question about gm tech 2
question about gm tech 2 hey guys my dad has a small chevy dealership and i borrowed our tech 2 scanner.What are some things i need to look at like the fuel and timing.I found it had Zero knock retared and 14.6 air fuel ratio.Thanks for any help 
That is the perceived fuel ratio by the PCM.
In a stock properly operating feedback system it's prolly close to accurate.
In a modded car it is pretty much useless.
The only thing that can give you the real A/F ratio is a wideband.
In a stock properly operating feedback system it's prolly close to accurate.
In a modded car it is pretty much useless.
The only thing that can give you the real A/F ratio is a wideband.
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Joined: Sep 2003
Posts: 2,065
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From: Atlanta, GA
actually i've found the narrowband sensors to be more accurate at 14.6(stoich) then widebands. If you put a wideband log next to a o2 sensor log you'll see at stoich the narrowband actually reports faster. Of course the wideband is a must if you are interested in an air fuel ratio other than stoich 
Only problem with that theroy is: 14.7 is NEVER a number you want to see at WOT. It will depend on what fuel you are running and what the application is. A turbo car running a 14.7 at wot is going to give you some cool carnage peices after a couple of runs. A REPORTED a/f number from a narrow band is like trusting a blind person to give you visual driving directions.
Im spoiled though...my wideband is tied to my DFI and it is within 2 points of our dyno.
just my 2 cents.....
A REPORTED a/f number from a narrow band is like trusting a blind person to give you visual driving directions. Im spoiled though...my wideband is tied to my DFI and it is within 2 points of our dyno.
just my 2 cents.....
Originally Posted by samz28
actually i've found the narrowband sensors to be more accurate at 14.6(stoich) then widebands. If you put a wideband log next to a o2 sensor log you'll see at stoich the narrowband actually reports faster. Of course the wideband is a must if you are interested in an air fuel ratio other than stoich
Originally Posted by Brian@AP-Engineering
Only problem with that theroy is: 14.7 is NEVER a number you want to see at WOT. It will depend on what fuel you are running and what the application is. A turbo car running a 14.7 at wot is going to give you some cool carnage peices after a couple of runs. A REPORTED a/f number from a narrow band is like trusting a blind person to give you visual driving directions.
Im spoiled though...my wideband is tied to my DFI and it is within 2 points of our dyno.
just my 2 cents.....
A REPORTED a/f number from a narrow band is like trusting a blind person to give you visual driving directions. Im spoiled though...my wideband is tied to my DFI and it is within 2 points of our dyno.
just my 2 cents.....
TECH Addict
Joined: Sep 2003
Posts: 2,065
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From: Atlanta, GA
Yeah i've got an old lambdaboy NTK sensor with 0-1V option and a innovative LM-1 with rpm pickup. Fun toys
Sucks when you got 2-3 laptops in the car I need more com ports on my vaio superslim.
EFILIVE is soon gonna support direct logging from a wideband (Guessing innovative) using two com ports. That will be the shiznit. hopefully a free upgrade too.
Honestly. I've run on my boosted VW (more egt's) and i can see at WOT about accuracy to 12.8:1 with a good (bosch 13953 mustang 5.0 o2 sensor) with rapid sampling rates (i coded it into the vw ecu). Back to the wideband, it was pretty close though. Problem is that both sensors are VERY heat sensitive with EGT's. If you overheat the wideband (bosch lsu) it will not be accurate. The NTK are very pulse sensitive so the output is very spikey.
Maybe i'll do this since i have no cats. weld two bungholes in, and log the Stock O2 sensor (all on one side for shiz n giggles), log the A/F from the NTK lambdaboy and the LM-1 and print them all out on excel so you guys can see the actually accuracy.
Really doesn't matter on my tune, cause my injectors go over 85% (static) so theres not much i can do tune wise until i go bigger on injectors.
(yes im a computer nerd who likes cars) so i would probably do something like this.
lol
Sucks when you got 2-3 laptops in the car
I need more com ports on my vaio superslim.EFILIVE is soon gonna support direct logging from a wideband (Guessing innovative) using two com ports. That will be the shiznit. hopefully a free upgrade too.
Honestly. I've run on my boosted VW (more egt's) and i can see at WOT about accuracy to 12.8:1 with a good (bosch 13953 mustang 5.0 o2 sensor) with rapid sampling rates (i coded it into the vw ecu). Back to the wideband, it was pretty close though. Problem is that both sensors are VERY heat sensitive with EGT's. If you overheat the wideband (bosch lsu) it will not be accurate. The NTK are very pulse sensitive so the output is very spikey.
Maybe i'll do this since i have no cats. weld two bungholes in, and log the Stock O2 sensor (all on one side for shiz n giggles), log the A/F from the NTK lambdaboy and the LM-1 and print them all out on excel so you guys can see the actually accuracy.
Really doesn't matter on my tune, cause my injectors go over 85% (static) so theres not much i can do tune wise until i go bigger on injectors.
(yes im a computer nerd who likes cars) so i would probably do something like this.
lol
Originally Posted by wrencher
Exactly! so that little # the PCM puts out is somewhat a novelity.
I personally would not trust a factory 02 for any kind of tuning.
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Joined: Sep 2003
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From: Atlanta, GA
Well if you can afford a tuning tool, you can afford (GB) a lsu-based wideband for $300.
Then again i wonder why folks strap on headers and cams and never tune. Maybe if you had a front wideband already (some GM and Most BOSCH ME) already do this. but i'd bet theres a ton of people out there with a lot of mods and no tune?? Or ghetto tuning (descreened mafs', MAFT's).
Then again i wonder why folks strap on headers and cams and never tune. Maybe if you had a front wideband already (some GM and Most BOSCH ME) already do this. but i'd bet theres a ton of people out there with a lot of mods and no tune?? Or ghetto tuning (descreened mafs', MAFT's).
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