MS1 needs to be "reset". Why?

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dggt6
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MS1 needs to be "reset". Why?

Post by dggt6 »

Hi Guys, me again!
I have isolated my "starting problem" from my previous post.(How many volts to start a MS1). It appears that it was NOT a low battery voltage issue (thanks James) but something quite weird.
To start the car I turn the ignition on and try cranking it. Usually it will not fire. With the ignition still ON, I remove and replace the main MS1 relay, then the car will fire up when I crank the engine. If the engine does not continue to run (if it is cold etc), I can crank it a few times and it will eventually continue to run.
However, if the engine has been running for a while and you turn the engine off (or it stalls) it will NOT fire up again until you remove and replace the relay!!(or pull the relay power wire from the fuse box).
I did have the wires from the switched power and the battery power to the main relay opposite to the MS wiring diagram, but have since swapped them around with NO change to my problem.
Has anyone any ideas on this one??!!!

Thanks again,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
DaveEFI
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Re: MS1 needs to be "reset". Why?

Post by DaveEFI »

Best to do a log of it not starting/starting and compare. See if is is loosing sync, etc.
Rover SD1 3.5 EFI
MS2 V3
EDIS
Tech Edge O2
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dggt6
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Re: MS1 needs to be "reset". Why?

Post by dggt6 »

Hi Dave,
attached is a short log starting with 2 cranking attempts that failed, unplugging the relay, then one crank with it firing.
It was cold and didn't keep running, but it did nearly fire a few times, then I had to reset it again before it would run properly with a bit of acceleration.
I hope you can find something pretty screwy in there!

Thanks again,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
DaveEFI
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Re: MS1 needs to be "reset". Why?

Post by DaveEFI »

Your log shows 0 rpm when cranking (looking at the battery volts to determine when). So for whatever reason, MS is not seeing a tach signal. And without that tach signal, it won't inject fuel.
Just why re-plugging the power relay to the MS makes this come good - as shown later in the log - I dunno. How are you deriving the tach signal?
Rover SD1 3.5 EFI
MS2 V3
EDIS
Tech Edge O2
London UK.
dggt6
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Re: MS1 needs to be "reset". Why?

Post by dggt6 »

Thanks Dave,
I have a VR sensor and using an EDIS 6 unit. This zero RPM at cranking is why I thought I had a "battery" problem and the MS unit was not getting enough volts. This problem has been with me for a LONG time, it is just now that I have been able to replicate and identify it.
I had also noticed a while ago that after cranking at zero RPM, I always got a "blip" in the RPM after the cranking stopped.
Looking at the log in Excel, the Spark Angle drops to -0.1 during these RPM "blips". It seems wherever there is a -0.1 spark angle there is trouble, sometimes being a "false" RPM reading (blip) also under 350 RPM gets a -0.1. Very strange.
I was out driving the car yesterday for hours and she is going very well!!!

I did blow up part of my chip when installing the circuit for the cooling fans and the MS unit was second hand when I bought it.
Do you think a new chip might be in order?

Cheers,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
DeadStiff
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Re: MS1 needs to be "reset". Why?

Post by DeadStiff »

How is the EDIS getting its pretty power? It's not powered off the fuel pump relay is it? Have you used a timing light when the MS doesn't see rpm to make sure the EDIS is working?
MS3+X on 73 Karmann Ghia ignition only with LS2 truck coils firing in sequential, fuel next.
2333(103*70) Type 4 with DTM also sitting in living room just need exhaust.
dggt6
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Re: MS1 needs to be "reset". Why?

Post by dggt6 »

Hi Deadstiff and thanks for the suggestion.
I have re-checked the EDIS wiring and it gets it power from the fuse box powered by the main relay, through a circuit breaker, from the battery terminal. So all "should" be good.

Thanks anyway,
Regards,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
dggt6
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Re: MS1 needs to be "reset". Why?

Post by dggt6 »

I have tried installing a diode between terminals 85 and 86 with no change to the problem.

Any other suggestions?

Thanks,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
DaveEFI
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Re: MS1 needs to be "reset". Why?

Post by DaveEFI »

I'd first make sure EDIS is sparking when cranking. Either with a timing light, or a spark tester, etc.
Rover SD1 3.5 EFI
MS2 V3
EDIS
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dggt6
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Re: MS1 needs to be "reset". Why?

Post by dggt6 »

Hi Dave,
Connected a timing light to No.1 lead and to battery.
Cranked the engine and the timing light was flashing but the engine would not fire up until I unplugged and re-plugged the main relay.

Thanks again,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
Matt Cramer
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Re: MS1 needs to be "reset". Why?

Post by Matt Cramer »

Do you by any chance have an oscilloscope you can use to check the EDIS PIP signal?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
dggt6
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Re: MS1 needs to be "reset". Why?

Post by dggt6 »

Hi Matt,
I may be able to borrow one , but I have never used one before and the guy who has it hasn't used it for decades!
Is it a "simple " process?

Thanks,
Doug
http://dggt6.blogspot.com.au/ Memoirs of a Megasquirt Triumph.
Matt Cramer
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Re: MS1 needs to be "reset". Why?

Post by Matt Cramer »

This one should be - just put the positive probe on PIP, negative on ground, see if you get a square wave when the motor's cranking.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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