The GMTN word of the day....

[McGMT]

I think we need to throw in some of these words that get thrown around here as sort of a glossary of GMTNspeak....
And who better than to have the first word than the roadie... This one caught my eye today....

Microcracks.... Definition - A tiny break in electrical pathways too small to be seen with the naked eye.

Post the word of the day you think of , if your definition is wrong then who cares, they can have more than one definition, everyones perception is different.

 

[The_Roadie]

Oh, what a good idea. I'm notorious for using engineering terms on the forums.

Algorithm: Really, a program or set of instructions for solving a problem or controlling a process. I use it a lot to refer to the software (actually firmware, but that's another word for another day) inside the various intelligent modules in the vehicle, like the PCM contains algorithms for controlling the fan clutch, and the HVAC control module has algorithms for recalibrating (and breaking) the actuators.

 

[Voymom]

I think this should be a sticky, and that Roadie needs to fill in more blanks....reading his posts make me feel like I'm in Kindergarten all over again when I've been through college already lol

 

[cody_s]

Haha, as a computer science major, I love seeing someone talking about algorithms when I log on

But really though, great idea for a thread

 

[Denali n DOO]

Can we make requests for a possible brief explanation of words or terms that we are not familiar with . For example, I had my scanner plugged in and was looking at the Fuel Trim numbers. What is "Fuel Trim", can someone provide a brief explanation for me?

Thanks.

 

[The_Roadie]

Can we make requests for a possible brief explanation of words or terms that we are not familiar with . For example, I had my scanner plugged in and was looking at the Fuel Trim numbers. What is "Fuel Trim", can someone provide a brief explanation for me?

I was hoping this wouldn't be a substitute for better tutorials already posted elsewhere, but you're right that it's not explained well in most scanner's manuals - I had to dig for a while to understand the new term.

What are fuel trims all about?

For the visual learners:

[video=youtube;mzsOY_AhgY4]http://www.youtube.com/watch?v=mzsOY_AhgY4[/video]

 

[McGMT]

Can we make requests for a possible brief explanation of words or terms that we are not familiar with . For example, I had my scanner plugged in and was looking at the Fuel Trim numbers. What is "Fuel Trim", can someone provide a brief explanation for me?

Thanks.

Ask and ye` shall recieve.

Fuel trim is the PCM trying to keep the engine at 14.7:1 Air/fuel ratio... Changes in altitude, engine temp, ambient temp, engine components, etc. all will change the amount of fuel the engine needs at a given time to keep the right air/fuel ratio. If the PCM trims lets say -5% then it is shortening the amount of time the fuel injectors are open or the "Pulse Width". While a fuel trim of +5% would lengthen the amount of time the injector is open.

Long term fuel trim and short term are pretty simple, short term is what the engine needs right now, long term is an overall average learned over a given time (which is why you reset the PCM to "Re-Learn" after a TB clean").

- - - Updated - - -

Good thread ...... spoiled.......

I cannot safely comment on this:

I REALLY needed that laugh right there....

 

[Dad-O-Matic]

14.7:1 Air/fuel ratio...

aka stoichiometric ratio

http://www.cdxetextbook.com/fuelSys/gasoline/fund/stoichiometricratio.html

 

[McGMT]

aka stoichiometric ratio

NOW were getting somewhere.... If you throw out a 5 syllable word, define it for the fine folks... LOL

 

[Dad-O-Matic]

NOW were getting somewhere.... If you throw out a 5 syllable word, define it for the fine folks... LOL

LOL you were too quick, link added to above post

 

[Denali n DOO]

I was hoping this wouldn't be a substitute for better tutorials already posted elsewhere, but you're right that it's not explained well in most scanner's manuals - I had to dig for a while to understand the new term.

What are fuel trims all about?

For the visual learners:

[video=youtube;mzsOY_AhgY4]http://www.youtube.com/watch?v=mzsOY_AhgY4[/video]

Thanks Roadie for providing a quick understanding of "Fuel Trim", now I can go look at those numbers with a better understanding of what they are. I guess there would be a normal Fuel Trim range with a +/- limit that would throw a code one way or the other.

Thanks again

 

[The_Roadie]

OK, *mine* for the day is "PWM" - Pulse Width Modulation.

It's the electronic method by which various systems are controlled. For digital-based controllers like the BCM and PCM, it's much easier for them to turn control signals full on and full off (12 or 5V [high], then ground [low]) than to put out a varying voltage that smoothly goes from 0->1->2->3->4 ... and so forth. Like flicking a light switch on and off in your house. Imagine if you could flick it on and off fast enough, like The Flash. If you could flick it on and off 200-500 times a SECOND, your hand would appear as a blur to the observer, and in the same way, the flickering of the lamp couldn't be seen by your eye because of the "persistence of vision".

Headlights (in the Daytime Running Light mode), dimmable dashboard lamps, the fan clutch, the HVAC blower motor (for those with digital/automatic systems), all are examples of systems that use PWM signals to control.

They flicker faster than a handheld meter can tell you about the high and low voltage levels, but there's an electronic filter in most meters that will smooth out the signal and tell you about what the "equivalent" DC signal would be.

PULSE just means the signal goes up and down.

WIDTH is a measure of how much time the signal stays high compared to low, so the more HIGH the more control authority the signal is commanding.

MODULATION is an electronics term for the process of varying some property of a periodic waveform, similar to the way a singer who slightly varies a steady note is said to be using vibrato.

For those who know about oscilloscopes, this is what a PWM signal looks like:

View attachment 22835

 

[Denali n DOO]

Ask and ye` shall recieve.

Fuel trim is the PCM trying to keep the engine at 14.7:1 Air/fuel ratio... Changes in altitude, engine temp, ambient temp, engine components, etc. all will change the amount of fuel the engine needs at a given time to keep the right air/fuel ratio. If the PCM trims lets say -5% then it is shortening the amount of time the fuel injectors are open or the "Pulse Width". While a fuel trim of +5% would lengthen the amount of time the injector is open.

Long term fuel trim and short term are pretty simple, short term is what the engine needs right now, long term is an overall average learned over a given time (which is why you reset the PCM to "Re-Learn" after a TB clean").

aka stoichiometric ratio

Stoichiometric ratio

I like this thread, thanks for everyone's input !!

 

[McGMT]

Little late, been a long day... WOTD - MAF

Mass Air Flow - Usually referring to the Mass Air Flow sensor. Uses measured resistance to determine the amount of air passing the sensor.

 

[McGMT]

Need some more suggestions for WOTD.... Let's hear some of those words you may have seen around and not quite comprehended.

 

[Voymom]

My WOTD is

Little Red Wire- This is a little red wire found under the hood, by the battery and fuse box.

View attachment 22887

If you install it to the stud on the left of this picture, it feeds 30A of 12V to a designated pin on the trailer receptacle on the rear of the truck that will recharge a trailer battery as you drive. Most large trailers have this connection, but many smaller ones don't.

View attachment 22888

 

[McGMT]

KOER and KOEO


Key On Engine Running

Key On Engine Off

 

[northcreek]

Old...old George Carlin line on words that nobody has ever answered:
>flamable
>inflamable
>nonflamable
Why are there three? it either flams or it doesn't.