6 cyl wheel decode spark A inverted NOT bug?

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ion332
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6 cyl wheel decode spark A inverted NOT bug?

Post by ion332 »

The A spark ignitor tends to hang up and the LED stays on, while the other 2 LEDs just run fine. As I increase the rpms, sometimes A and B will operate and C will hang up. Then, if I put the decoder to rising edge, then C hangs up.

I tried everything I could think of, changed wheel decoder type, etc etc but nothing works for this issue.

It seems like this issue here.

http://www.msefi.com/viewtopic.php?p=137437#137437

OK I THINK I FIGURED IT OUT, HERE IT GOES:

First, I had to set Multiplex ignition : ON
Then, dual dizzy :ON

THEN, after MUCH MESSING AROUND WITH A SCOPE, I FIGURED OUT WHAT IS GOING ON!!!!

OK, for some reason, it LOOKS like spark A signal is INVERTED, while all the others remain fine.

So, its just a matter of putting in a transistor buffer circuit to invert it again from the input side. I am going to check the timing first but it looks like this should work ok.

It ALSO seems to be inter-related to the dwell: when I put the dwell to a fixed amount I don't even get any signal to spark C.
MSnS 029t
94 Probe GT custom headers/ short ram intake/282dur cams/modded intake
147wtq@6800/197whp@7700rpms
newtyres1
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Post by newtyres1 »

If you'd like to post your msq and let me know what code version you are running I'd like to take a look. It's very easy to get one setting wrong and it all falls to bits. You shouldn't need to invert one of the channels.

Ian.
jsmcortina
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Post by jsmcortina »

This is a joke isn't it?
Why on earth have you enabled the Toyota Multiplex and Dual Dizzy when you are running neither?
That will totally confuse the code as is a great way of melting coils and VB921.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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ion332
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Post by ion332 »

jsmcortina wrote:This is a joke isn't it?
Why on earth have you enabled the Toyota Multiplex and Dual Dizzy when you are running neither?
That will totally confuse the code as is a great way of melting coils and VB921.

James
I see one techical issue that MIGHT be causing this: while its only supposed to read the *edge* of the signal, my 2nd wheel stays high for an entire 180 degrees and maybe this is causing the processor to wait and hold the spark A on? I noticed all the examples have a 2nd wheel that has an event that doesn't overlap the first tooth on the wheel trigger.

Any way I look at it though, I am going to prlly have to scrap this idea in the nearterm and go with a 36-1 crankwheel just to get the car running.
MSnS 029t
94 Probe GT custom headers/ short ram intake/282dur cams/modded intake
147wtq@6800/197whp@7700rpms
jsmcortina
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Post by jsmcortina »

The extended second trigger input shouldn't cause a problem in itself because the code only looks at the change from 0v to 5v or 5v to 0v. As long as the edge is in a consistent place it should be ok. Ideally then, the change of state of the second trigger should occur between teeth on the main wheel.

If you have VR sensors, check that they are not reversed because you will get odd results. Also try not using tooth no. 1.

Be sure to only use dual dizzy or Toyota multiplex if you actually have those systems connected. The multiplex setup turns the three LEDs into a multiplex system that is totally incompatible with direct coil control using VB921.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
ion332
Helpful MS/Extra'er
Posts: 112
Joined: Sun Sep 25, 2005 5:47 pm

Post by ion332 »

newtyres1 wrote:If you'd like to post your msq and let me know what code version you are running I'd like to take a look. It's very easy to get one setting wrong and it all falls to bits. You shouldn't need to invert one of the channels.

Ian.
Its 29s. I upgraded to 29q2 after I saw that there was a possible decode issue that jsm posted concerning the Northstar.

Both 29q2 and 29s exhibited the same behavior.

OK, I will post the msq that was set up correctly, but was hanging up spark A.

To see what I described above with the nearly operational dual wheel decoding with the inverted spark A, set multiplex to Toyota DLI multiplex and set to dual dizzy. With those set, the dwell seems to work somewhat.

If it makes anyone feel better about it, I also have swapped CPUs, and tried it on a second spare MS that I have with the same results.

With the standard non multiplex non dual dizzy wheel configuration, the dwell settings don't work. The vb921s are staying on for the entire count ie each VB921 stays on for 3 trigger wheel events, then turns off for 3 trigger events.

Also, I am using Hall Effects for both inputs, and they are completely clean, sharp transisitions. I will do a tooth logging just to take a look, but I think I am wasting my time with that.

Its SO close to working. I could only hope it was just a one setting fix but I think this is well beyond that.
MSnS 029t
94 Probe GT custom headers/ short ram intake/282dur cams/modded intake
147wtq@6800/197whp@7700rpms
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