E39 lfx kr

[Rhino79]

Anyone noticing a rediculous amount of KR at wot with premium fuel. I have reduced the timing a bit and still seems to be showing crfazy knock. Ive drained the tank and refilled and still the same. Is this normal and are the kr settings overly sensative in this ECM?

[joecar]

Post log files.

[GMPX]

Not only seen it, you can hear them knocking sometimes :ermm:, well, that is on the LFW I must admit, but isn't the LFX just a bigger version of that engine?

[Rhino79]

10:1 compression (stock is 11.6:1), stock engine with forged pistons and twin 62s on 93 octane, zl1 pump and running 50/50 water meth.

[GMPX]

Ahhh, ok, that's a little different then. LFX is E85 capable right?

[Rhino79]

I have enough fuel system for it yes. I am also going to try another spark plug. I have found the coldest I can run is an LTR7ix11

[swingtan]

If it's anything like the E39 SIDI motor, then I think the knock is a "design feature". The only way I could effectively reduce it in mine was to run a 17% ethanol blend (as a test I added about 15L of E85 fuel to the tank). This made a significant difference to power and the knock levels.

Generally though, I work on the usual fuel and spark tables to tune out the KR. I actually increase the sensitivity settings to try and reduce the audible knock as well.

If you think you are getting false KR, then look into "Knock Balance Rates" {B1940} in my OS. Any positive value in here has the tendency of adding KR even when nothing is detected. I should do some more work on that table to see if it can be effectively used when tuning, or if it's just a stock OS fail safe for the all encompassing tune.

Simon.

[Rhino79]

It is an sidi motor. So for tomorrow I'm gonna swap/read plugs. Go colder if needed. I'll check those tables Simon. I actually bumped the noise threshold up in hopes I would see a change in kr reported but no. I'd like to give the owner an 93 and e 85 tune, but I hate to have to detune it son much if it"may" be false knock.

[Rhino79]

Another reason for me to believe its false is that the pistons are now 2618 forged and run much more skirt clearance than stock. Nearly .003" more than stock I do believe.

[joecar]

If you can, use a listening device (e.g. Chassis Ear) to listen to the block while running on the dyno, real knock will be apparent and distinct from other mechanical noise.

[gmh308]

If there are now 2618 pistons in the motor you will need to turn up the knock noise thresholds per cylinder. >> EDIT - Just saw you turned up the noise floor already. You could keep turning it up until you hear real knock (like Joe mentions) to establish whether you have real knock or not - the 2618's will handle it ok.

It depends whether they have offset pins as to how noisy they really are. "Dont you just love the sound of piston slap in the morning" :)

[joecar]

"...it smells like victory"

[gmh308]

"...it smells like victory"

ROFL. You got it Joe!

[Rhino79]

Could the kr pid be wrong or could the ecm's kr strategy be different than what we are used to seeing? today on the dyno, I had a flat 15* timing commanded and I had a spike at 5500 rpms where it said 5* of kr but it only pulled about 1* from commanded timing........Ill log with the mdi tomorrow first thing to see if anything looks different.

[GMPX]

Actually I think the final timing you are seeing is not taking in to account knock retard, I remember seeing that on our E39 car as well. So although the PID might be wrong, it is what it is, we can't change how the ECM reports timing via the PID.

[Rhino79]

SO i logged some on the dyno with the mdi today. At one point it showed 4.9* kr, Im commanding 18* and it only dropped it to 17*, sometimes it didnt drop at all. I have verified the kr and timing pid in efi read exactly what the mdi does. One benifit of the mdi was to see which cylinders it was triggered by, which I still dont buy into. Im running almost 10* less timing than the stock table on 9 psi, meth, and 1.5 less compression. Oh well , the pistons are forged, plugs look good, and it picked up 100 rwhp from 10* of timing to 18* and I was showing the same kr at 10* as I am at 18*. Gonna tidy up this 93 tune for the customer, then move on to e85. Will keep posted

[Rhino79]

501 rwhp on 93 octane, meth, and 15 lbs! E85 tomorrow!

[GMPX]

Yikes!

[Rhino79]

E85 is a no go, the di pump maxed out. SO tomorrow is race gas, and more boost! The 93 octane ended up at 532 rwhp, 450 rwtq!!

[Boost]

FWIW, my Cruze on a bone stock tune and 93 octane knocks terribly and audible. I made a high horsepower / boost tune where I actually sensitized it and it kept up with an Abarth to 110 mph with no knock. My worst knock always occurs at part throttle (burst?)

So back on topic I agree that it almost seems like audible knock is a design feature on some of these. How terrible...

I am still looking for a scientific article that is allegedly out there that claims knock is beneficial in cleaning carbon :anitoof:

[swingtan]

That article must have come from Toyota.......

[Boost]

:funnypost:


LOL - .... I think it was Robert Bosch. But I can't find it for the life of me.

:laugh:

[joecar]

Knock does break up crusted carbon deposits... and also head gaskets and pistons.

[Rhino79]

Lol. Chassis ear after kr desensatizing showed no kr, just a smooth sewing maching sound. We ended up with 546 rwhp on 101 octane.

[Boost]

:muahaha::exactly: @ Joe

Great work Rhino, impressive results !!!

[GMPX]

Lol. Chassis ear after kr desensatizing showed no kr, just a smooth sewing maching sound. We ended up with 546 rwhp on 101 octane.
:rotflmao:
I wonder if GM will ever go ahead with the rumoured LF3 (Twin Turbo SIDI V6)? Because that is a pretty decent number for a 'sewing machine'.

[Rhino79]

Its on the 2014 rpo list.

[GMPX]

For what cars? Initially they had considered it for the Corvette I believe.

[ScarabEpic22]

Its on the 2014 rpo list.

Awesome, a 3L or 3.2L twin turbo SIDI V6? Sounds great to me!


For what cars? Initially they had considered it for the Corvette I believe.

We might know more tomorrow, C7 Vette is going to be unveiled.

[Rhino79]

3.6 sidi tt.... dont know what vehicles yet though. I believe mid size suv applications at first though, but I could be wrong.

[GMPX]

Awesome, a 3L or 3.2L twin turbo SIDI V6? Sounds great to me!
I am of the old school that says a Corvette should have a V8 or stop making it!, but there is some other applications that the LF3 (TT 3.0L SIDI) would go really well in. The 3.0L delivers in highway fuel economy but is dismal around town due to the lack of low end torque, the turbo's would cure that issue. But then, the dilemma (for GM) is the GenV SIDI's are probably going to be even better on fuel economy so they'll make the power and torque we like with the V8's and get large V6 fuel economy too. The problem then is cost, how much is an LF3 v's a GenV going to cost them to make? Probably double, but for GM selling a Twin Turbo direct injection DOHC Cadillac in Europe is going to look better on paper for the European market than a pushrod V8.

[VTuner]

The LF3 is going in the 2014 Cadillac ATS-V :)

[ScarabEpic22]

3.6 sidi tt.... dont know what vehicles yet though. I believe mid size suv applications at first though, but I could be wrong.

Even better, bigger displacement! :D


I am of the old school that says a Corvette should have a V8 or stop making it!, but there is some other applications that the LF3 (TT 3.0L SIDI) would go really well in. The 3.0L delivers in highway fuel economy but is dismal around town due to the lack of low end torque, the turbo's would cure that issue. But then, the dilemma (for GM) is the GenV SIDI's are probably going to be even better on fuel economy so they'll make the power and torque we like with the V8's and get large V6 fuel economy too. The problem then is cost, how much is an LF3 v's a GenV going to cost them to make? Probably double, but for GM selling a Twin Turbo direct injection DOHC Cadillac in Europe is going to look better on paper for the European market than a pushrod V8.

Me to, the Vette's only been a V8 (except for 53-55 per wikipedia so who knows) and it should stay that way. If you want fuel economy, why the heck are you looking at a Vette? And again, if you can afford a Vette, why are you worried about 1-2mpg?


The LF3 is going in the 2014 Cadillac ATS-V :)

Crap, I wanted a V8. :( I was hoping LSA, but I didnt think GM would want the ATS to be faster than its big brother CTS-V with the same engine. TT DI V6 will work too I guess...lol.

[Boost]

for what cars? Initially they had considered it for the corvette i believe.

GRAND. NATIONAL. :Eyecrazy:

The first Corvette was a 6 cylinder. And most of the newer ones get close to 30 mpg on the highway.

That being said, I think the 3.6TT should go in the Spark and Sonic :exactly:

[GretchenGotGrowl]

GRAND. NATIONAL. :Eyecrazy:

The first Corvette was a 6 cylinder. And most of the newer ones get close to 30 mpg on the highway.

That being said, I think the 3.6TT should go in the Spark and Sonic :exactly:

Thought I would jump in here after watching from afar. First of all, a Spark with a 3.6TT would be good competition for a Juke-R for sure.

The car Rhino79 has been tuning is mine. It has been a fun project and it runs/drives like it came from the factory with the turbos. Our first outing at the track we pulled down a 9.53 at 111 MPH in the 1000'. There's a little bit more tweaking to do and this thing has a good shot at breaking into the 10s with slicks and skinnies.

Thanks everyone on this forum for your help and support. I'll try to keep you updated on the progress.

[joecar]

Good ET... I thought TS was low, but then I saw 1000' (short track)... so very good ET/TS good job :cheers:

[Rhino79]

Its trapping 97-98 in the 1/8th! It runs really good.

[GretchenGotGrowl]

Here's the time slip. Going to try the new tune out this weekend, but can't get back to the track until March.
http://img.tapatalk.com/d/13/02/05/vapabu8y.jpg

[Boost]

Nice! Looks almost identical to my old '95 Rx-7 R2 slips, and that thing was fully built!

About the E39 KR, would you guys mind taking a peep at this? I am trying to get it to run a tick faster than 9.2 in the 1/8 and I have 7 degrees reported KR, none audible though and pulls smooth.