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Old 01-03-2011, 09:38 AM   #1
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Question Maf?

Tried searching and couldn't come up with anything. Probably a stupid question but...

Is the transmission(4L65E)affected by the MAF at all? Like to know when to shift or when not to?

The issue I'm having is a 2-3 flare that only occurs now and then and never occurred before a certain incident.

That incident was back in the summer right after I had the trans replaced due to a bad 3-4 clutch pack(just went ahead and had a perf. trans built because I knew I would need it with upcoming mods). I took off my lid to clean the airfilter and I see this long black thing hanging out of the inside of the MAF. I take off the bellow and pull on the black piece and it just keeps coming and coming. It was a freakin' rubber seal that was on the bottom of my lid that had apparently gotten old and became unstuck and got sucked into my MAF(which was descreened when I purchased the car). It could only have been there for a week or so as I had had the lid off then and didnt see it. Thankfully it didn't go into the intake so I know I'm lucky there!

But my question is with as long as the piece was I'm sure it was flopping around inside and had to of been sucked in there violently due to the fact it was wedge so hard it didnt go into the intake, I'm sure this could have damaged the MAF and if so could that be causing the flare?

Thanks!
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Old 01-03-2011, 10:50 AM   #2
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Bump!!! Really need some info
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Old 01-03-2011, 12:54 PM   #3
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Yes the maf info is used for the trans.
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Old 01-03-2011, 01:44 PM   #4
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So could a damaged MAF be causing this problem? It doesn't do it all the time and will only do it at WOT every now and then and not at all if we back the shift point down very low
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Old 01-03-2011, 03:07 PM   #5
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the pcm uses the MAF signal to know how much air is entering the engine and bases the a/f ratio calculation from it. If that were damaged then you would have some major engine performance problems that you would notice. The MAF is just a heated wire so they basically work or don't work, there's no real in between such as working sometimes and not others.
For your tranmission shift problem, I highly doubt the MAF has anything to do with it.
Input signals to the transmission to base shift points and shift firmness would be trans fluid temperature, possibly engine coolant temp, engine rpm, vehicle speed, and probably engine load. Engine load i'm not sure on but is probably calculated from throttle position sensor, MAP sensor, and possibly the MAF signal but again I don't see the MAF sensor being a cause of the shift problem without showing other major signs.
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Old 01-03-2011, 03:26 PM   #6
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Are the other shifts ok? The maf info is used along with other things to set the line pressure. But if the maf was messed up other things besides the trans shifting woooood be too. Sounds like you have a trans problem.

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Old 01-03-2011, 05:45 PM   #7
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Originally Posted by ParkerSS View Post
Tried searching and couldn't come up with anything. Probably a stupid question but...

Is the transmission(4L65E)affected by the MAF at all? Like to know when to shift or when not to?

The issue I'm having is a 2-3 flare that only occurs now and then and never occurred before a certain incident.

That incident was back in the summer right after I had the trans replaced due to a bad 3-4 clutch pack(just went ahead and had a perf. trans built because I knew I would need it with upcoming mods). I took off my lid to clean the airfilter and I see this long black thing hanging out of the inside of the MAF. I take off the bellow and pull on the black piece and it just keeps coming and coming. It was a freakin' rubber seal that was on the bottom of my lid that had apparently gotten old and became unstuck and got sucked into my MAF(which was descreened when I purchased the car). It could only have been there for a week or so as I had had the lid off then and didnt see it. Thankfully it didn't go into the intake so I know I'm lucky there!

But my question is with as long as the piece was I'm sure it was flopping around inside and had to of been sucked in there violently due to the fact it was wedge so hard it didnt go into the intake, I'm sure this could have damaged the MAF and if so could that be causing the flare?

Thanks!
I had a transmission issue that was directly related to the MAF. My gears would bang into gear when going from PARK to either....DRIVE or REVERSE. Reverse really hit hard. Did it 100% of the time too.
Nobody could help me out for over a year, nobody here, not FLP who originally built it, not Ed Wright who tuned my PCM......NOBODY.

When my PCM-to-Engine ground wire came loose and fried my PCM last year and I had to get a new one.....two things got fixed:
My fried PCM of course, along with a bunch of little tuning things.
and
My 12-14 month long issue with my tranny banging into gear was fixed.

What happened was, my PCM actually started to fry inside itself long before the ground wire came fully loose and totally shut me down by frying the PCM totally. IIRC, pin numbers 42 and 43 were burnt black when I removed the bad PCM. Those were the MAF signal pins. ((and again, not sure if I remember those exact pin numbers)).

For a long time before the total PCM failure, from that ground coming all the way loose.......my MAF was completely out of the loop. I could unplug it at cold start up, I could unplug with the engine running, I could leave it unplugged for a week, I could WOT with no problems and it was smooth as glass with it unplugged..........the engine ran 100% identical the entire time. I was in a Speed Density tune that the PCM had defaulted to for like 2 years when those pins got fried. BUT...the PCM still worked. I just said **** it, and let it go, since nobody could figure out what was wrong.

When my new PCM went in.......the banging into gear disappeared. Its been gone ever since and my MAF was back in the loop after the new PCM went in. Ed Wright downloaded my same tune from back in 2002 into my new PCM....and bang, I was back. But it was even better. My engine ran sooo much better, MAF was back in play, idle was better, I could start it up cold and "immediately" back out of the driveway and drive away without the engine stalling and giving it zero pedal to keep it running (I used to have warm it up for 1-2 minutes to reach closed loop, according to the tuning gurus, and I always had to pedal it to keep it running) and at WOT from a roll I don't leave a trail of black smoke from being rich.

A bunch of things got fixed. But the tranny was directly fixed with the MAF being back in the game......

......I've learned that these PCM's do things and use signals from different sensors that not even GM knows about and not even the best tuners on here know about. THATS A FACT......

If I were you I would see if you just need a new MAF, make sure its bad before you look into a tranny issue. Make sure the wires are good from the MAF to the PCM, signals are there...ect...... If the MAF cannot be brought back into play...pop the two tops of your PCM off and look for burnt pins. Check your grounds too, these PCMs burn up from the inside out and will still run the car as its being fried over time. Then one day, like me, driving at 45 mph down a street...boom, half my engine is shut down, and the other 4 cylinders that are firing on the passengers side are spitting and backfiring like crazy.
Too bad you don't live around here....the guy that came to my house to fix it is a sick, guru, crazy ***.....PCM and wiring maniac. He knows every centimeter of of every wire in the LS1 harness.

Its funny...you'll probably find out its a bad fuel filter or something way out there.......maybe a blown "engine sensor fuse" which is common for MAF failure, but I thought I'd tell my story of my MAF/Tranny issue.......

Good luck..........

.

Last edited by LS6427; 01-03-2011 at 06:04 PM.
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Old 01-03-2011, 08:35 PM   #8
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Yea, at WOT the PCM "believes" the MAF over other sensors. The PCM will also cut gas to the engine if the MAF is going bad.

The MAF elements heat up. If some of the rubber melted on to them, then that could be creating an issue. (BTW - there is a reason the screen is there!)

Do you have a K&N filter in the car? It sounds like that gasket is the suplemental one that comes with the K&N.
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Old 01-03-2011, 11:35 PM   #9
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at wide open the pcm does not necessarily believe the MAF over other sensors. It still uses the MAF primarily. The pcm however goes into open-loop mode at w.o.t. which means it's not relying on feedback from the O2 sensors to calculate the a/f ratio.

and according to my 2002 service manual, which is for a 4L60e not a 65, the scan tool data list for the transmission has nothing specifically stating MAF signal, nor MAP signal, but it does have the value of engine torque which may or may not be calculated from those.

If and when the MAF has a problem, and a DTC should be thrown, then the pcm relies on the MAP sensor to do a/f calculations. Proof of this is if you disconnect your MAF sensor the engine still runs.

back to the original question, if the maf is damaged then a P0100 through P0104 DTC should be set indicating that. Now like in LS6427's case where he had a pcm going south, then all bets are off regarding everything... because everything relies on the pcm functioning properly to begin with. And i wouldn't necessarily conclude the MAF also having a bad or burnt connection to the pcm as the sole cause of his transmission problems. He also had other transmission problems, not just a 2-3 shift problem which is all you are having which leads me to believe it's mechanical in your trans which would be from a bad setup.
check out https://ls1tech.com/forums/automatic...ease-help.html

you would probably get better answers in the auto trans section,
and with the proper scan tool you should see be able to see all sorts of data and figure out what's going on such as difference between desired and actual 2-3 shift time,
and there's TAPS - transmission adaptive pressures which is the learning curve that adjusts fluid pressures. Your trans builder should be able to do this, but i agree with 427 that most tuners don't know how everything works regarding pcm input signals and algorithms. I have the gm service manual and there's many areas where they missed editing and the guy writing the stuff didn't know whether a sensor gets energized or grounded by the pcm, and the sentence reads "... energized, grounded, by the pcm".
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Old 01-04-2011, 01:18 PM   #10
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Thanks for all the help guys.

And yes it was from the K&N filter.

Had Mike at Vengeance take a look at i today and the MAF seems to be working fine so we backed down the 2-3 shift point by a few hundered RPM to see if that solves the problem.

If not looks like I'm going to Illinois because that is where my builder is located and the trans has a lifetime warrenty.
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Old 03-09-2017, 06:08 PM   #11
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Digging up a old thread looking for some answers to my issue....

I have a 2004 Blazer Xtreme 4.3 with 4L60E with a tune & CAI & shift kit. Everything had been running OK then noticed when I went to take off from a dead stop after it had been sitting & it was low power till Ihad 3 grand & then it seemed to run OK.

Long story short I took the Spectre air filter off to clean & drove it without a filter & the difference was amazing !! I cleaned the filter & didnt oil it & reinstalled & the problem returned,removed filter ran good again,bought a K&N filter & it ran great.

All of a sudden after a couple of weeks it started a 2-3 shift problem,sometimes it would shift just fine & other times it would go to shift to 3rd & pause then shift & other times it would go to shift & hicup & start slipping till I backed off & let it shift & then everything was good.

The other day I started to check codes & found P0101 cleared it,checked again & it was back,no check engine light but was def throwing the code quite a few times. I had a spare MAF sensor & installed that & no more codes & the 2-3 shifting is working just fine.

So IMO yes the MAF does control something that controls shifting.
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Old 03-10-2017, 07:04 AM   #12
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Originally Posted by ZQ8LS1 View Post
So IMO yes the MAF does control something that controls shifting.
No, it doesn't. Your transmission is just reacting globally to the engine bogging.

Why didn't you clean your MAF? The problems you describe are classic dirty MAF issues related to those filters?

^ Why are you still using those filters, which are killing you???
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Old 03-10-2017, 12:43 PM   #13
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I remember playing around with aftermarket MAF ends years ago, they came without a screen for improved flow and allowed one to go back to stock without permanently modifying the stock ends. What some of us auto trans guys discovered while using these were some minor changes to shift performance - so the MAF can/does have input/effect in this way. I've also seen some shift flare/line pressure issues cleared up by cleaning very dirty (with K&N oil) MAFs on a couple different 4L60E cars.

As there is no TV cable or direct vacuum input to the [stock] trans, various sensors (directly or indirectly) are relied upon for overall trans behavior and performance. Without a specific MAF code being tripped, it's reasonable to assume that fail safe secondaries would not override any input it may have, therefore things that cause false values (but not failure DTCs) could be even more likely to have undesirable effects.
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Old 03-11-2017, 10:05 AM   #14
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What some of us auto trans guys
When the machines take over, you all will be the first to be taken. I don't trust these "automatic" devices one bit.


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I remember playing around with aftermarket MAF ends years ago, they came without a screen for improved flow and allowed one to go back to stock without permanently modifying the stock ends.
I would expect that any effect on the trans would be a secondary effect of the MAF changing something in the PCM/engine behavior that would then change the formulas for shifting. I can't think of any rational reason to tie shifting to air flow going into the intake. (If this were the case, anyone with air modifications and auto trans would have a hell of a time.)
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Old 03-11-2017, 11:40 AM   #15
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Originally Posted by wssix99 View Post
When the machines take over, you all will be the first to be taken. I don't trust these "automatic" devices one bit.
Save the autos!!

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I can't think of any rational reason to tie shifting to air flow going into the intake. (If this were the case, anyone with air modifications and auto trans would have a hell of a time.)
Modifications that increase airflow wouldn't be the problem, the issue would lie with anything that causes false readings - especially if a code is not triggered to potentially take MAF values out of the equation. Prime suspects would be something like gummed up wires (due to filter oil) or MAF modifications that might affect calibration or reporting.

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I would expect that any effect on the trans would be a secondary effect of the MAF changing something in the PCM/engine behavior that would then change the formulas for shifting.
I think the explanation is this:

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Originally Posted by 1 FMF View Post
and according to my 2002 service manual, which is for a 4L60e not a 65, the scan tool data list for the transmission has nothing specifically stating MAF signal, nor MAP signal, but it does have the value of engine torque which may or may not be calculated from those.
Here are some links which confirm MAF involvement in torque value calculations, and how that directly relates to transmission operation:

https://ls1tech.com/forums/automatic...egatively.html

...and posts #8 & #9 in this one from two of our in-house auto trans experts:

https://ls1tech.com/forums/automatic...l#post18289165
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Old 03-11-2017, 04:09 PM   #16
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Sorry I missed 1 FMF's catch. That's what I meant by secondary effects.


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Save the autos!!
You all have been warned. The transmission apocalypse will initiate with all automatics (in unison) refusing to shift out of first gear...
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Old 03-12-2017, 03:06 AM   #17
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You all have been warned. The transmission apocalypse will initiate with all automatics (in unison) refusing to shift out of first gear...
Even the ones without electronics?! How will they synchronize? Perhaps by sundial.
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Old 03-12-2017, 09:18 AM   #18
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Even the ones without electronics?! How will they synchronize? Perhaps by sundial.
The machines are in league with the Gremlins, who control this type of pre-World War II mechanically automated machinery.
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