DFCO Tuner Fueling Question?

1280 Views 10 Replies 5 Participants Last post by random84, 7 mo ago

kittyboy

Discussion Starter · 7 mo ago

I'm running a B15 on 94 10%, 2 Bar OS, LS7 cam and throttle body, ETC Area Scaler configured 5636. Tune is overall responsive without issue at idle, cruise, WOT. I do have a couple questions and areas I need experienced help with. Thanks in advance.

I'm mindful of the inherent condition cylinders #7 and #8 can suffer, so I run a richer mix at boost to accommodate the lowest common denominator, 10.5-11 AFR. I've inspected my plugs in the past, heads, valves. Just normal indication of slightly richer fuel, nothing extreme, .028 plug gap, 3" open exhaust. MAF and SD dynamic value dialed-in for the most part.

I need help with a conservative suggested AFR at boost levels, not trying to achieve maximum power, just a playing it safe number. I've read running a richer mix can present issues as well. It's all just not completely crystal clear to me yet?

I realize with richer fuel, engine and exhaust heated-up, excess fuel ignites causing backfire. In my case its minimal, nothing loud, no flames out the tail pipes. I'm just wondering if I were to make DFCO changes it might help to mitigate some mild backfire during deceleration after WOT, or if it's just the nature of things?

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mememe123

· #2 · 7 mo ago

You can make it go into DFCO faster, but it will still back fire a couple of times. It will not be nowhere close / as obnoxious as it would with DFCO disabled, in my experience. Also, will save your pads in the long run, lol.

I do .76 - .78 on mine, I believe those are more or less safe numbers for LS.

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07GTS

· #3 · 7 mo ago

yea DFCO will help i always use it (except on a track day as it will help keep your IAT down) but just for normal stuff is good and does quieten the backfires, i usually have mine so it takes a little to go into it cos i dont want to miss a gear change and it then start to cut fuel when im back on the throttle, i dont use CFCO, or some times u can set the above say 4000rpm delay really long so it dosnt cut it for performance driving where ur keeping the revs up for track days too and then under the 4k it will cut like normal for cruising around

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PGA2B

· #4 · 7 mo ago

You make reference to AFR. If you are not doing so, learn to tune in Lambda. That way if you go E85 or a mix it is easier to tune. Lambda 1.00 is stoich no matter what, so you don't have to worry about what the correct stoich of your fuel is. Lower than one is richer, higher than one is leaner. Your wideband doesn't actually read AFR it reads lambda and converts it to gasoline AFR. So if your Wideband can display in Lambda change to that. I run mine at .78 λ or 11.47 AFR. Most will say .75 to .80 λ for WOT.

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kittyboy

Discussion Starter · #5 · 7 mo ago

PGA2B said:
You make reference to AFR. If you are not doing so, learn to tune in Lambda. That way if you go E85 or a mix it is easier to tune. Lambda 1.00 is stoich no matter what, so you don't have to worry about what the correct stoich of your fuel is. Lower than one is richer, higher than one is leaner. Your wideband doesn't actually read AFR it reads lambda and converts it to gasoline AFR. So if your Wideband can display in Lambda change to that. I run mine at .78 λ or 11.47 AFR. Most will say .75 to .80 λ for WOT.

I log both, but I'm always thinking in AFR mode, maybe too old? But thanks for the push to step-up and get with it.

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PGA2B

· #6 · 7 mo ago

I tuned in AFR for years. Old dog, new tricks, but made the switch and it is much easier.

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07GTS

· #7 · 7 mo ago

soon as i started getting into tuning i was going to e85 so i barely got into AFR when i went straight to Lambda and so glad i did much easier when mixing fuels, also its a simple maths already done for u lambda 1.0 is spot on lambda 1.01 is 1% rich, lambda 0.99 is 1% lean the same as what your fuel error is doing just u dont have to back calculate it from AFR readings

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07GTS

· #8 · 7 mo ago

sorry wrong way around 1.01 is lean and .99 is rich, i was thinking when ur multiplying it u add fuel by the 1.01

mixed myself up

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kittyboy

Discussion Starter · #9 · 7 mo ago

PGA2B said:
I tuned in AFR for years. Old dog, new tricks, but made the switch and it is much easier.

PS:
I have Billyboat 1.75" headers and axle back, would never consider any thing else at this point, been super pleased! However, I did replace the BB center section with a custom 3" x-pipe, the BB was only 2.5" with resonators. V-banded everything too.

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PGA2B

· #10 · 7 mo ago (Edited)

Yeah, I have 1.75" Billy Boat headers and all Billy Boat from there back as well but I have his front section with Cats. Happy with them! Had a couple of issues. First they sent the wrong O2 extensions with them. Then I should have done V bands but used the included gaskets that blew out within 300 miles. Replaced them with GrimSpeed gaskets and has been good since. All hail Amazon!

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random84

· #11 · 7 mo ago

I leave DFCO off... because I love the "CRACKLE CRACKLE POP!" Sound with a M6.

Also, your plugs look maybe a touch hot and slightly oily - you could probably run one step cooler and how's your catch can setup?

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