Made a couple of changes to the car and added a wideband, wondering if somebody here knows some answers to these Q's. Thanks in advance.

1) Exhaust leaks make it look lean, how lean? The car is running around 14.5-15.2 idle and light throttle cruise can drop to 13.8 though usually higher. I think this is legitimate and not leak influenced, what does a leak look like on a wideband. Thoughts?

2) Assuming the wbo2 values are right, which I do believe they are, when I blip the throttle in neutral I can see a blip to 22 then immediately it drops down to 11-12ish. I'm assuming the blip is unavoidable? How do you tune this in gear and in neutral, previously I had a tip in lean backfire, that is gone but besides fixing that I don't know what to target.

3) WOT afr? What are you guys shooting for, 12.8? Mine is lean right now.

Thanks and sorry for all the questions.

 

Depends where the leak is at and how much of a leak. I honestly had leaks i could hear at the header flange but never noticed anything major on the wideband.

Depends on the wideband but most are fast enough to catch throttle blips. it could be possible you have a slight lean "tip in" issue on the throttle before AE catches up and overly richens it back to 11-12's. As long as the motor isnt stumbling or hesitating on these hits, its ok IMO.

Any of the Acceleration enrichment functions vs changes in MAP or LV8 or TPS% will help the throttle blip stuff. Just work it til its crisp for you. Too lean it will hesitate. Too rich it may stumble abit on a quick throttle blip. You want the motor to response smoothly and with a fast crisp response.

I start out with low AE fuel and just increase it a tiny bit at a time til the motor starts waking up and becoming more crisp with the throttle response. Dont necessarily have an air fuel ratio in mind, as its not necessary.

WOT air fuel, typical 12.8 is good value for n/a builds but it can be anywhere from 12 to 13's for max power depending on the head chamber design, how well the cam valve events are working with the head port, and type of fuel you burn


Also keep in mind timing will change the wideband readout you see since timing controls burn point in the cycle. If you time it too late, the burn will take place in the exhaust and may show more "lean" since all the oxygen hasnt been consumed yet.

 

Thanks Orr!

I can't hear the leak but I figured I'd ask before getting all worked up and messing with the tune. I figure at WOT, leak or no leak it will probably be correct, just didn't know how sensitive it is. The timing is a very good point though...

Tip in doesn't feel crisp, so I think it could use a touch more fuel. 5% steps?

OK good to know, with the new maf and a few other changes it is running about 13.8 at wot, so I'll dump some more fuel in for that and see.

Around 1500 rpm part throttle she still seems a bit rough, but no stumbles if I floor it through that range on 5th gear so I think maybe I'll try a bit more fuel and see of that helps as well.

Timing is mild with AFR 1095 comps only going to 36,but the curve is also very mild and I might try waking that up a bit.

Thanks!

 

See what it does. AFR's typically dont need alot of timing. I only ran 34 deg for best power. All in by 3200 rpm

 

Your wideband will catch any lean condition when TB opens. You may not be able to feel it? There might be a filter in your def that allows you to bring in the AE sooner avoiding the enleanment. It is TPS as well as MAP based. Reduce the value for sooner.

When I blipped the throttle I did not get a desired response it that there was a delay. annoying to say the least. I needed to reduce that filter a lot.


My ext leak caused a higher and higher BLM which required more fuel in my VE table(SD). I finally realized it and fixed it. BLM stabilized.

 

On mine (6E) there is a table for AE. I had to give it a ton on the first few injects, then taper to very little at the top. It all depends on your cam/heads/intake etc. I got mine to only show about 16 on the wideband on a blip. It actually stumbles a just hair if I gun it hard while sitting in neutral, but when in gear it is perfect and I don't see any leanness on the wideband then. I don't know your code but if you do have a table that lets you add AE per injects, give it a bunch on the first few injects then taper off to almost none by the last injects and see how it likes it.

Also, on the Innovate LC-1 wideband, there is a setting that lets you slow down the refresh rate. Basically means the gauge will only change like 3 or 4 times a second instead of like 8 or 10. Don't quote me on the numbers as I'm working from memory, but I know slowing it down makes it much easier to watch the gauge and it helps eliminate seeing the instant flash changes of tipping the throttle open before even the AE can richen it up.

 

Thanks guys, I got it to go away by adding some fuel to the "AE Factor % BPW Inj" table I think. It is still spiking but it drops down to 11 and then goes to where it should, I am going to play with it more.

I am tuning in 32b but I'm not even sure what this table does, does anybody?

- Async Accel Enrich if Neg Diff TPS > 3.9%
value: 3.91msec
Can I reduce this value to make AE come in sooner?

The other tables I have are:
- AE Factor % BPW Inj
- AE Factor vs Change in LV8
- AE Decay Factor vs Coolant Temp

Thanks for all the replies!