MAF-BARO readings
03-25-2013, 10:02 PM
#1
Member
Thread Starter
MAF-BARO readings
So...lets try this again. Maybe someone will have an idea what is happening. 04 FX4 5.4 3v. HP is way down after new phasers, plugs, FPDM, IMRC and welded in new pre-cats. Timing was checked twice at dealership. Fuel PSI holds 40.
WOT MAF readings only getting about 18lbs/min or 135g/s at 4700 rpm. Should be about 25lbs/min or 200g/s.
Vacuum at idle is 20. Tried Mapp gas and carb cleaner all over the intake and can't find a vacuum leak.
One weird thing though...besides the crappy HP is when we hooked up a Snap-On scanner the IAT read inverse..instead of 28 it read -28 degrees.
That is probably just a polarity issue with the scanner. It reads correct with a little cheap scanner.
The kicker is the Barometric reading. It's only reading 145 hz. Should be 156 to 157 for local altitude. I know there is no separate Baro sensor. I took the MAF out and cleaned it twice now and also sprayed the connectors. No change at all. Unplugging the MAF makes it run like junk.
Trims are a little positive but not bad and otherwise nothing is blatant. Did get a P0171-174 code a week ago when I was really pushing it. Also noticed VCTADVERR on bank 2 was about .3 degrees. Is that acceptable?
So maybe someone can give me a little insight on why the Baro reading is so far skewed. 145 would be normal for 4000 feet. We're about 1200 feet above sea level. I hate to spend $150 on a new MAF. Already have $6k in it.
The dealership gave up on me...I REALLY would appreciate some help.
Thanks! Jeff
WOT MAF readings only getting about 18lbs/min or 135g/s at 4700 rpm. Should be about 25lbs/min or 200g/s.
Vacuum at idle is 20. Tried Mapp gas and carb cleaner all over the intake and can't find a vacuum leak.
One weird thing though...besides the crappy HP is when we hooked up a Snap-On scanner the IAT read inverse..instead of 28 it read -28 degrees.
That is probably just a polarity issue with the scanner. It reads correct with a little cheap scanner.
The kicker is the Barometric reading. It's only reading 145 hz. Should be 156 to 157 for local altitude. I know there is no separate Baro sensor. I took the MAF out and cleaned it twice now and also sprayed the connectors. No change at all. Unplugging the MAF makes it run like junk.
Trims are a little positive but not bad and otherwise nothing is blatant. Did get a P0171-174 code a week ago when I was really pushing it. Also noticed VCTADVERR on bank 2 was about .3 degrees. Is that acceptable?
So maybe someone can give me a little insight on why the Baro reading is so far skewed. 145 would be normal for 4000 feet. We're about 1200 feet above sea level. I hate to spend $150 on a new MAF. Already have $6k in it.
The dealership gave up on me...I REALLY would appreciate some help.
Thanks! Jeff
03-26-2013, 06:13 AM
#2
Mark
iTrader: (1)
do you have a stock air intake...
03-26-2013, 09:45 PM
#3
Member
Thread Starter
Stock everything except the welded in cats. Both the dealership and the muffler shop said backpressure is fine. The bank 2 VCTADVERR was actually negative 0.3. Actual position was +.3 but command was zero. Bank one is 0s on command-position and error.
I've been trying to find out what is acceptable...no luck. Soon as it warms up a little we're going to pull the valve covers off and check the phasers for binding. Thanks!
I've been trying to find out what is acceptable...no luck. Soon as it warms up a little we're going to pull the valve covers off and check the phasers for binding. Thanks!