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Author: Subject: BMW engine wheel speed simulation???
craigdiver

posted on 15/1/18 at 06:20 PM Reply With Quote
BMW engine wheel speed simulation???

Was just googling the t’internet, as you do, and came across this http://people.zeelandnet.nl/jeejansen/

It is claiming that with BMW engines the power will be limited if the ECU isn’t seeing a wheel speed signal? I have done a great deal of research on my M52TUB25 engine and have a custom ECU but no mention of this speed signal. Anybody heard of this or is it a lot of rubbish?





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Nickp

posted on 15/1/18 at 06:52 PM Reply With Quote
My understanding is that once you've got the ABS/ ASC deleted from the ECU then it'll no longer look for the wheel speed signals.
That's all I did with mine and I don't think it's missing any power tbh

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craigdiver

posted on 15/1/18 at 10:33 PM Reply With Quote
quote:
Originally posted by Nickp
My understanding is that once you've got the ABS/ ASC deleted from the ECU then it'll no longer look for the wheel speed signals.
That's all I did with mine and I don't think it's missing any power tbh


Thats good news :-)





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britishtrident

posted on 15/1/18 at 11:21 PM Reply With Quote
On OBD2 compliant cars I have worked on the wheel speed sensors are used by the PCM for rough road detection by looking for sudden variations in wheel speed if a rough road condition is detected, misfire detection by the PCM is turned off and P0300 , P0301 ...... P0306 misfire fault codes will not be flagged up.

[Edited on 15/1/18 by britishtrident]





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coozer

posted on 16/1/18 at 12:12 AM Reply With Quote
My Merc dropped into limp mode with a message on the dash saying top speed exceeded..

Now honest guv Ive not tampered with the speed limiter and im sure the tachograph will show this...

Limp home mode is murder on a 44 tonner thats fully loaded...





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rodgling

posted on 18/1/18 at 10:20 AM Reply With Quote
quote:
Originally posted by craigdiver
Was just googling the t’internet, as you do, and came across this http://people.zeelandnet.nl/jeejansen/

It is claiming that with BMW engines the power will be limited if the ECU isn’t seeing a wheel speed signal? I have done a great deal of research on my M52TUB25 engine and have a custom ECU but no mention of this speed signal. Anybody heard of this or is it a lot of rubbish?


Yeah, this is true: normally the ABS signal feeds into the ECU. If it doesn't see the wheels moving, it sets a hard rev limit at around 5k. Fortunately, you don't need to spend $200 on £2 worth of electronics to fix it. All the ECU needs is a pulse train, so the signal from the diff will do fine. You can just join a couple of pins in the X20 connector to achieve this (I forget which ones - they're different on different E36 engines - but you can get this from the wiring diagrams).

Alternatively, if you've had your ECU tweaked to remove EWS and set a higher rev limit, they might have disabled this feature.

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craigdiver

posted on 18/1/18 at 10:31 AM Reply With Quote
quote:
Originally posted by rodgling
quote:
Originally posted by craigdiver
Was just googling the t’internet, as you do, and came across this http://people.zeelandnet.nl/jeejansen/

It is claiming that with BMW engines the power will be limited if the ECU isn’t seeing a wheel speed signal? I have done a great deal of research on my M52TUB25 engine and have a custom ECU but no mention of this speed signal. Anybody heard of this or is it a lot of rubbish?


Yeah, this is true: normally the ABS signal feeds into the ECU. If it doesn't see the wheels moving, it sets a hard rev limit at around 5k. Fortunately, you don't need to spend $200 on £2 worth of electronics to fix it. All the ECU needs is a pulse train, so the signal from the diff will do fine. You can just join a couple of pins in the X20 connector to achieve this (I forget which ones - they're different on different E36 engines - but you can get this from the wiring diagrams).

Alternatively, if you've had your ECU tweaked to remove EWS and set a higher rev limit, they might have disabled this feature.


Thanks for that, so in theory you shouldn’t be able to rev the b0ll0cks off your BMW sitting at traffic lights.

My ECU is custom with ABS removed so hopefully as per Nick’s post it should be ok.





If it ain't broken, fix it anyway (just because).

Building - BMW powered Haynes Roadster/442E hybrid.

Classic Fiat 126 aircooled
Aprilia Mana 850
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rodgling

posted on 18/1/18 at 10:59 AM Reply With Quote
Strangely, you can (initially) rev it while stationary, which makes testing for the issue a bit tricky! I think the ECU lets you do this if there's no engine load. So you can only really test when moving - although if I remember rightly, once it's kicked in while moving, it will be present when stationary as well. (I think resetting the ECU codes clears it again).
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