Maf Comp vs Latency question
Jun 2, 2014, 01:46 PM
#16
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If you have an aftermarket intake I can almost give you a 100% guarantee that's why your uego does that. You should check your rom's maf scaling and compensation tables and compare them with a "stock" version of the same rom. If the values are the same then you know why it does that. Either get your maf scaled properly by a professional or buy a stock intake accordion rubber pipe off Ebay for $20. I can still here the turbo spool fine with the cone filter I'm using. FWIW it didn't change audibles a single bit switching between the two intakes.
Jun 3, 2014, 12:00 PM
#17
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Is there something about the design of the intake that makes the AFRs so sporadic? It makes me think there is a leak, or something egr related. I did a log on the highway on the way to work this morning, see attached. With airflow, TPS, timing etc constant, you can see the AFR dipping randomly to 13 of high 12s. Have you ever tried to log EGR duty cycle and see how it compares?
Fuel trip is hovering around 0, so is there anything to scale here? I was looking at the below post to figure out how to scale the MAF. Is there anything I should be doing here based on the below log?
https://www.evolutionm.net/forums/ec...f-scratch.html
Fuel trip is hovering around 0, so is there anything to scale here? I was looking at the below post to figure out how to scale the MAF. Is there anything I should be doing here based on the below log?
https://www.evolutionm.net/forums/ec...f-scratch.html
Jun 3, 2014, 03:09 PM
#20
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I have my egr deleted as of two weeks ago - did it myself when installing a new stock ported IM 
and it didn't help with trying to scale the other JM pipe intake. It still did the rich swinging crap FWIW. I think looking at egr as a related cause isn't worth it, its not that. Mychailo told us exactly what to do, except no matter what I do with the scaling and comp tables it still swings rich at cruising speeds.
and it didn't help with trying to scale the other JM pipe intake. It still did the rich swinging crap FWIW. I think looking at egr as a related cause isn't worth it, its not that. Mychailo told us exactly what to do, except no matter what I do with the scaling and comp tables it still swings rich at cruising speeds.
Jun 3, 2014, 06:20 PM
#21
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Ahh good to know, should save me some time from messing with that system any more. Below is a video of what my gauge is doing on the highway - let me know if this is similar to yours. With how sporadic it is i'm struggling to see how it would be MAF scaling related. Almost seems like a bad ground on the gauge or something.
I feel like if the MAF scaling was off , the fuel trims would be starting to peg one way which would eventually end up with a lean or rich code correct?
The only thing I can think, is that the MAF hz scaling conversion to load is right on some edge and is not making a "smooth" conversion to load. The ecu is calculating a "large" changing load based on a small change in Hz and is therefore changing the fuel to compensate. Hindsight I should have logged load to insure it was steady with the MAF hz.
I feel like if the MAF scaling was off , the fuel trims would be starting to peg one way which would eventually end up with a lean or rich code correct?
The only thing I can think, is that the MAF hz scaling conversion to load is right on some edge and is not making a "smooth" conversion to load. The ecu is calculating a "large" changing load based on a small change in Hz and is therefore changing the fuel to compensate. Hindsight I should have logged load to insure it was steady with the MAF hz.
Jun 4, 2014, 11:09 AM
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The MAF comp or MAF scaling tables are what's needed to clean up the AFR the best. The procedure takes an hour or two of driving and tweaking. You'll need to log MAF Hz and STFT at steady rpm and throttle at several different MAF Hz values, e.g., at 100 Hz, 150 Hz, 200 Hz, etc. Adjust MAF compensation or MAF scaling until STFT hovers around zero for each MAF Hz point you choose. Make sure you have at least 10 seconds of steady rpm and TPS to observe STFT. It's a bit more in depth than tuning injector settings.
e.g STFT negative = raise or lower maf comensation ?
and which one is better to adjust, maf hz or maf comp
Jun 4, 2014, 12:35 PM
#25
Both tables do exactly the same thing. I ended up setting the MAF compensation to all 128 and then retuning the entire MAF scaling table over the entire MAF Hz range. I found this to be the easier way to create a smooth curve with no unintended spikes or steps. Remember that the car needs to be at steady TPS, load, and rpm for a few seconds before the STFT gives an applicable value. And make sure that the LTFTs aren't changing.
Jun 4, 2014, 07:41 PM
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negative STFT = lower MAF compensation or MAF scaling
Both tables do exactly the same thing. I ended up setting the MAF compensation to all 128 and then retuning the entire MAF scaling table over the entire MAF Hz range. I found this to be the easier way to create a smooth curve with no unintended spikes or steps. Remember that the car needs to be at steady TPS, load, and rpm for a few seconds before the STFT gives an applicable value. And make sure that the LTFTs aren't changing.
Jun 4, 2014, 11:30 PM
#27
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negative STFT = lower MAF compensation or MAF scaling
Both tables do exactly the same thing. I ended up setting the MAF compensation to all 128 and then retuning the entire MAF scaling table over the entire MAF Hz range. I found this to be the easier way to create a smooth curve with no unintended spikes or steps. Remember that the car needs to be at steady TPS, load, and rpm for a few seconds before the STFT gives an applicable value. And make sure that the LTFTs aren't changing.
Both tables do exactly the same thing. I ended up setting the MAF compensation to all 128 and then retuning the entire MAF scaling table over the entire MAF Hz range. I found this to be the easier way to create a smooth curve with no unintended spikes or steps. Remember that the car needs to be at steady TPS, load, and rpm for a few seconds before the STFT gives an applicable value. And make sure that the LTFTs aren't changing.
won't it work to adjust at least lower Hz's ?
Jun 5, 2014, 07:20 AM
#29
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So I did a log on the highway on the way to work looking at Airflow, Load, Wideband, O2 feedback etc. The STFT did not change, yet I'm getting these sporadic AFRs. Starting to wonder if the airflow across the sensor is just less steady with this intake than with the stock air intake and that is what is causing the AFRs to jump around at these conditions.
Could someone check their logs and see if Airflow jumps around like it does on mine? Seems the resolution is 6Hz for my recorded airflow values.
Note I subtracted 50 from the egr duty cycle value to make it graph a little cleaner.
Could someone check their logs and see if Airflow jumps around like it does on mine? Seems the resolution is 6Hz for my recorded airflow values.
Note I subtracted 50 from the egr duty cycle value to make it graph a little cleaner.
Jun 5, 2014, 10:26 AM
#30
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Merlin was talking about the radiator fan kicking on and blowing air across the cone filter which would screw up these values obviously. Just something to consider. Is your intake positioned in a way where that cooling fan would blow air across it? Although @ highway speeds I don't know if that would come into play as much.