Engine Instrumentation Project - Page 2 - PeachParts Mercedes-Benz Forum

Dan Stokes · #1 01-22-2014, 05:23 PM

I'm not sure of M-B's fuel delivery strategy but I wouldn't expect rack (IP) position to be much related to fuel delivery. Generally speaking on a mechanical Diesel injection system fuel delivery is determined by rack position and load. So even if you held the accelerator pedal dead steady the IP would add fuel if you hit a hill and pull fuel out on a downhill (or any other change in load).

Cat traditionally used a speed priority system where the IP would maintain engine speed regardless of load while other US engine builders (Cummins, Detroit Diesel, etc.) used a load priority system where engine speed would vary depending on what it took to maintain the torque output which was determined by the operator's pedal position. Two different ways of getting to the same point. Again, I'm not sure of M-B's methods.

Hope that confuses the issue!

Dan

winmutt · #2 01-23-2014, 08:44 AM

Here is what I did : EngineSystemsManagement

My video in action.

http://youtu.be/yFyMZ4urR9U

Tach is not so easy to do, its a VR not a hall effect sensor. My only real concern is overvoltage. I've had the tach plug hanging out of the cluster for a while now wiating for some voltage readings and just haven't had time/interest. Too many house chores.

Using the stock boost sensor is def the way to go IMO. Be careful of ground looping your EGT. I spent days cursing because it would work when powered off the laptop but not the engine. Like you I had high hopes of using my android for a display using BT for comm, but at the end of it all an LCD was way easier and more sensible. I still have the BT shield, probably going to use it to make a nest like tstat for the house.

I don't think your choice of arduino's is great, not nearly enough pins.

mach4 · #3 01-23-2014, 01:11 PM

Quote:

Originally Posted by winmutt

Tach is not so easy to do, its a VR not a hall effect sensor. My only real concern is overvoltage. I've had the tach plug hanging out of the cluster for a while now wiating for some voltage readings and just haven't had time/interest. Too many house chores.

Using the stock boost sensor is def the way to go IMO. Be careful of ground looping your EGT. I spent days cursing because it would work when powered off the laptop but not the engine. Like you I had high hopes of using my android for a display using BT for comm, but at the end of it all an LCD was way easier and more sensible. I still have the BT shield, probably going to use it to make a nest like tstat for the house.

I don't think your choice of arduino's is great, not nearly enough pins.

Great read - thanks. Using a stock 3-bar boost sensor is the plan - just need to find a cheap one, preferably in the junk yard. I'm pretty confident I can get the BT working. With any luck it will be here today and I can start playing.

I don't think I'll have any trouble with pins on the Arduino ProMini. Unless I'm missing something (entirely possible) I'll need 2 digital pins for the EGT and one analog each for temps and pressures. The BT takes 2 digital, so that's a total of 4 digital and 5 analog. I've got 12 digital (plus tx and rx) and 8 analog pins on the ProMini. All the same pins as the Uno R3.

Edit: Just remembered that the temp sensors use 1-Wire to communicate, so all the temp gauges combined use only one pin. So as currently conceived the system would take 5 digital and 1 analog.

There is some good info on the tach input that should be helpful here - Quick Fix: 1985 w123 Tach & A/C after EGR Failure

The logic for using the phone as a display is

I've already got an extra one
I won't have to modify the dash in any way
It's easier to program in Processing
I can use an analog gauge display
I can have multiple display options
I can upgrade to a tablet later on
I've already got my phone mount
No wires from the engine to the dash
It will be a fun programming challenge

winmutt · #4 01-24-2014, 08:15 PM

What are you going to do the EGT with?

RE LCD vs BT, I had tge BT working but decided I really ddint want to have my phone always on always working etc. What I do need is EGT ALWAYS on, Dunno. Keep us posted!

mach4 · #5 01-24-2014, 08:21 PM

Quote:

Originally Posted by winmutt

What are you going to do the EGT with?

RE LCD vs BT, I had tge BT working but decided I really ddint want to have my phone always on always working etc. What I do need is EGT ALWAYS on, Dunno. Keep us posted!

The EGT will be running on the Android. Remember, the Android is an old one that is no longer used as a phone, so I'll literally be just using it as a Bluetooth receiver and a presentation screen. My iPhone will be providing phone/navigation/Pandora capabilities as always.

mach4 · #6 01-24-2014, 08:35 PM

Here's a quick video of the Gauge App running on the Android.

Android App - YouTube

winmutt · #7 01-24-2014, 08:49 PM

Quote:

Originally Posted by mach4

The EGT will be running on the Android. Remember, the Android is an old one that is no longer used as a phone, so I'll literally be just using it as a Bluetooth receiver and a presentation screen. My iPhone will be providing phone/navigation/Pandora capabilities as always.

Yes but what adc chip are you going to be using to convert the EGT signal?

mach4 · #8 01-24-2014, 08:17 PM

Here's a quick update on the project.

One of the big accomplishments was getting the application compiled, uploaded and actually running on the HTC Incredible Android phone. I say big accomplishments because it was one of the most frustrating and tricky things I've done. Just lots and lots of Googling, trial and error and luck. It's actually quite responsive running on the phone.

Starting to work on sourcing the sensors and thinking through the mounting issues a little more.

I've also made significant progress on the Android app. Here's a screen capture of the current application running in demo mode on the PC. I anticipate having lots of different screens available and this just demonstrates the options and capabilities.

https://www.youtube.com/watch?v=KYmL555em38

yvairguy · #9 02-01-2014, 02:50 PM

if all the sensors are wired why not bring the hard wired signals through the firewall and have the bluetooth located in the cabin?

mach4 · #10 02-01-2014, 05:31 PM

Quote:

Originally Posted by yvairguy

if all the sensors are wired why not bring the hard wired signals through the firewall and have the bluetooth located in the cabin?

Several reasons:

With bluetooth, no wires need to traverse the firewall
Everything can be contained in one convenient location
It's an interesting exercise in programming

mach4 · #11 02-05-2014, 05:04 PM

I'm really struggling with the software end of things. I've been able to reliably get data across the Bluetooth from the Arduino to the Android and I've been able to get the gauge program running locally, but when I try to bring the two code pieces together it has thus far failed. So I decided to take a bit of a break and focus on other pieces of the system.

The way I'm going to source the oil, trans snf intake temps is using a very slick DS18B20 temp module. I got this breadboarded with 4 sensors, so that part is ready to go. A common way to get oil and trans temps is to T into the line with the sensor. I have no interest in adding 6 additional points of potential leaks, so I'm going to use an external pickup. I'll clamp an aluminum block with the sensor epoxied inside to the line going to the respective cooler. Here's the trans temp pickup block ready to install the sensor. The oil temp pickup is identical, though with a larger hole.

yvairguy · #12 02-05-2014, 06:18 PM

if they are steel lines may want to wrap the lines with something to insulate the line from the block so you don't get electrolysis with the dissimilar metals. if they are aluminium and you can bolt it right on maybe try using thermal paste like you do on processors

Simpler=Better · #13 02-10-2014, 10:27 AM

I like it

I'd definitely use thermal paste (or at least antisieze) between the clamp-on sensors and the lines. Insulation isn't a bad idea either, that block of aluminum looks like a nice heatsink.

mach4 · #14 02-11-2014, 12:48 PM

Progress continues...but I have one question - which side of the transmission provides the supply to the cooler in the radiator? It seems like it's the drivers side, but I can't find a definitive answer.

Got the board wired up as far as I can go without the thermocouple amplifier module. Also got the relay box mounted in the car and mocked up ready to start doing the chassis-side wiring. The boost sensor and the vacuum sensor are also mounted and ready to go.

I also tackled the piece of the project to include a vertical card compass and got the compass working with simulated data. The compass module will be here in about a week. Unfortunately I don't think there will be room inside the box... of course it probably doesn't make any sense to have the sensor module in the box anyway due to interference.

winmutt · #15 02-11-2014, 04:56 PM

Not using the stock 3bar boost sensor?

Why not use the phones compass?

Lookin good!