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How is that possible?!
My rpm gauge was reading like 400 rpms above of wha it should. Like my idle speed was 1100 indicated however the diagnostics computer read 700 rpms.
Finally I ended up purchasing a used cluster really cheap. I replaced it and my surprise was that the car performed much better and it gained some torque around 4K rpm, where previously used to have some sort of dip in power. Just at the point where the vanos comes to play. It had a really noticeable dip from 4500 to 5500 or so. I could clearly notice it if I went WOT for the first time from down low rpms all the way up to the rev limiter. First time doing this after driving normal, and you could clearly feel it had some sort of torque dip around that rpms...
And well, just swapped the clusters and a few kms later that thing is completely gone!
Does that make any sense!?
I read somewhere that the VSS signal on the speedo has something to do with how the VANOS operates... and as long as there is some sort of VSS signal, be it right or wrong, the DME does its stuff...
My speed cluster was working properly... I think so...
What if I try to run the car without the cluster connected? Would it work the same? Does the DME need some sort of feedback coming from the clusters?
Member
The DME does use vehicle speed and the vehicle speed IS processed through the cluster so....
Who'd have thunk it though?
One for the memory banks.
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
Member
Was the battery disconnected while changing clusters? That might have resetted the DME. Or what the guy above said...
Sent from my Samshit SM-G900F using Tapatalk
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It was somehow weird cause I wasnt expecting any kind of improvement... but it did..
I had some issues when driving below 2K rpms, like sometimes it missfired and run like crap when too low engine speed and 3rd gear or so... it didnt when 1st and 2nd gear. 4th gear was even worse. 5th better not try.
And then it was that dip in power when above 4K.
All of that is gone.
Awesome, isnt it? I wasnt expecting that...
Last edited by 4dri4n; 08-16-2017 at 06:50 PM.
Member
Given that I'm sure that the car runs without a cluster installed, I'm pretty sure you're just experiencing a placebo effect.
Member
Originally Posted by Creesic
That would be true if I was expecting it, but I wasnt!
Some members of other forums told me that the e34 tds , for instance, has poor performance and hesitation while accelerating without the cluster connected. Maybe this is true for the e34 m50 aswell. Maybe you can run a while without it connected and no symptoms I dont know... for instance I drove the car without the TPS connected for 10 miles or so and didnt notice it...
To me, it clearly showed some improved noticeable performance... which is still right now... in fact, a friend of mine has just told me a few minutes ago he did notice it aswell... but there is the chance it is some sort of placebo effect who knows...
Member
Nope, entirely plausible.
The engine management needs all of the inputs at correct values for best performance. When wrong it will either respond incorrectly or substitute fixed values not optimal.
The speed signal is processed through the cluster, a deviated signal could cause running issues.
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
Member
Just found that out looking at diagrams. Makes sense now.
Member
Where are you looking? In the BMW electrical diagnostic manual? If so what index number is it?
Member
I'm doing some megasquirt wiring, and it appears that speed and tacho data is called from the ECU to the cluster in some way, and then spat back out.
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