2003 Yukon Denali MAF delete
12-21-2018, 12:39 PM
#1
2003 Yukon Denali MAF delete I’m getting a p0101 code and my Tranmission shifts horribly when the maf is connected. If I unplug it I get a p0102 code and the transmission shifts great.
the engine runs great with or without the maf connected. I know I’ll need to re-connect the IAT sensor if I run without a maf because the truck thinks it’s -38f all the time when it’s unplugged (iat sensor is in the Maf).
so with the MAF unplugged I’m getting full line pressure in the transmission, the tune is using the factory SD calculations....
i replaced the maf with a known good one and it made no difference. I suspect there’s some issue with the circuit so I’d like to just cut the wires for the maf leaving the iat sensor wires and entire maf unit where it is.
id like to know if there’s any downside to doing this on a daily driver used for long road trips?
Don’t plan on tuning it, hoping the stock SD tune would be ok. I removed the cats but other then that it’s totally stock.
if you think SD doesn’t work for all seasons or if you think solid shifts are bad for automatic transmissions please don’t reply
the engine runs great with or without the maf connected. I know I’ll need to re-connect the IAT sensor if I run without a maf because the truck thinks it’s -38f all the time when it’s unplugged (iat sensor is in the Maf).
so with the MAF unplugged I’m getting full line pressure in the transmission, the tune is using the factory SD calculations....
i replaced the maf with a known good one and it made no difference. I suspect there’s some issue with the circuit so I’d like to just cut the wires for the maf leaving the iat sensor wires and entire maf unit where it is.
id like to know if there’s any downside to doing this on a daily driver used for long road trips?
Don’t plan on tuning it, hoping the stock SD tune would be ok. I removed the cats but other then that it’s totally stock.
if you think SD doesn’t work for all seasons or if you think solid shifts are bad for automatic transmissions please don’t reply
12-21-2018, 12:45 PM
#2
I had a response, then I read the last sentence and I see where this is going.
Cut the MAF out dude. Who needs a stupid *** MAF. Especially when the factory computer uses SD and never used the MAF.
I'm with you, why fix something you can rig up. AMIRIGHT?
Cut the MAF out dude. Who needs a stupid *** MAF. Especially when the factory computer uses SD and never used the MAF.
I'm with you, why fix something you can rig up. AMIRIGHT?
12-21-2018, 12:58 PM
#4
The second maf I tried was from a parts truck that ran fine when I pulled it...next step is either a brand new maf, maybe a new ECM because the wires all tested fine (got good power and ground to maf) I couldn’t test the Hz on the signal wire (not an option on my stupid scanner)
12-21-2018, 01:04 PM
#6
12-21-2018, 01:06 PM
#7
Does your scanner have data capability? Assuming not by you saying you couldn't check the hz. I'm curious what the g/s is reading.
My first guess would be a faulty MAF connector, most likely you have a broken wire there at the connector. You can pull on the wires near the connector and if one starts stretching the wiring itself is broken inside the sheathing.
Maybe throw a new pigtail on it before you just run it unplugged and see what happens.
Figuring out the issue shouldn't be too complex, running it unplugged isn't something I would be interested in doing long term.
My first guess would be a faulty MAF connector, most likely you have a broken wire there at the connector. You can pull on the wires near the connector and if one starts stretching the wiring itself is broken inside the sheathing.
Maybe throw a new pigtail on it before you just run it unplugged and see what happens.
Figuring out the issue shouldn't be too complex, running it unplugged isn't something I would be interested in doing long term.
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12-21-2018, 01:17 PM
#9
Check the pink wire for battery voltage, use a volt meter and a test light to load the circuit. Check it at the metal terminal in the connector so you're checking the entire connection, if you tap the wire before the connector you won't be checking the wire all the way to the end and the metal pin. Connect a test light and touch it to the pin and touch your volt meter lead to the test light stem so that you see the voltage the test light is getting. If you use a volt meter only and have high resistance it may still show voltage but if the connection is really weak it can pass voltage but not amperage so if you connect the light and volt meter you load the circuit a little bit which makes sure it's doesn't have high resistance, because if you can load the circuit and still get good voltage then it should be good enough for carrying the slight amperage the maf will use.
Do the same with the black wire looking for ground
If all that is good the yellow wire is signal return. I would ohm across the pin to say a foot or so down the wiring.
When doing all these checks bend and twist the connector to see if it blanks out at any time which will show a break in the wiring.
I say all of this because I've seen a few of the connectors have a broken wire right near the connector itself.
Do the same with the black wire looking for ground
If all that is good the yellow wire is signal return. I would ohm across the pin to say a foot or so down the wiring.
When doing all these checks bend and twist the connector to see if it blanks out at any time which will show a break in the wiring.
I say all of this because I've seen a few of the connectors have a broken wire right near the connector itself.
12-21-2018, 01:32 PM
#11
i was also thinking to change the plug since I got one sitting here from a parts truck but I literally used a magnifying glass to inspect the existing one and it looks mint...the only wire I can’t say 100% is good is the actual signal wire since I can’t test it but I know it’s connected because the maf readings did change when it was plugged in.
im in MN - they had inspections years ago but they learned for every 3 million they spent on inspections they only reduced emissions by like .000000000000000000002% so they shut down the inspection stations and we’ve never had any sort of road side inspections except for 18wheelers
12-21-2018, 01:46 PM
#12
Both mafs I have are pretty dirty but the spare I had “should be” good since it worked fine in the Suburban parts truck I had
i was really shocked by how badly the tranny was shifting, it acted as if it was totally used up, slipping
every shift as if the computer thought I was shifting at 1500rpm when it was actually shifting over 4 grand
Unplugged the maf and it shifts fine again, i’m Not 100% sure that issue will go away with the maf plugged in (even if I can fully resolve whatever the issue with the maf is)
12-21-2018, 01:51 PM
#13
See what the g/s are with it plugged in and start attacking that. The trans seems to be a by product of what's going on with the MAF so forego fiddling with that until after the MAF is straightened out.
Magnifying glasses don't read ohms, and that's what you need is to ohm out all wiring from one end to the other.
If they are both dirty they are both not reading correctly.
Plug the maf in DIRTY and record the g/s
Then spray it with brake clean or MAF cleaner, use a q tip very gently if need be on the wires to get them clean.
Then read the g/s again and see where it is.
Let us know.
Magnifying glasses don't read ohms, and that's what you need is to ohm out all wiring from one end to the other.
If they are both dirty they are both not reading correctly.
Plug the maf in DIRTY and record the g/s
Then spray it with brake clean or MAF cleaner, use a q tip very gently if need be on the wires to get them clean.
Then read the g/s again and see where it is.
Let us know.
12-22-2018, 11:03 AM
#14
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I’m getting a p0101 code and my Tranmission shifts horribly when the maf is connected. If I unplug it I get a p0102 code and the transmission shifts great.
the engine runs great with or without the maf connected. I know I’ll need to re-connect the IAT sensor if I run without a maf because the truck thinks it’s -38f all the time when it’s unplugged (iat sensor is in the Maf).
so with the MAF unplugged I’m getting full line pressure in the transmission, the tune is using the factory SD calculations....
i replaced the maf with a known good one and it made no difference. I suspect there’s some issue with the circuit so I’d like to just cut the wires for the maf leaving the iat sensor wires and entire maf unit where it is.
id like to know if there’s any downside to doing this on a daily driver used for long road trips?
Don’t plan on tuning it, hoping the stock SD tune would be ok. I removed the cats but other then that it’s totally stock.
if you think SD doesn’t work for all seasons or if you think solid shifts are bad for automatic transmissions please don’t reply
the engine runs great with or without the maf connected. I know I’ll need to re-connect the IAT sensor if I run without a maf because the truck thinks it’s -38f all the time when it’s unplugged (iat sensor is in the Maf).
so with the MAF unplugged I’m getting full line pressure in the transmission, the tune is using the factory SD calculations....
i replaced the maf with a known good one and it made no difference. I suspect there’s some issue with the circuit so I’d like to just cut the wires for the maf leaving the iat sensor wires and entire maf unit where it is.
id like to know if there’s any downside to doing this on a daily driver used for long road trips?
Don’t plan on tuning it, hoping the stock SD tune would be ok. I removed the cats but other then that it’s totally stock.
if you think SD doesn’t work for all seasons or if you think solid shifts are bad for automatic transmissions please don’t reply
it will use the low octane spark table only, the trans will use max line pressure and it will use the factory VE table for fueling which isn’t all that close.
to delete the MAF you need to apply the SD OS. Otherwise you’ll have to either put up with or tune around the default operational functions
12-22-2018, 09:20 PM
#15
without applying the custom OS and full time failing the MAF in the PCM the car will be in default SD factory mode.
it will use the low octane spark table only, the trans will use max line pressure and it will use the factory VE table for fueling which isn’t all that close.
to delete the MAF you need to apply the SD OS. Otherwise you’ll have to either put up with or tune around the default operational functions
low octane spark table is fine since it’ll get low octane fuel only.
when you say custom OS your talking about a custom SD tune right?
OS is operating system in my line of work
12-22-2018, 09:59 PM
#17
i do know that might lead to an over rich Air fuel ratio but that’s easy enough to reconnect by connecting the iat sensor
i just dont don’t want to cut the wires for the MAF and regret it later but right now that seems like a logical step...I want full line pressure in the transmission so it seems like a win win
side note: I actually bought the truck to learn HP tuners for a turbo LS engine swap I started so I planned to use SD and tune it but it’s 2 credits for the engine and I think another 4 for the tranny...extra $300 dollars in credits is making me want to just spend it on the swap and learn as I go with that
12-23-2018, 07:04 PM
#18
Did you try cleaning the MAF and reinstalling it? Have you ohmed from the pin in the connector to a few inches down the wire?
Full line pressure isn't necessarily horrible, it'll keep things from slipping. May cause excess beating on things but I don't hate it myself either.
Full line pressure isn't necessarily horrible, it'll keep things from slipping. May cause excess beating on things but I don't hate it myself either.
12-24-2018, 09:07 AM
#19
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not this specific year/vehicle it goes until CL as soon as it warms up even when the MAF is unplugged....that seems strange because the iat sensor was also unplugged but I guess it just uses a default (-38)
i do know that might lead to an over rich Air fuel ratio but that’s easy enough to reconnect by connecting the iat sensor
i just dont don’t want to cut the wires for the MAF and regret it later but right now that seems like a logical step...I want full line pressure in the transmission so it seems like a win win
side note: I actually bought the truck to learn HP tuners for a turbo LS engine swap I started so I planned to use SD and tune it but it’s 2 credits for the engine and I think another 4 for the tranny...extra $300 dollars in credits is making me want to just spend it on the swap and learn as I go with that
cut them where you can re-join them later or get an independent IAT sensor and connect the correct 2 wires.
you don't want max line pressure all the time. you want the trans to use the TCM data to operate it not in default mode.
you want the engine using the high octane table with a correct calibration for your fuel type so that if is picks up detonation it can revert to the low octane table which should be a lower value to protect the engine.... as intended from the factory calibration.
if you want to tune SD and run SD only apply the custom OS... its what its for. stop trying to trick it or cheat, it will never be correct.
12-28-2018, 04:55 PM
#20
you need the IAT input for the airflow algorithm used for fueling, it needs it period. -38 is open circuit and the engine thinks its intake air is -38 degrees. SD needs the IAT input even more so! connect it and stop tuning until you do. youre wasting your time, all data collected and used to edit is void and useless.
cut them where you can re-join them later or get an independent IAT sensor and connect the correct 2 wires.
you don't want max line pressure all the time. you want the trans to use the TCM data to operate it not in default mode.
you want the engine using the high octane table with a correct calibration for your fuel type so that if is picks up detonation it can revert to the low octane table which should be a lower value to protect the engine.... as intended from the factory calibration.
if you want to tune SD and run SD only apply the custom OS... its what its for. stop trying to trick it or cheat, it will never be correct.
cut them where you can re-join them later or get an independent IAT sensor and connect the correct 2 wires.
you don't want max line pressure all the time. you want the trans to use the TCM data to operate it not in default mode.
you want the engine using the high octane table with a correct calibration for your fuel type so that if is picks up detonation it can revert to the low octane table which should be a lower value to protect the engine.... as intended from the factory calibration.
if you want to tune SD and run SD only apply the custom OS... its what its for. stop trying to trick it or cheat, it will never be correct.
Seems like the MAF is useless on this specific truck unless your worried about emissions (and I am NOT)