I ask only b/c I am trying to learn about tuning in general, but SD really interests me. Thanks! 
SD redundancy question
Thread Starter
TECH Addict
Joined: Feb 2004
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Originally Posted by HumpinSS
Maybe it defaults to some tables that fuel based on TP% that would be the only other backup it would have.
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
Interesting... if the MAP stopped working I wonder what it'd output ? Constant 0? or Constant 100 ? (prolly 0v so 0kpa) ? if this is the case, it'd prolly not add enough fuel to keep the car running at any RPM high enough to keep the car idling...
I can't imagine GM built in 2 fail safes... SD was supposed to be the failsafe in case of MAF failure... seems like it'd be a bit much for them to build in a failsafe for simultaneous MAF and MAP failure...
I can't imagine GM built in 2 fail safes... SD was supposed to be the failsafe in case of MAF failure... seems like it'd be a bit much for them to build in a failsafe for simultaneous MAF and MAP failure...
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Originally Posted by Black02SS
Not me. I'll pass on this one Humpin. 
LMFAO. Hey I never said go WOT down the street. you could test this out at idle or a few revs in the driveway
11 Second Club
iTrader: (20)
Joined: Sep 2002
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From: Albuquerque NM - The Land of 8000ft DA
My brother has a 97 V6 Firebird and his MAP was not getting enough voltage for some odd reason.
The car ran like TOTAL crap. I got some logs with HPT as I was trying to diagnose why his car was running so bad. The MAP read a constant 10Kpa iirc. His MAF was working just fine.
To try and diagnose the problem I used the 5V source from the A/C pressure sensor and the car ran better but still having issues.
fwiw
p.s. I am not to sure how the 97 V6 cars are setup but his passenger injector bank isn't fueling correctly. I think its an electrical issure but I am not to sure. They should run more or less the same right, being OBDII, having a right and left bank? He has some serious knock issues and I think one back isn't running correctly. Any ideas? I have logs..
The car ran like TOTAL crap. I got some logs with HPT as I was trying to diagnose why his car was running so bad. The MAP read a constant 10Kpa iirc. His MAF was working just fine.
To try and diagnose the problem I used the 5V source from the A/C pressure sensor and the car ran better but still having issues.
fwiw
p.s. I am not to sure how the 97 V6 cars are setup but his passenger injector bank isn't fueling correctly. I think its an electrical issure but I am not to sure. They should run more or less the same right, being OBDII, having a right and left bank? He has some serious knock issues and I think one back isn't running correctly. Any ideas? I have logs..
FormerVendor
Joined: Jan 2003
Posts: 525
Likes: 0
From: Melbourne, Australia
if MAF fails then PCM calculates a TPS-RPM based cylair estimate that it then uses to estimate the MAP value if then the MAP sensor fails.
If the MAF is still working and just the MAP fails it uses the MAF cylair to estimate MAP (not the TPS-RPM estimate).
The tables that it uses to calculate this stuff aren't in our editor.
Chris...
If the MAF is still working and just the MAP fails it uses the MAF cylair to estimate MAP (not the TPS-RPM estimate).
The tables that it uses to calculate this stuff aren't in our editor.
Chris...
Thread Starter
TECH Addict
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GM does a bunch of stupid stuff most of the time, but man...they really put some redundancy in there. I was figuring they would do that. It only made sense. I would imagine we would need to tune those tables for it to be any good to us on cammed cars.
