DME Chips
03-18-2003 | 03:58 PM
#1
Thread Starter
Three Wheelin'
Joined: Jan 2003
Posts: 1,567
Likes: 0
From: Schenectady, NY
DME Chips
At this website <a href="http://www.9xauto.com/944.html" target="_blank">http://www.9xauto.com/944.html</a> the following caution was posted;
"IMPORTANT NOTE: many DME chips are programmed to interfere between the reading of this sensor(temperature sensor), and your DME unit, by telling the DME unit "the sensor reports "Cold Engine" condition" even though the engine is hot. In turn, the DME unit creates a "rich" condition, allowing a little faster operation by fooling your plugs, oxygen sensor, and exhaust valves. Stay away from these chips! When buying an unknown manufacturrer's chip, always ask for details of it's operation"
Any comments regarding the above with various brands of aftermarket chips on the market? Specifically I wonder how the newest, greatest GURU chips fall in place on this issue?
"IMPORTANT NOTE: many DME chips are programmed to interfere between the reading of this sensor(temperature sensor), and your DME unit, by telling the DME unit "the sensor reports "Cold Engine" condition" even though the engine is hot. In turn, the DME unit creates a "rich" condition, allowing a little faster operation by fooling your plugs, oxygen sensor, and exhaust valves. Stay away from these chips! When buying an unknown manufacturrer's chip, always ask for details of it's operation"
Any comments regarding the above with various brands of aftermarket chips on the market? Specifically I wonder how the newest, greatest GURU chips fall in place on this issue?
03-18-2003 | 06:37 PM
#2
Race Director
Joined: Jul 2001
Posts: 14,075
Likes: 3
From: Santa Barbara, CA
Where do you find that disclaimer? I can't see it anywhere.
Anyway, that's a bunch of BS. The sensor for the guages are completely separate from the sensors used by the DME. At the very bottom firmware/hardware level of operation, the chips are the last step in the control mechanism. They can not sit in between anything. If anything, sensor-signal massaging like the ARC2 interceptor will interfere with proper operation because they deprive the DME of the correct air-temp signal and changes the air-flow meter signal.
There is a difference between a signal generator or output versus a signal input. Sensors output a signal that describes a physical state, and are 'active'. Input devices that receives the signal from sensors like gauges and the DME are 'passive' and can only react to the sensors' signals, but can do nothing to change them. In fact, the chips only contain data is that reference by the DME circuitry. Changing the data on the chips can do nothing to change the sensors' signal.
And one also has to distinguish between the air-temp sensor and the engine-temp sensor (coolant) and how they contribute to engine operations.
The first sensor-related step the DME computer does when activated is to check the engine/coolant-temp sensor. If the engine is warm, then the computer skips straight to the normal operating routine and reads air-flow and meters fuel from the appropriate data-cell from the chip.
However, if the engine-temp is cold, then the cold-start enrichment is triggered. Exactly how much fuel to add is based upon the air-temp sensor output. Cold air doesn't vaporize easily, with some of it passing though the engine in liquid form and not burnt. So extra fuel is injected to ensure that the part that DOES vaporize, is matched to the air-flow amount. The exact amount of fuel to add is stored in a separate ColdStartEnrichment table that is referenced to the temperature sent by the air-temp sensor; the colder the air, the more fuel is added for cold-start enrichment. This amount is a fixed percentage above the normal fuel value read off the normal operating fuel-maps. As you can figure out, cold-start enrichment can only work if you have an air-temp sensor. Otherwise, there's no enrichment beyond stoich..
Once the the engine/coolant-temp indicates the engine has warmed up to operating temps, all cold-start enrichments is turned off. At this point, the only contribution the air-temp sensor makes is to allow the DME to compensate for air-density (minor).
So the chips really only contain reference data to be used by the DME. The function of the DME is actually hard-coded into the circuit board and there's nothing you can do on the chips to change that. You can't change the DME's function like adding traction-control with just chips. The only thing adjustments you can do with chips, is alter fuel & ignition tables and adjust the redline.
Anyway, that's a bunch of BS. The sensor for the guages are completely separate from the sensors used by the DME. At the very bottom firmware/hardware level of operation, the chips are the last step in the control mechanism. They can not sit in between anything. If anything, sensor-signal massaging like the ARC2 interceptor will interfere with proper operation because they deprive the DME of the correct air-temp signal and changes the air-flow meter signal.
There is a difference between a signal generator or output versus a signal input. Sensors output a signal that describes a physical state, and are 'active'. Input devices that receives the signal from sensors like gauges and the DME are 'passive' and can only react to the sensors' signals, but can do nothing to change them. In fact, the chips only contain data is that reference by the DME circuitry. Changing the data on the chips can do nothing to change the sensors' signal.
And one also has to distinguish between the air-temp sensor and the engine-temp sensor (coolant) and how they contribute to engine operations.
The first sensor-related step the DME computer does when activated is to check the engine/coolant-temp sensor. If the engine is warm, then the computer skips straight to the normal operating routine and reads air-flow and meters fuel from the appropriate data-cell from the chip.
However, if the engine-temp is cold, then the cold-start enrichment is triggered. Exactly how much fuel to add is based upon the air-temp sensor output. Cold air doesn't vaporize easily, with some of it passing though the engine in liquid form and not burnt. So extra fuel is injected to ensure that the part that DOES vaporize, is matched to the air-flow amount. The exact amount of fuel to add is stored in a separate ColdStartEnrichment table that is referenced to the temperature sent by the air-temp sensor; the colder the air, the more fuel is added for cold-start enrichment. This amount is a fixed percentage above the normal fuel value read off the normal operating fuel-maps. As you can figure out, cold-start enrichment can only work if you have an air-temp sensor. Otherwise, there's no enrichment beyond stoich..
Once the the engine/coolant-temp indicates the engine has warmed up to operating temps, all cold-start enrichments is turned off. At this point, the only contribution the air-temp sensor makes is to allow the DME to compensate for air-density (minor).
So the chips really only contain reference data to be used by the DME. The function of the DME is actually hard-coded into the circuit board and there's nothing you can do on the chips to change that. You can't change the DME's function like adding traction-control with just chips. The only thing adjustments you can do with chips, is alter fuel & ignition tables and adjust the redline.