Speed Limiter
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BURTON said:
I am told that the limiter cable is the one nearest the firewall and simple physical disconnection is all that is needed. There are no electronics involved.
That said, when I thought about disconnecting mine I found that of the 3 cables involved only the cable furthest from the firewall both accelerated and decelerated and we thought that might be the cruise control and I left it for then. I then managed 163 mph in a place south of the English channel and thought that I had one of the early 3.8's that didn't have a speed limiter. I then found out that 163 is possible on a 3.6 before the limiter cuts in so I don't really know now.
There are a fair few discussions about this on M5board from about 2002 or so. Try a search for further info.
:cheers:
ralph (vadas1)
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Farrell did mine. Took about 1 min.BURTON said:
PM him, I'm sure he'll help.
Steve
BURTON said:
Yep
Dead easy
Speed limiter is attached to throttle.
trace cable that goes down to a stepper motor affixed to lhs inner wing reinforcement flitch.
Its mounted quite low down as opposed to cruise module & cable thats mounted to top of wing in front of diagnostic port & behind hydraulic reservoir.
Once cabe is identified you will find an adjustment nut & thread.
undo this & remove threaded portion & tuck the rest back under plastic cable outer.
Hey presto...
No more speed limiter.
The stepper motor still actuates but there is no tension in the cable to pull the throttle back.
Job done.
Farrell
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7 Posts
well it's not quite that easy :grrrr:
It is true that when the throttle servo is disconnected on the 3.8 it will run faster then the speedlimiters 155.
But above that speed engine power is not the full 340...
The ecu need a speedsignal on both the 3.6 and 3.8
this is the black/white wire that runs from the tacho/dash pin 29
On the 3.6 without this signal / above 155 (tested on dyno) it had 38 HP at the rear wheel less then With the speedsignal.
haven't tested it yet on my 3.8 but i imagine it will be even more :grrrr:
speedsignal-simulator : speedsignal simulator
Due to my engine not being in an original bmw m5 body i didn't have the signal and needed to fabicate a speedsignal duplicator in order for the ECU not to run in lower power
This lower power will occur above the 155 limiter or when the signal isn't there at all
Regards, Joeri
It is true that when the throttle servo is disconnected on the 3.8 it will run faster then the speedlimiters 155.
But above that speed engine power is not the full 340...
The ecu need a speedsignal on both the 3.6 and 3.8
this is the black/white wire that runs from the tacho/dash pin 29
On the 3.6 without this signal / above 155 (tested on dyno) it had 38 HP at the rear wheel less then With the speedsignal.
haven't tested it yet on my 3.8 but i imagine it will be even more :grrrr:
speedsignal-simulator : speedsignal simulator
Due to my engine not being in an original bmw m5 body i didn't have the signal and needed to fabicate a speedsignal duplicator in order for the ECU not to run in lower power
This lower power will occur above the 155 limiter or when the signal isn't there at all
Regards, Joeri
The 3.8 has completely different Motronic system to 3.6oldtimerfan said:
Speed limiter is mechanical but operating via a speed input to the ECU to actuate a stepper motor which mechanically retards the throttle.
3.6 has electronic limter as you say.
I dont agree with the hypothesis that fuel & spark is altered on the 3.8 above a certain road speed input which in this case is from the Hypoid main casing.
Any alteration to fuel & spark are engine rpm based.
Thats my understanding but Mark Dsylva or Raymond Woertmann or such may have more to add.
Not many 3.8 's have 340 bhp as quoted unless they have had emissions related parts like EGR & cats removed in my experience.
Regards
Farrell
Interesting that because a group of E34's went up to Noble for a group dyno test. Of the original cars I think 4 or 5 got 339bhp or better ( up to 345bhp I think ) and the 330+ range were all chipped. Granted the cars may well have been pristine low mileage examples.farrell said:
:cheers:
ralph (vadas1)
Yep Ralphvadas1 said:
Corrected figures on a rollong road though.
I remember the thread well.
The figures were good in that they were comparative with other vehicles on the day, but you could go to another rolling road & find corrected figures 5% below these.
Ive been informed that those who have sone some engine dyno work to produce a modified eprom have shown figures closer to 325bhp prior to modification.
Its really up to what you think is realistic but I dont doubt that there are cars out there delivering the full output.
Mine is not one of them.
Farrell
I can understand the need for a "speed simulator" when the engine is transplanted into another car without the original speedometer, as you point out, the speedometer sends a signal to the ECU.
But, I was under the impression that when you delimit a 3.6 in the E34 shell, it is the ECU that is altered, so the diff sensor and speedo continue as they were. I understood that the 155mph "limit" was not removed as such, but the value simply increased, say to 199mph or an arbitrary figure, as changing the EEPROMs hex value in one location is a whole world easier than reprogramming the whole limited mechanism. Isn't it?
This would also negate any system that tries to electronically limit power (if one even exists) as the routine would never be called.
Hey ho, perhaps I'm wrong! Awaiting clarification from all the chip-making experts, black magicians are they! Witches and Wizards! Burn them!!
Ivan
But, I was under the impression that when you delimit a 3.6 in the E34 shell, it is the ECU that is altered, so the diff sensor and speedo continue as they were. I understood that the 155mph "limit" was not removed as such, but the value simply increased, say to 199mph or an arbitrary figure, as changing the EEPROMs hex value in one location is a whole world easier than reprogramming the whole limited mechanism. Isn't it?
This would also negate any system that tries to electronically limit power (if one even exists) as the routine would never be called.
Hey ho, perhaps I'm wrong! Awaiting clarification from all the chip-making experts, black magicians are they! Witches and Wizards! Burn them!!
Ivan
It depends what you expect from the modification.batmonger said:
Outright power gains are very small.
Midrange gains in drivreability could be realised as long as you are getting a chip from someone who knows what they are doing.
Read some of the threads on this Forum & you may gain most of the knowledge you need to make an educated decision.
You must be sure of the condition of your own vehicle though.
I would recommend avoiding those chips that extend the rpm limiter.
Not good.
Farrell
Burton
Firstly, the cruise control actuator is not associated with the limiter.
The cruise unit is very visible on the top of the n/s inner wing in front of the suspension turret.
The limter is a stepper motor fitted to the side of the inner wing low down.
Theres no need to remove this motor as once the cable adjustment nut & threaded sleeve are adjusted to add slack, the cable attached to the throttle linkage from the motor will still operate but will not hold the throttle back.
Ive tested mine a few times & de-restricted a few 3.8 's now.
All works fine.
Farrell
Firstly, the cruise control actuator is not associated with the limiter.
The cruise unit is very visible on the top of the n/s inner wing in front of the suspension turret.
The limter is a stepper motor fitted to the side of the inner wing low down.
Theres no need to remove this motor as once the cable adjustment nut & threaded sleeve are adjusted to add slack, the cable attached to the throttle linkage from the motor will still operate but will not hold the throttle back.
Ive tested mine a few times & de-restricted a few 3.8 's now.
All works fine.
Farrell
But you could remove if you so wished..
I don't mean that does it do both jobs of limitering and cruise controling. (good english I know) But are the control units themselves the same.
Its just that I have a cruise control kit. Motor, Stalk, ECU. And the stepper motor looks the same. Also I was wondering if I could remove it as my Cruise control kit stepper motor is not for a M car as the lead won't reach..
I don't mean that does it do both jobs of limitering and cruise controling. (good english I know) But are the control units themselves the same.
Its just that I have a cruise control kit. Motor, Stalk, ECU. And the stepper motor looks the same. Also I was wondering if I could remove it as my Cruise control kit stepper motor is not for a M car as the lead won't reach..
Yes
You could remove it, but as the motor is electronically controlled via the engine management, I would leave well alone.
I dont know if it will thow up an error if disconnected.
Leaving the unit insitu with the engine management thinking all is well is no bad thing.
The cruise control & speed limiter units are not the same unit as far as Im aware.
As far a the aftermarket cruise system is concerned, I have no idea.
Farrell
You could remove it, but as the motor is electronically controlled via the engine management, I would leave well alone.
I dont know if it will thow up an error if disconnected.
Leaving the unit insitu with the engine management thinking all is well is no bad thing.
The cruise control & speed limiter units are not the same unit as far as Im aware.
As far a the aftermarket cruise system is concerned, I have no idea.
Farrell
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1,298 Posts
Takes 1 minute and there is no other restriction other
than gearing & rev limit.
![]()
than gearing & rev limit.
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OK that's real comforting, that means that I will be cut off when I try to go for 200..shame...:hihi:IvanDias said:
I have seen speeds over 260 on the clock in my car, am told by the prev owner that the car has had a limiter removal. I have driven several german cars that surely still have the limiter (FI E39) and they seem to go to 260 on the clock as well!! ( you can imagine my heart skipping a beat when I saw the needle easily pass 250!)
So not too sure then..I know my speedo is pretty accurate below 100 but the real loss is above 150.
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