a knock sensor issue and will eventually throw that code. Many of these codes are set to need multiple instances of it occurring before it actually throws a check engine light (MIL on 2nd error).

 

Yeah, I don't know what to make of it.
Same 80%+ flex fuel I had 2 days prior when I test drove the new rear gears.
Same fuel, for all 7 passes
No KR for 2 N/A passes, and one Nitrous pass.
Then same exact KR (matching 100% TPS position) logged for the next 4 passes

I was under the impression that REAL KR shows up as "steps" or sawteeth, on a datalog, like my truck did when I first got it...
2008 Silverado KNOCK RETARD stock, un-tuned, NON FLEX

TRUCK:



Not like how this one is showing up?

CAR:

 

Personally I would still be taking out 6-7 for a 150 shot seeing as how your timing is all the way up at 31 deg on ethanol. Of course reading the plugs will tell the tale but I'm guessing it's almost on the wrong side of the timing curve (past MBT) with that much timing in it even if it isn't pinging.

 

Oh, I do pull some timing...just not as much as I did with 93. My target was to stay 3 degrees higher than what it was dyno-tuned for, on 93, whether running N/A or when spraying. I'll be the first to admit, I haven't gotten confident with my E-85 N2O jetting combos yet.

Yeah, that's true. I wonder why I never got a MIL then? It did it (4* KR) on four separate spaced apart runs, in the span of about 3 hours

Again, just to clarify.
The 4* KR I logged, was naturally aspirated...with same tune (31* total) as I've made probably 40 passes on with no KR whatsoever, in much hotter weather. Probably 100 passes with 28* total on 93 octane, with never any KR whatsoever.

 

P.S. Not trying to be a hard head...just puzzled as to why the 4* is in direct correlation with the throttle.

Mostly puzzled as to why it would be doing it in the burnout box, with virtually no load whatsoever??

 

Just trying to run 3 more degs on E vs 93 isnt a great plan. You will need to either have it on a loaded dyno or at the track and read your plugs to see what timing it wants. My guess is your timing is to high. On stuff we re-tune we run less timing almost 99% of the time and make the same power and or go faster at the track over the old tune.

 

When it goes into PE it will trigger a static max timing retard with a pending knock sensor code as a fail safe, I can't think of any other code off the top of my head that will cause this same exact condition. This is the last time I'm going to repeat myself.

 

Agreed. Most every time I tune a nitrous car we end up with less timing then before and it ends up making the same power and/or going faster.

 

Fair enough, and I agree.
I just figured since 28* was what it liked on the dyno (and the track), with 93 unleaded, a safe bet with the extra octane from the E-85, was to simply add 3* until I could get back on dyno. It ran 2 mph faster and 2/10ths quicker doing that, FWIW.

Assuming the car has too much timing, even though I have made several passes with zero KR as it is configured right now, any opinion why it could, or would, even see KR in the burnout box?

I grabbed a screenshot of the KR Graph. KR is locked at 4*, as it's MAX VALUE, it's MIN VALUE, and it's AVG VALUE, even in all the cells that only had just ONE hit? That doesn't make sense, does it?