Attached is a partial data log from my new Preditor U7170. Does anybody have a graph of MAP signal for comparison?

The image attached is at 2500 RPM, 15 psi manifold gage and a pretty wild range of "MAP Signal Freq", from 0 to 250 A/D counts.

I'm not sure what the MAP signal is supposed to behave like but this looks unusual. With a fairly constant intake manafold boost pressure I would think the MAP would also be fairly constant.

Details: 2001 manual trans, stock truck with DP U7170 tuner only.

Ford Truck Enthusiasts Forums - mgmadness's Album: MAP Graph - Picture

 

Does anyone have a data log they can share of MAP signal and RPM from a 7.3?

 

Instead of trying to read the frequency, can you monitor voltage? 15 psi should be in the neighborhood of 1.5 volts on the MAP sensor.

 

As Chris said.

The frequency of the signal is irrelevant, so is rpm.

You need to compare the manifold pressure to the voltage the sensor is sending back to the pcm.

Are you having trouble with your map sensor? or did the signal frequency just conscern you?

 

I just checked the list of PIDs I can record with the Diablo Preditor U7170 and MAP voltage is not available.

I have been looking to figure out where my calculated 20 MPG went and thought this scanner might give me a clue. So far I'm still stuck at 18.5 mpg.

Below are some PIDs I have recorded.

Intake Air Temperature F
Injection Control Pressure Duty Cycle % duty cycle on time
Manifold Absolute Pressure - High Res psi
Manifold Gage Pressure - High Res psi
Barometric Pressure - High Res psi
Injection Control Pressure MPaA (Absolute)
Air Charge Temperature - Degrees F
Accelerator Pedal Position % full open
MAP Signal Frequency - MAP_FREQ A/D counts
EGO2 Adaptive Fuel Correction %
Engine Speed rpm
Absolute Value of Slip rpm
Vehicle Speed mph
Fuel Injector Pulse Width s
Mass Fuel Desired in3

 

When did you notice the loss? Has it gradually gotten worse or just suddenly appear? How many miles on the injectors? Checked for boost leaks? Been getting fuel at a different spot or did your fuel station change suppliers? Are your lower calculations from winter fuel vs. 20 mpg for summer fuel?

2,500 rpm's aren't helping your mileage either.

 

Well, I guess I can get MAP voltage. I start the long story of reduced MPG tomorrow and the stuff I've looked at to find the problem.

Intake Manifold Absolute Pressure and Manifold Absolute Pressure - High Res

Volts psi

1.704 15.88
2.007 17.62
3.354 28.57
1.592 15.16

 

Those voltage numbers are spot on vs the pressure for the MAP sensor. I'll wait for you to elaborate on what you have already gone over before I say anything else.

 

It's funny you are logging frequency since the PCM on the 99-up trucks doesn't use frequency for a MAP reading.

The 97 and prior trucks used MAP sensors that had a frequency-based output. The newer trucks just use voltage.

 

I'm looking for a list of items to inspect or service to return to 20 MPG (calculated).

I purchased a stock 2001 F250, 5 sp w/ 210K miles on the clock, August 2009. August through October 2009, I was able to get 20 MPG (calculated) driving mostly highway. The MPG dropped to as low as 14 on winter blend fuel, 2009-2010. Now that it is warmed up, April 2010, I have 225K miles on the clock and my MPG has returned to 17.3. The best summer 2010 mileage was 18.5 mpg. Over the winter 2010-11 the mpg again returned to ~16 mpg.
I purchased a Diablo Preditor U7170 in early March 2011 and calculated 17.5 mpg at 85 hp tune on winter blend fuel. Now that the mid-west is about to return to summer fuel I am trying to achieve 20 MPG. With the U7170 I have limited PCM scanner capability and maybe I can find where did my 2.5 MPGs went.

Current status / Items checked
Same oil brand Rotella T6 syn 5-40, same tires, the brakes are free and not hanging up, air filter and fuel filter replaced 20K ago. Recent repairs include EPBS tube clean-out and intercooler boots. When I get after it hard and stand on the brake, I can get about 17 psi boost at 3K rpm using a gauge "T"ed into MAP hose. Truck runs great but seems a little underpowered at lower rpm (<2000). I checked the up pipes and they are soot free. When I did the EBP sensor tube cleanout I verified the gate linkage is free. I checked the turbo inlet (intake side) for shaft play and it is fine.
The EOT checked out fine with an Ohm meter.
I dropped the tank and and modified the fuel pickup and trimmed the air/overfill.

 

Boost is pretty low if that's with an 85hp setting! My truck makes 20 psi stock, something to look at.

 

What about the fuel supplier? Have you tried switching to a different station to see if that helps? When did they switch over to ULSD? Was it before or after your 20 mpg? Did they start blending in a percent of biodiesel? What about the 6 boots on the intercooler plumbing? Any of them loose? I change my fuel filter every 15k miles, so you might want to at least inspect yours. I'd also program the truck back to stock since that's how you got the 20 mpg's last time. Need to rule out all the possibilities.

 

I buy most of my fuel at one truck stop but have jumped around a little over the last 18 months. All the fuel has been ULSD.

When I ran the 85hp tune I got much better boost pressure. I usually chug down the highway at ~2050RPM.

Manifold Absolute Pressure - 30.42 psi
High Res Air Charge Temperature - 38 F
Engine Speed RPM 2439.5
Intake Manifold Absolute Pressure Volts 3.628

 

In my opinion, if you want to see 20 mpg's, keep it below 2,000 rpm's, including while accelerating. See what happens if you chug down the highway at 1900 rpm.

 

I can build 30 psi of boost in my 80 hp setting. Your actuator arm might be. Little loose. Do ou hv the red line on the actuator disconnected.