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DFI warning light 14 Nov 2021 16:27 #857941

  • woodyvale
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Hey all,

my 84 gpz1100 unitrack is throwing up a dfi warning light on the dash.

it comes up after around 20 mins of riding and stays on until the ignition is switched off.

code on the computer is 1 long, 3 short - engine temp sensor. I’ve swopped out the engine sensor and computer with spares but still get the error message at the same time.

the bike runs OK with the error message.

only other issues i have which may or may not be connected are:

1. Popping exhaust on closed throttle. Running a delkevic. And all carb and inlet boots have been replaced and are tight.
2. uneven running just off closed throttle up to about 2,500 rpm, then it clears up.

its also had the fuel pump, fuel pressure regulator and tank return valve replaced with new. Injectors cleaned and serviced. New coils and leads fitted.

running the oem airbox.

I know the bike is trying to tell me something I just can’t seem to figure out what!

any ideas?

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DFI warning light 14 Nov 2021 17:47 #857945

  • Scirocco
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The grey wire of the engine temp sensor had an extra 30 OHM resistor in the wiring harness. He could be shot or give the EFI computer wrong values.

 
 
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DFI warning light 14 Nov 2021 22:23 #857951

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Thanks Scirocco, never knew there was a resistor between the sensor and the computer. Will check that out.

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DFI warning light 15 Nov 2021 03:24 #857953

  • woodyvale
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OK, checked the engine temp sensor as per sciroccos illustration. Measured 1.98ohms at 25C so I guess its within tolerance.

located the resistor in the dfi loom which measured 30ohms between its ends.

I've swopped the resistor for a spare I have to see if it will make a difference.

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DFI warning light 15 Nov 2021 04:53 #857955

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Measured 1.98ohms at 25C so I guess its within tolerance.

 


1.98 ohm, or 1.98 K-ohm (thousand ohm)?

1.98 ohm would definitely not be good.
'78 Z1-R in blue, '78 Z1-R in black, '78 Z1-R in pieces
'95 GPZ1100 (sold) , '00 ZRX1100

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DFI warning light 15 Nov 2021 05:25 #857956

  • DOHC
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Here is the page from the manual for the temp sensor test.  The error-code blink-chart points to this page in the manual.  This test will confirm both the sensor and the control box are working, since it's measuring the voltage on the signal line.

Another thing to check is the ground connections.  The temp sensor signal returns through the case ground wire.  It's probably a good idea to see if you can figure out where the control box connects to ground if you can find it.  And I would also clean all the contacts on the vehicle harness side of the control box connector.

One final test idea would be to temporally replace the temp sensor with a fixed resistor.  I don't know what the temp sensor connector looks like, but it's probably not too hard to replace it with a fixed 2.0k resistor and ground that resistor directly to the battery.  It that still trips the error light, it's probably not a sensor issue.  Of course, the bike isn't going to run super well because it will not adjust fuel as the engine heats up.  But it should provide a good sensor signal to the computer.



 
'78 Z1-R in blue, '78 Z1-R in black, '78 Z1-R in pieces
'95 GPZ1100 (sold) , '00 ZRX1100
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DFI warning light 15 Nov 2021 06:14 #857957

  • woodyvale
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Thanks for the input DOHC. Yes it would be 1,980 ohms. 

good idea about the earth grounds, will definitely check those out. And also test as the manual suggests.

i’ve also ordered a new temp sensor as well just in case i have a dodgy one fitted.

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