North American Turbocoupe Organization



Custom 140 is WAY off!
booksix Offline
Junior Member
#1
Ok, I got my new 140 together using this capacitor as told on the coolcats site: http://www.digikey.com/digihome.html part no.: BC1650-ND

I connected it to my computer and pumped sine wav's through it and here what I got (parenthese are the numbers they SHOULD be)

45 hz: 26 mph (20 mph)
111 hz: 69 mph (50 mph)
178 hz: 120 mph (80 mph)

What gives?!? Could it just be this far off and I need to masively turn screws OR is my capcitor wrong? and yes, I checked the packaging and they sent the right part...
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Jeff K Offline
Administrator
#2
First of all, did you check the calibration of the original 85 mph unit before you did the conversion? I always check the original calibration before conversion to get a baseline. Stock units, I have found all read high, especially at higher speeds (like read 67 when it should read 60), but I have never seen one as far out of calibration as yours.

Did you use a DMM to verify the capacitor was in fact the stated capacitance?

As far off as yours is, the sliding calibration weights will not be able to bring it back into calibration.

ONE MORE IMPORTANT THING!!!!!!!! The calibration of the speedo is orientation sensitive (gravity sensitive). Calibration MUST be checked with the speedo sitting at EXACTLY THE SAME ANGLE as it sits when installed in the car (tilted back).
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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booksix Offline
Junior Member
#3
Actually, i know jack about capacitors....DMM = digital multi meter? What setting do i use to test a capacitor? I got ten capacitors....maybe I'll try another...

I didnt check it as an 85 unit..too bad. I figured the weights would be worthless with it like this...hmm but I'll go check out the gravity thing but I'm pretty sure I had it upright like in the car....
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booksix Offline
Junior Member
#4
Ok, BIG discovery. I get the same readings with the original capacitor in and better yet....with NO capacitor in! Ok, so what's going on?!?!

I swapped out the capacitor labeled "c473" (the coolcats write up says "The capacitor that will need to be changed is marked "473K" in the "cv" position.").

The only other close capacitor is labeled c4.7. Am I confused, did I change the wrong capacitor?
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Jeff K Offline
Administrator
#5
Can you post a pic of your circuit board so I can see what cap you changed? The cap that you change should be green, and right near the 3 terminal voltage regulator chip.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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tps87turbo Offline
Posting Freak
#6
My suggestion is to ship it to Jeff K & Have him calibrate for $50. He does a good job & very knowlegable
Tony Sceia -

HIS Red 88 TC
http://turbotbird.com/showroom/data_r-z/...a_88tc.php
HERS - Blue 87 TC, fully loaded with every option, Work in Progress
87 Gray TC Parts Car - Gave to BJL and is now his daily driver
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booksix Offline
Junior Member
#7
Yeah, looks like I may have changed the wrong one. I'll get a pic up tonight...
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booksix Offline
Junior Member
#8
Ok, i found time to take one. Here it is:

http://www.booksixrecords.com/speedo.jpg

I circled the capacitor I changed in red (it is now completely out, so the slot is blank. Could some one circle the correct one. I'm 99% sure which now, but just to be safe....thanks
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Jeff K Offline
Administrator
#9
Yup, wrong cap! I will check for sure tonight on one of the converted ones I ahve laying around, but I am nearly certain it is the green one just under the regulator chip (black rectangular thing with 3 leads) at the top of your pic.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

booksix Offline
Junior Member
#10
Ok, let me know if and when you can figure it out. Maybe I'll just trying swapping the one by that chip... It's just so weird cause the numbers of the cap I changed were almost exact to the coolcats write up and the one we are talking about it titled very different on there...
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