Fuel pump & knock sensors.

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chevyowner
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Fuel pump & knock sensors.

Post by chevyowner »

I have the Fuel Pump connected to pin 37 on the main 37 pin connector, and I cant get the MS3 to turn on the relay.
I can unhook this wire and apply B+ and turn on the relay.

I was given a link for a knock sensor module, but it seems that this module does not support one wire sensors that I will be using.
What are my options for connecting two one wire knock sensors?

I can attach a msq if needed after i get it from the PC it is on. (not at that PC)
DeadStiff
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Re: Fuel pump & knock sensors.

Post by DeadStiff »

You should be supplying 12v to the relay, the MS supplies the ground.

Someone else will have to comment about the knock sensors.
MS3+X on 73 Karmann Ghia ignition only with LS2 truck coils firing in sequential, fuel next.
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chevyowner
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Re: Fuel pump & knock sensors.

Post by chevyowner »

DeadStiff wrote:You should be supplying 12v to the relay, the MS supplies the ground.

Someone else will have to comment about the knock sensors.
Thanks I am not sure how I missed that.

Update
I corrected the fuel pump wiring, and it runs with out manually turning on the relay.
Matt Cramer
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Re: Fuel pump & knock sensors.

Post by Matt Cramer »

One wire sensors are not a problem. They are simply grounded through the body so you do not use a sensor return. I believe the idea is that most of the noise from ground offsets won't make it through the bandpass filter.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
jsmcortina
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Re: Fuel pump & knock sensors.

Post by jsmcortina »

chevyowner wrote:
DeadStiff wrote:You should be supplying 12v to the relay, the MS supplies the ground.

Someone else will have to comment about the knock sensors.
Thanks I am not sure how I missed that.
The (new) hardware manuals have the external wiring diagram in section 3. Please download the correct manual to match your Megasquirt from
http://www.msextra.com/doc/index.html#ms3

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
chevyowner
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Re: Fuel pump & knock sensors.

Post by chevyowner »

I downloaded those, and before I go to apply these modifications. What methods would people here recommend to set the timing to avoid detonation?

PS
I have the car running. I just want to make sure I don't break something.
elutionsdesign
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Re: Fuel pump & knock sensors.

Post by elutionsdesign »

Every motor is different, the BEST method is find a steady state dyno and someone that understands tuning for best torque at minimum timing advance. Lacking that just find the factory specs for centrifugal advance and build a table yourself.
Graduate of EFI University.

I build, repair, install and tune Megasquirt systems in North Dakota and beyond!
chevyowner
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Re: Fuel pump & knock sensors.

Post by chevyowner »

IF I understand what I am reading on page 36-37 from MS3baseV357_Hardware-1.3.pdf, and from Tunerstudio correctly I can use analog mode with what I have here using spare adc (adc13) and one knock sensor. I remember a few GM vehicles had two knock sensors merge into one wire before connecting to the PCM/ECM. Will connecting two sensors like this work?

PS
I downloaded both, but entered the wrong file name for the one I was looking at. The file is MS3XV357_Hardware-1.3.pdf not MS3baseV357_Hardware-1.3.pdf
chevyowner
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Re: Fuel pump & knock sensors.

Post by chevyowner »

chevyowner wrote:IF I understand what I am reading on page 36-37 from MS3baseV357_Hardware-1.3.pdf, and from Tunerstudio correctly I can use analog mode with what I have here using spare adc (adc13) and one knock sensor. I remember a few GM vehicles had two knock sensors merge into one wire before connecting to the PCM/ECM. Will connecting two sensors like this work?

PS
I downloaded both, but entered the wrong file name for the one I was looking at. The file is MS3XV357_Hardware-1.3.pdf not MS3baseV357_Hardware-1.3.pdf

I am just going to assume that this will work and cause no problems because no one can bother to reply and say it wont work.
arran
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Re: Fuel pump & knock sensors.

Post by arran »

I would not think that connecting two knock sensors in parallel would be a great idea. The signals form these devices are very low level, connecting them together will have one trying to drive the other as well as the front end of whatever is supposed to be listening to the signals. They are a high impedance device, meaning their ability to drive loads is low.

Arran
RX7 Series 2 13B Turbo. Megasquirt 3 with 3X Expander and V3 CPU. Firmware 1.4.1
Knock module, twin EGT, real time clock, WBO2, full sequential fuel and spark
http://web.aanet.com.au/arran
chevyowner
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Re: Fuel pump & knock sensors.

Post by chevyowner »

arran wrote:I would not think that connecting two knock sensors in parallel would be a great idea. The signals form these devices are very low level, connecting them together will have one trying to drive the other as well as the front end of whatever is supposed to be listening to the signals. They are a high impedance device, meaning their ability to drive loads is low.

Arran

I know about high impedance and low impedance devices. There is also a basic amplifier that goes from high to low impedance that can be built for ~$2 depending on parts used, and their prices. I actually have one sitting here.
If I connected the knock sensors to this I could play the audio from them on the car stereo if I wanted to. It would also be possible to record them on a laptop.

The part of the picture I don't know much about here is not the knock sensors or how they work. It is the MS3x I don't know much about right now.
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