KR with cruise control light load up hill.

[Polonda]

2013 6.2 Silverado

I've been fighting an KR issue when I have the cruise control on set to approx. 70 mph. All is fine until I start to get to a slight uphill and the truck starts to knock. I have played with the timing in that area with no luck. I understand some say the truck sensors are very sensitive, however I'm leery of de-sensitizing them. I halved my burst know and adjusted the decay on the sensors but have not changed the sensitivity. Is it just how the trucks are and I shouldn't be worried about it? Or possibly something in my tune as I'm still learning a lot. Any advice on the KR and tune in general would be great!

I just notice I actually had some KR at idle after startup in this log as well. I had just flashed the PCM so not sure if that caused it?

2013 Silverado 5-30-14.hpt
6-30 drive to work added timing at 70mph.hpl
tuning histogram.cfg
2013 Silverado Stock Tune 19213 miles.hpt

[CSTune]

2013 6.2 Silverado

I've been fighting an KR issue when I have the cruise control on set to approx. 70 mph. All is fine until I start to get to a slight uphill and the truck starts to knock. I have played with the timing in that area with no luck. I understand some say the truck sensors are very sensitive, however I'm leery of de-sensitizing them. I halved my burst know and adjusted the decay on the sensors but have not changed the sensitivity. Is it just how the trucks are and I shouldn't be worried about it? Or possibly something in my tune as I'm still learning a lot. Any advice on the KR and tune in general would be great!

I just notice I actually had some KR at idle after startup in this log as well. I had just flashed the PCM so not sure if that caused it?

2013 Silverado 5-30-14.hpt
6-30 drive to work added timing at 70mph.hpl
tuning histogram.cfg
2013 Silverado Stock Tune 19213 miles.hpt

Do you have headers/exhaust on the truck?

[Polonda]

Do you have headers/exhaust on the truck?

Nope. Truck is bone stock besides the tune.

[ingsteve]

What kind of fuel? Try with premium...if kr are still present they should be false kr...else i would check your spark plugs and cables...

[Polonda]

I always run 93.

[ingsteve]

Try reduce spark and see...

[Polonda]

I'm almost positive I'm already running significantly less spark in the trouble area over stock. I have zeroed out the AFR and variable cam table. I'm going load the stock tune tomorrow and do a data log and see if it goes away or gets worse. I'm thinking its the sensitive knock sensors but I'm just not sure if I want to make any adjustments on them.

[Polonda]

I'm almost positive I'm already running significantly less spark in the trouble area over stock. I have zeroed out the AFR and variable cam table. I'm going load the stock tune tomorrow and do a data log and see if it goes away or gets worse. I'm thinking its the sensitive knock sensors but I'm just not sure if I want to make any adjustments on them.

Loaded the factory tune today. Still knocks on up hills with cruise at 70.

[GXPLS4]

Increasing the tcc lockup helped me whenit used to that.

[Polonda]

Increasing the tcc lockup helped me whenit used to that.

I'm still somewhat new to HPtuners. Do you mean you increased the rpm it locked up at?

[BigDaddyCool]

Your LTFT's are simply adding too much fuel and thats what brings on the knocking. Typically speaking the cars seem to knock when their rich part throttle..... Log the cells on the MAF in that spot. Switch off LTFT and log without it......

---

By the looks of it you need to add fuel around that area so that LTFT's dont add more to compensate..... Make a small adjustment after logging with the LTFT's off, and then if it's still occuring and you dont feel the knocking, I'd say just leave it ...... the stock setups are really designed to 'play nice', over and under compensate for events so you dont really feel it...

[Polonda]

I'll give that a shot. I did my maf tuning with ltfts off and used stfts. Stfts seem to be plus or minus 1. Thanks for the ideas.

[Polonda]

Your LTFT's are simply adding too much fuel and thats what brings on the knocking. Typically speaking the cars seem to knock when their rich part throttle..... Log the cells on the MAF in that spot. Switch off LTFT and log without it......

---

By the looks of it you need to add fuel around that area so that LTFT's dont add more to compensate..... Make a small adjustment after logging with the LTFT's off, and then if it's still occuring and you dont feel the knocking, I'd say just leave it ...... the stock setups are really designed to 'play nice', over and under compensate for events so you dont really feel it...

Any harm in leaving the LTFT's disabled?

[ingsteve]

No usefull...if you tune correclty the fuel, your LTFT shall be within 0% and -4%

[8850]

You have added a lot of timing in the lower Cylinder Air frames. I would put back to stock up to around .68. And stock PE up to about 3000 rpm. I always keep the Spark Limiters tables stock too. Unless you are trying to get a faster downshifts.

I have my Corvette with LTFTs off, VE table disabled and running OL. Makes for easy tuning and runs great.

If your stock tune is creating kr as well then might have to look farther.

[BigDaddyCool]

You have added a lot of timing in the lower Cylinder Air frames. I would put back to stock up to around .68. And stock PE up to about 3000 rpm. I always keep the Spark Limiters tables stock too. Unless you are trying to get a faster downshifts.

I have my Corvette with LTFTs off, VE table disabled and running OL. Makes for easy tuning and runs great.

If your stock tune is creating kr as well then might have to look farther.

Openloop just works so well Esp if you have a wideband guage on the dash to keep an eye on it

[Polonda]

You have added a lot of timing in the lower Cylinder Air frames. I would put back to stock up to around .68. And stock PE up to about 3000 rpm. I always keep the Spark Limiters tables stock too. Unless you are trying to get a faster downshifts.

I have my Corvette with LTFTs off, VE table disabled and running OL. Makes for easy tuning and runs great.

If your stock tune is creating kr as well then might have to look farther.

Stock tune does the same thing and timing didn't have an affect on the KR.

[Polonda]

Your LTFT's are simply adding too much fuel and thats what brings on the knocking. Typically speaking the cars seem to knock when their rich part throttle..... Log the cells on the MAF in that spot. Switch off LTFT and log without it......

---

By the looks of it you need to add fuel around that area so that LTFT's dont add more to compensate..... Make a small adjustment after logging with the LTFT's off, and then if it's still occuring and you dont feel the knocking, I'd say just leave it ...... the stock setups are really designed to 'play nice', over and under compensate for events so you dont really feel it...

Looks like you may of been correct on the LTFT causeing the issue. I disabled them and did a log in that area. Made adjusted in the tune for the MAF. As soon as I got the STFT's to the -1 to -2 area and did a few more test logs the KR was completely gone. I will attempt to re enable the LTFT's and see if the KR stays away.