Anyone getting "false knock" with a built motor?

Quick335XI · 02-13-2021, 01:34 PM

Since the beginning of tuning my motor after building it with closed deck, steel rods, JE forged pistoms stage 4 heads with titanium valvetrain, it's always pulled timing even with low timing, and it's been frustrating... we're at the point now where we're thinking maybe it's "false knock" so I did some googling and found some threads saying that built motors, "especially with closed deck conversions and forged pistons" cause alot of false knock. With more than enough that tuninf; new Eldor coils, new 2 step closer NGK plugs, it's hard to believe this knock is real.

Has anyone else seen that with theirs? Here's a recent log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21

I found this very interesting thread and am wondering if maybe I need to replace my knock sensors with these:

https://www.german**********/showthr...-Knock-Sensors

I re-flashed with the "desensitive knock tables" and it made a difference, am seeing 0's on a couple columns now, but still some negatives in 2 and 3.

Anyone else run into this?

Thanks

feuer · 02-13-2021, 02:23 PM

If you are still getting timing corrections even with desensitive knock tables probably something else is the reason. I’m assuming you have eliminated possibility of fuel issue or poor quality fuel?

Saif2018 · 02-13-2021, 03:08 PM

Quote:

Originally Posted by Quick335XI

Since the beginning of tuning my motor after building it with closed deck, steel rods, stage 4 heads with titanium valvetrain, it's always pulled timing even with low timing, and it's been frustrating... we're at the point now where we're thinking maybe it's "false knock" so I did some googling and found some threads saying that built motors, "especially with closed deck conversions and forged pistons" cause alot of false knock. With more than enough that tuninf; new Eldor coils, new 2 step closer NGK plugs, it's hard to believe this knock is real.

Has anyone else seen that with theirs? Here's a recent log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21

I found this very interesting thread and am wondering if maybe I need to replace my knock sensors with these:

https://www.german**********/showthr...-Knock-Sensors

I re-flashed with the "desensitive knock tables" and it made a difference, am seeing 0's on a couple columns now, but still some negatives in 2 and 3.

Anyone else run into this?

Thanks

Which fuel are you running exactly?

Quick335XI · 02-13-2021, 03:20 PM

I'm running PI with around 60% ethanol. Plenty of fuel, trims look good and rail pressure is good, see lot above... Thats why I'm thinking this knock is false...

Saif2018 · 02-13-2021, 03:34 PM

Quote:

Originally Posted by Quick335XI

I'm running PI with around 60% ethanol. Plenty of fuel, trims look good and rail pressure is good, see lot above... Thats why I'm thinking this knock is false...

Mixed with 91 Oct or 93oct?

Quick335XI · 02-13-2021, 03:35 PM

Quote:

Originally Posted by Saif2018

Mixed with 91 Oct or 93oct?

No E8, usually around 60% ethanol.

Saif2018 · 02-13-2021, 03:36 PM

Quote:

Originally Posted by Quick335XI

No E8, usually around 60% ethanol.

E8?

Quick335XI · 02-13-2021, 04:03 PM

Sorry, E85

Saif2018 · 02-13-2021, 10:57 PM

Quote:

Originally Posted by Quick335XI

Sorry, E85

60% so it must be mixed with Gas right?

Or you on E85 only (100%)?

Quick335XI · 02-14-2021, 02:37 PM

No E85 is 100% pure ethanol... The pump I go to says E85 but usually the sensor says it's around 60%

Saif2018 · 02-14-2021, 03:05 PM

Quote:

Originally Posted by Quick335XI

No E85 is 100% pure ethanol... The pump I go to says E85 but usually the sensor says it's around 60%

Have you tried a different pump, just to rule out quality of the fuel being the cause?

Quick335XI · 02-14-2021, 03:13 PM

Quote:

Originally Posted by Saif2018

Have you tried a different pump, just to rule out quality of the fuel being the cause?

It's difficult because there's not a lot of them but I plan on driving across town next time I need to fill up. The thing is, as we back of timing it makes no difference as when the timing is more advanced... Which sounds like it's false knock.

Saif2018 · 02-14-2021, 03:16 PM

Quote:

Originally Posted by Quick335XI

It's difficult because there's not a lot of them but I plan on driving across town next time I need to fill up. The thing is, as we back of timing it makes no difference as when the timing is more advanced... Which sounds like it's false knock.

Could be false knock,

have you tried running a pump map with 93oct fuel?

Just to see if timing corrections still occur,

tisdrew · 02-15-2021, 07:14 AM

It could be false knock. Dedicated dyno time with a set of "det cans" and competent tuner will likely be able to tell if the sensors are being overly sensitive.

I've read about BMS and VTT using customized knock sensors/tables on their built n54 motors but don't have personal experience.

FEDE/E92 · 02-15-2021, 12:29 PM

How aggressive is your timing? Few people use nylon washers to quite down the knock sensors. Have u tried lowering boost and going full e85 not mixing. Who's your tuner?

iqraceworks · 02-16-2021, 07:23 PM

I would check with your tunner.....the knock sensors are picking something up. To say it's "false knock" sounds like an excuse because you can't find the real issue. Keep backing down timing until it goes away.....and see where you are at. Just assuming the sensors are wrong is a good way to destroy the motor.

This all boils down to the tuner you are using....if he's lost, find a new tuner. If you are going to the cheapest guy to save money, that's the wrong approach. There are several well known guys that do this a for a living. If your tuner can't figure it out...find someone new. That's too much money in a motor build to just roll the dice.

Quick335XI · 02-21-2021, 02:33 PM

But how do you tell if the knock is false or not for sure, esp when the plugs are new, new Eldor coils and lots shows all fuel trims and such are fine?

iqraceworks · 02-21-2021, 04:19 PM

Pull the plugs, and check for signs of detonation...little black specles on the white porcelain of the plugs. If your tuner doesn't know how to read spark plugs....find a new tuner.

Quick335XI · 02-26-2021, 05:58 PM

Plus are clean as a whistle...

latest log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21

Fuel trims looks good, rail pressure, etc... kinda frustrating

Thanks

Saif2018 · 02-26-2021, 07:06 PM

Quote:

Originally Posted by Quick335XI

Plus are clean as a whistle...

latest log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21

Fuel trims looks good, rail pressure, etc... kinda frustrating

Thanks

Still have some nasty timing corrections up top,

What's your tuner saying?

feuer · 02-26-2021, 08:45 PM

Quote:

Originally Posted by Quick335XI

Plus are clean as a whistle...

latest log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21

Fuel trims looks good, rail pressure, etc... kinda frustrating

Thanks

IAT isn’t spiking either. That would cause timing corrections too. Is tuner offering different timing mapping to remedy this or just asking to check hardware and fuel?

Velocity+ · 03-02-2021, 11:45 AM

Take a look at your engine mounts. They could be worn, which causes the engine to move under acceleration and triggers the knock sensors.

02-13-2021, 01:34 PM	#1
Quick335XI First Lieutenant 134 Rep 354 Posts Drives: 2010 335xi Join Date: Dec 2017 Location: Dallas iTrader: (0)	Anyone getting "false knock" with a built motor? Since the beginning of tuning my motor after building it with closed deck, steel rods, JE forged pistoms stage 4 heads with titanium valvetrain, it's always pulled timing even with low timing, and it's been frustrating... we're at the point now where we're thinking maybe it's "false knock" so I did some googling and found some threads saying that built motors, "especially with closed deck conversions and forged pistons" cause alot of false knock. With more than enough that tuninf; new Eldor coils, new 2 step closer NGK plugs, it's hard to believe this knock is real. Has anyone else seen that with theirs? Here's a recent log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21 I found this very interesting thread and am wondering if maybe I need to replace my knock sensors with these: https://www.german*********/showthr...-Knock-Sensors I re-flashed with the "desensitive knock tables" and it made a difference, am seeing 0's on a couple columns now, but still some negatives in 2 and 3. Anyone else run into this? Thanks __________________ 2010 335XI, Carillo Steel rods, JE pistons, Closed Deck, Stage 4 race heads, 6mt, Pure Stage 2 High Flows, B58 Coils, VRSF\|Vu Brothers (Ft Worth, TX)\|JSRTuning, https://youtube.com/channel/UC_kL3RvFSGv9QmTVt6787gg Last edited by Quick335XI; 02-13-2021 at 03:34 PM..*
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02-13-2021, 02:23 PM	#2
feuer Major General 4355 Rep 9,231 Posts Drives: wife crazy! Join Date: Apr 2015 Location: Chicago, IL iTrader: (5)	If you are still getting timing corrections even with desensitive knock tables probably something else is the reason. I’m assuming you have eliminated possibility of fuel issue or poor quality fuel?
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02-13-2021, 03:20 PM	#4
Quick335XI First Lieutenant 134 Rep 354 Posts Drives: 2010 335xi Join Date: Dec 2017 Location: Dallas iTrader: (0)	I'm running PI with around 60% ethanol. Plenty of fuel, trims look good and rail pressure is good, see lot above... Thats why I'm thinking this knock is false...
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02-13-2021, 04:03 PM	#8
Quick335XI First Lieutenant 134 Rep 354 Posts Drives: 2010 335xi Join Date: Dec 2017 Location: Dallas iTrader: (0)	Sorry, E85
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02-14-2021, 02:37 PM	#10
Quick335XI First Lieutenant 134 Rep 354 Posts Drives: 2010 335xi Join Date: Dec 2017 Location: Dallas iTrader: (0)	No E85 is 100% pure ethanol... The pump I go to says E85 but usually the sensor says it's around 60%
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02-15-2021, 07:14 AM	#14
tisdrew First Lieutenant 101 Rep 300 Posts Drives: 2009 335i Join Date: Dec 2015 Location: Melbourne, FL iTrader: (0)	It could be false knock. Dedicated dyno time with a set of "det cans" and competent tuner will likely be able to tell if the sensors are being overly sensitive. I've read about BMS and VTT using customized knock sensors/tables on their built n54 motors but don't have personal experience. __________________ "Wheels and exhaust aren't a build"
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02-15-2021, 12:29 PM	#15
FEDE/E92 Lieutenant 110 Rep 547 Posts Drives: 2007 BMW 335i Join Date: Jun 2012 Location: Tampa, FL iTrader: (3)	How aggressive is your timing? Few people use nylon washers to quite down the knock sensors. Have u tried lowering boost and going full e85 not mixing. Who's your tuner?
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02-16-2021, 07:23 PM	#16
iqraceworks Brigadier General 2218 Rep 3,816 Posts Drives: 2007 335i Join Date: Aug 2019 Location: Missouri iTrader: (0)	I would check with your tunner.....the knock sensors are picking something up. To say it's "false knock" sounds like an excuse because you can't find the real issue. Keep backing down timing until it goes away.....and see where you are at. Just assuming the sensors are wrong is a good way to destroy the motor. This all boils down to the tuner you are using....if he's lost, find a new tuner. If you are going to the cheapest guy to save money, that's the wrong approach. There are several well known guys that do this a for a living. If your tuner can't figure it out...find someone new. That's too much money in a motor build to just roll the dice.
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02-21-2021, 02:33 PM	#17
Quick335XI First Lieutenant 134 Rep 354 Posts Drives: 2010 335xi Join Date: Dec 2017 Location: Dallas iTrader: (0)	But how do you tell if the knock is false or not for sure, esp when the plugs are new, new Eldor coils and lots shows all fuel trims and such are fine?
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02-21-2021, 04:19 PM	#18
iqraceworks Brigadier General 2218 Rep 3,816 Posts Drives: 2007 335i Join Date: Aug 2019 Location: Missouri iTrader: (0)	Pull the plugs, and check for signs of detonation...little black specles on the white porcelain of the plugs. If your tuner doesn't know how to read spark plugs....find a new tuner.
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02-26-2021, 05:58 PM	#19
Quick335XI First Lieutenant 134 Rep 354 Posts Drives: 2010 335xi Join Date: Dec 2017 Location: Dallas iTrader: (0)	Plus are clean as a whistle... latest log: https://datazap.me/u/terryeaton/log-...og=0&data=3-21 Fuel trims looks good, rail pressure, etc... kinda frustrating Thanks __________________ 2010 335XI, Carillo Steel rods, JE pistons, Closed Deck, Stage 4 race heads, 6mt, Pure Stage 2 High Flows, B58 Coils, VRSF\|Vu Brothers (Ft Worth, TX)\|JSRTuning, https://youtube.com/channel/UC_kL3RvFSGv9QmTVt6787gg
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03-02-2021, 11:45 AM	#22
Velocity+ Private First Class 126 Rep 101 Posts Drives: 2018 M240i RWD Join Date: Jan 2017 Location: San Diego, CA iTrader: (0)	Take a look at your engine mounts. They could be worn, which causes the engine to move under acceleration and triggers the knock sensors.
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