MAFless tranny (A4) tuning
02-04-2005, 11:25 AM
#1
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MAFless tranny (A4) tuning A friend called GM tech support and they said the tranny reads the MAF to figure out engine load and if you unplug your MAF the tranny won't shift right anymore. This doesn't make much sense to me, can anyone else shed some light on this for me? I thought load was determined by MAP vs. RPM.
02-04-2005, 11:34 AM
#2
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Good question... i'm not 100% sure on this...
I was always under the impression that the MAF was needed to calculate the proper line pressure... but I've run vacuum modulated for almost 3 years now so never got around to testing
I read some info a while back about some cars not being as affected as others, and another about this being kind of an urban legend ....
I've also heard that even ported MAF ends can mess w/tranny line pressure
I was always under the impression that the MAF was needed to calculate the proper line pressure... but I've run vacuum modulated for almost 3 years now so never got around to testing
I read some info a while back about some cars not being as affected as others, and another about this being kind of an urban legend ....
I've also heard that even ported MAF ends can mess w/tranny line pressure
02-04-2005, 11:49 AM
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Chris stated older pcms did that 00 and down and the newer ones shouldnt have a problem. Search on the tuners website for the post regarding it (the search feature sucks and aggrevates the beejesus outta me if i have to look for stuff over ther)
02-04-2005, 11:58 AM
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Go unplug your MAF and try driving around like that for a little bit(without tuning it out). The transmission line pressure will get set to 100% for any throttle angle. I accidently left my MAF unplugged one day after some intake work and it took a few miles but, the transmission felt like it was going to jump out the truck it was shifting so hard. I think this shows that the transmission line pressure is definately dependent on the MAF in some way.
It would have been nice if GM made it so that the transmission relied on MAP vs. RPM(load) data in the event of a MAF failure but, I don't know if that is in the code somewhere or not. How do the holden A4 cars run MAFless I wonder?
Probably the best thing to do for an A4 Mafless tune is to get a vacuum modulated tranny like whorist.
I was thinking this was in my truck so maybe the cars are not the same, don't know.
It would have been nice if GM made it so that the transmission relied on MAP vs. RPM(load) data in the event of a MAF failure but, I don't know if that is in the code somewhere or not. How do the holden A4 cars run MAFless I wonder?
Probably the best thing to do for an A4 Mafless tune is to get a vacuum modulated tranny like whorist.
I was thinking this was in my truck so maybe the cars are not the same, don't know.
02-04-2005, 12:31 PM
#6
This morning I did some logs of my 2001 Camaro SS with te MAF unplugged. The car shifted exactly the same as always, not firmer, not softer. I think the newer ones are not as affected as Chris has mentioned.
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02-07-2005, 12:13 AM
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My 05 A4 handles it ok , shifts feel normal just the car has so much more power after tuning mafless - big problem was hooking up the IAT as it was in the MAF , once I got that sorted eveything worked fine
02-07-2005, 09:26 AM
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Originally Posted by Drifter
My 05 A4 handles it ok , shifts feel normal just the car has so much more power after tuning mafless - big problem was hooking up the IAT as it was in the MAF , once I got that sorted eveything worked fine
02-07-2005, 05:47 PM
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Originally Posted by Magic Chicken
What did you do to get your IAT back?
Cut the IAT wires out and rewired them to a early IAT sensor in the intake pipe.
Without that mod it sees a fault and has harsh line pressure
02-07-2005, 05:51 PM
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Originally Posted by Drifter
Cut the IAT wires out and rewired them to a early IAT sensor in the intake pipe.
Without that mod it sees a fault and has harsh line pressure
Without that mod it sees a fault and has harsh line pressure
02-07-2005, 05:59 PM
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Originally Posted by Drifter
Cut the IAT wires out and rewired them to a early IAT sensor in the intake pipe.
Without that mod it sees a fault and has harsh line pressure
Without that mod it sees a fault and has harsh line pressure
