Hi Guys,

Just about finished the car with the exception of a few little jobs. I have an acewell 3251 dash and all is well except the following. When I entered the settings for wheel diameter for the speedo, I entered the correct numbers as per the instructions. I.E the wheel circumference in mm, after that I have another menu that is not in the instructions. It's a P-100 which I can change the numbers from 1 to 9 but no idea what this is for.

Also when I reversed the car out the garage at a very slow crawl the speedo showed 8mph, so obviously wrong. I have the magnet glued to the prop shaft and the sensor is about 5mm away from the magnet.

Also what is rpm signal of a 2.0 blacktop? I have options for 1, 2,3 or 0.5 which relates to the number of engine rotations per signal.

Hopefully some one can help.

Thanks

Andy

Doesn't the magnet need to be much closer to the sensor usually? Like 0.5 - 1 mm?

quote:

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Originally posted by rodgling
Doesn't the magnet need to be much closer to the sensor usually? Like 0.5 - 1 mm?

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look at the website
http://www.acewell.co.uk/User%20Manuals/index.htm
at the 325x-395X manual its says that
It displays " P-­001", the pulses screen, the number of pulses into the computer per turn of the wheel. Follow item 2 of button operation to
finish the setting and jump to unit setting..

sorry I just realised this bit was the bit you had done Doh and your lookin for P-100 not p-001



I also agree the magnet should be mauch closer mines about 2 mm away much further and it starts missing the sense at high speeds.


Pete

[Edited on 22/5/13 by watsonpj]

[Edited on 22/5/13 by watsonpj]

My magnet is also much closer - max 3mm

Stu

OK so the instructions on line shows the P--- figure to be the number of pulses per turn of wheel, mine is set to P100 which I assume means its picking up 1 turn and thinks its 100, so I will change that to P001.

Next question relates to the rpm signal. So does anyone know the engine turns to output signal for a 2.0 standard blacktop rpm. I.E how many rotations does the engine do to give a rpm signal?

Confused dot com.......

I'm not convince about the turns per pulse thing but if you are getting you signal off of the prop then its related to the diff that you have fitted so I would have though its more like 3 something. In fact if you read the manual for the 4XXX manual its a little clearer

The details below have been calculated using following formula:
Tire Diameter (inches) x 25.4(mm/inches) x 3.1416
= wheel circumference (in mm).
2. Identify the tire size of your ATV/Motorcycle when you need
to change different tire size and key in the corresponding
number shown in the following chart.
3. These values are approximate and will differ for different brands of
tyre, we would always recommend that you measure the distance
travelled per revolution of the wheel in mm and enter this into the
computer.
4. The computer calculates the wheel rotating length between 2 passes
of the magnet; use this table to find the settings when you are using
a reed sensor or an universal hall sensor with magnet to measure your
speed.
5. If you are using a cable drive speed sensor then divide the number in
the above table by the number of turns of the cable drive for each
revolution of the wheel. For example if 1 wheel revolution equals 5
turns of speed cable then the wheel circumference has to be divided 5.

so for the propshaft if the diff ratio is 3.49 then take your circum and divide by 3.49 and set your P value to 1 and you should be there.

!!!!!!!!!!!!!! I THINK !!!!!!!!!!!!!!!

Pete

quote:

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Originally posted by watsonpj
so for the propshaft if the diff ratio is 3.49 then take your circum and divide by 3.49 and set your P value to 1 and you should be there.
Pete

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thanks Pete

i think i will try and get hold of russbost who i got it from and see if he can shed any light on it.

thanks for your help!!!

Andy

You need to divide the wheel circumference with the diff ratio!

Ok Mate good luck with it.

Well I'm not hard to find!

The P screen is "no. of pulses per wheel revolution", you want it set on 1, it's purpose is for when you are using an OE gearbox sensor which may give 30 40, 50 or more pulses per wheel revolution (they are all different).

If you've got the magnet on the prop you need the wheel circumference in mm (probs around 1500 on most 7 style cars) & divide that by the diff ratio, so, say 1500/3.6 would give 417 to enter into the C screen . We always increase this figure by about 2% as you always want the speedo to be indicating a higher speed than you are actually doing, not vice versa, particularly for IVA as if it's the other way around you will fail.

Re the RPM signal, the no.'s that the Acewell is looking for 0.5, 1, 2 etc are the no. of engine rotations per spark, so for a 4 cyl 4 stroke with a single coil that would be 0.5 (half an engine rev per spark), when you have multiple coils &/or wasted spark you'll need either 1 or 2, - this is assuming you're picking up from the coil LT rather than using the yellow wire as an inductive pickup around a coil lead, in practice it should be pretty obvious as your engine should idle at around 1000rpm, if the tacho shows 2000 or 500 that might give a clue as to which way to go!

If you have an uneven tacho signal/reading at either idle or high revs (will nearly always be one or the other, rarely both) then add the resistor which comes in the kit in line (series) with the yellow wire, this will damp the signal & give a smooth rpm reading - this is another bit you won't find in the instructions!

There's loads more info in the FAQ's on my website www.furoreproducts.co.uk

Edited to add, the instructions say use 2 - 8mm as a magnet to sensor gap - in practice we always use about 1 - 4mm. One further thing that people sometimes get wrong if they have the plastic "barrel" shape sensor with 2 mounting holes, the sensor has 2 lines cast into the plastic, one near each end, the magnet should run ALONG one of these lines, NOT cross the line & run along the centre of the barrel so it crosses both lines, if you have it set up the latter way it will read up to about 20 mph then start jumping speeds all over the place

[Edited on 22/5/13 by russbost]

quote:

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Originally posted by coozer
You need to divide the wheel circumference with the diff ratio!

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quote:

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Originally posted by AndyW

quote:

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Originally posted by coozer
You need to divide the wheel circumference with the diff ratio!

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ok so my wheel circumference is 15inch or 1197mm. my diff is 3.92 so:

15 / 3.92 = 3.826

3.826 then gets entered where??

Im really getting confuddled with this

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in the instructions it states 15 inch tyre is 1197mm circumference, thats where i got the info, but i have just done a search and it shows that a 195/45/15 overall circumference is 1748mm.

But after I enter the circumference then next menu shows P-100 whats that for? as my instructions dont show it.

[Edited on 22/5/13 by AndyW]

Have you not read my post above?

"The P screen is "no. of pulses per wheel revolution", you want it set on 1, it's purpose is for when you are using an OE gearbox sensor which may give 30 40, 50 or more pulses per wheel revolution (they are all different)."

Just set the P screen to 1 then forget about it, it's irrelevant if you are using the magnet & sensor

quote:

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Originally posted by russbost
Have you not read my post above?

"The P screen is "no. of pulses per wheel revolution", you want it set on 1, it's purpose is for when you are using an OE gearbox sensor which may give 30 40, 50 or more pulses per wheel revolution (they are all different)."

Just set the P screen to 1 then forget about it, it's irrelevant if you are using the magnet & sensor

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