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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E30 (1982 - 1993)

E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 11-29-2016, 07:43 PM
snaponbob snaponbob is offline
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Massive speedo error

I am working on a UK E30 Touring. Yup, in the Kansas City area. Lots of "normal" E30 issues, plus a few station wagon problems. Most everything is sorted. However, the speedo is off by 18% +/-. So -- details---

This is a late model E30 325iT 5 speed. Except for being stupidly stanced (now resolved to a sane level), this is an unmolested E30. When I started working on refreshing the rear subframe I saw that the wires to the speedo sensor were broken. Because of a smashed oil pan (please refer to the "stanced" comment) I received the wagon on a roll back. Once up and running again, at 40mph indicated my GPS phone app showed 33mph. At 70mph, the GPS showed 58mph. I checked the diff and it is the correct 3.8x to 1 ratio. The Motometer instrument cluster is original. Odo is function. ALL cluster functions are correct except the speedo, but I have not had the car out on an interstate to cross check the odometer. The tires are correct diameter as well.

Any constructive input would be appreciated.
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  #2  
Old 11-29-2016, 08:05 PM
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hornhospital hornhospital is offline
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Tire/wheel size? And every BMW speedometer I've seen has been "optomistic", some even worse than yours.
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BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"


Last edited by hornhospital; 11-29-2016 at 08:06 PM.
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  #3  
Old 11-29-2016, 08:10 PM
snaponbob snaponbob is offline
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205/50/15

VERY close to stock.

I have noticed variances in speedos (I am retired, but work on 30s, 36s, and 46s all the time, and own a 36 coupe and 39 Touring). I can understand 1-3 mph, but not TWELVE at 70mph.
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  #4  
Old 11-29-2016, 08:20 PM
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hornhospital hornhospital is offline
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If you'd used 60 series instead of 50 it would be a lot closer. My 87 325is is off 6mph at 60 (GPS indicates 54). That's with stock 185 65 14 size tires. I recently finished a revival of an 85 325e that was off 10 mph at 60. The owner went to two-steps over tires (205 60 14) which got it to within 2 mph across the board.
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Quotes to live by:
guessing gets expensive...drivinfaster
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BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #5  
Old 11-29-2016, 08:54 PM
snaponbob snaponbob is offline
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We are discussing an 18% error.

So, the car came equipped with 195/65x14, and this car has 205/50x15 tires. Guess what? The difference in revolutions per mile is less than 1%. That is about .5mph at 60mph. The car is going 49 mph at an indicated 60.
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  #6  
Old 11-29-2016, 09:05 PM
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hornhospital hornhospital is offline
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Then you got me. I have no clue why it's off that much. Sorry.
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Quotes to live by:
guessing gets expensive...drivinfaster
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Ken Kanne, Silverhill, AL, E36 & New Member Intro Forum Mod/Bimmerfest Misplaced-Posting Tow Truck
BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #7  
Old 11-30-2016, 05:31 PM
M-technik-3 M-technik-3 is offline
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Was gonna suggest codec plug but that's tachometer related. OEM is off by roughly 7 mph and then add the smaller size so the gap will grow. Might want to check if you have the right cluster in the car.
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  #8  
Old 11-30-2016, 06:34 PM
snaponbob snaponbob is offline
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Turns out the Motometer speedo has a potentiometer on its circuit board. VDO's do not. Anyway, I took some need tools to access the speedo, and test drove the car. I simply took a swing at the pot, which took the error the wrong way. Soooo, I went 120 degrees the OTHER way. At 40mph indicated the GPS showed 42. A minor twist back and the speedo was dead on at 30, 50, and 70.

As Edd China would say -- "Sorted". Job done.
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  #9  
Old 11-30-2016, 07:25 PM
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hornhospital hornhospital is offline
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Wish mine was a Motometer. I'd pop it out and adjust it tomorrow. Thanks for posting the solution!
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guessing gets expensive...drivinfaster
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buying a ratty example (of a BMW) is a parasitic relationship.(and you ain't the mosquito) 7pilot
Ken Kanne, Silverhill, AL, E36 & New Member Intro Forum Mod/Bimmerfest Misplaced-Posting Tow Truck
BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #10  
Old 11-30-2016, 07:35 PM
snaponbob snaponbob is offline
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What year is your car? Where are you located?
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  #11  
Old 11-30-2016, 08:22 PM
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hornhospital hornhospital is offline
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87, Alabama, near Mobile.
__________________
Quotes to live by:
guessing gets expensive...drivinfaster
nothing is more expensive than a cheap BMW...c4harpe13
buying a ratty example (of a BMW) is a parasitic relationship.(and you ain't the mosquito) 7pilot
Ken Kanne, Silverhill, AL, E36 & New Member Intro Forum Mod/Bimmerfest Misplaced-Posting Tow Truck
BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #12  
Old 11-30-2016, 08:24 PM
snaponbob snaponbob is offline
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Swap it !!! It MAY be that the speedo can be swapped on its own. Also, Bavarian Restoration can fit a rheostat to a VDO. Just got one back like that.
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  #13  
Old 11-30-2016, 09:03 PM
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hornhospital hornhospital is offline
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I was thinking about retrofitting a rheostat to the VDO I have. I had Bavarian rebuild a AFM. Did a fine job. I'll talk to them.
__________________
Quotes to live by:
guessing gets expensive...drivinfaster
nothing is more expensive than a cheap BMW...c4harpe13
buying a ratty example (of a BMW) is a parasitic relationship.(and you ain't the mosquito) 7pilot
Ken Kanne, Silverhill, AL, E36 & New Member Intro Forum Mod/Bimmerfest Misplaced-Posting Tow Truck
BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #14  
Old 11-30-2016, 09:04 PM
snaponbob snaponbob is offline
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Location: Kansas City, Mo.
 
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Had did the AFM work out? What was wrong with it?
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  #15  
Old 11-30-2016, 10:36 PM
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hornhospital hornhospital is offline
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Location: In the Grumpy Chair
 
Join Date: Jan 2008
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Mein Auto: E24x2,E36x2,E30x1, F150
Works perfectly now. Before rebuild it was all over the map, data-wise to the ECU. The car had a phantom miss that nothing would change. CPS, cap rotor and wires, plugs, new injectors, fuel pump and filter, fuel pressure regulator, the miss kept moving from cylinder to cylinder. All that went away and the engine runs strong from smooth idle to WOT. Best $185 we spent on this car.
__________________
Quotes to live by:
guessing gets expensive...drivinfaster
nothing is more expensive than a cheap BMW...c4harpe13
buying a ratty example (of a BMW) is a parasitic relationship.(and you ain't the mosquito) 7pilot
Ken Kanne, Silverhill, AL, E36 & New Member Intro Forum Mod/Bimmerfest Misplaced-Posting Tow Truck
BMW-CCA #441426 Which is worse, ignorance or apathy? I don't know, and I don't care!

1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #16  
Old 12-01-2016, 05:26 AM
M-technik-3 M-technik-3 is offline
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Mein Auto: 88 M3x2 86 330i 4 e36's
Think I have a spare moto-meter in the basement. I did notice an article on www.e30zone.net
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