TPI MSnS fired up

[mobythevan]

Good news, got MSnS to fire up TPI sbc setup. I used the 8 pin HEI module in the small cap TPI distributor to trigger megasquirt. That only required connecting two wires to the distributor. One wire to power the 8 pin module and one wire to connect pin R to the tach input of megasquirt. This uses the variable reluctor star in the distributor to give trigger angle timing for spark to megasquirt. Then used FIDLE output to trigger a 4 pin HEI module just like the L28ET install. 4 pin HEI then fires the coil. I cut the side off an extra small cap dizzy to aid in setting up correct trigger angles and rotor to post relationship. It is also cool to watch the spark inside while its running. I did not use the 8 pin HEI module to fire the coil because there is still some question to the reliability of dwell control in 021u code.

 

I also had to change the value of R10 in the megasquirt so it would reliably trigger from the 8 pin module. Megasquirt is intended to trigger from a 12 volt source. The 8 pin module has a 5 volt signal so I lowered R10 to keep the current at a similar level as if a 12 volt source was used.

 

Did run into a couple problems that we introduced. One was a bad connection to the air temp sensor. The other was using a 7 year old battery that won't hold a charge. That caused some really strange sparks to come out.

 

After the install is completed and tested out some more I may make a quick post that has the schematic for TPI install. This would also work for anyone running megasquirt on any sbc and just using the TPI distributor. The triggering of megasquirt and wiring of the coil is the most useful information.

[mobythevan]

The TPI install isn't out of the woods yet. Found out that the engine starts and sounds great, then after a few minutes of running something heats up or goes south and I start loosing spark. Its gets worse and dies. Let it set for a while and then it sounds great again. This is built with ebay parts, so I'll try a different coil next. Also, the grounding setup right now leaves a lot to be desired. The battery is in the trunk and I am not happy with the amount of grounding to the frame/engine/body for all the electronics. More to follow.

[mobythevan]

Got all of the grounding issues cleaned up, but the new coil didn't make it in yet. The problem seems to be more solid now, which makes it easier to troubleshoot. If the new coil doesn't help I am just going to get rid of the 4 pin HEI module and only use the 8 pin module to fire the coil and use dwell control in the extra code.

[Tim240z]

Hey Mobe....

Although I never post comments to your updates, I read them with great interest!! Keep 'em coming, please!

Tim

[Forrest]

Hey Mobe....

Although I never post comments to your updates' date=' I read them with great interest!! Keep 'em coming, please!

Tim[/quote']

Ditto.

[quicker240]

Thinking of going megasquirt soon.Getting that wiring and programming in the ballpark will be a great asset.Keep up the great info

[Guest Bris280zx]

very nice moby,

 

I'm interested why you need to control the dwell for these modules?

 

Mat.

[mario_82_ZXT]

4 Pin HEI controls dwell, 8 Pin module doesn't.

 

If he uses the 8 Pin to fire the coil, then he needs MSnS-E to control the dwell (something that is still experimental).

 

Mario

(It idles, I hope to drive it around this weekend)

[mobythevan]

4 Pin HEI controls dwell, 8 Pin module doesn't.

 

If he uses the 8 Pin to fire the coil, then he needs MSnS-E to control the dwell (something that is still experimental).

 

That is correct. And the fact that the code is still a little bit in the experimental stage made me avoid it.

 

However, I decided last night that if I am going to troubleshoot a problem I would rather spend my time to get the 8 pin setup working because it gives the cranking bypass mode which allows the car to crank and start fast in cold weather and any other time. So tonight I will remove the 4 pin module and use the 8 pin for both functions: trigger the ECU and fire the coil. I will be upgraded to MSnS_Extra024e code so the dwell control fixes are the best available.

 

I am just going to start by putting the 8 pin module into the bypass mode permanently so I can run the engine and check a few other things. The bypass mode gives a fixed 10 degree BTDC timing. Then I will set it up to go back to computer timing control once the engine is running.

[mobythevan]

update, pulled the 4 pin module and just went to using the 8 pin module ony. Set it in bypass mode for now. The car ran 5 minutes or so and then the trigger started going in and out to the ECU. I figure that lowering the value of R10 is putting to much current draw on the 8 pin module to trigger the ECU. So tonight I hooked up pin R from the 8 pin module to a 2k resistor and then to pin 6 of the opto isolator. Removed diode D5 and resistor R10. Now what I am doing is not even using the opto part of the opto isolator and just running it through pin 6 like it was a regular transistor. This is working great. Ran the car for 40 minutes with no issues. After this is tested out more I will make a schematic to show what I am doing here. I don't see a reason to use the opto isolator as an isolator because that was for systems that may introduce high voltages on the line and burn up stuff(original type fuel hookups that run from the coil as trigger). With the 8 pin module it only puts out 5 volts on pin R. So far so good. I downloaded MSnS_extra024f code to try out the dwell control. Tomorrow I will wire up so the megasuirt uses cranking bypass mode during cranking and then reverts back to ECU control once rpm is above 300.