RobZ

My buddy just got the Innovative wide band.We haven't done any Wot runs on my ls1 and his ls1 vehicle yet.What A/F ratio should we be looking for?Part throttle and WoT.These vehicles are somewhat stock.

Bill Bowling

iTrader: (6)

Idea A/F is 12.8 or .9 at WOT. As I understand it the computer tries to keep a 14.6 everywhere except WOT.

BowlingSS

WS6 GreeN

Yea, I'd go with 12.9 as well.

RobZ

Great Is that 12.9 for overall performance.I taught we should be somewhere around 13.1 or 13.4.

JNorris

iTrader: (4)

I have the LM1 as well and my A/F was 11.6:1 at WOT.
Please post the results of your WOT runs with the wide band.

Thanks

John

samz28

well what do you expect when you injectors go static? You basically got 0-85%DC and 100% DC. Where are you running at with your logger? I see 100% DC by 6100 rpm and peak whp at 6600.

Need some big-un injectors so avoid the nasty static

JNorris

iTrader: (4)

I am running 30# SVO injectors. They rarely (only when it is really cold weather) go over 80% at WOT.

NoGo

iTrader: (2)

Peak power occurs at 12.8:1 air to fuel ratio.

When tuning on the dyno (dynojet, not mustang dyno) for a naturally aspirated car, it is generally a good idea to park the a/f a little richer than 12.8 (~12.2 to 12.5) being the extra load of the vehicle on the street will lean the mixture slightly.

The a/f target for a stock car is 11.9. This is a safe rich running condition. There is some HP to be gained by raising this to 12.8 on the street.

Good Luck

jimmyblue

iTrader: (11)

I thought the WOT commanded AFR was 12.5? That's what seems
to show up on a lot of peoples' ATAP / EFI logs.

JNorris

iTrader: (4)

My commanded A/F is 13:1 at WOT but my wide band O2 showed 11.6:1.

NoGo

iTrader: (2)

It actually differs on the year / model.

My 2000 F-bod used to be 11.9 at WOT.


Target A/F = 14.8 / PE Value

For example: A stock 2000 Fbod PE table has 1.240 across the board.

14.8 / 1.240 = 11.93

NoGo

iTrader: (2)

You could also be looking at the open loop commanded a/f ratio, which has no bearing on your closed loop operation.

This value is determined by the open loop commanded a/f table using the same math as stipulated above.

RobZ

I have a question for Nogo.You say that a car should be tuned at around 12.2:1 or 12.5:1 that is on the dynojet and I understand that idea of it.Lets say I tune my car at a A/F ratio of 12.5:1 on the Dynojet,How many points will or should the A/F change when driven on the street?

samz28

you should find a portable wideband, weld a bunghole in, and datalog it on the street.

Don't guess, do it right. They've figured out how to interface the $300 (GB) lm-1 into efilive iirc using some trickery.

you'll be suprised at how engine dynamics change (air fuel) in 1-6 (or 1-4) gear when your hauling ***. dyno's do not represent the real world as well as you think.

There's no way the stock o2 sensors can read past 13:1 reliably, and they are too slow. If you get 11:1 from your narrowband, lol. Just disregard that. It's lying.

Put a narrowband and wideband log next to each other and you'll understand why its important for tuners to have portable widebands and run their cars down the (track/strip/private road) to get the real picture.

There's more to tuning on the street than there is on the dyno. Most dyno-tuners don't run the cars in every gear to redline and tweak it so that all gears/mph/airfuel is perfect now do they?

They should.
And they should run them on the strip/private roads (dont condone doing 160 on the streets myself), because dynamics do change, and you really wanna know where you stand. Hell i'd run two widebands, one for each header output, so you are sure one bank isn't leaning out more than another.

But thats a perfect world right? We don't live in a perfect world. Otherwise we'd have EGT thermocouples on every exhaust runner too

RobZ

Sam are you referring to me?

NoGo

iTrader: (2)

Bring your car to the shop. We'll run it WOT on every gear on the dyno. I'll even offer a free tow home after it bounces off the dyno and shoots out the front of the shop.

With a 300+ HP car there is no other option but to dyno them in 4th gear. Anything lower and the tires light up.

Those are the limitations of dyno tuning......

NoGo

iTrader: (2)

Honestly, anything between the mid 11's and the high 12's is going to be adequate for street use. People try to dial them in on the dyno's exactly, and there really is no point in getting the a/f to 12.5 instead of 12.1. Hell, even the widebands themselves aren't perfectly accurate.

As sam pointed out, your cars a/f on the street is different than on the dyno.

Your car loads different in every gear. If your car is tuned on the dyno in 4th gear then it will run richer in 1st, 2nd and 3rd on the street than it did on the dyno. In 4th, on the street, it will run slightly leaner.

Your torque calculation determines the a/f correction that is suppose to be made according to load on the engine. Keeping this calculation as correct as possible will yield the best and most consist a/f results on the street that these cars can provide.

Good Luck

Steve98Z

My car was dyno tuned to 13.2/1 , does this sound a little lean??

NoGo

iTrader: (2)

That sounds fine.

Like I said above what your car shows on the dyno and what it shows on the street under variable loads is going to be different.

Even if your car is running at a 13.5 on the street it is not going to blow. It may be a couple ponies short of peak power, and may be a little more prone to KR than another car at 12.5 a/f, but you shouldn't notice any differences.

Again, your car will be running richer in 1,2,3rd than it did on the dyno, so you may actually be closer to the ideal a/f in the lower gears than somebody else would be tuned at 12.5 on the rollers.

Also your a/f swings on the street and the load shifts with the rpm. It isn't a perfectly level a/f throughout the rpm range.

samz28

Those are the limitations of dyno tuning......
^^^ BINGO - reason for using portable widebands/dataloggers and street/strip tuning.

Just like you don't tune an A4 shift points on the dyno do you? heh.

Dyno tuning is half the battle. Start throwing on power adders the mix gets even hairier.

Generally speaking (i tune vw's with boost/nytrous+) the street tune goes in first, using a wideband, to ensure driveability, cold start, warm start, idle, and then runs are made (hours worth) on the street. Once that is sufficient, take it to the dyno, for any fine tuning of your 3 or 4th gear run, any anomalies in the a/f can be flattened out, and the #'s are presented for the owner (dyno queen).

I'd bet that half the tuners out there use a program (timing/fueling) baseline map that is within 90% of each other, within each respective app to begin with anyways

we'll see when hptuners comes out and folks start downloading and COMPARING your tunes