Mikes 1987 Chevy Camaro - Comments thread

[Dan]

malcom2073 - there is a file called "ravage.pdf" which is a pdf replica of the Altium schematics. I would grab the latest one off git though, as it is updated quite regularly.

[Fred]

I would git clone the project from github though, and git pull before reading it, as it is updated quite regularly.

Fixed! :-)

[malcom2073]

malcom2073 - there is a file called "ravage.pdf" which is a pdf replica of the Altium schematics. I would grab the latest one off git though, as it is updated quite regularly.

Will do, thanks!

[Peter]

TA Card

Have you seen this? viewtopic.php?f=62&t=1315

Ignitor Driver: Need 2 of these for 8 ignitors. I may actually not need this, I think my dist has a regular input for ignition, I have to check.

Your XOR gate's current rating is 24mA, and the copy of Ravage that I'm using has XOR gates rated at 32mA. I have no idea if it's an issue, so I just thought I'd point it out for somebody else to check. Also the cost difference for 1% tolerance resistors is pretty small so I always try to order them if I'm buying resistors from somewhere that has 1% resistors. This is far more important for the analog signal conditioning circuits.

Analog Input: 7 of these? (CTS,IAT,TPS,WBO2,MAF,Fuel/Oil Pressure)

viewtopic.php?f=54&t=1580&p=23568&hilit ... sor#p23568
Use all 1% resistors. The 470Ohm resistors don't make much difference, but there's very little reason not to order them as 1%ers too. I'd recommend a better heat rating on your capacitors like x7r, and I usually try to find a nice balance between cost and tolerance on the capacitors. I'd definitely try and find something better than 20%. I don't know much of anything about diodes so somebody else should review them, but the current rating looks a little high to me. I think that generally results in a higher current leakage, and a higher price tag for no reason.

MAP Sensor Input: 1 of these

I assume that's the sensor that the Jaguar uses. If your board has no plans of ever seeing a boosted engine that sensor should give you a finer pressure resolution, but I like Ravage's sensor better MPXH6250AC6U ~3-36psi I think. More of a personal choice.

Power Supply: 1 of these

No, I don't think 500mA will do it. My original board had a 1A LDO reg on it, and the heat sink got too hot for my taste. My latest board has 2A of capacity, and bigger heat sinks.

Injector driver: Need 8 of these, the them together on the back-end so I do 4 sets of 2 injectors.

I don't know if that MOSFET will work or not. It looks quite a bit different than the one used in the Ravage schematics. The first thing that I notice that I don't like about it is that it has about 20 times more resistance. It might need a heat sink. Are your injectors high or low impedance?

Optoisolated digital inputs for... knock input?

I'm not sure where you got this idea. I think an opto in the knock sensor circuit would effectively block the frequency spectrum that you're trying to analyze with the knock sensor chip.

Digital Outputs (relay controls) for fuel pump, cooling fan, torque converter lockup, anything else?

I think Fred has some plans/ideas on using PWM on fuel pumps, and cooling fans.

VR frontend for reading dist tooth output.

A VR sensor probably isn't going to like the distributor's tooth shape. Why do you want a sensor on the distributor?

IAT - I can wire this to a switch for cold starting, but eventually I want the ecu to run it.

I guarantee you that Fred won't like this plan.

[malcom2073]

Thanks for all the feedback!

Have you seen this? viewtopic.php?f=62&t=1315

Yep

Your XOR gate's current rating is 24mA, and the copy of Ravage that I'm using has XOR gates rated at 32mA. I have no idea if it's an issue, so I just thought I'd point it out for somebody else to check. Also the cost difference for 1% tolerance resistors is pretty small so I always try to order them if I'm buying resistors from somewhere that has 1% resistors. This is far more important for the analog signal conditioning circuits.

I'll double check my math, but I think 24mA was plenty

viewtopic.php?f=54&t=1580&p=23568&hilit ... sor#p23568
Use all 1% resistors. The 470Ohm resistors don't make much difference, but there's very little reason not to order them as 1%ers too. I'd recommend a better heat rating on your capacitors like x7r, and I usually try to find a nice balance between cost and tolerance on the capacitors. I'd definitely try and find something better than 20%. I don't know much of anything about diodes so somebody else should review them, but the current rating looks a little high to me. I think that generally results in a higher current leakage, and a higher price tag for no reason.

Thanks for the link. I'll switch over to 1% for all the resistors. Also, the inside of my old ECU never got above 50c even on a hot day, but it wouldn't hurt to overrate the caps.

I assume that's the sensor that the Jaguar uses. If your board has no plans of ever seeing a boosted engine that sensor should give you a finer pressure resolution, but I like Ravage's sensor better MPXH6250AC6U ~3-36psi I think. More of a personal choice.

yeah I need two inputs, ambient and intake. And my board has zero plans of ever seeing a boosted engine.

No, I don't think 500mA will do it. My original board had a 1A LDO reg on it, and the heat sink got too hot for my taste. My latest board has 2A of capacity, and bigger heat sinks.

I got that from Ravage I think. The power supply will be last, and I'll rate that based on how much current my breadboard setup uses.

I don't know if that MOSFET will work or not. It looks quite a bit different than the one used in the Ravage schematics. The first thing that I notice that I don't like about it is that it has about 20 times more resistance. It might need a heat sink. Are your injectors high or low impedance?

I double checked, you're right they won't work. The resistance isn't the problem, the 1.4V drop across the source/drain is, so I'll spec a different one out

I'm not sure where you got this idea. I think an opto in the knock sensor circuit would effectively block the frequency spectrum that you're trying to analyze with the knock sensor chip.

Talking out my arse. I have no clue what kind of frontend a knock sensor needs. Just another thing I have to look into. I do want optoisolated digital inputs though.

I think Fred has some plans/ideas on using PWM on fuel pumps, and cooling fans.

That scares me. I don't know why. Probably ignorance.

A VR sensor probably isn't going to like the distributor's tooth shape. Why do you want a sensor on the distributor?

My distributor has a VR sensor in it, I'm not adding it.

I guarantee you that Fred won't like this plan.

That I want to control it with a switch until he gets support in the ECU?

[Peter]

I'll double check my math, but I think 24mA was plenty

I don't know what math you're doing, but I'm guessing that all it needs to be able to do is drive the TC4427. It's supply current is 4.5mA so I think it'll be fine.

Also, the inside of my old ECU never got above 50c even on a hot day, but it wouldn't hurt to overrate the caps.

I'm more worried about the cold, because if it's above 80C you probably have more serious problems to worry about. The ones you have picked out are only rated to go down to 10C. So when it gets to be -30 out you might end up blaming FreeEMS for a problem that's actually being caused by capacitors that are too far out of their operating temperature range. Plus the price difference isn't worth having cheap components. Unless you're Fred in which case you buy loner chips that don't talk to others, and thermocouples that are only made from one type of metal.

I do want optoisolated digital inputs though.

Whatever turns you on I suppose. You might want to post a wiring schematic up of what you're trying to do before you spend any money on it.

My distributor has a VR sensor in it, I'm not adding it.

I assume it has 8 equally spaced teeth. You could cut one tooth off to get an 8-1 trigger wheel, but that probably isn't going to be fine enough resolution for ignition timing.

That I want to control it with a switch until he gets support in the ECU?

The Intake Air Temperature sensor is used by the ecu. It sounds like we're talking about different things. I'm guessing that you're talking about the idle air valve.

[malcom2073]

The Intake Air Temperature sensor is used by the ecu. It sounds like we're talking about different things. I'm guessing that you're talking about the idle air valve.

Doh, I meant IAC not IAT (Idle Air Control), so yes. Acronym failure.

And yes I will post a schematic before I buy anything.

[Dan]

I would like to see your schematic, I am happy to review it prior to you making anything too if you wish?

[Dan]

Unless you're Fred in which case you buy loner chips that don't talk to others, and thermocouples that are only made from one type of metal.

ROFL!

[Fred]

Indeed, this WAS ROFL. The above ROFL comment is whole heartedly endorsed by yours truly in his somewhat inebriated state.