Can timing affect wide band reading?
05-27-2017, 07:05 PM
#1
Can timing affect wide band reading? So I recently looked at my tune and fig my timing was too high @ WOT. (24*). I bumped it down to a max of *18 and now car runs leaner @WOT (10-11 lbs boost. 83 cutlass ly6/whipple 2.9. Mast ecm/tune.. AFR used to be 10.8-11.0 now it's 12.8-13.0 @ WOT do make it richer, or is something else going on?
05-28-2017, 12:03 AM
#2
generally,the more efficient the burn, the "leaner" itll read, so you may have leaned out due to a more efficient timing curve. But such a drastic change, id say your pump is weakening, or there could be an increased ethanol content in your fuel.
05-28-2017, 08:55 AM
#3
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EGT vs UEGO Read Hi, yes though more based on EGT.
The EGO/UEGO uses gas temperature to have a heat range like a Spark Plug.
The EGO works best from 600F-1600F with higher temp as a "drift" read.
The UEGO has a lower "drift with temperature change.
LITTLE KNOWN is the same type of "drift" when in a exhaust pipe with pressure increase such as a turbo manifold before the turbo mount position.
NOW, your case Jimmy is that you NOW HAVE A Correct Spark Instant @ 16-18 degrees AND the AFR at 12.8 is good.
I would do a plug read before a change is made.
Lance
The EGO/UEGO uses gas temperature to have a heat range like a Spark Plug.
The EGO works best from 600F-1600F with higher temp as a "drift" read.
The UEGO has a lower "drift with temperature change.
LITTLE KNOWN is the same type of "drift" when in a exhaust pipe with pressure increase such as a turbo manifold before the turbo mount position.
NOW, your case Jimmy is that you NOW HAVE A Correct Spark Instant @ 16-18 degrees AND the AFR at 12.8 is good.
I would do a plug read before a change is made.
Lance
05-28-2017, 06:00 PM
#6
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When timing doesn't let the burn get done, you get
more oxygen (and other spooge) left in the exhaust.
Meter just responds to the oxygen, and -assumes-
about the fuel relation. So early it misfires, or so late
it either misfires or blows still-combusting stuff out
the pipe, either way can jack the meter.
Dumping more fuel (VE change) might cover it up.
Does not seem like a 6% fuel change should result in a
~20% reading change. Something more to it, I think.
Of course telling it more VE tells it more cylinder air
mass and the timing also dials back as well (if the
spark map is sane).
If it were me, I'd be disinclined to assume I had 97%
VE up top (look at somebody else's similar build and
believe that torque follows VE, what does their dyno
curve say about that?). I'd be trying some simple stuff
with timing, like pull out 3 degrees (or whatever the
effect of telling it more VE, resulted in according to logs)
and see if the meter responds to spark alone.
more oxygen (and other spooge) left in the exhaust.
Meter just responds to the oxygen, and -assumes-
about the fuel relation. So early it misfires, or so late
it either misfires or blows still-combusting stuff out
the pipe, either way can jack the meter.
Dumping more fuel (VE change) might cover it up.
Does not seem like a 6% fuel change should result in a
~20% reading change. Something more to it, I think.
Of course telling it more VE tells it more cylinder air
mass and the timing also dials back as well (if the
spark map is sane).
If it were me, I'd be disinclined to assume I had 97%
VE up top (look at somebody else's similar build and
believe that torque follows VE, what does their dyno
curve say about that?). I'd be trying some simple stuff
with timing, like pull out 3 degrees (or whatever the
effect of telling it more VE, resulted in according to logs)
and see if the meter responds to spark alone.
05-28-2017, 07:12 PM
#7
Mast sent me this tune. It was fine for 4-5 mo until I looked at the timing . It was at 24*@WOTthe VE was at 91.0 in that cell everybody said it was too much timing for pump. It was assumed the knock sensors were pulling timing. I bumped it down to 18* max . Now it would go lean in 3rd at 6000-6500. So I added in those cells to 97.0 (probably too much) now with meth it's like 10.3. My plan was to keep it @18*and read the plugs. To see where I'm at. I'm not a tuner by any means. I just don't know anybody with the info I need to tune this except mast .(I I've been emailing back and forth) and trying to do it myself.
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05-28-2017, 10:46 PM
#8
Tune it in lambda. When you add meth, you change the stoich value...
Also, 24 degrees may not be too much with methanol. Especially 100% methanol. It adds a ton of octane. But you have to set your timing to pull timing like crazy if the IATs climb. At least that's how you should do it with meth... otherwise, if the meth cuts out it'll burn the **** out of the motor if you've tuned for the meth.
And 97 in the VE table? MAST PCM a Gen III or something else? With the blower, you should be up close to 200 VE @ 200kPa with 14psi.
Also, 24 degrees may not be too much with methanol. Especially 100% methanol. It adds a ton of octane. But you have to set your timing to pull timing like crazy if the IATs climb. At least that's how you should do it with meth... otherwise, if the meth cuts out it'll burn the **** out of the motor if you've tuned for the meth.
And 97 in the VE table? MAST PCM a Gen III or something else? With the blower, you should be up close to 200 VE @ 200kPa with 14psi.
05-30-2017, 06:54 AM
#11
I guess with the meth, I want 12.5 without meth, 11.5 with? I'm gonna shoot for 12.0/11.0. My next problem is how do I check for knock? Software has a knock page but I really don't understand it yet
05-30-2017, 04:21 PM
#17
I think the car was only tuned to hit 24 on the map( 10lbs boost) it actually hits 26 (11.5 lbs) I think it was just lean in that 1 cell. I had to have my wife watch laptop while I was on it just to see where it was landing on the ve scale. I fattened it up and it was fine. I need to go to test n tune at the track on a sat and mess around with it. 3rd gear 11.5 boost is like 135mph lol
06-04-2017, 10:44 PM
#18
Methanol is much richer stoich than that. 6.45 @ stoich... and rich would be 4...
So if you pump 100% methanol, depending on how much, would read a lot richer than 11.5 potentially.
Which is why you need to tune in stoich. To calculate, use something like this (20/80 split):
Blend A/F ratio = (0.20 × Methanol Rich A/F Ratio) + (0.80 × Gas Rich A/F Ratio)
= (0.20 × 4) + (0.80 ×12.5)
= 10.8
Blend A/F ratio for stoich = (0.20 × Methanold A/F Ratio) + (0.80 × Gasoline A/F Ratio)
= (0.20 × 6.45) + (0.80 ×14.7)
= 12.94
λ = 10.8 ÷ 12.94 = 0.835... which is pretty much what it always is no matter the fuel. You want to be closer to .78 or so boosted. So an EQ ratio of 1.28 for lambda of .78 or so.
So if you pump 100% methanol, depending on how much, would read a lot richer than 11.5 potentially.
Which is why you need to tune in stoich. To calculate, use something like this (20/80 split):
Blend A/F ratio = (0.20 × Methanol Rich A/F Ratio) + (0.80 × Gas Rich A/F Ratio)
= (0.20 × 4) + (0.80 ×12.5)
= 10.8
Blend A/F ratio for stoich = (0.20 × Methanold A/F Ratio) + (0.80 × Gasoline A/F Ratio)
= (0.20 × 6.45) + (0.80 ×14.7)
= 12.94
λ = 10.8 ÷ 12.94 = 0.835... which is pretty much what it always is no matter the fuel. You want to be closer to .78 or so boosted. So an EQ ratio of 1.28 for lambda of .78 or so.
06-05-2017, 04:15 PM
#19
Methanol is much richer stoich than that. 6.45 @ stoich... and rich would be 4...
So if you pump 100% methanol, depending on how much, would read a lot richer than 11.5 potentially.
Which is why you need to tune in stoich. To calculate, use something like this (20/80 split):
Blend A/F ratio = (0.20 × Methanol Rich A/F Ratio) + (0.80 × Gas Rich A/F Ratio)
= (0.20 × 4) + (0.80 ×12.5)
= 10.8
Blend A/F ratio for stoich = (0.20 × Methanold A/F Ratio) + (0.80 × Gasoline A/F Ratio)
= (0.20 × 6.45) + (0.80 ×14.7)
= 12.94
λ = 10.8 ÷ 12.94 = 0.835... which is pretty much what it always is no matter the fuel. You want to be closer to .78 or so boosted. So an EQ ratio of 1.28 for lambda of .78 or so.
So if you pump 100% methanol, depending on how much, would read a lot richer than 11.5 potentially.
Which is why you need to tune in stoich. To calculate, use something like this (20/80 split):
Blend A/F ratio = (0.20 × Methanol Rich A/F Ratio) + (0.80 × Gas Rich A/F Ratio)
= (0.20 × 4) + (0.80 ×12.5)
= 10.8
Blend A/F ratio for stoich = (0.20 × Methanold A/F Ratio) + (0.80 × Gasoline A/F Ratio)
= (0.20 × 6.45) + (0.80 ×14.7)
= 12.94
λ = 10.8 ÷ 12.94 = 0.835... which is pretty much what it always is no matter the fuel. You want to be closer to .78 or so boosted. So an EQ ratio of 1.28 for lambda of .78 or so.
06-05-2017, 05:06 PM
#20
If you know how much fuel you're using of each, you can calculate your A/F that way. But, that's the point I was trying to make. Why do that? Use lambda, and it's already done for you.
At least that's the point I was trying to make. In the end, you still use lambda based on usage, not fuel. .78 lambda boosted. Doesn't matter the fuel.
At least that's the point I was trying to make. In the end, you still use lambda based on usage, not fuel. .78 lambda boosted. Doesn't matter the fuel.