Megasquirt2 Install AMC360 TBI 83' Cherokee

[FSJ Guy]

Play nice everyone.

Now back to your regularly scheduled programming.

[myk]

It runs , fired it up on Sunday after finishing up all the wiring. So far so good, had it running for a few hours in the driveway checking everything out, just need to get out and do some tuning now. I went ahead and removed all the factory ignition system while I was making the wiring harness and let MS control the ignition as well.

One thing I had to do was add a diode to the alternator sense line, as it was back feeding the ECU with the key off and the engine wouldn't turn off with the factory resistance wire. Just took the resistor wire out all together and replaced it with the diode setup..problem solved.

Just need to finish up a few odds and ends and it will be road worthy and I can get to the tuning phase.

Mike

[FSJ Guy]

Sweet! You'll enjoy the computer controlled timing!

[PITFSJ]

Is she still working?

It runs , fired it up on Sunday after finishing up all the wiring. So far so good, had it running for a few hours in the driveway checking everything out, just need to get out and do some tuning now. I went ahead and removed all the factory ignition system while I was making the wiring harness and let MS control the ignition as well.

One thing I had to do was add a diode to the alternator sense line, as it was back feeding the ECU with the key off and the engine wouldn't turn off with the factory resistance wire. Just took the resistor wire out all together and replaced it with the diode setup..problem solved.

Just need to finish up a few odds and ends and it will be road worthy and I can get to the tuning phase.

Mike

Hi Mike

Have done fine tunning?

How has been she working now?

[myk]

Hi Mike

Have done fine tunning?

How has been she working now?

It running very well, I've got the fuel side pretty well sorted, been running the stock MS timing table but have a new one that I'm going to try, was also able to find the factory timing curves as a reference. One thing about diy efi is there's always something to tinker with It's very drivable as it is now, I really need to focus on getting the cage done.

Mike

[FSJ Guy]

It IS fun to tinker with, isn't it?!!!

[myk]

Here's the ignition table I've been running, so far so good no signs of knock with regular unleaded. Any comments or suggestions?

Note: the load axis is percent barometer.



Mike

[myk]

In the process of installing 8 LS2 "yukon" coils on the 360. Just finished machining the distributor down to a short post just to drive the oil pump. More fun, seems I don't know where or when to stop on this EFI project Will post up some pics when I get a chance.

Mike

[JeepsAndGuns]

55 degrees of advance? How are you getting that with a distributor?

And if your getting ready to install coil per plug ignition, what are you doing about a crankshaft trigger wheel and pickup?

[myk]

55 degrees of advance? How are you getting that with a distributor?

The dizzy was locked and the phase was set at 32deg btdc, the width of the rotor tip and cap posts allowed for +/-12deg which = +/-24 crank deg, this covered the range of my timing map. The MS2 decides the advance bases on the table above and knows engine position from the crank trigger.

And if your getting ready to install coil per plug ignition, what are you doing about a crankshaft trigger wheel and pickup?

It's been crank triggered since day one, see the first page of this tread for details. Yes it will be a coil per plug setup firing in wasted spark mode, there are 4 spark outputs from the MS2 each goes to a pair of coils that are fired each revolution of the crank. Cylinders 1/6 are spark A, cyl 8/5 are spark B, cyl 4/7 are spark C and cyl 3/2 are spark D.

Just waiting on the coils to arrive, I've got most everything else done.

Mike

[JeepsAndGuns]

The dizzy was locked and the phase was set at 32deg btdc, the width of the rotor tip and cap posts allowed for +/-12deg which = +/-24 crank deg, this covered the range of my timing map. The MS2 decides the advance bases on the table above and knows engine position from the crank trigger.

Guess that MS does things way diffrent than the stock GM systems I am used to. On mine, what the table says it what I get.

It's been crank triggered since day one, see the first page of this tread for details. Yes it will be a coil per plug setup firing in wasted spark mode, there are 4 spark outputs from the MS2 each goes to a pair of coils that are fired each revolution of the crank. Cylinders 1/6 are spark A, cyl 8/5 are spark B, cyl 4/7 are spark C and cyl 3/2 are spark D.

Just waiting on the coils to arrive, I've got most everything else done.

Mike

My bad. I hadnt read the first page since you originally posted it, and I just saw new posts and jumped right to the last page without re reading the rest of the post.

So if doing a wasted spark, why chose the 8 individual coils over a coil pack? For example, the coil pack off of something like a caddy northstar V8. Seems there would be a lot less wiring to do and would be easyer to mount and hook up.

[myk]

Guess that MS does things way diffrent than the stock GM systems I am used to. On mine, what the table says it what I get.

No it's the same, what the table says is what I get...maybe I missed your original question?? I was just trying to explain how the dizzy can handle that much advance from the ECU.

So if doing a wasted spark, why chose the 8 individual coils over a coil pack? For example, the coil pack off of something like a caddy northstar V8. Seems there would be a lot less wiring to do and would be easyer to mount and hook up.

The LS2 coils are really slick as they have the ignitors built in so they only require a low level TTL signal from the ECU to trigger them, the wiring is pretty straight forward as the GM coil packs come with a sub-harness and brackets that bolt on the valve covers. They are very powerful coils too and I think they look pretty trick. Ohhh and it's maybe never been done on an AMC engine

Mike

[sflier]

Great info and thanks for sharing.

1. Did you end up phasing the distributor so the rotor tip was centered in the middle of a cap post (sorry, I hope that made sense)? If so, how did you end up doing that? Did you run with a hole cut in an old cap to set that up? I was going to try that myself using a timing light but I wasn't sure how'd it work out.

2. If you set your phased timing at 32 BTDC, wouldn't you be cranking with that setting as the base? Or is the base cranking setting different from the initial phase position? I was thinking about setting the base timing to 12 degrees to ease cranking.

Edit: I think I found the answer to my second question here: http://www.diyautotune.com/tech_arti...part2-nova.htm. But I'm curious to know if you phased your rotor tip to the center of a cap post similar to this procedure: http://www.msdignition.com/uploadedF...or_phasing.pdf

[myk]

Center of the rotor tip was aligned to the center of the cap post with the engine at 32deg btdc, I have timing tape on the balancer. Cranking timing is independent of this and set in the software to whatever you like...mine is 10deg. Please remember that my motor is crank triggered so moving the dizzy has absolutely no effect on the timing, yours may be totally different if your taking the timing signal from the factory VR sensor in the dizzy, which is a very common thing to do.

I have all the LS2 coils now, just fabbing up all the standoffs to weld to the valve covers...a bit of work but this is gonna be sweet

Mike

[sflier]

Ah, yes I forgot you're setup using crank sensing. I'll be triggered off VR from a MSD distributor, but still managing timing and spark from MS.

Also, just something to consider: If you have a physical spark range of 24 degrees (based on the limits of your rotor tip), and your base offset is 10 degrees, you may want to try centering your rotor tip at 44 degrees (32 where you say it's centered today + 24 / 2). That way, you'd pick up a healthier spark in the normal operating range. Unless, of course, you've already taken that into account when you selected 32 initially.