Multiple CAN connections (MR2)

[BenAmr2turbo]

Hi there, I was wondering if anyone could clarify how to connect my CAN devices? I have;

-Toyota MR2 V1 Link G4x ST185 (G4X)

-Link Strada MXG 7" Street Dash

I have a 5 pin CAN to PCB loom to connect a laptop to tune the car - but I also want to connect a canlambda AND an MXG dash...

How could I use the lambda, dash and tuning cable all at once? As it specifically says in the manual that a series connection may cause problems with USB tuning..

There is only the one 5 pin plug in the ECU, as far as I know?

 

Any suggestions are welcome.

Thanks.

 

[Adamw]

28 minutes ago, BenAmr2turbo said:

There is only the one 5 pin plug in the ECU, as far as I know?

There are 2 on that ECU, the one on the top board is USB and the one on the bottom board is CAN1 and serial.  You will need another CANJST (easiest) or CANPCB cable. 

 

 

[BenAmr2turbo]

Great, thank you, I appreciate the reply, I didn't realize there was another connection.

Is it fine to connect the MXG dash and the canlambda in series to the second CANJST?

Or would you connect the dash to CANJST and then the CANlambda to the MXG dash?

As far as I know I don't need the canlambda connected to the ECU, just to show on the dash. Is either route OK?

Many thanks

[koracing]

CAN Bus can have several items on the same bus as long as they are set up to operate at the same connection speed.

 

Also, why would you think you didn't need the Canlambda to go to the ecu?  The whole point of a lambda sensor is to allow the ecu to use it's feedback to aid in tuning or correcting via closed loop.  Do you have a different lambda sensor for the ecu already?

 

[BenAmr2turbo]

3 hours ago, koracing said:

Do you have a different lambda sensor for the ecu already?

Most of the tuning will be done on a rolling road with it's own probe..

So I have a 5 pin CAN 1 on the bottom board, and a CAN to PCB.

My problem is with this part of the manual...

So I can wire the MXG dash to the bottom and tune via the top boards.

Where can I connect the lambda?

I'm fine with it just displaying on the dash to visually monitor.. I still have a dizzy cap and it wont be able to pull ignition timing anyway.

Unless there are any other solutions for a third connection to the ECU?

Thanks.

 

[Vaughan]

2 hours ago, BenAmr2turbo said:

Where can I connect the lambda?

To the same CAN Bus as the dash as shown in the screenshot from the PCLink help manual above.

2 hours ago, BenAmr2turbo said:

My problem is with this part of the manual...

This bit says that if you are using the 5 pin plug for CAN then make sure you don't have big long wires running off the serial plugs, this was only an issue when using one of the older CAN Dash looms that had the serial wires as well as the CAN wires in it. If using a loom with those wires present the easiest solution is to cut the serial wires off at the connector.

[BenAmr2turbo]

1 hour ago, Vaughan said:

make sure you don't have big long wires running off the serial plugs

Thank you! I misread that quite badly..

Would a CANJST from the bottom board to a CANTEE, then to the lambda/dash be the easiest solution?

I would prefer not to solder the CANF plug if I can help it.

Apologies for my silly questions

Thanks for the replies!

[Vaughan]

Yes a CAN JST, a CANTEE and an appropriate number of extensions would do the job. Note you want to keep the distance of the CAN Lambda stub from the main CAN bus nice and short.

[koracing]

9 hours ago, BenAmr2turbo said:

Most of the tuning will be done on a rolling road with it's own probe..

.....

I'm fine with it just displaying on the dash to visually monitor.. I still have a dizzy cap and it wont be able to pull ignition timing anyway.

Ben, I'm unsure if you're simply unaware of the capabilities of the link ecu, or you have been mislead somehow.

1. The idea that you'll just be watching the display on a rolling road and not logging internally on the ecu to me feels like tuning with one hand behind your back. Personally, no matter how good the wideband is on a dyno, I always require a wideband on the car and wired in to the ecu with aftermarket engine management. The CAN lambda has the advantage of a much better capability to interact with the ecu as you do runs or hold steady state than any external display being monitored solely by human eyes.  Laptop logs through the tuning software with lambda right there with all the other engine parameters is extremely useful when looking back over any data.  During steady state tuning you also have the ability to use features like the quick tune function when the lambda is setup properly.  Comparing how the car acts on the real road once off of the dyno also will be extremely useful once you have completed tuning there.

2. I have no idea what makes you think that having a distributor cap means you can't pull ignition timing?  The ecu still controls ignition advance and if you've ever looked at the rotor tip on your 3SGTE you may notice it's quite wide to accommodate a wide range of ignition advance (and retard) as commanded by the ecu while maintaining good rotor phasing.  I've tuned hundreds of 3SGTEs and 90+% of them were with a distributor and I was able to successfully trim ignition per cylinder when necessary, and advance and retard the ignition timing without moving the distributor. 

I'm concerned a little bit that perhaps you did not properly sync the ignition advance in the ecu to the engine with a timing light as part of your installation?  

Please don't misunderstand - I am only trying to ensure you have the best possible tuning experience with your project and am just trying to help.

[BenAmr2turbo]

No problem, I appreciate any thoughts, I still have loads to learn about tuning generally.

1.  I was told the rolling roads hardware is more accurate than the wideband sensor. Maybe this is incorrect? I will connect it directly to the ECU with a canjst to canext, and cantee with the dash. That will give the ECU lots of data/sensor info. Simple enough... and the RR can choose..

2.  I simply did not know that the ignition timing is still adjustable regardless of the physical dizzy adjustment, I have just never had chance to play with any tuning software, please forgive my knowlegde gaps. Planning to physically set the dizzy with a timing light on first crank, to 10⁰ BTDC, hopefully that is correct?

 

Just trying to connect the ECU as best as I can before taking it to a rolling road, goal is to make it easy for the tuner to map. I threw everything I could at the engine in regards to money and would love to get it right first time.

Can't thank you enough for sharing your thoughts.

Regards

Ben.

 

[koracing]

I would start by just locking the distributor down with the bolts dead center in the slots as this is 95% of the time correct. 

Next, the procedure for syncing the timing is to have the trigger calibration window up while the engine is running - that window locks the timing to the displayed value.  Then you adjust the offset angle (hitting the enter key after each change) until the timing light matches the value set in that window (can be 10 deg or 15 deg - I find 15deg is easier to see as it's more vertically lined up with your line of sight).  Then close that calibration window and save and store the tune.

[BenAmr2turbo]

On 9/11/2023 at 12:20 AM, Adamw said:

You will need another CANJST (easiest)

Is the ECU able to power the CANLambda and MXG via the CANJST?  (If I use a splitter i.e CANTEE going to each)

Or -do they need their own power and ground?

It doesn't look like I can modify the canext or cantee to add anything, it looks like the DTM-4 plug go together - but it just seems too easy....

Can anyone confirm if I need separate 12v/GND?

Thanks,

Ben.

 

edit - Just noticed there is a splice on the JST for power! Thanks anyway!

[koracing]

The CAN Lambda will likely pull up to 2A and the MXG I *think* draws less than 1A.  So while you *might* be ok to power both from the CAN2 port if you had a ST205X ecu, you don't have the possibility of using this on the ST185X ecu as the CAN1 port doesn't have power and ground on it.  The CANJST connector will have the two wires coming out for power and ground that you can definitly hook up to a 12v switched source (ECU switched supply power for example) that should have no issue supporting both the CANLambda and MXG dash.  There should be switched power at the dash via the OEM harness, however, that should be fairly easy to get at to power the MXG.