dimented24x7

iTrader: (2)

So youve got your motor together, now its time to tune it. As youve probably guessed, the topic of this thread will be:

Datalogging and Tuning with TBI

***Rules***

Id like to have one new topic come up each week or when the present one has run its coarse. One of us (shifty, 90RS, or myself) will post the next topic to be covered in the thread. While the present topic is up, only discuss that topic!. It would be nice to maintain some order as not to just have a bunch of stuff jumbled together.

Also, play nice! Dont get carried away by giving your opinions on what can and cant be done. Just the facts... Try not to stray off topic. Anyone posting off topic posts is liable to have the posts deleted at a mods discretion. As always all the usual board rules apply.

dimented24x7

iTrader: (2)

Some of the most basic things youll need to datalog and tune are:

Laptop: Any old computer will pretty much do. You dont need, or really want anything fancy. Mine is quite beat up and dirty from being in and around the car.

Parts: Youll need some odds and ends for a cable.

Programmer: One of the more popular units out there is the PPII from http://www.xtronics.com/. Its not too expensive and its geared toward people like us that are just doing light work with E/EEPROMS and such. www.moates.net also carries good hardware as well as a basic chip programmer. You may also need a UV eraser but with adapters available at www.moates.net such stone age devices dont have to be used.

Software: For datalogging Joby's winALDL is a good package to use with the 160 baud ALDL. Its cheap and it has a great interface. It can be found here: http://w1.605.telia.com/~u60505093/index.htm It also comes with schematics on the DIY cable as well.

Also consider getting a WB-O2. Youll really need it for WOT tuning. The stock O2 thats only reported once every ~1.2 seconds through the ALDL is of little use.

Also see the tech article https://www.thirdgen.org/newdesign/tech/promintro.shtml Tim gives a good overview of some of the tuning software and hardware in tha article.

As for the more advanced things. There is a whole host of mods you can do. There is lockers to provide a comprehensive high speed datalogging system with extra features. If someone out there is using lockers provide some more info here. I also found that the ecm's onboard hardware can be used to turbocharge the ALDL to 38,400 baud/1280 bps. You can also go romless and have the entire ecm under your control, which really gives one alot more power when it comes to tuning. At some point in the future the Speed Reader will come out wich will roll all the neat features into one package. These are beyond the scope of this thread and the tbi board for that matter and wont be discussed much more, but it should give you an idea of what else can be done in addition to the basics. Alot of the info on this can be found here at TGO on other related boards.

Ok... That should get some of the 'what do I need' stuff out of the way. Now we can discuss tuning and any aspects of actual datalogging that might need to be covered. My fingers are tired so this is all Ill say for now.

If anyone has useful related info, by all means post it . And do feel free to discuss.

dimented24x7

iTrader: (2)

hmmm... kinda quiet in here. Anyone have any tips on tuning a tbi system that they want to post?

Cadillac

I'm sorry D. I'm just taking all this in. I'm also a computer nerd in Silicon Valley.



~C

dimented24x7

iTrader: (2)

Its all good... I jsut want to motivate people and make sure the post jsut doesnt sit up here and collect dust.

Cadillac

I would kill to live near folks like you, 90RS, Shifty, etc.. I just have the kind of luck where if I wrench it, it will break. I'm better at gauging people who might work on my car.

dimented24x7

iTrader: (2)

How about this to start tuning off...

Lets talk about tuning accel. enrich with a tbi system. Both the 8063 and 8746 use the same AE algorithm.

There are three parameters to consider.

delta TPS AE: This is the difference in tps seen over a time interval of 12.5 milliseconds as teh throttle is opening. The ecm will then take that value and perform a lookup and get the ammount of additional pulsewitdth.

Delta MAP AE: If the MAP is rising, the ECM takes the current map reading and subtracts a slow filtered, or lagged, map to get a difference in MAP to use for the lookup. The looked up value is also additional pulsewidth.

IAC opening AE: If the IAC has begun to open, the ecm will also add a small ammount of AE.

There is also a table with multipliers that provides temperature correction since an engine will need more AE when cold. This is important to look at if there is a bog or hesitation at cold temperatures.

Additionally, the ECM will double the ammount of AE if the TPS is above 50%. I found that this can cause the motor to bog down when I slam the pedal to the floor.

All of this is summed up and then outputted to the ecms async PW counter. In async both injectors fire together at 80 times a second as opposed to alternating fires in sync. with the engines speed. The pulsewidth from the AE is overlaid onto the sync PW.

There are some important notes to this. Small injectors need to be open for longer then larger ones will. This is important because there may not be enough time for the additional pulsewidth if the injectors are already at a high duty cycle. This means that the engine may go lean during accel. due to the injectors not being able to meet all the demands placed on them. If the overall pulsewidth is longer then that available, the injectors will just be open all the time. Another reason to consider getting the largest injectors you can feasibly run with your motor.

Ok, lets get some discussion on AE since it can be one of the harder things to get right with TBI, especially if one doesnt ahve a WB-O2

Dewey316

your covering most of it.

Important points, again. WBO2, it will make things SO much easier.

Also, don't be affraid to make fairly large changes in the AE values. It seems to take a rather large adjustment to get anywhere, if you go with a large plenum setup.

And now, i have a question.

In the 8746 there is a WOT commanded AFR, we don't have a PE table like the TPI folks. Has anyone actualy tuned the 100kpa cells to 128, and then checked the command AFR vs a WBO2? I would be very interested in how close it turnes out.

dimented24x7

iTrader: (2)

I had to double the ammount of AE I had in order to not go real lean and get lots of knock counts as well as near zero narrow band O2 volts. Its important to note that the most AE pulswidth that can be achieved is around 12 milliseconds given the time interval between injector PW programming. This doesnt include time taken by the sync PW.

I wish I had a WB-O2. Ive always wanted to check how close the fueling was to what is commanded by the computer.

BronYrAur

iTrader: (1)

IIRC "Ronny" has a WB-O2 on his Crossfire car and did a lot of tuning with the WOT afr's to see how close they were to the commanded AFR. Hopefully he'll make his way in here and confirm that, I'm not sure what his results were though.

Also, I'd like to add that with any change in engine characteristics the VE changes and Jon Prevosts Aldltobin program is great. You simply plug in aldl readings into it as well as your bin and it kicks out a new bin. It's an easy quick way to rough in the VE table if it's off a lot. Mine was reading anywhere from 117 to 141 after the intake and headers and it tooks 2 datalogs to get almost all of them between 127 and 129. Just a quick time saver for people.

adambros

iTrader: (2)

My experience using Jons Aldltobin program is that it doesn't correctly recalculate the checksum (or something along those lines). After I run aldltobin and load the new bin the car will run fine with no errors -- i should say i download the new bin to the prominator with the key on and ignition off. But as soon as I turn the key to "off" and turn it back on, I get a flashing SES light, and a PROM error flag.

This is simply fixed by opening the file in TC or TunerPro and resaving the bin.

Dewey316

are you adding the correct switches. I get that error when i forget to tell it, that i am using the 8746 ECU. by default, i think it goes the 747 configuration.

Pablo

iTrader: (1)

You will definately need larger injectors and a high pressure capable/high volume fuel pump if you plan on producing any meaningful power.

One of the biggest things overlooked is rpm range of the engine. People sit there and use the typical fuel calcs and think thats all the fuel they need. They are forgetting one huge variable; the RPM that the engine makes that power.

TBI fires the injectors twice as often as tpi which is batch fire. This is one big obstacle in getting the fuel needed to make HP and is compounded by the higher the rpm the power is made.

Think of it like this, the injectors fire relative to ignition pulses and you have a window of time where the injector can fire, as rpms increase the time for that window decreases. Eventually, even the largest injectors on earth will be static even on a 100 hp engine if it revved high enough.

You need a certain amount of off time so that the injector can fully close and then fully open again accurately so you automatically chalk that up as a loss in your "window". The most you want to push those injectors is 85% of the available window time which occurs twice per ignition event if im not mistaken. So basically you have two 85s going on in a certain amount of time.

Consider this when sizing your injectors and fuel pressure (if you run anything that is going to rev id suggest at a minimum the big block injectors and high pressure)

Another thing to consider is that you can easily make your injectors static with the factory BPW and anything really remotely close to the factory bpw setting.

What i mean is, if you were to put 100% ve which is the most the chip will allow, at 5500 rpm with the stock bpw you will with out question be static. To me its pretty silly that while even using the formula for injector size for displacement to get BPW that is in the hack you can still do this which tells me that the VE tables are next to meaningless.

What I did was increase my pressure to 20 lbs and use BB injectors which allowed me to use a BPW of 68. This oughta prevent me from accidentally going static (or is pretty darned close considering my rpm range) without even realizing it.

Another thing i have found, I suggest getting a carburetor and tuning it to your engine, it provides a valid "control" to your work with the TBI. Youll be so much happier to go back to FI if you do.

I think for tuning an FI a WB is mandatory. I simply think there is no way to accurately tune an FI setup without one. With the carb and WB it was very easy but, I still could have accomplished most of the same results without one (given enough time). I am quickly discovering that fuel curves are very touchy at WOT with FI and arent as easy to tune in as I had hoped.

I really wish that the tables in the prom were pulse width based and not some imaginary number, granted there are PW modifiers that would make the pw numbers in the table not always accurate but those are reduced in number at WOT and open loop where I think most of the TBI tuning troubles and concerns lie. Would be way easier to compare bins and the like I think.

dimented24x7

iTrader: (2)

Quote:

You will definately need larger injectors and a high pressure capable/high volume fuel pump if you plan on producing any meaningful power.

One of the biggest things overlooked is rpm range of the engine. People sit there and use the typical fuel calcs and think thats all the fuel they need. They are forgetting one huge variable; the RPM that the engine makes that power.

TBI fires the injectors twice as often as tpi which is batch fire. This is one big obstacle in getting the fuel needed to make HP and is compounded by the higher the rpm the power is made.

Think of it like this, the injectors fire relative to ignition pulses and you have a window of time where the injector can fire, as rpms increase the time for that window decreases. Eventually, even the largest injectors on earth will be static even on a 100 hp engine if it revved high enough.

You need a certain amount of off time so that the injector can fully close and then fully open again accurately so you automatically chalk that up as a loss in your "window". The most you want to push those injectors is 85% of the available window time which occurs twice per ignition event if im not mistaken. So basically you have two 85s going on in a certain amount of time.

Thats definatly true. The additional firings eat into the saftey margin. The tbi injectors fire once per cylinder firing to replace the fuel. Kinda neat the way they did that as all the fueling is done on a single cylinder basis.

Doesnt help with the injectors, though. Really hurts at idle as it really narrows the PW down and makes running larger injectors without running out of pulsewidth difficult.

Quote:

Another thing to consider is that you can easily make your injectors static with the factory BPW and anything really remotely close to the factory bpw setting.

What i mean is, if you were to put 100% ve which is the most the chip will allow, at 5500 rpm with the stock bpw you will with out question be static. To me its pretty silly that while even using the formula for injector size for displacement to get BPW that is in the hack you can still do this which tells me that the VE tables are next to meaningless.

Another thing i have found, I suggest getting a carburetor and tuning it to your engine, it provides a valid "control" to your work with the TBI. Youll be so much happier to go back to FI if you do.

I really wish that the tables in the prom were pulse width based and not some imaginary number, granted there are PW modifiers that would make the pw numbers in the table not always accurate but those are reduced in number at WOT and open loop where I think most of the TBI tuning troubles and concerns lie. Would be way easier to compare bins and the like I think.

The factory settings are almost static at anything over around 3600 rpm so there isnt really any more fuel available with the stock cal. I think the VE tables are fine. They certainly probably made the engineers tasks at gm simpler by using ideal gas laws for calculating the fueling. They make tuning much more intuative as well. The only real 'gotcha!' about them is that the injector flowrate and cylinder volume must be correct in order for the VE to really have any meaning and it goes without saying that the injectors must not be static. If they are then obviously adding additional VE does nothing as teh injectors are already stuck wide open.

Ronny

iTrader: (1)

Quote: IIRC "Ronny" has a WB-O2 on his Crossfire car and did a lot of tuning with the WOT afr's to see how close they were to the commanded AFR. Hopefully he'll make his way in here and confirm that, I'm not sure what his results were though.

just dumb luck. underlying VE were worked on for 2 months last year(neubie) and commanded PE was 12/1. on dyno showed 11.9/1 and 12.1/1(2 runs). i did work on VE at upper rpms with PE disabled. someone suggested NOT to do that but in 3rd gear on level hiway seemed to work. the cells i did not populate i guessed at. now past friday the Innovative WB
went on. commanded 12.75 and showed 12.9/1 in PE. also showed i was ridiculously rich on AE MAP. dropped it 10% twice(aemap) and i will burn one more tonight at 5% less and will be spot on. should make car a bit quicker.

blackr1

delete

90RS305

LMAO, I love how this gets used so much now! Glad to see I had a lasting impression on TGO

I'm supprised nobody has brought up the Prominator! I sure as heck am no expert on tuning, but from what I've heard (and seen) that thing kicks some serious butt...

beatercamaro4me

This is a hill billy idea I bring from the tuner side. 1 guy was too cheap to guy larger fuel rail, injectors, FP regulator etc., so he plumbed in a 5th injector upstream of the of the main throttle plate. The pulses made no difference because it was mixed with the air pretty good by the time it spilt into the different cylinders. It looks like you have plenty of air, just not enough fuel to match the growing RPMs. With the fuel pressure and the injectors at their max points, you are limited.

This is just a thought. Grab an injector and plumb it in upstream and maybe splice it in with the pulses of either of the other 2. Or have it toggle operated. Use your imagination but at wide open throttle, even a slightly rich mixture shouldn't throw off the ECM. In the tuner world everyone has a cold air intake. If you are running a K&N or like item, that would be a perfect place. Just food for thought.

dimented24x7

iTrader: (2)

The problem isnt as much about not having enough fuel, but having enough dynamic range.

I can get lots of fuel by cranking up the pressure, but the flowrate will be so large with the big injectors that the injectors will barely open at idle since the pulsewidth will be so small.

Using a vac ref'd fuel pressure regulator or some form of load based fuel pressure would work, but it requires that the computer be able to see and adjust for the changes in fuel pressure.

ben73

I prefer not to do it that way. The idea of turning off power enrichment and forcing the ecm to target 14.7:1 at high loads and rpm bothers me.
I set all the cells in the PE AFR table to 12.8, then I do WOT runs and tweak the VE table in the 100MAP column until the wideband draws a nice flat line at 12.8. Then I make any required changes to the PE AFR table if I want to make it a bit richer or leaner at WOT.

Same result, less chance of damage, and in fact, I think if you did it by tuning the BLM's to 128 at 100MAP in closed loop, then switching to commanding AFR x.x, you would still end up doing it my way to correct any actual AFR vs commanded AFR offset error.

TierAngst

Hopefully this isn't too much of a tangent, I've heard/read a lot of different things about the perfect AFR on TGO it seems to pretty much run with 12.8 other places I've seen 12.3, 12.5, and 12.8-13.3. How did everyone manage to agree on one setting here?

BronYrAur

iTrader: (1)

I don't think anyone has agreed on a universal AFR setting for WOT. Not everyone says 12.8 is the best. Every motor is different and will make the most power with a different AFR its just a matter of finding what makes the most power and going with that while keeping it in a safe range.

ben73

Yep, they are all different..
I played with mine on a dyno once, and any leaner than about 12.8 and the power started to drop off..

TierAngst

Is there a way to tell without using a dyno?

ben73

Dragstrip terminal speed......

Dominic Sorresso

Agree with Bron and Ben. No real "agreed upon" best AFR for WOT. When I last went to the track I used 12.6 AFR for PE. My first run was just sitting there with the wheels spinning and I ran a 14.8 at 103.4mph. I had brought a couple of chips with me using different timing curves. The one that worked the best as far as ET was concerned used 36d Total by 3200rpm. This bin resulted in a 13.3 @ 102.1mph. The others bins proved slower with a lazier advance curve utilizing the Spark Slope setting in the $42 cal. Unfortunately I didn't log the drag runs. But I did go out later with the final bin in the car and saw that the AFR was in the 13.4 range and lower. I hadn't taken into account that the faster advance curve would affect the AFR. So the car ran quicker but made a bit less HP with the leaner AFR. Now I am tuning for the current advance curve but looking for something like 12.8 WOT.
A couple of other points regarding commanded v observed.

1. WB O2 is an absolute must. Period.

2. Getting the VE right in C/L really helps in making commanded and observed AFR close. I'm not sure that its necessary to get the 100kPa cells all that right. I set the TPS% for PE up around 80-85% for tuning. Actually I have run around town with it at 70% with no problem or detonation issues. You'll be in PE long before you ever hit 100kPa (Rbob, correct me if I'm wrong) but the PE PW calc is based on the last VE cell the motor was still in C/L. I try to get the VE tables right into the 80kpa cells up around 4000rpm.

3. A real key parameter that seems to get overlooked is the Injector Bias setting. Particularly with motors that are running higher FP (I'm at 20psi using 80# BB injectors), the IB allows you to make the most of the PW by correctly anticipating the injector opening. When you start to play with this, you'll notice that the AFR will get richer (assuming you increase the IB) without making any other changes. That's because with the same commanded PW, you'll actually be getting more fuel. My IB is set at 671msec. Stock is 390 or so. It appears to control the injectors more accurately and I have found that the AFR curve is smoother and more accurately tracks the cal settings.

4. Finally, IMO, start with correct WOT tuning first. Make sure you have the correct FP and injectors for the requirements of your motor's config. Tuning a great VE table for PT and then finding out you're lean at the top is a waste of time. My motor ran great at 10.5 psi for PT. But it got very lean at the top. Basically started from scratch taking PW and DC% into account for arriving at the required FP.

My $.02. Sorry for going long.

kdrolt

And richer the power might also drop off, but not at the same rate as when going lean.... and the extra fuel wouldn't get burned so the BSFC would increase. IOW the extra fuel is wasted and never burns (inside the engine) so it never contributes to doing work.

The optimum air:fuel ratio for optimum power should be the same number for all engines from a chemistry viewpoint..... except that this assumes all engines (which really means the heads) burn identically --- but they don't because the heads aren't identical and their burn characteristics are not the same.

So the more efficient the head is as a fuel burner, the larger numerically the air:fuel ratio you can get away with --- which in turn means the leaner you can run. IOW a very efficient head might need 12.8:1 air:fuel and 30 degs ignition advance to make optimum WOT power. The same engine with a different head might need 12.5:1 and 33 degs (more fuel, more timing advance).

And efficient burn head, in GM speak, is a fast burn head.

Queen's University (in Canada) has a nice web site with some good ppt slides from their Combustion for IC Engines course:

http://me.queensu.ca/courses/MECH435/

DM91RS

Please continue to "go long".....I like to read and it helps to learn.

ahusted

I understand the need for a wideband o2 sensor. But from a beginners perspective, would tuning without a wideband be beneficial? Or would it be better to wait until I can afford the burning equipment and a wide band?

I'm on a budget with a LO5/small cam combo. I'd like to work with my bpw so I can rev past 4000rpm. But I am leery without a wideband that I could cause damage from going lean.

ben73

Well I think we all started doing this without owning wb02's, and you can definately inprove the 'driveability' of your car without one..
BUT
Like you said, you'll never know exactly where you are at WOT, and that could be bad..

Its the best tuning tool in my box.

Dominic Sorresso

ahusted,

As Ben said, we all started tuning before WB became widely available at a reasonable cost. Using a C3 ECM, it has been pretty time consuming with the 165 baud rate. In additon, if you have modified your tbi motor to any significant extent, the 7747 just can't provide enough data fast enough to allow decent tuning. Before the WB, I "locked" the BLMs and tuned using the INT just because it would change a lot faster. Well the WB gives me 30times the datapoints that the 7747 gave me. So frankly, I don't bother with a scantool at this point except to tell me about spark counts and maybe PW/DC%. With the EBL/HUD, everything will be on one screen. And the processor is fast with a very robust code for modded motors.

BMmonteSS

Just to give an example of how usefull a WB is, it took me 6 months and around 300 chips to get "in the ball Park" without useing a WB for WOT. My best guess and tuning for best SOP feel and NB numbers (dumb idea) was actually 12.2 to 1. I verified this with my WB once I got it. I picked up a small bit of power going up to 12.6, and gained nothing going any leaner, and started dropping power around 13.1 to 1. I verified this by using a G-tech pro and looking at the HP numbers from a second gear pull.

The last motor I threw in the car took me 5 chips, to get a solid 12.6 to 1 AFR. Did you read that......5 chips to get WOT in the ball park and making power. A WB saves you that much time. I still have about 50 chips to go to get part throttle to where I like it, and I know alot more now than I did when I tuned without a WB. I would honestly give a WB a 10 to 1 time advantage over tuning any other way. If it took you 100 chips before it will take you 10 now. A WB is pretty much the only way to tune your transient conditions (pump shot). You'll learn real quick this is where FI has the advantage over carb. If you get your pump shot right, you'll have so much throttle response it can be amazing. You won't be albe to "get it right" without a WB.

Fast355

iTrader: (2)

BM-has it 100%. Properly tuned TBI systems are SHARP, real SHARP. I have a 2,800 stall in mine. It will flash stall to almost 4,000 right off the line, IF i MASH it. Have you ever seen a VAN with 3.73 gears, P295/50/R17s, and a 305 TBI light the tires up without power braking?

Dominic Sorresso

One of the reasons I delay PE till 70%+ TPS is because I have absolutely no bog off the line. Great throttle response.

RBob

iTrader: (1)

I'd like to give a slightly different perspective then the others here have. However, their advice is good, so don't completely discount it.

For me, tuning a mild engine without a WB is do-able. And, the chance of damaging the engine is greatly reduced. This is because it is a mild engine.

If you were tuning a higher output engine then I would recommend the WB. However, as long as the engine gets enough fuel and is kept out of detonation and pre-ignition it is safe.

And, with a mild engine this is easy. Just need to go slow, build up to the higher RPMs and load areas, check the injector DC, look at the plugs from time to time, and listen to the engine.

It may sound a little crazy, but the sounds the engine is making helps to understand what it is doing. It is an experience thing. Listen to your engine now, then pull some timing out at 100 KPa, 3200 RPM, and listen again. Hear the difference, it gets a dull sound to it (try 8 degrees less SA).

Can do the same with fuel. Enrich it and listen and feel the engine. See how it is different.

RBob.

ThraxXx

I am planning on getting into the chip burning scene this summer when the transam comes back out to play. I have done some mods to the car and haven't benefited much from them so I believe my next step is tuning. I was looking at the programmer on Moates's site and was wondering if this would work with a 1988 305 TBI's computer/Chip?

TierAngst

You're going to need a number for the chip, mine is a 16136965 to give you an idea of what you're looking for on yours. Once you find the number we can tell you if it'll work which most likely it will.

ThraxXx

I take it I have to crack open the ECU to find that number...cuz if thats the case...then I will tell you in april. Car is stored for the winter right now.

RBob

iTrader: (1)

The ECM number is on the ouside of the case. It is listed as the service number. Your car should have the 1228063. The Flash'nBurn will work, will also need a G2 adaptor along with some of the AT29C256 chips.

The stock chip (EPROM) is a 2732, which you really don't want to deal with.

RBob.

dimented24x7

iTrader: (2)

I dont think its crazy at all. I tuned that way and compared with a WB at the end. The actual and desired AFRs where pretty close even without the aid of a WB. I personally think you learn alot more that way since you actually have to listen to and see whats actually going on. For things like AE, though, having the WB helps alot. Its hard to tune it just by watching for smoke and bogging IMO.

TierAngst

Are those of us going to the Locker system going to need a WB now that the ECM is going to be putting out info a ton faster? Will the regular O2 sensor going to be up to the task?

beatercamaro4me

I just pulled the ECM out and it had a ADS Super Chips sticker on it. Whith my curiosity sparked, I pulled the PROM cover and it surley is chipped.

It is red with the label Super Chips printed on the back. On one side it has RM molded in the plastic and on the other side the # "1" with a circle around it. Have you guys seen this before and if so, what can I expect from it compared to a stock TBI 305?

Any info is helpful.

TierAngst

The plastic thing with RM on it is the company that makes that little plastic holder to make it easier to change your chips thats all its there for. IIRC the number is on the outside of the ECM case not on the chip itself.

ahusted

Thanks! I would rather tune with a wideband, but because of cash flow I only have enough for the basics. Its good to know that tuning a very mild combo without a wideband isn't a complete waste of time.

Dominic Sorresso

I don't think any of us ever said it was a "complete waste of time." In fact, we all said we started tuning without a WB. Some, like Grumpy, didn't even have a scantool. He used a vacuum gauge.
I'd have to agree with RBob, that the tools we have today for tuning are still no substitute for the intuition and knowledge that you gain from doing it the "hard way". Regardless, you still need to understand the basics and the relationships of the various parameters. And there's no more fundamental tool than your own ear when listening to a nicely tuned motor at cruise.

Fast355

iTrader: (2)

People have tuned carbed engines without a wideband for years. Plug cuts, vacuum gauge, track times, etc. Even with just a narrow band O2 we are ahead of them as far as technology goes.

TierAngst

So the stock O2 sensor is a narrow band? Will this be good enough to get a fair tune? Or can I get a perfect tune just that its going to take much longer than if I were to use a wb?

Dominic Sorresso

Look. Part of the issue with "getting a tune sooner" when driving a TBI car, is that the 7747 is a slow damn ECM. A WB O2 has a much higher data rate than a 7747. If you have a modded motor, the WB is much more accurate tool especially if its giving you data at 30x the rate a 7747 does.

TierAngst

Which brings me back to my question that went unanswered...

Dominic Sorresso

TierAngst,

Let me be a bit more clear. I think most of us here have already answered your question by saying that we didn't start out using a WB to tune Part Throttle, at least. With a 7747, it has been very tedious but we did it anyway. EBL/HUD makes that process much simpler. Tuning WOT is a whole different thing. Since you're in Open Loop at WOT, and since the desired AFR is much lower than stoich, the NB O2 is of little to no use. You need a WB to accurately tell you you're at 12.7:1 or so. Is that any better?