Mazda Rotary MS1 ecu cuts out until warm. help needed please

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Mazda808
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Mazda Rotary MS1 ecu cuts out until warm. help needed please

Post by Mazda808 »

Hi Guys,
Have an issue with what appear to be ecu rests (not sure though) that are very frequent when the engine is cold ~20degC and get better as the engine warms up. Once the engine has warmed up completely is when the issue appears to be gone as far as I can tell but haven’t done any drives longer than about 20mins. Car drives fine once hot enough
Details are;
MS1 using latest high res firmware
12a Bridgeport turbo
Coils are 4x IGN1a (one for each plug)
RX7 CAS with missing tooth
Injectors are 4x 550cc from at turbo II RX7 (two primary and two secondary)

Engine will start, run for a few seconds, relays click & lights on the ecu flash and it dies. Sometimes it doesn’t completely die, but mostly it stops and I need to cycle the key to get it to start again.

Two videos available here so you can see and hear whats going on. One from cold and one almost warm where you can see it running happily then the event happens.
https://drive.google.com/open?id=0B414_ ... HhTaW1LUE0

Data log attached is of one of the events happening. Tooth log is from when engine was warm sorry.

I’ve tried replacing relays and coil wiring and everything I can think of in between like earthing and unearthing the case of the ecu with nothing having any effect on the problem.

I’m just not sure what to try or where to go from here.. Does anyone have any ideas? Any help is greatly appreciated.

Kind regards
Steve
Mazda808
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

Could this be caused by not enough resistance in my spark plug wires? They are only around 500 ohms as they are really short.
I am using resistor type spark plugs. NGK BR9ES

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slow_hemi6
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by slow_hemi6 »

Are they the low impedance rx7 injectors pre88 or the high impedance 88 on?
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
Mazda808
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

Hi, thanks for the reply.
I have just done a quick Google and it appears they are high impedance. Part number on them is 195500-2020 they have an oval shape plug.
IMAG1316.jpg
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Matt Cramer
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Matt Cramer »

The log shows a processor reset. How is the MS1 grounded?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Mazda808
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

Hi Matt,
The plain black wires coming from the db37 (there's a few of them) are all joined together via a soldered eye terminal which is connected to a clean part of the body under the dash.
The battery is mounted in the boot and it has a short earth strap to the body.

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Matt Cramer
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Matt Cramer »

Ground it to the battery.

Rule of thumb is that a good chassis ground is bad, and a bad chassis ground is horrible.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Mazda808
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

Will pop down to my local electronics store at lunchtime grab some wire and get this done. I should be able to report results later tonight NZ time.
Thanks heaps
Steve
Mazda808
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

Removed the plain black wires
Turned the key on to check I had them all disconnected.
Weirdly the led closest to the db9 had a dim glow. I wonder if that's back feed from the sensors?
Continued on anyway and ran a nice new earth from the negative of the battery and soldered to the black wires of the db37.
Engine was still too warm to know if the problem is gone. (I don't get the resets when engine is hot)
Fingers crossed for the test from cold in the morning.


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Mazda808
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Posts: 15
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

Hi,
Car started mint this morning and all appears ok. Best it's ever started I think
Sadly the project on my laptop appears corrupt or something so I was unable to log the warmup to see if the resets are gone.
Message was "unexpected error occured opening project"

Once I figure out how to sort the tunerstudio corruption i'll do some more data logging and report the results.

Really appreciate all the help and assistance

Regards
Steve
prof315
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Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by prof315 »

Mazda808 wrote:Hi,
Car started mint this morning and all appears ok. Best it's ever started I think
Sadly the project on my laptop appears corrupt or something so I was unable to log the warmup to see if the resets are gone.
Message was "unexpected error occured opening project"

Once I figure out how to sort the tunerstudio corruption i'll do some more data logging and report the results.

Really appreciate all the help and assistance

Regards
Steve
Just start a new project and delete the corrupt one..... it can happen with crappy grounds
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Mazda808
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Joined: Sat Jul 23, 2016 11:38 pm

Re: Mazda Rotary MS1 ecu cuts out until warm. help needed pl

Post by Mazda808 »

OK new laptop now too. Old one died... This one's Linux. How do I get the sucker to connect? What am I missing?Image

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