Knock when coming into boost

[ttls1]

Hi, A mate and I have been tuning my turbo LQ4 landcruiser and seem to be getting knock that we can not hear or get rid off. I have no doubt its definitely there as its in the log but would like a few ideas if possible on ways to correct it as neither of us are experts and were learning along the way. I have attached the tune and a couple of logs. It has been quiet hot here and the IAT's have been up there but I took it for a run at night when it was a bit cooler (log 7) and it still had it. Were running 98 fuel. Have tried pulling some timing out and giving it more fuel but its still there. Any info would be great. We had it in closed loop for the Log 7 run but it was OL for the others.

[darcy]

You sure it's not just too lean?

Its 14:1+ just before it knocks

[ttls1]

Well we took 5 degrees out of the whole table and added lots more fuel. As you can see in the log it still has knock. Any ideas on where to go from here? The fuel is 98

[wesam]

You have to set B3613 to 55 kpa you have it at 120 kpa which make delay before entering PE
Also try to make B3643 1.5 so it will enter PE faster then try to make your AFR 11.4 with 12 degree of timing along the line
then try it

[ddnspider]

The first log looks like its too lean as stated above and too much timing. Then when you added fuel and pulled timing it looks like its very rich and not enough timing. Too rich/too little timing can cause knock too. I've experience that where I actually had to add timing to clean u the knock. Do what wesam said and make it enter PE faster, set the A/F to something reasonable, low 11:1's and timing safe as well like 10-12*. Your IAT's are getting high, but you are also running 98 octane so you have more cushion than 93.

[barbermi]

Thanks for the info we will try that. Should there be a transition to 11.4:1 or should it be there at 100kpa?

[ddnspider]

Thanks for the info we will try that. Should there be a transition to 11.4:1 or should it be there at 100kpa?

Pretty much you should always have a transition. My open loop fuel table transitions from stoic at low map to ~13:1@100kPA, but I have my PE table ramped from 14:1 to 11.2-11.4:1 over the rpm range. I.E. off idle and low RPM, you don't need to have it rich since you won't generate much if any boost. You just need to monitor and see at what rpm it will make boost and go from there.

[barbermi]

Thanks for the reply. We will adjust the boost VE so as it comes onto boost we see ~ 13:1. We will then transition it to 11:2 or so at 185kPa MAP. Once we have the AFR's sorted we will increase the spark table 5deg across the whole lot (we dropped it this much yesterday trying to eliminate knock). We are going to use the KR histogram to help us tune spark. Has there been much success using this histogram for tuning previously?

[ddnspider]

if the knock is real, yes it can help. I would start by setting the timing to something like 10* across the board in any g/cyl where you're in boost. Get your A/F sorted out first and then start worrying about adjusting the timing. Make sure that you get it rich enough once youre actually in boost. Anything over a couple psi and you'll want the A/F into the 11's with the richest spot at peak torque.

[barbermi]

Thanks again.
Should the boost VE and spark table be tuned while in open or closed loop?