knock settings

[chenz]

Hey fellow TBrickers. I have also posted this question on msefi.com but It may be Volvo specific so I though I'd post it here to. I have a b23ft in my 242gt.

I have MS2 with code 2.88. Boris knock sensor wired through IAC2B (no idle control) strait to JS4, noting that Boris sensor is 5v so it can be handled directly. With the default megatune settings (threshhold(V) 0v, knock threshold 2v) I get a slow knock retard 1 degree at a time. Knock disabled, the problem is not there. When setting the Threshold(V) to 1.5v I get a constant 3 degrees of retard and no more (see end of datalog). When I set it to 3v I get none at all. Megatune seems to act independintly of the knock sensing unit. When I adjust the pot on the sensing unit to make the light turn on I get no corresponding reaction in megatunes regardless of the settings.

When the knock light is on I get 0 volts at JS4 and no light 5 volts so it must be a setting problem. I have rebooted the code with no change. could someone please take a look at my MSQ and direct me on what to do as I'm sure it's a settings problem but what. Also attached is a datalog where you can see what's going on.

Thanks, Vincent

I have trouble posting my MSQ's here as I can't find the "advanced settings" so an MSQ and datalog are here
http://www.msefi.com/viewtopic.php?f=89&t=33366&p=204358#p204358

[chenz]

So it stopped knock retarding at idle. Why I don't know?:wtf: (enough changing settings and changing back maybe:roll:) but I still have knock issues when driving.

looking at the datalogs, I see when knock retard is shown. I get no light on the LED for Boris knock sensor. Is this possible? I thought that when the boris knock sensing unit sensed knock it would send a simultaneous signal to the LED and to megasquirt. But megasquirt is registering knock without the LED lit?

The engine is not quick as it used to be. My AFR is good at about 12.5 as average in boost so I need more advance. and the engine is in great shape (not just a slug motor) so it's definently a tunning issue. Adding more advance makes the car pull harder, but with this knock issue I want to get it sorted before I fine tune the map incase I novicely break somthing. If I disable knock control I get no knock retard so what is happening is settings defined. And at 3500rpm the settings say to ignore knock due to engine noise, my datalogs show knock retard shuts off.

Could someone post their knock settings so I can compare. or any suggestions would be great.

I will keep this thread up to date and try to get more info. What gear it's knocking in etc. because it knock's only sometimes just seems way to sensitive. And when at full 10 degrees knock retard it takes almost 40 seconds to fall back to 0 even with throttle, RPM and MAP change :wtf:

Thanks, Vincent

[chenz]

Just to note I have JohnMc's spark map from
http://forums.turbobricks.com/showthread.php?t=145367
just retard 5 degrees to be safe.

[Karl Buchka]

Not sure this has any bearing on your problem, but I tried running some spare outputs pins (for fan control and such) through my unused IAC pins and it caused some really really wonky behavior from the Megasquirt. I would try moving the knock-sense wire to one of the SPR pins or just seperate from the DB37 entirely.

[Boris740]

Your knock threshold is low so you might be picking up ambient noise. KnockesnseMS has output that swings between 0 and 5V Set your thresholds to 1v and 4v