Alex Buchka
8 cylinders
- Joined
- Apr 8, 2004
- Location
- Los Angeles
I recently wrestled with this and I decided to get the most important information down in one place to make it easier for other people. This will NOT be a hold-your-hand-every-step-of-the-way guide. If you need an article like that you shouldn't be megasquirting an engine in the first place, let alone a 5 cylinder that requires some of the most complicated setup there is. When I say MS in this article I will be referring to Megasquirt-Extra running the latest 029y4 firmware. Also the engine I did this on is a '94 b5234t with S80 T6 ignition coils. I believe the information presented here should be applicable to any 5 cylinder built before '99 (possibly '01 but I'm not sure).
I'm going to assume all throughout this article that the reader is familiar with the setup and operation of megasquirt. If not, I strongly suggest you read the megamanual and the MSExtra manual several times first.
RPM signal/triggering and ignition settings:
MS MUST be run in second trigger mode using the generic wheel code. The engine has a 60-2 trigger wheel on the crank with a VR sensor and a one tooth cam wheel with a Hall sensor. You want to set up megatune exactly as is listed here:
http://www.msextra.com/manuals/MS_Extra_Basic_Configuration_Manual.htm#5cylinder
EXCEPT, for a few things. Dwell should be set to 3.0ms cranking and 2.7ms running and the last screen with trigger positions and trigger return should look like this:
IMPORTANT: I made a mistake with this screenshot. Base teeth should be set to 120, NOT 60 as it says in the picture.
Cam wheel setup:
This gave me more grief than any other single thing, so read carefully. The wheel decoder takes the second trigger signal as an indicator that the next missing tooth is where to reset the tooth count. The second trigger needs to pass the sensor about 40-50 degrees BEFORE the missing tooth you want to be the start of the count. Take the little trigger wheel disc and grind the indexing tangs off, then turn the wheel so it's about to pass under the sensor when the crank sensor is 8 teeth before the missing tooth, then tighten it down hard.
S80 T6 ignition coil information:
IMPORTANT UPDATE: Use these coils at your own risk. I chased a resetting problem for weeks that was fixed by replacing the S80 coils with 960 coils. I soldered a +5v pull-up for each ignition output and connected them to 960 powerstages. The information in this section is being kept for posterity and for the part numbers listed.
These are internally identical to Bosch Motorsport Single Fire PT coils but with a 4 pin connector instead of a 3 pin. The pin out is as follows:
1 - Trigger
2 - Not Used
3 - Ground
4 - +12v
These coils pull to +5v to fire so the spark MUST BE SET TO INVERTED, this is VERY IMPORTANT. If you don't do this you WILL burn up the coils.
Unless you pull these of an S80 T6 and get the connectors and wiring included, you will need new connectors. These can be had from Volvo on special order. Getting part numbers was a royal pain in the ass and took me quite a while (thanks to doug for digging these up for me):
The plastic connector itself is part number: 9456341
The +12v feed pigtail is part number: 30656689 (you will need 5 of these)
The ground and signal pigtails are part number: 30656688 (you will need 10 of these)
VR and Hall Sensor information:
I used a V3 pcb which has a VR conditioner and an opto isolator on board. Lucky for us they are completely separated from anything else on the pcb so they can both be used at once for dual trigger applications. The VR sensor gets wired up just like normal according to MS instructions and the Hall sensor is wired up according to this diagram:
Coolant temp sensor resistance table:
Temperature F (C).....................Resistance (ohms)
32 (0) .............................................. 7300
68 (20) ............................................. 2800
176 (80) ............................................. 300
212 (100) ............................................ 150
Use this to configure easytherm.
I'm going to assume all throughout this article that the reader is familiar with the setup and operation of megasquirt. If not, I strongly suggest you read the megamanual and the MSExtra manual several times first.
RPM signal/triggering and ignition settings:
MS MUST be run in second trigger mode using the generic wheel code. The engine has a 60-2 trigger wheel on the crank with a VR sensor and a one tooth cam wheel with a Hall sensor. You want to set up megatune exactly as is listed here:
http://www.msextra.com/manuals/MS_Extra_Basic_Configuration_Manual.htm#5cylinder
EXCEPT, for a few things. Dwell should be set to 3.0ms cranking and 2.7ms running and the last screen with trigger positions and trigger return should look like this:
IMPORTANT: I made a mistake with this screenshot. Base teeth should be set to 120, NOT 60 as it says in the picture.
Cam wheel setup:
This gave me more grief than any other single thing, so read carefully. The wheel decoder takes the second trigger signal as an indicator that the next missing tooth is where to reset the tooth count. The second trigger needs to pass the sensor about 40-50 degrees BEFORE the missing tooth you want to be the start of the count. Take the little trigger wheel disc and grind the indexing tangs off, then turn the wheel so it's about to pass under the sensor when the crank sensor is 8 teeth before the missing tooth, then tighten it down hard.
S80 T6 ignition coil information:
IMPORTANT UPDATE: Use these coils at your own risk. I chased a resetting problem for weeks that was fixed by replacing the S80 coils with 960 coils. I soldered a +5v pull-up for each ignition output and connected them to 960 powerstages. The information in this section is being kept for posterity and for the part numbers listed.
These are internally identical to Bosch Motorsport Single Fire PT coils but with a 4 pin connector instead of a 3 pin. The pin out is as follows:
1 - Trigger
2 - Not Used
3 - Ground
4 - +12v
These coils pull to +5v to fire so the spark MUST BE SET TO INVERTED, this is VERY IMPORTANT. If you don't do this you WILL burn up the coils.
Unless you pull these of an S80 T6 and get the connectors and wiring included, you will need new connectors. These can be had from Volvo on special order. Getting part numbers was a royal pain in the ass and took me quite a while (thanks to doug for digging these up for me):
The plastic connector itself is part number: 9456341
The +12v feed pigtail is part number: 30656689 (you will need 5 of these)
The ground and signal pigtails are part number: 30656688 (you will need 10 of these)
VR and Hall Sensor information:
I used a V3 pcb which has a VR conditioner and an opto isolator on board. Lucky for us they are completely separated from anything else on the pcb so they can both be used at once for dual trigger applications. The VR sensor gets wired up just like normal according to MS instructions and the Hall sensor is wired up according to this diagram:
Coolant temp sensor resistance table:
Temperature F (C).....................Resistance (ohms)
32 (0) .............................................. 7300
68 (20) ............................................. 2800
176 (80) ............................................. 300
212 (100) ............................................ 150
Use this to configure easytherm.
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