Street Build 1G Build: Return of the DSMer!

[Vegas Smith]

Just as a suggestion, I think you should log knock sensor voltage this time.
Were you logging it before?
Anyway, even if the Link ecu doesn't have a way to pull back timing based on knock, at least you'd know from looking at a log if you have any knock, and then you could do some prevention.
Did you see my knock log screen shots that I posted over in dwb's thread yesterday and today?
There's actually one advantage to doing it this way. You could use a new 2g knock sensor, or probably any sensor that fits in the hole. You'd still see the spikes.
Post #30 here:

https://www.dsmtuners.com/threads/crazy-knock-under-part-throttle-low-load-open-loop.543706/page-2#post-153885803

Sorry, I didn't see this post. I wasn't logging knock at the time and don't currently have the ability to. I might look into it in the future, but I'd have to send in the ecu to have the capability added.

 

[We're on Boost]

Sorry, I didn't see this post. I wasn't logging knock at the time and don't currently have the ability to. I might look into it in the future, but I'd have to send in the ecu to have the capability added.

Well, what I meant was that with your Link ECU you probably have one unused channel (input) where you could log raw voltage, just any DC voltage that is 0 to 5 volts, and see a graph of it.

You could connect the wire from a knock sensor to that input and log it. It wouldn't even have to be a 1g knock sensor. It could be a 2g or a Miata, I don't know what all, just so it fits in the hole like it should and is a good working sensor.

Then you would get a graph that looks like the 3rd one down in the 4 graphs I show in post #30 in that other thread.

The idea is that those sharp spikes occur in the knock sensor voltage when there is knock. So even if you don't have a way to set up immediate knock retard as a safety feature, you could at least look for these spikes in your logs to see if you ever get knock under any conditions during your drives. Then you could decide if you want to try to do anything about it.

People have mystified how the ecu interprets knock internally. It looks a lot less mysterious to me when you can see the actual sensor voltage side by side with what the ecu says is knock, like you can with the 3rd and 4th graphs side by side in that post #30.
There is kind of a noise floor that bumbles along at some voltage that doesn't vary wildly. Then if there is knock, it's like bang, you get a spike of voltage from this little microphone that we call a knock sensor, and that voltage spike sticks right out on the graph.

I suppose an advantage of using a good working 1g sensor is that it would be easier to relate it to the records I have like I showed in post #30, and I have several of those. Or, the advantage of other sensors is they have a stronger voltage output usually. I remember in the early days of AEM EMS, one of the AEM guys had a demo of how "crappy" the 1g DSM knock sensor was. He was urging 1g users of EMS to switch to a 2g knock sensor because it has a stronger output. He would put the 1g sensor into a vise and hit it with a hammer and I guess it didn't put out any voltage (he said). Maybe he had a dead one, or whatever, who knows. Anyway, you can see my 1g knock sensor is working just fine in the graphs I showed. It's just that the noise floor with no knock runs along at about a quarter to a third of a volt (on my engine when it was more stock). Not much. My ecu+ had no trouble logging it. I imagine your LinkECU should be at least as good for that, if it has all modern internals (which I don't know if it does).

 

[Anfurnyy]

Sorry, I didn't see this post. I wasn't logging knock at the time and don't currently have the ability to. I might look into it in the future, but I'd have to send in the ecu to have the capability added.

I think all you have to do is solder a wire from one pin to another. If you reach out to Link they will tell you which pins. Mines the white wire.

It seems silly to me that they wouldnt have it connected in the first place, and just have it disabled with a user agreement type of approval to enable it.

 

[Vegas Smith]

I think all you have to do is solder a wire from one pin to another. If you reach out to Link they will tell you which pins. Mines the white wire.

It seems silly to me that they wouldnt have it connected in the first place, and just have it disabled with a user agreement type of approval to enable it.

View attachment 702481

Oh cool, what knock sensor are you running? What input is it using?

 

[Anfurnyy]

Oh cool, what knock sensor are you running? What input is it using?

I'm using a Bosch wideband sensor, it uses the factory wideband input. According to link that input is specifically for the knock sensor and can't be used for anything else.

 

[Vegas Smith]

I'm using a Bosch wideband sensor, it uses the factory wideband input. According to link that input is specifically for the knock sensor and can't be used for anything else.

Im confused, you’re using a Bosch wideband for your knock sensor?

 

[Anfurnyy]

Im confused, you’re using a Bosch wideband for your knock sensor?

Sorry Bosch wideband knock sensor. Or a "donut" sensor. The knock frequency is adjustable in Link software so you can set what knock frequency it listens for

 

[We're on Boost]

Sorry Bosch wideband knock sensor. Or a "donut" sensor. The knock frequency is adjustable in Link software so you can set what knock frequency it listens for

Nice, I didn’t know about those. So I read the specs for the KS4-P sensor, and then read the “knock” topics in the G4X help.

Some interesting things about knock control in the G4X help. It gives a simple formula for what the knock frequency will probably be for any engine:
knock frequency (kHz) = 1800 / (3.14 x Piston Dia (mm)). So for our engines that would be about 6,750 Hz.

It says the filters available in Link are narrow band filters. A narrow band filter is a band-pass filter with a narrow band pass. You can use this once you know what frequency range to pay attention to (it rejects the rest).

You need to set a threshold level for the knock sensor signal strength above which correction will occur (like timing retard). Then you set a schedule for how to increase correction for increasing knock signal level. I think you can also let it try to figure that stuff out for itself.

It says that most OEM knock sensors are narrow band sensors, not wide band. That is news to me, because I thought our filters were in the ecu, and that our sensor would be putting out a wide range of frequencies.

If our sensors are narrow band, that would explain why the sensor voltage spikes I’ve logged are so clearly there, standing out clearly from the normal engine noise voltage. It’s completely obvious where the knock is just by looking for those voltage spikes in the log.

So I think that would be another option for us, rather than using a wideband sensor. We could use a regular 1g or 2g knock sensor (2g pref I think). In Link, we would turn filtering off. You wouldn’t need those filters because the OEM sensor already has that part figured out. We’d determine the threshold value – that would be the value at the base of any spikes that occur in the signal level. And the schedule for increasing correction.

Or, the completely manual method I proposed before. Just logging knock sensor voltage from a 1g or 2g OEM sensor, and not using it directly to control the engine at all. Just look for spikes in the voltage log. Just use that as an indicator, like we use air/fuel ratio from a wideband O2 sensor to indicate where something in the tune isn’t right.

 

[Spleen8urLSX]

I can tell you the Bosch knock sensor is also compatible with AEM v2 and Infinity at the least, if anything it’s a nice option in place of the oem ones that are getting hard to get.

Also kinda related but unrelated, did LinkECU start completing the knock circuit in their vr4 g4x plug and play? We found on the g4+ vr4 plug and play that there was no knock capabilities as LinkECU opted to not finish that feature, we easily corrected it by adding a jumper wire on one of the boards per instruction of their staff on the LinkECU forum. I thought this had been corrected when the g4x came out for us but found out after I bought mine it had not been, another reason I opted not to use it as I wasn’t into the idea of soldering on a brand new $1000 standalone but wanted knock control and logging capabilities. Just a general curiosity if they corrected this, and I guess could be a warning as well for new LinkECU users.

 

[Anfurnyy]

I can tell you the Bosch knock sensor is also compatible with AEM v2 and Infinity at the least, if anything it’s a nice option in place of the oem ones that are getting hard to get.

Also kinda related but unrelated, did LinkECU start completing the knock circuit in their vr4 g4x plug and play? We found on the g4+ vr4 plug and play that there was no knock capabilities as LinkECU opted to not finish that feature, we easily corrected it by adding a jumper wire on one of the boards per instruction of their staff on the LinkECU forum. I thought this had been corrected when the g4x came out for us but found out after I bought mine it had not been, another reason I opted not to use it as I wasn’t into the idea of soldering on a brand new $1000 standalone but wanted knock control and logging capabilities. Just a general curiosity if they corrected this, and I guess could be a warning as well for new LinkECU users.

I'm Not sure about the full standalones, but I believe that the PNP units do not have the knock sensor connected internally on both G4+ and G4x.

I also had to wire a jumper

 

[Vegas Smith]

Under construction...

 

[92AWDHX40]

Yay man your still at it.

 

[Anfurnyy]

Under construction...

View attachment 704281

You using a CDI box with those coils?

I'd love to run a COP setup but I though I remember reading the the G4+ didn't support COP. Might have to look into that more.

 

[Vegas Smith]

You using a CDI box with those coils?

I'd love to run a COP setup but I though I remember reading the the G4+ didn't support COP. Might have to look into that more.

No need to use a CDI. These coils are good for probably 1200hp or more. I sold my arc-2 and told the guy building my harness to wire it for sequential ignition with smart coils. Link can do sequential ignition you just have to change settings and wire the coils differently. No ptu, cdi or stock coils for me.

 

[DreamChaser7]

No need to use a CDI. These coils are good for probably 1200hp or more. I sold my arc-2 and told the guy building my harness to wire it for sequential ignition with smart coils. Link can do sequential ignition you just have to change settings and wire the coils differently. No ptu, cdi or stock coils for me.

Would that setup work with DSM link V3 on SD? I need more info on this especially the wiring although a ways off for me, would like to know how to do it.

 

[Anfurnyy]

No need to use a CDI. These coils are good for probably 1200hp or more. I sold my arc-2 and told the guy building my harness to wire it for sequential ignition with smart coils. Link can do sequential ignition you just have to change settings and wire the coils differently. No ptu, cdi or stock coils for me.

Definitely going to read up on that then. Thanks

 

[Vegas Smith]

Would that setup work with DSM link V3 on SD? I need more info on this especially the wiring although a ways off for me, would like to know how to do it.

No, dsm link can only do stock-style wasted spark. I’m running Link g4+ which is totally different.

 

[Vegas Smith]

Taking it one step at a time and trying to enjoy the process as much as I can with daily 103-106 degree heat. I hit a couple potholes at the beginning that I'll be detailing later but it has been smooth sailing at end.

 

[pieceofcloth]

The heat is soon bad out here, I feel you. My garage bakes me.

 

[Anfurnyy]

You run a g4x right? Do you have a speed sensor input wired in?

 

[Vegas Smith]

You run a g4x right? Do you have a speed sensor input wired in?

I have g4+ which is basically the same. In my first setup I used stock speed cable. On current build I’m using gps.

 

[Anfurnyy]

I have g4+ which is basically the same. In my first setup I used stock speed cable. On current build I’m using gps.

Oh I thought you made the switch to an X.
Reason I ask is that the g4+ doesn't seem to have a speed sensor input by default. Sounds like you'd need to wire it in to an input somehow.

Want it for rolling antilag and launch control stuff.

 

[Vegas Smith]

Oh I thought you made the switch to an X.
Reason I ask is that the g4+ doesn't seem to have a speed sensor input by default. Sounds like you'd need to wire it in to an input somehow.

Want it for rolling antilag and launch control stuff.

Yeah it has a speed sensor input. I believe it’s the digital input 3 pin 18. If you switch to gps then you can do all sorts of cool stuff like 1/4 times etc

 

[Anfurnyy]

Yeah it has a speed sensor input. I believe it’s the digital input 3 pin 18. If you switch to gps then you can do all sorts of cool stuff like 1/4 times etc

Gps requires a separate CAN module it sounds like?

 

[Vegas Smith]

Yeah something like a digital dash or a new ecu with built in gps. I have mine connected to my powertune dash.