Fuel computer

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ilovedmymantas
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Fuel computer

Post by ilovedmymantas »

Help ! I just can't find that yellow plug behind the dash. I've pulled the glove box and clock out to have a good look and just don't see it.
Image
The centre console has the plug fitted...Image
The diagnostics plug has the wire coming out of pot D. just can't find this plug.
What's the big yellow one behind the drivers kickplate for ?
Image
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

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Matt
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James McGrath
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Re: Fuel computer

Post by James McGrath »

Err, that one behind the drivers kickplate looks like the right one to me.
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

If that is it, I wonder how it ended up there !
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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Robsey
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Re: Fuel computer

Post by Robsey »

The one behind the kick panel should be up by the light switch..
It is the 4x4 connector if I recall correctly.
I have one of those too.

On my car, the fuel computer plug looks exactly the same, but was taped up between the glove box and the central dash blower vents.

Keep looking up to the side of the glove box near the blue heater bowden cable.
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

Thanks for the info. There was something niggling me about this from way back, I thought there were two, with that being the wrong one.
Don't know how I didn't find it when I was changing all the bulbs & fitting radio (even had the top vents out to fit gps aerial), I think I assumed it was between the glovebox/clock plastic, as some others had found.
I'll give it a go again tomorrow, if I don't find it then it's back to the end of the queue, I've got lots of little things work on :-)
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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Robsey
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Re: Fuel computer

Post by Robsey »

Your car must have the fuel computer plug if it has the switch connector.

Mine had the fuel computer plug, but no floor loom wiring and so no switch connector.

The 26 pin yellow connector has to be somewhere taped up out of the way - up next to the glove box - up near the blue plastic-sheathed heater blower control cable.

Is that an air bag dash you have there?
I would be convinced that the vertical panel immediately above the glove box is hiding the plug - to the far right end behind that panel.

Looks odd, because I have never seen the air-bag dash in a Cav before.
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

Finally found the little bu**er , with the help of a camcorder. It even appears to be mocking me by pretending it glows like some mystical object :?
Image
It was between the two looms along with this ?
Image
Looking at a comparison photo for fitting, I've just realised two things.
1. The car needs a good clean! There's nothing like a close-up photo to advertise you've got a dog and a skin condition :oops: :lol:
2. that a big chunk of my wiring connector under the console is missing, including the locking bar. - If anyone's got one they could sell me that'd be great ( & save me a wanted ad) - Can't be good for all those pins to be rattling around.
Tomorrow's the "final fitting" for the switch after cutting out the coin holder, still a few minor adjustments to make.(btw is the raised button forward or back facing?)
Thought i'd do a basic circuit test of the switches. I assumed COM was the lonely single wire on one side. Only two of the other four wires gave a reading when a button was pressed, I have no idea if this is right, though I suspect not.
My 94 sri eco didn't have a dash airbag but this one, a 95 cdx eco has, might be a year thing. I was a bit miffed at first because that's a lot of handy storage to lose but I suppose if it gives the passenger an equal chance in an accident then it's worth the sacrifice
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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James McGrath
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Re: Fuel computer

Post by James McGrath »

The small raised button is forward favoring on my CDX and that was factory fitted.

If I remember correctly the passenger air bag was introduced in late 1994 and was standard on the CDX but an optional extra on all other models. I'll check and make sure of this this when I get home.
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Robsey
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Re: Fuel computer

Post by Robsey »

The green plug is one of your heated seat switch sockets. The other side is black for some reason...

Regarding the other two wires on the computer switch panel.
There are two tiny dimples in the switch panel. One is to set the seconds and one to set the hours on the computer screen. You need a small stylus, pencil or ball point pen to press these tiny buttons.
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

Thanks guys !
All fitted and looking good to go :thumb , the lcd lettering is crisp
Image
Looks like I've got a new rainy day project- stick it on the scanner then fix scratches & print new fascia onto clear media, with cut-to-size phone screen protector on top. ( If only these were available when the car was produced! ) That's the theory anyway :scratch .
What threw me was the 12 hour clock setup, I wasn't expecting that. I haven't used that system since school, 20 years before my car was built !
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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Robsey
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Re: Fuel computer

Post by Robsey »

From memory, you can have either 12 or 24 hour modes...

Sadly the display legend sticker is totally pants - it scratches far too easily, and it is so well bonded in place, that it can only be over laid - it cannot be removed and replaced with a fresh sticker.

did you know that you can even check what set up the fuel computer is configured to.

Program Code
You do not need to short out the diagnostics pins to do this:-

To check what your computer is set up for (engine, tyres, speed sensor, units miles/km)

Hold down both buttons.  (The Reset "R" button and the Set / Select "S" button)
The Program memory code is displayed in the top window. 
This number should be the same as what is stamped on the factory configuration plate on the bonnet slam panel. The number at the bottom right. ( last number in the ‘colour’ row.) - but only if the fuel computer was fitted at the factory.
The three digit figure should be something like: -
118 ish for C18NZ
120 ish for C20NE
130 for the C20XE

In the bottom window two letters and two numbers are displayed.
 The Alpha code represents what country it was made for, the language of the modes printed on the front and also the colour. 
The number is the version.
Such as EU 01

Once the buttons are released the bottom display displays what speed sensor the unit is set up for. Pulse per/Km

6200   = 16200 
6500   = 16500
5458   = 15458  (ABS)
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

Robsey wrote:From memory, you can have either 12 or 24 hour modes...

Sadly the display legend sticker is totally pants - it scratches far too easily, and it is so well bonded in place, that it can only be over laid - it cannot be removed and replaced with a fresh sticker.

did you know that you can even check what set up the fuel computer is configured to.

Program Code
You do not need to short out the diagnostics pins to do this:-

To check what your computer is set up for (engine, tyres, speed sensor, units miles/km)

Hold down both buttons.  (The Reset "R" button and the Set / Select "S" button)
The Program memory code is displayed in the top window. 
This number should be the same as what is stamped on the factory configuration plate on the bonnet slam panel. The number at the bottom right. ( last number in the ‘colour’ row.) - but only if the fuel computer was fitted at the factory.
The three digit figure should be something like: -
118 ish for C18NZ
120 ish for C20NE
130 for the C20XE

In the bottom window two letters and two numbers are displayed.
 The Alpha code represents what country it was made for, the language of the modes printed on the front and also the colour. 
The number is the version.
Such as EU 01

Once the buttons are released the bottom display displays what speed sensor the unit is set up for. Pulse per/Km

6200   = 16200 
6500   = 16500
5458   = 15458  (ABS)
Thanks Robsey. Thinking about it, it's actually easier in 12 hr mode, I realised I convert it to that anyway :scratch It'll make it easier for the missus when she dozes on long journeys :lol:
Tbh I lost you after hold down both buttons :oops:
The module has no. 130 written, not factory fitted, and mine's an x20xevImage
Sorry, I'm a novice in this field but those pulse numbers mean nothing to me, but I like to learn :)
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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Robsey
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Re: Fuel computer

Post by Robsey »

For all stuff "Fuel Computers"

Visit Ian Till's new-ish website.
He is the "grand-daddy" of fuel computer boffins.

X20XEV is indeed covered in his Excel speadsheet... numbers 128 and 132 dependent upon your car configuration.

http://www.abs-zero.com/fuel-computer-p ... computers/
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

That wasn't too hard, it all fell into place after the button pushing bit, - thanks for the link.
Everything matches - bar the 4wd bit in column L, and wheel size is correct
Top code 130
Bottom EC01 , 6200
I only checked this because the readings were odd ( 2 short runs ) e.g. 243 miles range on just over 1/4 tank - 81mpg ! Average speed seemed well out too. Longer runs tomorrow so I'll have a better idea then.
Do they need any sort of calibration ?
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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Robsey
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Re: Fuel computer

Post by Robsey »

Ideally, you want the correct fuel computer program number.

I have 130 on mine too... it appears to be the most common non-v6 engine program.
It works moderately accurately on my C20NE.
It was totally off the mark when I still had a C18NZ central injection fitted.

The accuracy tends to improve as you cover more and more mileage and you have had a lot more data stored.

There is a test for checking tank gauge accuracy.
You should disconnect the sender plug at the front of the tank.
Then insert a moderately high wattage 120 ohm resistor across the two sender plug wires.
The gauge should read just above the red (reserve) area on the gauge.

It is possible to also adjust the reserve of fuel in the tank when you get zero range on the display. It is adjustable in +/- 6 miles increments.
The correct reserve at zero on the display is 12 miles... but you cannot really set this 100% accurately without making the car run out of fuel.

All these tests and calibrations are done whilst shorting pin D to pin A in the diagnostic socket in the rear of the engine bay...
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Robsey
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Re: Fuel computer

Post by Robsey »

Here is some info taken from my other diagnostics website.

On Vehicles fitted with the 10 Pin ALDL Diagnostic Socket, the Fuel Computer often has a Self-Test function.

The most common of these is the Unit used on the Cavalier MK3 and Calibra.
There are similar units used on the Astra Mk2 (E) and the Carlton

The following information is taken from the Andy Kirwan Technical web-page - this has been updated and edited.

A fault code will be stored if an F is displayed. These can be read out from the fuel computer. 

To put the Board Computer into Diagnostic mode, simply use a paper-clip or wire to short out Pin A to Pin D.

Mode D1 - Fault Codes.
Switch on the ignition. 
First 12 is flashed 3 times in the top display.
Then if a fault code is stored it will be flashed 3 times.
Otherwise - - - is flashed 3 times.
To clear the fault codes press the raised button. 

167 Tank sensor voltage low,  short circuit
168 Tank sensor voltage high, open circuit
169 Outside air temp sensor short circuit
171 Outside air temp sensor open circuit
173 Fault with fuel signal from ecu

Other Modes can be selected by pressing the mode button.

D1 fault code reading / clearing
D2 speed and fuel signal testing
D3 button testing
D4 Segment Test
D5 Fuel Tank sensor calibration 
D2 Speed and Fuel signal testing. 

Select mode D2 - Speed and fuel signals.
‘S-‘ will change to ‘So’ when the MPH speed sensor is triggering. (drive the car above approx 8mph)
‘E-‘ will change to ‘Eo’ when the ecu fuel signal is working (when you rev the engine)

D3 - Button testing.

Press the remaining 3 buttons. If all buttons work  - - -  will be displayed

D4 - Display LCD Segment check.

Hold down the rear button in mode D4.
All segments will be turned on so you can check for a faulty segment on the display,
 
D5 - Calibration of Range

If you feel the range is not accurate you can adjust it.
Deviations of up to 3 litres can be adjusted in 0.5 litre steps.
When correctly adjusted, the car should drive for 3 to 6 miles  before it runs out of fuel.
(I prefer to set to 12 miles for a better safety margin).

Method - 
Select mode D5.
Press the hours pin.
A: should be displayed next to a positive or negative even number, this is followed by the range @ 28.3 mpg.

The range can be adjusted from –A12 to A0 to +A12.
If the display says you have miles left and you believe you are about to run out of fuel then it should be adjusted in the negatve direction.
If the display says you have 0 miles to travel yet you can drive over 6 miles then you should adjust it in the positive direction.

Use the mode button to select the A value you require. Then hold the raised button until - - - is displayed.
 
--------------------------

How to find out what sensor is failing on your fuel computer by looking at what doesn't work any more.

Outside temperature - Uses the outside temp sensor only. Located under the front passenger side of the bumper. Blue and Blue/white wires.

Instant MPG - If the ecu fuel signal is faulty the fuel computer will display 0.0 when the engine is running and stationary.

If the speed signal is faulty, low values will be displayed in gal/hour and will not move into miles/gal when driving.

Average MPG - If the speed signal is faulty this will stay at --- or 0 when reset.

Average Speed - If the speed signal is faulty this will stay at --- or 0 when reset.

Range - If the fuel tank sensor is faulty, the range will probably display --- when reset.

The speed signal comes from a sensor mounted in the back of the speedo itself on early models. 

Later models without mechanical speedo cables, the speed signal is derived from the ABS. Either the rear right or the front left wheel sensor. If this signal is faulty the speedo itself won't work either.

The fuel signal comes from the ecu. On V6 models this is across injector 1. 

The fuel tank sensor is the same one used for the fuel gauge.
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ilovedmymantas
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Re: Fuel computer

Post by ilovedmymantas »

Wow. Thanks for all that info.
When I read it enough to think I understand it :lol: , I'll give it a go .....
" It's not rust. It's age-related patina " ;)

1980 vauxhall cavalier MK1 1.6L, 1982 opel manta berlinetta 1.8s, 1985 opel manta 2.0 gte, 1990 cavalier 2.0 gl ,1994 cavalier sri x20xev

-1995 cdx x20xev

---------------
Matt
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Re: Fuel computer

Post by sribobby »

I have a turbo computer in my ecotec Sri. Average speed and mpg aren't accurate but it still looks nicer than the ordinary clock!
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Re: Fuel computer

Post by Robsey »

If you go to Billing, I am sure Ian Till will be there with his Tech 1...
Otherwise, I wonder if Humbucker could be talked into taking his.

Just need a different numbered program programming into your memory block.
(White lego brick in the back of your fuel computer).
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