One of the number one failures of modern transmission comes from torque report problems, and most often than others, from the engine not knowing it should be at a certain load. When I get a vehicle in for a tune to fix flair shifts and try to save the trans, the first thing I do is check the maf. Many times if you catch it as soon as you notice the flair or slip, it can fix the problem and report the proper torque to the trans to apply the proper shift and pre-fill/exit pressures.
A heads up for y'all.
- Thread starter hagar
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maf = Mass Airflow Sensor in this case? If so, is there any action we should take in the short term to help prevent problems?
Thank you for the heads-up!
Yep, i would pop the mass air flow out once a year and give it a shot of electronic cleaner. Such a random post, but I had two high mileage 6 speeds come in this week with the same issue. Obviously won't fix all of them, but something to keep in mind.
THANK YOU!!!
Side question: Anything I should look for with HP Tuners to check the health of the MAF?
Yes, in your case since you are active with it, watch for your fuel trims starting to drift positive.
At hot idle the MAF reading in g/sec should be very close to the engine displacement in liters. If it's much different from that, either way, it's time to take a look at the MAF and how well the air intake is sealed.
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when I cleaned my maf, I could see in the logs that I was in a different part of the Dynamic airflow vs rpm map under the same condition. in my case I was logging timing. it moved me higher in the map where it actually ran less timing for the same "load". dynamic airflow bring a blend of maf and map values. they say about 95% of it is map, especially steady state throttle.
I could definitely see the tcm using lower dynamic airflow numbers than it should messing with tranny shift times and pressures.
I could definitely see the tcm using lower dynamic airflow numbers than it should messing with tranny shift times and pressures.
I can only assume that, depending on the conditions the vehicle is driven in, cleaning every 3-6 months would not be too much, correct?
No such thing as too often, just gets worse and worse over time. More often would not be a bad idea.
swathdiver
Full Access Member
I would assume the quality of the air filter makes a time frame difference as well.
It's true. If you for example went into your maf transfer function and added 20 percent to the calibration, thus telling the engine it is getting more air flow, your truck would run higher in the load and timing tables. If you pulled fuel out of the maf calibration, the truck would run more ignition timing and show lower in the load based tables such as shift pressures and oncoming clutch volumes and such. It's why so many people used to/still do, wreck the 6/8/10 speeds, they don't calibrate the engine computer to report the correct torque value to the tranny control module. The days of a tranny using rpm and throttle position as it's way to control pressures are gone, it's all about making sure the trans knows what torque the engine is running at. That's why a dirty maf not showing the proper amount of air, makes the computer think it is running at lighter load, then it tells the tranny control module the engine is making less power, so it doesn't need as much line pressure and such.
when I cleaned mine, it looked more like black oily stuff. like it came firm the pvc system or intake than anything that could come thru the air filter. but yeah, makes sense if you say over oil a k&n style.
Marky Dissod
Full Access Member
So, is it a good idea to try to 'trick' the ecm into thinking its load is slightly higher than actual?
I really do not see the draw of the K&N filter.
I personally set the tranny tunes up so they don't go below a certain shift torque factor setting. There is a lot of room in the part throttle shifting range to make things more aggressive, without making the shifts annoying. The benefit is not only better shift feel, but tranny longevity by getting the trans in and out of gear quicker, and with less slip time.
mikez71
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Where is this shift torque factor setting? And what should it be set to?
Very good point.
Coincidentally, our 2015 Impala with the 3.6 V6 developed a very slight flair at times and after some digging, we discovered that the intake boot was torn in the flexible portion. This made the PCM think the airflow over the MAF was low, thus a lower load and lower trans pressure.....and no codes. The engine was still getting air, but some was unmetered.
Once we replaced the tube, all was good.
Coincidentally, our 2015 Impala with the 3.6 V6 developed a very slight flair at times and after some digging, we discovered that the intake boot was torn in the flexible portion. This made the PCM think the airflow over the MAF was low, thus a lower load and lower trans pressure.....and no codes. The engine was still getting air, but some was unmetered.
Once we replaced the tube, all was good.
A very cool example of the problem, thank you for sharing. It's important.
