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Topic: Car rev limiter (Read 2 times) previous topic - next topic

drother

Jul 26, 2012, 08:00 pm Last Edit: Jul 26, 2012, 08:06 pm by drother Reason: 1
I want to build a rev limiter for my car, and it uses a logic level coil input from the pcm. If I did my homework right, I would use a PNP transistor. Also, I would set the Base to pull down resistor, so that for some reason if the arduino fails, the transistor would default to "on" to let the coil fire.

The logic level coils like this: as soon as it sees a +3-5V logic input, it begins charging the coil. It fires as soon as it loses the +5V input.

Am I correct that I will use a PNP transistor?
Also, it draws around 40mA. What would be a good transistor to use?

CoolJ

#1
Jul 27, 2012, 06:08 am Last Edit: Jul 28, 2012, 02:22 am by CoolJ Reason: 1
I know this is my first post. I wouldn't normally answer a question on a forum with a first post.
However, I have unique knowledge in this area. (I have done it)
It was for traction control using front wheel speed vs rear wheel speed. Slightly different application, same outcome.

I tried spark cut first because it was easy with the ignition setup used in the car at the time. The results where undesirable and sloppy.

Spark cut is a terrible way to rev limit the engine. You have an Arduino. You can do better.

Put in an up stream flapper in the intake. You can easily move it with a servo. Center bias the flapper so it can not get sucked closed.
Failure mode = OPEN.

Track engine RPM(several different ways). When the RPM reaches the limit, close flapper whatever amount you are happy with.
This will work for all fuel injected cars Alpha-N or Speed Density. **DO NOT DO THIS IF YOU USE A CARBURETOR**
You have been warned. I wash my hands. ]:D

drother


I know this is my first post. I wouldn't normally answer a question on a forum with a first post.
However, I have unique knowledge in this area. (I have done it)
It was for traction control using front wheel speed vs rear wheel speed. Slightly different application, same outcome.

I tried spark cut first because it was easy with the ignition setup used in the car at the time. The results where undesirable and sloppy.

Spark cut is a terrible way to rev limit the engine. You have an Arduino. You can do better.

Put in an up stream flapper in the intake. You can easily move it with a server. Center bias the flapper so it can not get sucked closed.
Failure mode = OPEN.

Track engine RPM(several different ways). When the RPM reaches the limit, close flapper whatever amount you are happy with.
This will work for all fuel injected cars Alpha-N or Speed Density. **DO NOT DO THIS IF YOU USE A CARBURETOR**
You have been warned. I wash my hands. ]:D


Sorry, but not using it for traction control  :P

I need it because my factory PCM has only a fuel cut rev limiter. I'm adding boost, and need a rev limiter since I will be adding water/methanol injection, and if it was still injecting and the PCM cuts fuel, that could be destructive.

Also a 2/3 step rev limiter for drag racing will also be used (this will be on a turbo car).

Also, one of the world's fastest traction control systems uses merely 2 stages of timing retard for traction control....
http://www.moretraction.com/

DuaneB

Just a reply so I can follow this one.

Duane B

rcarduino.blogspot.com

drother

Once my P channel transistors come in, I'll test it with some LEDs.

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