VR sensor - Resistance ?

[MadsF]

Hi

I have a VR sensor for my B230FK build with 170-180 ohm at 17 degree celcius.

Question is --> I have a v3.8 VEMS and, i belive VEMS have some trouble with low resistance VR sensors, i am considering adding a resistor. Because i believe a 300-700 ohm sensor would be better. Both heard and read about this ....

So where should the resistor be added ? And what value should the resistor have ?

[fphil]

I have a VR sensor for my B230FK build with 170-180 ohm at 17 degree celcius.
Question is --> I have a v3.8 VEMS and, i belive VEMS have some trouble with low resistance VR sensors, i am considering adding a resistor. Because i believe a 300-700 ohm sensor would be better. Both hear and read about this ....

Why do you think so? Usually the lower the internal impedance of a source is the better is.

[MadsF]

Because the supplier of VEMS in Denmark says so, i also have a friend which have had problem with the original volvo low resistance VR sensor. He changed it to ~ 500 ohms VR sensors from a Opel 2.0 16v and had good results with this.

It should be possible to put a resistor in the VR curcuit .... Anyone knows anything ?

[MWfire]

Use that sensor. I have many cars with low resistance VR sensor.
Putting resistance in series will only decrease amplitude of signal, what is bad.

[fphil]

The LM1815 VR chip of the genboard works with an adaptive threshold in order to differentiate the signal from the noise which may be collected by the line set from the sensor to the genboard. This chip has got also several detection modes (see the datasheet).
Any resistance at the input of the genboard would lower the VR signal and the noise level, this could help to match better the adaptation band of the chip in some case. Anyway better to get rid of the line noise first.

[MWfire]

btw i like to remove pullup resistor if using VR sensor.

[MadsF]

Alright .... But even think i read something about frying the board by using low resistance VR sensor? Hope it isn't true 

[MWfire]

Alright .... But even think i read something about frying the board by using low resistance VR sensor? Hope it isn't true 

Not true. Lm1815 can handle +-120V.
It's very hard to destroy that input.

[MadsF]

Okay, thats what i like to hear. I appreciate your quick answers. Thanks. - I'll keep going with the 170-180 ohms VR sensor if i don't run into trouble.

[Kamuto]

Alright .... But even think i read something about frying the board by using low resistance VR sensor? Hope it isn't true 

Not true. Lm1815 can handle +-120V.
It's very hard to destroy that input.

btw, what is your recomendations if I want to rev s54 10000+ rpm? remove pullup at all? now it's with 27k pullup and looses sync at about 9200 rpm

[MWfire]

Alright .... But even think i read something about frying the board by using low resistance VR sensor? Hope it isn't true 

Not true. Lm1815 can handle +-120V.
It's very hard to destroy that input.

btw, what is your recomendations if I want to rev s54 10000+ rpm? remove pullup at all? now it's with 27k pullup and looses sync at about 9200 rpm

I did few s54(N/A and turbo), but max rpm is 8400rpm(stock head). I always remove 27k pullup for vr sensor with multi tooth(60-2). Try that.

I did few formula with engine from motorcycles, rev limit 15000rpm wasn't a problem with removed pullup.

[Kamuto]

Alright .... But even think i read something about frying the board by using low resistance VR sensor? Hope it isn't true 

Not true. Lm1815 can handle +-120V.
It's very hard to destroy that input.

btw, what is your recomendations if I want to rev s54 10000+ rpm? remove pullup at all? now it's with 27k pullup and looses sync at about 9200 rpm

I did few s54(N/A and turbo), but max rpm is 8400rpm(stock head). I always remove 27k pullup for vr sensor with multi tooth(60-2). Try that.

I did few formula with engine from motorcycles, rev limit 15000rpm wasn't a problem with removed pullup.

never have removed it at all with vr sensors willing to try one day

[MWfire]

Alright .... But even think i read something about frying the board by using low resistance VR sensor? Hope it isn't true 

Not true. Lm1815 can handle +-120V.
It's very hard to destroy that input.

btw, what is your recomendations if I want to rev s54 10000+ rpm? remove pullup at all? now it's with 27k pullup and looses sync at about 9200 rpm

I did few s54(N/A and turbo), but max rpm is 8400rpm(stock head). I always remove 27k pullup for vr sensor with multi tooth(60-2). Try that.

I did few formula with engine from motorcycles, rev limit 15000rpm wasn't a problem with removed pullup.

never have removed it at all with vr sensors willing to try one day

i had a problem with one astra after 9200rpm with pull up resistor. Without resistor no problems. Cars is FWD and goes 9.6s on 402m.

[Kamuto]

yes, had the issue with c20let on that put the bigger resistor, but didn't thought about removing it

[MWfire]

I found one log of miss shifting from 3rd to 2nd gear. No trigger errors with removed pullup resistor

That was nice car, opel 2.0 16v with 3.2bar of boost.