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Old 12-13-2008, 03:48 PM   #1
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Default Troubleshoot Timing Issues - MSII

This is really a split from my original thread Troubleshoot Jumpy RPMs - MSII I believe I've fixed the input circuits as I now have good RPMs in MegaTune. I'm now struggling with timing that's WAY off. Here's the last post describing the issues.

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Fired it back-up on the MS and had the same symptoms, but this time I was armed with a timing light. ALL cylinders are getting spark, but timing is WAY off, causing what seemed to be running on two cylinders. My timing marks don't go beyond about +5TDC, but the mark was well beyond that to the positive.

I loosened the CAS and was able to get the car idling MUCH better, almost normal, just lumpy, but the timing was off the chart BTDC by a wide margin. I also had to turn the CAS completely to the left (If standing in front of the car) to achieve this result.

Turning the CAS to the point where it's at about 16BTDC starts the crappy idle again. I can't seem to get anywhere near 10 and have a decent idle. I also tried just about every number from -5 to 90 on the trigger offset. Some numbers had a decent idle, but always with the timing WAY, WAY off the chart in the BTDC direction. Oh, all of this is with the timing locked at 10* in MegaTune.
The last suggestion by patsmx5 was to ensure that the harmonic balancer was good. I did that test this morning and all is well. The highest point of the extension corresponds to 0* on the timing mark.

I warmed it up again on the stock ECU and ensured with a timing light that the CAS was set at 10* of advance. I then hooked up the MegaSquirt. It starts just fine but idles extremely rough at a very low RPM. During this time I checked the timing and it's probably about 16* RETARDED from 0*.

Had my wife get in the driver's seat so I could watch the timing while she pushed the gas. Timing stayed pretty stable but the car won't rev much past 3k even with the gas floored.

The last thing I did was settle in on a trigger angle of 73.5 That seems to give the "best" idle, even though it's still horrible.

I've attached the .msq and log. TIA.
Attached Files
File Type: msq megasquirt200812131338.msq (47.6 KB, 54 views)
File Type: xls datalog200812131335.xls (170.4 KB, 68 views)
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Old 12-13-2008, 06:20 PM   #2
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With MSnSE you have to 'syn' both the hardware and software in terms of timing.

to do this there's an option in MSnSE to 'fix' the timing to 10 degrees, (or what the MS *thinks* is 10 deg BTDC). As far as I can tell this function in MSII Extra is Tools>Trigger wizard.

Once this is done you then hook up you timing light and either:

* Adjust the CAS until the timing light says 10Deg BTDC, or
* Adjust the trigger angle until the timing light says 10Deg BTDC

Do this and MS should then idle far better.

Idle being low could be many things. What's controlling the idle valve?

Last edited by richyvrlimited; 12-13-2008 at 06:23 PM. Reason: Didn't read the Other Thread properly...
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Old 12-13-2008, 06:43 PM   #3
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I used the Trigger Wizard to arrive at the 73.5 setting after trying what seemed like the whole range of numbers (see the quoted portion of my first post for the full details).

Should I have to physically move the CAS to get to 10* BTDC? I thought the theory was set it to 10* on the stock ECU via CAS movement then adjust the trigger angle to calibrate the software. Am I misunderstanding the "proper" technique?

I'll try again tomorrow with a full-sweep of the trigger wizard numbers to see if I missed something the first time.

I'm using the PWM mod for idle. I think if I get the timing sorted out, the idle will come up naturally. When I rotated the CAS to its max advance point before, the idle rose as well. Thanks for the tips.
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Old 12-13-2008, 07:31 PM   #4
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Quote:
Originally Posted by mj71 View Post
I used the Trigger Wizard to arrive at the 73.5 setting after trying what seemed like the whole range of numbers (see the quoted portion of my first post for the full details).

Should I have to physically move the CAS to get to 10* BTDC? I thought the theory was set it to 10* on the stock ECU via CAS movement then adjust the trigger angle to calibrate the software. Am I misunderstanding the "proper" technique?

I'll try again tomorrow with a full-sweep of the trigger wizard numbers to see if I missed something the first time.

I'm using the PWM mod for idle. I think if I get the timing sorted out, the idle will come up naturally. When I rotated the CAS to its max advance point before, the idle rose as well. Thanks for the tips.

When I setup mine I moved the CAS, but only because my laptop cable wan't long enough for me to see the timing light and the laptop screen at the same time.
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Old 12-20-2008, 12:55 PM   #5
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Weekly update time. I think I've found a middle-ground that I can live with. A combination of moving the CAS just about as far advanced as possible and a setting of 60.00 on trigger angle gets a lumpy, but RPM correct idle with a pretty solid 10* of timing advance according to my timing light.

I had been hoping to not muck with the CAS so that I could flip between stock ECU and MS without any hardware tweaking, but honestly, it's no big deal.

Thanks for everyone's suggestions! Time to start tuning!
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