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Help me understand widebands

 
Old 04-10-2019, 09:15 PM
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Default Help me understand widebands

Could anyone help me understand why widebands cant datalog cranking AFR? I've read the only way to get an accurate reading is to hardwire to another battery, drill, 12v, whatever can keep it on. I don't understand wiring very well, so what about the switched wiring makes it unable to log start up. I remember a thread where 18psi discussed hardwiring a wideband to tune start up, do you just need a second wideband or is there an easy way to swap from wired in the car to hardwired and back seamlessly? I feel stupid asking and i'm sure i'll get flamed but i'm very curious. Mostly because i'm annoyed with my cold starts and it seems like the only way to dial it in, is trial and error once a day.

My only guess is the switched ignition is short pulses of the power and essentially turns the wideband on and off repeatedly?
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Old 04-10-2019, 09:22 PM
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Really simple answer.

Turning the starter motor, and engine, over takes a lot of power.
That's why the starter wires are so thick.

So that the car has enough battery power there to do it, they usually cut power to the rest of the systems while it's cranking.
Even if the power isnt cut, there's usually a decent voltage drop anyway (hence why lights dim if they're on during crank)


Wiring the WBO2 to a separate power supply (ie: 12v drill battery etc) means it's powered independantly to the car.





Also, widebands need to heat up in order to read properly.
during crank there will usually be pulses of cold air that come down the pipework.
In theory these cold pulses, hitting the hot sensor, can cause shock cooling and kill the sensor. (I say in theory since the manual on my MTXL warns about it, but i've never actually heard of it happening)
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Old 04-10-2019, 09:28 PM
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Thanks for the simple to understand reply!

So is there an effective way to wire gauge to be easily swapped? Or I just need to get a second wideband for dialing in start ups? I assume most dyno tuners have an exhaust wideband they can use that runs off an external source?

Right now its directly spliced into a switched source. Is there an unused fuse on the NA8 fuse box that could be wired into and undone easily to connect to a drill battery?

Last edited by thebigtuna; 04-10-2019 at 09:41 PM.
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Old 04-10-2019, 09:43 PM
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The question is - is it worth it to have a perfect AFR in the 30 seconds or so you're blind to AFR?

The answer is no.

If it starts easily in different temperatures, both coolant and outside weather - call it good enough.
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Old 04-10-2019, 09:49 PM
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No second wideband. Just a second power supply and move the Red and Black (power and ground) that go to the WB controller from the car source and ground to the auxiliary supply.

You can parallel the blacks and use a single pole double throw switch on the Red if you want. Or temporarily use wire nuts.

You only need to use the aux supply for about 20 seconds before starting until the sensor is hot and the controller is giving a reading, until the car starts and you go through ASE.
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Old 04-10-2019, 10:12 PM
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Thanks DNMakinson! That's what i was looking for! I will have to google half of what you said

Goof, I know getting the starting AFRs isnt necessary but i want to improve and get better at tuning. I've realized repeatedly, anytime i think I've learned something I realize I know nothing compared to the OG's on here. Anything that improves my skill, regardless of how worth it, I will do.
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Old 04-10-2019, 10:16 PM
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Hook up a set of jumper cables to a running car while cranking. It is what I do.

Edit: it is not 100% representative during cranking, as the lower voltages without the jumpers do change fueling. It does on the other hand have the advantage of keepi g tunerstudio connected during cranking, and the SD logging can log cranking, which is super key.
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Old 04-10-2019, 10:31 PM
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Tbh the car has been jumped most of the time these past couple days, bad battery. So when logged it reads full lean - full rich - full lean -accurate reading with ase. So either that strategy isn't working for me or I really am that rich on startup. Or because the battery is semi dead its more like cranking a normal battery. I dont feel like my cranking pw is that crazy. I recently fixed some wacky prime pw which has made me retune alot.
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Old 04-10-2019, 10:34 PM
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E85? EAE?

Edit: Does it bounce between run and cranking?

Edit again: there is a bug in 1.51 that starts the ASE timer after the first crank to run transition but doesn't reset it if you go back from run to crank.

Look at your spark advance for crazy changes as well.
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Old 04-10-2019, 10:39 PM
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Used to be e85, tbh i had it starting better on e85 than now. No EAE as far as i know but ill look onto that. I can link tune and a log. Are the msq links still broken? Second start is always quick. Cold start is meh. it pretty much catches and runs, just takes a while to catch. I've tried adding and removing 5-10% to analyze changes in start time but no luck.
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Old 04-10-2019, 10:43 PM
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Are you logging to SD with a good sample rate, say 5msec?

Do you actually have a problem, or are you curious as to if what you see is normal?

If it fires on the second crank, you may try increasing the pump prime to the max (not prime pulse). Be sure to wait until the prime period is finished before cranking.
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Old 04-10-2019, 10:48 PM
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If it started better on e85 that it is very possible the crank pw is way too long.
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Old 04-10-2019, 10:53 PM
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Just logging to the computers c drive. I'll have to look at getting a micro sd to datalog to.

Not sure tbh, i dont think it's necessarily a problem. But, it isnt up to par with what i want or with my 4 hours or less restarts.

I'll try to increase the pump prime and see how that helps. Cranking pw is around 330 at 40*. It seems aftee the cylinder gets a bit warmer after a few tries at catching it starts. Or a pause and re try it starts in less revolutions. It seems im either too lean or rich off the cranking pw. As brain would say i think in need to l2t
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Old 04-10-2019, 11:03 PM
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This is my recent tune and a start up a day or two before more tweaks.

e85 starts were a while ago when i lived in missouri. I now live in the UP where its regularly much colder and no access to e85
Attached Files
File Type: msq
40 degree tune.msq (262.6 KB, 3 views)
File Type: msl
startup.msl (232.7 KB, 2 views)
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Old 04-11-2019, 11:32 AM
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would you say you are unhappy with the posted start-up? It looks reasonable to me. The readings from the wideband before ~7.6 seconds are not valid and can be ignored. As mentioned, widebands are sensitive to temperature and require some stabilization before they provide good readings.

couple tune comments:

I see some funkiness in the ASE/ASE Taper at higher CLT temps, I assume this is an effort to combat heat soak. You can also try ignoring MAT during ASE to see if that helps at all. Startup/Idle -> Cranking/Startup -> Ignore MAT correction during ...
You have the priming pulse delay (same menu -> Prime Pulse Delay(s)) set to 0. You definitely want to bump this up to at least a second or two to see if it solves your needs-2-cranks problem. The rail has no pressure for your prime pulse as it is currently setup. You probably don't even have pressure for a bit during cranking. You have to wait for this duration KOEO for the prime to complete prior to cranking (don't go directly from off-to-crank).

Hope this helps
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Old 04-11-2019, 03:26 PM
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I honestly can't remember if that log was on a hot start, second crank, or not. I'm definitely not satisfied with the cold start but I couldn't upload the file I wanted because it was too big, so I said **** it. The car is in a shed for a couple days till this winter storm passes. I'll try and get another cold start logged.

The funkiness is absolutely for hot soak on hot restarts, but its worthless and I pretty much say **** it and hit 16 or so afr and just start moving quickly. I'll try that fix as it sounds much more effective than my current setup.

I wonder if that's a stock basemap setting. I've never heard to change that or look at it from my research. I'll absolutely play with that and see if it helps my cold start. I've always waited till the pump shuts off before trying to crank, so no issues there

All of your input has helped so much! Thanks for taking a look at that log and tune!
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Old 04-11-2019, 04:01 PM
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Originally Posted by thebigtuna View Post
I honestly can't remember if that log was on a hot start, second crank, or not. I'm definitely not satisfied with the cold start but I couldn't upload the file I wanted because it was too big, so I said **** it. The car is in a shed for a couple days till this winter storm passes. I'll try and get another cold start logged.

The funkiness is absolutely for hot soak on hot restarts, but its worthless and I pretty much say **** it and hit 16 or so afr and just start moving quickly. I'll try that fix as it sounds much more effective than my current setup.

I wonder if that's a stock basemap setting. I've never heard to change that or look at it from my research. I'll absolutely play with that and see if it helps my cold start. I've always waited till the pump shuts off before trying to crank, so no issues there

All of your input has helped so much! Thanks for taking a look at that log and tune!
Based on your published tune, it won't make any difference because you have your entire MAT "correction" set to 100%. Therefore, ignoring it will keep you at that same 100%.
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Old 04-14-2019, 07:58 PM
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Update:

Changing the pump delay seemed to have helped. The car sat for a couple days while it snowed and I was waiting on a new battery. New battery obviously helped dramatically but this is the most recent datalog, all one crank. Almost caught, stumbled fired up. About three seconds from start to run. Not terrible but i'm going to keep playing with it to get it better. Thanks for the help, any further input is still appreciated.
Attached Files
File Type: msl
363 cpw.msl (176.6 KB, 1 views)
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