Snow, are you seeing issues with KR similar to Ghost after the switch to the V plugs? Not suggesting they're the cure but just wondering if they have a positive effect at all?
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Snow, are you seeing issues with KR similar to Ghost after the switch to the V plugs? Not suggesting they're the cure but just wondering if they have a positive effect at all?
I am still seeing the same amount of knock as I did with the stock plugs. And thats just from watching my Dashhawk, I haven't done a scan to see if its any more or less. I just glance up at the Dashhawk where the knock used to happen and I still see it.
But, the car does run pretty good at WOT. I just got a 7.33 0/60 out of it.
Same. I put the plugs in and the knock still exists.
Fun Fact: The knock only starts happening once the fuel trims start kicking in...
Really really interesting...the plot thickens. Do you have the MAF/coeffs tuned to the point where you could disable trimming and see if you still get KR?Quote:
Originally Posted by Gh0st
I could tune the MAF off fuel trims, no wideband right now. Im' going to do more logging to confirm what I've been noticing.Quote:
Originally Posted by ScarabEpic22
I've been lurking a while and tuning my Sonic for the past couple of months. FWIW, do not get discouraged - I think it is noise that your knock sensor is picking up. The reason I say this is that I see the same behavior you do with part-throttle tip ins and "burst" knock. For shits and grins, I filled up with a full tank of Sunoco 100 octane, and guess what?Quote:
Originally Posted by Gh0st
The knock is still there. I've been calibrating production vehicles for about 20 years - and this looks like a poor knock window / noise calibration. I'm going to look at it further in the spring - but do not lose hope; you're not alone.
:cheers:
Yeah, that's pretty much what I figured when it did it no matter how much timing I pulled and regardless of what octane I ran. I am running the stock tune now. Too much crap going on in my life and not enough time to diagnose where the noise is coming from. Maybe someone, possibly you, will figure it out.Quote:
Originally Posted by Scot
Desensitize the knock sensors? (GASP!)
I havent logged my Sonic enough, been busy with my day job and tuning TBSSs. Leaves very little time for experimenting and playing with my Sonic unfortunately.
Fudging the sensor calibration on a turbo motor doesn't appeal to me.
If it's the knock sensors wouldn't you get KR at WOT as well?
That's why I'm not sure. I wish there were transient fueling tables in these tunes, I can't see to find them if they do exist. I get the feeling that the turbo is spooling so fast that the fuel isn't being added properly to accomdate the rapid influx of air. The knock is always registered around 2000-2600rpm and almost always after maintaining a speed. It's rarely when Im' actually accelerating to speed.Quote:
Originally Posted by Blue Angel
I have noticed same knock issue on my ATS, cruise speed and tip into throttle and would get knock, adjusted exhaust cam and went away, was actually able to add timing to HO map after that!
It also seems ATS falls out of power after 5600 rpm, boost would drop to 15-17psi, also adjusted intake and exhaust cams for that issue and now pulls 20-21 psi all the way to 7000! I believe there is too much overlap in cam adjustment from factory. I'm still working on tune and hope to learn more!
Great thread by the way!
You retarded the cams before peak torque and then advanced them up top? I've never messed with VVT so I have a lot to learn there.
This is getting interesting. I'm sure the timing I've pulled in these areas is costing me mileage.
Overlap would be for EGR, no? If so, reducing it would increase emissions but likely wouldn't affect anything else? The EGR effect would also keep combustion temperatures higher and may be contributing to the knock? Maybe it's real knock after all...
I have no idea, just thinking out loud.
http://www.hptuners.com/forum/showth...VT-Tuning-infoQuote:
Originally Posted by Blue Angel
Out of the box, the pre 2013 Cruze has really advanced cams down low. Maybe they are too advanced and combined with the boost/dymanic compression results in the part throttle knock. From that thread and what TRS said, we would want to introduce some overlap(retarding exhaust cam)?
I'm going to test it out by retarding by a value of 3 in the exhaust. Like I said, I know next to nothing about VVT so I'm not sure what effect 3 has compared to 5...6...and so on.
There's still no 100% evidence why the 2013 has such lower values for VVT, but I do know when I ran them the car did not sound good at WOT. Anything but WOT ran just fine imo.
there is benefit to moving cams into overlap to a certain degree. overlap will allow fresh air to flow through the cylinder. this might cause a cooling effect in the chamber and help you guys out but then you can run into less boost pushing the turbo out past its limits.
it will be a give and take situation.
Yeah. There has to be a reason GM so much changed how the cams work for the 2013+ model year...I want to fully understand.Quote:
Originally Posted by cobaltssoverbooster
One big difference between your engine and ours is the fuel system, and you can move your cams a whole lot more than we can for good scavenging (you can wait until the intake valve closes to add fuel! :D )Quote:
Originally Posted by TRS-FABRICATION
I'm also waiting on a friend to finish his chassis dyno to do some cam sweeps.
As it stands, I'm using VP 110 octane right now and I still get some knock on cyl 3 in areas I should not. Just like you - I see similar KR; if you ever get a chance, please log your individual cylinders and see which (if any) specific cylinders "knock" more than others. There are noise windows in the calibration, and I think they're a bit conservative in certain areas; I'm not suggesting anyone change their cals - I'm just hoping to make a few changes and log the result.Quote:
Originally Posted by Gh0st
I've calibrated several OEM knock ECM calibrations and with non-knocking fuel (Which VP110 certainly is), noise like this is false knock, especially at lower loads.
There's one other thing it could be (SPI), so I'm also trying to find out if that is the issue.
We cannot adjust transient timing, but let me dig into the airflow calibration; the transient airflow uses MAP/VE and a correction factor from the MAF - I may be able to multiply this a bit to increase the airflow the engine sees on a transient and give more net fuel.
Anyone have any time too look into this farther, or is everyone just trying to stay warm? :)