1995 Mustang GT Megasquirt Timing and ignition settings question

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Nov 23, 2019
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Duly noted
Lamrith, let me know if you need some help, I think I can help you. I got my car to run and I am able to tune it now, I will post what I found out so far.

First, thanks to those who help me get my ignition settings set correctly. I wanted to post what I was able to find out about my car below.

1. With the factory ignition setup, your car SHOULD run without the SPOUT plugged in. My car wouldn't at first and that was due to a ignition setting in tuner studio. Under Ignition Settings, "Cam Input Setting", if you notice mine says "MAP" on the picture I posted, it needs to be set on "Cam Input". This tells the Megasquirt to look at the PIP sensor in the Distributor. After I fixed that setting, the car would run without the SPOUT.

2. Timing, before yesterday my car would not hold timing even after I was able to get the car to run without the SPOUT connected. My car had a really really bad miss. I ran through 2 cans of carb cleaner this past weekend trying to track down a miss. I tested all 8 cylinders within an inline spark tester, checked for vacuum leaks, and I still couldn't figure it out. Then I remembered, if the ECM doesn't know where the cam is It will miss. So I went and started reading. https://www.w8ji.com/distributor_stabbing.htm Read this article, it explains distributor stabbing and how the ignition system actually works. I remember troubleshooting these systems when I was younger but it had been a very long time. I went and borrowed a scope from a friend of mine (which I ordered a Hantek yesterday after this), and BOOM!!! PIP signal was erratic. So I pulled the distributor, and my PIP sensor was all nasty and the distributor squeaked really bad. I then installed a new distributor, stabbed it at 10 degrees before TDC and fired it up without the SPOUT in. I set the base timing at 20 degrees before TDC, shut the car off, and then I put the SPOUT back in. I then went into Trigger Wizard and matched 20 degrees in the Trigger Wizard window with the balancer, let it run for a few minutes until it settled down and was happy and then set it to used table, and began tuning my idle.

3. I had been working on this for weeks. But now the car runs and I took it for a drive around the block. Nothing was more satisfying then hearing that car roar to life and sound like it should. I still have a lot of tuning to do, idle, cold start, warm start, etc. But I am so much closer than I was.

I am still a rookie by far, but if you need any assistance let me know, I am happy to help.
 

lamrith

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You wont get any spark with the spout unplugged. You lock the timing in TS and set the offset to 10*
Then adjust the distributor until you get you locked timing value
Does that go for the MSPnP Gen2 94/95 setups as well? Or should I get it close and then use the trigger wizard offset to adjust for any difference?
I had my MS set to fixed 10* and it happened to have 11 offset in it. Opened trigger wizard and while cranking the target on wizard was 12, but balancer read 18. What would be your recommendation at this point, should I move distributor to bring it to match the wizard target value, or adjust the wizard to match the balancer reading?

Lamrith, let me know if you need some help, I think I can help you. I got my car to run and I am able to tune it now, I will post what I found out so far.
I appreciate that, and will hold you to it. I have a thread over on the MS group on FB and they actually pointed me here to look for "A91What" then I found this thread.

Spout out for me was not an issue that timing is so far off it will not run. When I pulled spout with MSPnP Gen2 installed in my 1994 there was no spark at all. I thought my timing light was dead as I got nothing at all from it. Put SPOUT back in and off it went.

I am not sure what all my root issues are. I had timing problem and hoping getting that dialed from this thread and the FB group will get her running. But I am also seeing signs that my injectors may possibly be bad/leaking as the rail is not holding pressure. I expect pressure to drop over time, but I can see it dropping as I watch. Could be regulator as well, but the reg was working on my other car just fine. This is a brand new built 393 motor, so I am desperate to get it to fire and run on it's own to get rings set and basic breakin done. fingers crossed that will happen tonight!
 
Nov 23, 2019
26
6
13
39
Ohio
Does that go for the MSPnP Gen2 94/95 setups as well? Or should I get it close and then use the trigger wizard offset to adjust for any difference?
I had my MS set to fixed 10* and it happened to have 11 offset in it. Opened trigger wizard and while cranking the target on wizard was 12, but balancer read 18. What would be your recommendation at this point, should I move distributor to bring it to match the wizard target value, or adjust the wizard to match the balancer reading?


I appreciate that, and will hold you to it. I have a thread over on the MS group on FB and they actually pointed me here to look for "A91What" then I found this thread.

Spout out for me was not an issue that timing is so far off it will not run. When I pulled spout with MSPnP Gen2 installed in my 1994 there was no spark at all. I thought my timing light was dead as I got nothing at all from it. Put SPOUT back in and off it went.

I am not sure what all my root issues are. I had timing problem and hoping getting that dialed from this thread and the FB group will get her running. But I am also seeing signs that my injectors may possibly be bad/leaking as the rail is not holding pressure. I expect pressure to drop over time, but I can see it dropping as I watch. Could be regulator as well, but the reg was working on my other car just fine. This is a brand new built 393 motor, so I am desperate to get it to fire and run on it's own to get rings set and basic breakin done. fingers crossed that will happen tonight!
[/QUOTE


I have the same Megasquirt ECM you have, if you have the ignition settings set correctly, you should get spark with the SPOUT out. I can post a video on YouTube to prove it if you like.

That seems to be the least of your worries, did you upgrade the fuel pump to a higher volume when you upgraded your injectors??
 
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seijirou

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Does that go for the MSPnP Gen2 94/95 setups as well? Or should I get it close and then use the trigger wizard offset to adjust for any difference?
I had my MS set to fixed 10* and it happened to have 11 offset in it. Opened trigger wizard and while cranking the target on wizard was 12, but balancer read 18. What would be your recommendation at this point, should I move distributor to bring it to match the wizard target value, or adjust the wizard to match the balancer reading?
Yes it's the same. All Megasquirts operate the same way. Both of these techniques will work.
That said you can't set a timing that is less than your offset with Ford TFI or EDIS because these systems automatically spark at the offset.
For the same reason you can't use spark cut for rev limiting, you must use fuel cut. You also need to consider your base timing for anything like traction control or soft limiters. If you configure a subtraction that would bring you below your offset, the spark will occur at the offset timing.

I appreciate that, and will hold you to it. I have a thread over on the MS group on FB and they actually pointed me here to look for "A91What" then I found this thread.

Spout out for me was not an issue that timing is so far off it will not run. When I pulled spout with MSPnP Gen2 installed in my 1994 there was no spark at all. I thought my timing light was dead as I got nothing at all from it. Put SPOUT back in and off it went.
Then something is wrong. Set up correctly the TFI system will spark with the spout out. Captainwesome81 discovered the cause of his same symptom was an incorrect setting for Cam Input. I didn't know that could cause it so thanks to him for running that down. That may or may not be your problem, but I'll repeat no spark with the spout out is not normal. If it isn't the same problem as CA81 then it's something else.

I am not sure what all my root issues are. I had timing problem and hoping getting that dialed from this thread and the FB group will get her running. But I am also seeing signs that my injectors may possibly be bad/leaking as the rail is not holding pressure. I expect pressure to drop over time, but I can see it dropping as I watch. Could be regulator as well, but the reg was working on my other car just fine. This is a brand new built 393 motor, so I am desperate to get it to fire and run on it's own to get rings set and basic breakin done. fingers crossed that will happen tonight!
I've seen fuel pumps that bleed off pressure too. Disable priming pulse if you haven't already or you'll get a squirt every time the key is cycled.
 
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94tang

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Yes it's the same. All Megasquirts operate the same way. Both of these techniques will work.
That said you can't set a timing that is less than your offset with Ford TFI or EDIS because these systems automatically spark at the offset.
Please explain. The trigger wizard offset and whole timing thing for megasquirt has always confused the hell out of me.

I have my offset at 56.....the little help tips say that a setting of 10-19 OR 50-80 is acceptable
 

seijirou

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Sure I can write it up tomorrow. I'm just on my phone tonight.

An offset of 56 is interesting. Can you take a picture of your distributor cap with the #1 plug wire marked? I'm betting they're one position off standard, which is 45 degrees, and then you effectively have 11 degrees physical advance, totaling to 56. This would mean the minimum timing you can achieve is 11 BTDC if my guess is right.
 

94tang

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Aug 24, 2003
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Sure I can write it up tomorrow. I'm just on my phone tonight.

An offset of 56 is interesting. Can you take a picture of your distributor cap with the #1 plug wire marked? I'm betting they're one position off standard, which is 45 degrees, and then you effectively have 11 degrees physical advance, totaling to 56. This would mean the minimum timing you can achieve is 11 BTDC if my guess is right.
At work right now, but i will snap one tomorrow
 
Nov 23, 2019
26
6
13
39
Ohio
Yes it's the same. All Megasquirts operate the same way. Both of these techniques will work.
That said you can't set a timing that is less than your offset with Ford TFI or EDIS because these systems automatically spark at the offset.
For the same reason you can't use spark cut for rev limiting, you must use fuel cut. You also need to consider your base timing for anything like traction control or soft limiters. If you configure a subtraction that would bring you below your offset, the spark will occur at the offset timing.


Then something is wrong. Set up correctly the TFI system will spark with the spout out. Captainwesome81 discovered the cause of his same symptom was an incorrect setting for Cam Input. I didn't know that could cause it so thanks to him for running that down. That may or may not be your problem, but I'll repeat no spark with the spout out is not normal. If it isn't the same problem as CA81 then it's something else.



I've seen fuel pumps that bleed off pressure too. Disable priming pulse if you haven't already or you'll get a squirt every time the key is cycled.
I was thinking the same thing about the fuel pump, that is why I asked him if he upgraded the pump when he went to larger injectors, and a larger engine.
 
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seijirou

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Please explain. The trigger wizard offset and whole timing thing for megasquirt has always confused the hell out of me.

I have my offset at 56.....the little help tips say that a setting of 10-19 OR 50-80 is acceptable
To understand this the first thing to do is approach the subject from the same context megasquirt does. Everything megasquirt does for spark and injection first starts with identifying the moment of TDC for cylinder 1 in the firing order. From that moment megasquirt is taking all other actions in a specific sequence timed out in a cadence to match the RPM of the engine. Theoretically (I'm pretty sure MS doesn't support this but it's possible) you could operate MS on a single pulse indicating cylinder 1 TDC. If that pulse is coming once every 4 seconds on a 4 cylinder engine, it's clear that a new spark event needs to happen every 2 seconds (720 degrees in a 4 stroke). It's important to understand here that once that pulse happens at a time, say 10,000 milliseconds after MS was powered on, MS will immediately calculate to spark cylinder 2 at 12,000ms, cylinder 3 at 14,000ms, cylinder 4 at 16,000ms.

This is fine for an engine at a steady RPM, but if that engine is increasing RPM MS can't "see" that increase until the tooth comes around again it was 3 seconds since the last pulse instead of 4. Now it can re-calculate a faster cadence for cylinders 2-4 at this new 3-second revolution period. but clearly during the transition the previous spark events would have arrived late while MS still thought the engine was on a 4-second revolution period.

What would be better is a pulse for TDC of every cylinder. That way MS can see increase and decrease for every cylinder and re-calculate new times so none get left behind. This is actually a minimum to have an engine run reasonably.

Where does offset come in to play? Well what if your pulse per cylinder doesn't happen exactly at the moment of TDC? This is what offset tells MS. If you simplify back to that 1 pulse per revolution on cylinder 1 TDC. If that pulse happens exactly at TDC then you're only calculating for how fast is the pulse happening, divide that by the number of cylinders, and now I know the future moments in time that I need to spark each cylinder. But if that pulse is happening before the piston is actually at TDC, then I need to add some time to those calculations to "offset" when I spark each cylinder. If we're at 4 seconds per RPM, and your pulse is actually 10* before TDC then (if my morning head-math is correct) the pulse is actually coming 100ms before TDC. So back to the example if this happens at 10,000ms but with a 10* offset, at the 4 seconds per period speed, cylinder 1 spark is 10,100ms, 2 is 12,100ms, etc.

So where does TFI make things goofy? The TFI module is also getting these pulses. Ford calls it the PIP signal. It's a square wave signal with a rising edge and falling edge representing each cylinder so you actually have 2 pulses per cylinder, but Megasquirt is only using the 2nd of these to get RPM. The TFI is getting and using both. When the first pulse comes in the TFI knows the cylinder is okay to spark, if it gets a request to spark on the SPOUT it will. If the TFI sees the 2nd pulse on the PIP before any SPOUT request comes in it will go ahead spark automatically. This is the base timing.

This is why for the TFI ignition, the offset of the signal equals the "base timing" concept that SBF people are familiar with. The offset and base timing is adjustable by rotating the distributor, because it changes the physical relationship between the hall effect sensor that is mounted to the distributor body, and the shaft which is locked into the camshaft by the gear. Obviously that kind of adjustment isn't exactly precision and you don't know what you end up with until you check. You check by letting the TFI go ahead and spark automatically on the 2nd PIP pulse by removing the SPOUT connector to prevent any spark requests from making it, and you see where that spark happens in relationship to the crank with your timing light. That tells you what your offset is.

The other way to figure out what offset is, is to just set a spark timing that you want to achieve, see what you actually get, and if there's a difference that is your offset. I.E. if you want 20 degrees, you check and you see 30 degrees, your engine physically has 10 more degrees of offset then MS knows about, so you add 10 to the offset.

The Trigger Wizard is just trying to make this discovery convenient. Don't bother with the math just up and down the wizard until the 20 degrees you asked for matches the 20 degrees you see on the light.

They're all means to the exact same end. Hope that helps. If there's still any questions let me know and I can try to elaborate or explain a different way.
 
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a91what

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Bottom Line is the TFI system should work independently of the MS. Many people have documented the no spark condition with the spout removed, this is something that needs to be resolved on a case by case basis. No matter how the settings in TS are setup the TFI should fire without the spout and the pip signal should still come into the ecu.

How to tell if the pip may be failing from a datalog; when you are watching a datalog during decel the rpm input may become erratic. typically this is an indicator that the pip is failing, this also causes bucking issues at times. decreasing the rpm lag factor can help alleviate this issue
 
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seijirou

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Thanks for the explaination seijirou.......I forgot to snap a pic today like you requested, but i had an older one on file.......
That's the correct position. I realized today that my thought about +45 is wrong for a couple reasons. Can you post your MSQ? Not for any other reason than my own curiosity.
 

lamrith

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Bottom Line is the TFI system should work independently of the MS. Many people have documented the no spark condition with the spout removed, this is something that needs to be resolved on a case by case basis. No matter how the settings in TS are setup the TFI should fire without the spout and the pip signal should still come into the ecu.

How to tell if the pip may be failing from a datalog; when you are watching a datalog during decel the rpm input may become erratic. typically this is an indicator that the pip is failing, this also causes bucking issues at times. decreasing the rpm lag factor can help alleviate this issue
In your megasquirt timing video you had said you used PIP to disable your car? That made me think it was a normal thing and part of how the system worked, has that changed?

I would hope my PIP is not bad as I have a brand new distributor I purchased for this project. At this point I cannot get the car started to check anything. :p but given my timing issues I hope to change that tonight once I correct my errors.
 

a91what

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In your megasquirt timing video you had said you used PIP to disable your car? That made me think it was a normal thing and part of how the system worked, has that changed?

I would hope my PIP is not bad as I have a brand new distributor I purchased for this project. At this point I cannot get the car started to check anything. :p but given my timing issues I hope to change that tonight once I correct my errors.
Yes i did, I replaced everything and did quite a bit of testing. In the end the MS would stop functioning with the spout removed. I always assumed it was the DIYPNP, I have since always used a 36-1 wheel and coilpacks
 
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