Ok well its back to school and I had my first day in tech. and I feel like Im gonna pop with knowldge. anyhu I heard something that scraed me. I somehow got on the topic of A/f and asked aobut the use of a dyno. (@!#$eers dont have one). but sure enough he told me that you dont need a dyno to get A/F he said that it's possiable to use a scan tool and it will give an accurate readout of what your reading. is this true?
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Kick azz is my boost hero!!! 
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obd2 scantools will give you a A/F readout. at least the Tech2 and Snap-on ones do
I used to race cars, now I race myself.
5K PB: 24:50
10K PB: 54:26
manufactures have all the tools they need and im sure the motor at minimum is on a dyno to set base parimeters for the fuel curve , plus the road testing they do
and when i was working at the chevy dealer here i had the pleasure to work with a few guys from the proving grounds on a regal s/c , and they had more sensors reading everything
so they have more information , then anyone would ever need , if i had to guess there was a extra 3-4 computers and data loggers , and several hundred thousand feet of wires , plus the rack they built on top of the motor to house the wires and relays , and connectors , they even had the rack set up so it attached to the hood when it was up to axcess the motor
but for a small shop or dealer , there is no dyno to test cars with
Yeah but don't cars come stock w/ a narrow band oxygen sensor?
You could just get a wide band oxygen sensor w/ a gauge for cheaper right?
cheaper then a scan tool I dont think so. so wait let me guess this straight, you can use a scan tool to tune with. what the hell would you need a wideband for there so GD expsinsive. other then the preety numbers (Which make sense to have for on the fly)
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Kick azz is my boost hero!!! "
because that little tech 2 you have in class can sometimes cost around 2000 dollars, thats why.
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- Sold my beloved J in April 2010 -
Sounds like you need someone with some experience to answer this one.
No, you do not need a WBO2 to tune with.
Yes, you need a WBO2 to tune with.
How's that?
Before the WBO2 sensor was a reasonably priced item (the cheap ones were $1G) we tuned without WB sensors. We used plug readings, knock readings, narrow band O2 sensor voltage readings, and a whole lotta zen. It took time and effort, and it was something of an art form to get a car really right. I was among the guys involved in the push for a reasonably priced WBO2 sensor. After a couple of years of false starts, a few guys stepped up and made a working sensor design called the DIY-WB. After that, $200 - $500 WBO2 sensors seemed to pop out of the woodwork.
The problem with not using a WBO2 is that you have no idea what your AFR really is. When the scantool displays AFR, it's displaying a value based on stock airflow, stock displacement, stock injector size, and stock fuel pressure. If your engine's stock, then the displayed AFR is probably close to correct. But the more changes you make, the less correct the displayed number is. The displayed AFR is definitely not based on narrow band AFR readings. The narrow band sensor is only good for telling you 3 things. (1) you're running at stoich. (2) you're running richer than stoich, or (3) you're running leaner than stoich. This is why the factory ecm bounces from rich to lean and back, over and over. Because all it can tell in closed loop is whether the engine is rich, correct, or lean.
I have tuned my 93 Cavvy turbo without a WBO2. I've spent a *lot* of time with that car. I've done it because I'm stubborn about keeping the old skills honed. But there's plenty of guys that can do an effective job in a shorter time using a WBO2.
So if you want to tune without one, go ahead. My advice is to learn as much as possible about tuning before getting crazy with changes. Learn to read plugs, read the scantool, and understand the symptoms you're likely to see along the way. But if you aren't very patient, see if you can save up for the WBO2. And you can buy laptop based scantool software fairly cheap. I'd consider it a must have for tuning anyway. You could also look for the older Snap-On MT2500 for sale. With the right updates it will do the newest OBDII cars. They're selling for $300 - $600 around here, depending on condition.
BTW, If the instructor mentions using a narrow band O2 to get an accurate AFR reading, ask him how he intends to do this when the curve of voltage VS AFR switches from about .2V to .9V within the AFR range of 14.1:1 to 14.9:1 ( this narrow AFR range is where the term "narrow band O2" comes from). On either side of this, the voltage really levels out making changes extremely hard to read. If you really want to be his friend, ask what kind of compensation he plans to include to keep the Nernst equation balanced as exhaust pressure changes. lol... naah, better not.
Anyway, HTH. And good luck in school.
-->Slow
im not looking to show him up he seems preety cool, but I would really like to get things right. So Im proablby going to buy a wideband anyway. Im a freak when it comes to knowing what my engine is doing at all times. thanks for the words anyway
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Kick azz is my boost hero!!! "
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because that little tech 2 you have in class can sometimes cost around 2000 dollars, thats why.
I know the snap-on scan tool is around that price too............if not more expensive!
Don't some of those little red snap on ones with screens cost like 20 K? someone at a shop once told me that, and thats why they always have to charge so damn much to read codes ($60) cause they have to pay back the money they spend buying the tool. Anyone know if they actually cost that?
well my dad is now at 15k on his snap-on scan tool (cnd money) and he need to buy a new data cassette this year for the 2004/2005 wich is another 500$ i think
I know they are prety expensive!
The MT2500 is old. It's been out for at least ten years. It's now being replaced by the Modis, an $8000 scantool/ digital scope/ DVOM, etc. The older scantools are still being updated, but you don't need to get the latest updates if your car is a few years old.
Snap On MT2500 for $300
-->Slow
