live data help
Senior Member
Joined: Jul 2015
Posts: 3,627
Likes: 795
From: Michigan
This might help you.
http://www.underhoodservice.com/pull...y-does-matter/
The difference between P1151 and P1152 is rich and lean.
I can tell you what it meant years ago after drinking too much!
http://www.underhoodservice.com/pull...y-does-matter/
The difference between P1151 and P1152 is rich and lean.
I can tell you what it meant years ago after drinking too much!
Last edited by River1; Oct 22, 2019 at 06:50 PM.
Senior Member
Joined: Jul 2015
Posts: 3,627
Likes: 795
From: Michigan
Have you tried resetting the PCM?
Last edited by River1; Oct 23, 2019 at 12:22 AM.
Senior Member
Joined: Dec 2015
Posts: 23,191
Likes: 8,622
From: Utah
It may read fine right now, but when they are dirty they switch very slow or almost not at all. This appears to be at idle where air flow is at a minimum... and I am guessing that AK has seen the same thing. Reads fine at idle, and goes outta whack when AF increases.
Senior Member
Joined: Jul 2015
Posts: 3,627
Likes: 795
From: Michigan
White,
I'm not sure I remember this correctly but isn't there something about a certain number of hard accelerations needed to reset the memory for fuel trim and O2 sensor data?
Found this and what it's about:
Let's start with Ford vehicles, for a couple of reasons. First, they are so widespread that most of us are familiar with them. Second, most MAF sensor-equipped Ford products make use of a PID (Parameter IDentification) called BARO (barometric pressure). Up to 2001 models, this was an inferred, or calculated, value generated by the PCM (powertrain control module) in response to the maximum MAF flow rates observed on hard wide-open throttle (WOT) acceleration. Where this calculated BARO PID is available, it is of great diagnostic value, since it can confirm MAF sensor accuracy, if only under high flow rate conditions.
. . . .
To use the BARO PID, you must first know your approximate local barometric pressure. You might consult the BARO PID on a known-good MAP sensor-equipped vehicle. Alternatively, your local airport can provide this data. Do not rely on local weather stations, however, since these usually report a “corrected†barometric pressure. If weather information is the only available source, a rule of thumb is to subtract about 1 in. of mercury (1 in./Hg) for every 1000 ft. of elevation above sea level. This will yield a rough estimate of your actual local barometric pressure. For greater accuracy, you can purchase a functional barometer for something less than $40. Compare this data with the BARO PID. A large discrepancy here—say, more than 2 in./Hg—should direct your suspicions toward the MAF.
Confirm your hypothesis as follows: First, make sure you have followed the steps outlined in the two rules above. Next, record all freeze frame data and all DTCs, including pending DTCs. If the OBD monitor readiness status for oxygen sensors shows READY, proceed to the next step. If it doesn't, refer to the procedures in the following paragraph now. Next, perform a KAM (Keep Alive Memory) reset and drive the vehicle. Make sure your test drive includes at least three sustained WOT accelerations. (It's not necessary to speed to accomplish a sustained WOT acceleration. Rather than a WOT snap from idle, an uphill downshift at 20 to 30 mph is usually sufficient. The WOT prescription can be met at throttle openings as low as 50% to 70%.) The BARO PID should update from its default reading by the end of the third WOT acceleration. If it's now close to your local barometric pressure, the MAF sensor is not likely to be faulty. If BARO is not close, try one of the cleaning techniques explained in the sidebar "Keeping It Clean" on page 34, then again reset KAM and take a test drive. If the BARO is still out of range, a replacement MAF sensor is in your customer's future. Unfortunately, in many 2002 and later Fords, the calculated BARO PID is supplanted by a direct BARO reading taken from a sensor incorporated into the ESM (EGR System Management) valve, greatly lessening its diagnostic value for our current purposes.
I'm not sure I remember this correctly but isn't there something about a certain number of hard accelerations needed to reset the memory for fuel trim and O2 sensor data?
Found this and what it's about:
Let's start with Ford vehicles, for a couple of reasons. First, they are so widespread that most of us are familiar with them. Second, most MAF sensor-equipped Ford products make use of a PID (Parameter IDentification) called BARO (barometric pressure). Up to 2001 models, this was an inferred, or calculated, value generated by the PCM (powertrain control module) in response to the maximum MAF flow rates observed on hard wide-open throttle (WOT) acceleration. Where this calculated BARO PID is available, it is of great diagnostic value, since it can confirm MAF sensor accuracy, if only under high flow rate conditions.
. . . .
To use the BARO PID, you must first know your approximate local barometric pressure. You might consult the BARO PID on a known-good MAP sensor-equipped vehicle. Alternatively, your local airport can provide this data. Do not rely on local weather stations, however, since these usually report a “corrected†barometric pressure. If weather information is the only available source, a rule of thumb is to subtract about 1 in. of mercury (1 in./Hg) for every 1000 ft. of elevation above sea level. This will yield a rough estimate of your actual local barometric pressure. For greater accuracy, you can purchase a functional barometer for something less than $40. Compare this data with the BARO PID. A large discrepancy here—say, more than 2 in./Hg—should direct your suspicions toward the MAF.
Confirm your hypothesis as follows: First, make sure you have followed the steps outlined in the two rules above. Next, record all freeze frame data and all DTCs, including pending DTCs. If the OBD monitor readiness status for oxygen sensors shows READY, proceed to the next step. If it doesn't, refer to the procedures in the following paragraph now. Next, perform a KAM (Keep Alive Memory) reset and drive the vehicle. Make sure your test drive includes at least three sustained WOT accelerations. (It's not necessary to speed to accomplish a sustained WOT acceleration. Rather than a WOT snap from idle, an uphill downshift at 20 to 30 mph is usually sufficient. The WOT prescription can be met at throttle openings as low as 50% to 70%.) The BARO PID should update from its default reading by the end of the third WOT acceleration. If it's now close to your local barometric pressure, the MAF sensor is not likely to be faulty. If BARO is not close, try one of the cleaning techniques explained in the sidebar "Keeping It Clean" on page 34, then again reset KAM and take a test drive. If the BARO is still out of range, a replacement MAF sensor is in your customer's future. Unfortunately, in many 2002 and later Fords, the calculated BARO PID is supplanted by a direct BARO reading taken from a sensor incorporated into the ESM (EGR System Management) valve, greatly lessening its diagnostic value for our current purposes.
Last edited by River1; Oct 23, 2019 at 12:56 AM.