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Knock Light Causes

KnappAttack said:
This is true ClutchMaster, however the way a Winder is configured, a boost leak at the MAP sensor up in front of the sled would create a higher boost level and lower AF ratio. The MAP sensor in front of the Winder is controlling the boost and fueling. A leak at that sensor or going to it would allow it to boost higher and go lean too. Think about how a manual boost controller works bleeding off pressure to a wastegate in an aftermarket turbo system. This leak at or going to the map sensor would be the same effect, in essence it could be bleeding of a bit of pressure prior to getting to this MAP sensor. It would be the small lines going up front, not the large boost lines going to the engine leaking boost.




The stock 2 Bar sensor will read to 16.5 16.8 or so, beyond that is where it won't read higher. 240 tune is well below that threshold and not a concern.
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He is already seeing 14.8 on 240 wouldn’t it be low not high if leaking? Maybe sensor is bad. Wouldn’t be first. Other one is same thing right? Could swap to test.
 

cannondale27 said:
He is already seeing 14.8 on 240 wouldn’t it be low not high if leaking? Maybe sensor is bad. Wouldn’t be first. Other one is same thing right? Could swap to test.
Click to expand...

Well I suppose it could be the sensor, but if it was reading high he would be very rich on afr’s.
More than likely it’s actually overboosting actually causing some knock. I would first look for a pinched line going to the wastegate. Also I would blow out the ebc and check those lines too. EBC Solenoids don’t like moisture turning to ice, bad JuJu.
 
Running Precision Stage 3 (280 HP) with 3” Sandale Hyperflow. I run half a bottle of Torco in every tank, probably out of habit from running it in my Boosted 1100 Zook. Ive never seen a light on the Sidewinder. I run the Torco primarily for peace of mind, even though im sure it doesnt need it. I honestly dont always trust that im getting good/fresh 91 at the gas stations in N Wisconsin so thats my reasoning. Its probably overkill, but thats just me.
 
ClutchMaster said:
Well I suppose it could be the sensor, but if it was reading high he would be very rich on afr’s.
More than likely it’s actually overboosting actually causing some knock. I would first look for a pinched line going to the wastegate. Also I would blow out the ebc and check those lines too. EBC Solenoids don’t like moisture turning to ice, bad JuJu.
Click to expand...
Mike says this system is fuel pressure controlled for fuel in other words the boost gives 1 psi more fuel pressure per 1 lb of boost at the regulator. So is the Map sensor actually raising the fuel delivery via injector pulse or is the regulator? Maybe both? If so that seems like overkill.
 
ClutchMaster said:
Well I suppose it could be the sensor, but if it was reading high he would be very rich on afr’s.
More than likely it’s actually overboosting actually causing some knock. I would first look for a pinched line going to the wastegate. Also I would blow out the ebc and check those lines too. EBC Solenoids don’t like moisture turning to ice, bad JuJu.
Click to expand...
Another question regarding this statement. If in fact there is ice in lines then what? The sleds in question are in shop for days between rides. Ice would have to form as its being ridden. That would be a major issue.
 
Have to pull plenum and intake tube at a minimum to get at the Knock Sensor. Use a Crows Foot to get in there and torque to 15 Ft/Lbs..... Don't ask me how i know....
 
eightpilot said:
Have to pull plenum and intake tube at a minimum to get at the Knock Sensor. Use a Crows Foot to get in there and torque to 15 Ft/Lbs..... Don't ask me how i know....
Click to expand...
After you have done this let us know how it works, any difference?
 
cannondale27 said:
Mike says this system is fuel pressure controlled for fuel in other words the boost gives 1 psi more fuel pressure per 1 lb of boost at the regulator. So is the Map sensor actually raising the fuel delivery via injector pulse or is the regulator? Maybe both? If so that seems like overkill.
Click to expand...

Ok here’s the deal, as intake manifold pressure increases the fuel pressure also needs to increase to maintain the base fuel pressure. The base fuel pressure is the difference in pressure from the fuel rail to the intake manifold. Or in other words the pressure across the injectors. This regulator just keeps it constant at around 42 psi.
42 psi fuel pressure + 15 psi boost= 57 psi fuel pressure, still only 42 psi across the injectors.
So technically a 1:1 pressure regulator will not add any more fuel due to boost increases. The fuel is added via injector pulse width increase as boost goes up. Boost goes up, more air into engine, needs more injector pulse width.
Usually if the map sensor is flaking out you’ll
Have all kinds of drivability issues with speed density type ecu.
 
cannondale27 said:
Another question regarding this statement. If in fact there is ice in lines then what? The sleds in question are in shop for days between rides. Ice would have to form as its being ridden. That would be a major issue.
Click to expand...

I’m not sure about a Winder EBC (electronic boost controller) but most have some sort of restrictior built into them. Even if they don’t have a restrictor they can have issues. If your overboosting it could be the boost tuning or it could be the EBC not bleeding off the wastegate quickly enough. If it’s a quick spool tune it might be normal to overshoot somewhat then settle into the proper boost.
Atleast we know it’s not hitting 16~17 psi like mike said the stock 2 bar has a little extra headroom built in.
I doubt it’s actually knocking with 91 and 14.8 pounds of boost unless it’s very lean.
Dump a whole can of Torco in and see if it’s still doing it. If so it’s probably that knock sensor playing tidily winks with the ecu.
 
ClutchMaster said:
Ok here’s the deal, as intake manifold pressure increases the fuel pressure also needs to increase to maintain the base fuel pressure. The base fuel pressure is the difference in pressure from the fuel rail to the intake manifold. Or in other words the pressure across the injectors. This regulator just keeps it constant at around 42 psi.
42 psi fuel pressure + 15 psi boost= 57 psi fuel pressure, still only 42 psi across the injectors.
So technically a 1:1 pressure regulator will not add any more fuel due to boost increases. The fuel is added via injector pulse width increase as boost goes up. Boost goes up, more air into engine, needs more injector pulse width.
Usually if the map sensor is flaking out you’ll
Have all kinds of drivability issues with speed density type ecu.
Click to expand...
On the Turbo quads I worked on as boost increased the fuel pressure also increased which caused more fuel to flow through the injectors. This eliminated the need for bigger injectors to a point. We also ran 1:1 regulator and a pressure gauge. They always went well above the 42 psi base as boost was gained. Of course we still had to tune but very little really so I am not sure I believe the injectors are bleeding off all the extra psi. Clutchmaster At 240 tune No Octane boost should be needed according to many. So must be something wrong with something. Really thinking about what Knapp said about Vacuum leak to map sensor. Scary stuff. But very possible. In that case the knock sensor is doing its job.
 
To elaborate in what Kinger posted, knock sensors are a very finicky process to perfect, and each sensor much be tuned for each engines harmonics and "nose".
I know of one member (1CrazySledder)that had a Parker box on his sled, and he's said that the light would flicker and flash quite a bit at all times unless he adjusted it down to desensitize it enough that it was basically off.
To get one to actually work properly, you'd have to basically dyno the engine in various conditions with various grades of fuel and know 100% that it is NOT knocking. Then you'd have to continue assisting fuel quality, timing and AFR to get it to knock and calibrate the sensor to recognize the difference. Literally too scientific of a process without equipment that only OEM's can afford.
The way they combat knock is to run the engines with a bit more conservative timing and slightly richer AFR's.
There's plenty of threads here about tuning with boost so I won't get into that here, or tell you what you should do. Sorry to rain on your parade, but the knock sensor issue is one that can't feasibly or reliably be solved on a sled in the aftermarket.

Sent from my SM-N910R4 using Tapatalk

nate007, Mar 24, 2016EditDeleteIPReport
Click to expand...
I hope technology has progressed enough that this is no longer true and at least with a "Perfect" sensor this now works.
 
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