Code 22 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty
much the same sensor for both Mass Air & Speed Density cars. The main difference is
where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars
connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the
air/fuel mixture by sensing changes in barometric pressure. The MAP or BAP sensor puts out
a 5 volt square wave that changes frequency with variations in atmospheric pressure. The
base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees.
You need an oscilloscope or frequency meter to measure it. There is no way you can use a
common cheap voltmeter or DVM to accurately measure the output signal.
The MAP/BARO sensor is mounted on the firewall behind the upper manifold.
Baro or MAP test using frequency meter - run the test key on engine off. The noise from
the ignition system will likely upset the frequency meter. I used a 10 x oscilloscope probe
connected from the frequency meter to the MAP/BAP to reduce the jitter in the meter's
readout.
If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer
Some basic checks you can make to be sure that the sensor is getting power & ground:
Note that all resistance tests must be done with power off. Measuring resistance with a
circuit powered on will give false readings and possibly damage the meter.
Check the resistance between the black/white wire on the MAP/BARO sensor and then the
black/white wire on the EGR and the same wire on the TPS. It should be less than 1.5 ohm.
Next check the resistance between the black/white wire and the negative battery cable.
It should be less than 1.5 ohm.
The following power on check requires you to turn the ignition switch to the Run position.
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts
at the orange/white wire on the TPS or EGR sensors. Use the black/white wire for the
ground for the DVM.
Code 53 - Throttle Position sensor too high – TPS – TPS out of adjustment, bad
connections, missing signal ground, bad sensor.
Here’s a TPS tip I got from NoGo50…
When you installed the sensor make sure you place it on the peg right and then tighten it
down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the
front screw enough so you can move it just a little in very small increments. I wouldn’t try
to adjust it using marks. Set it at .97v-.99v, the closer to .99v the better. Just don’t go
over .99, or you upset the fuel calibration and idle quality will suffer.
(copied from MustangMax, Glendale AZ)
1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a
bit if you can and get it nice and warm.
2. When you probe the leads of the TPS, do not use an engine ground, put the ground
probe into the lead of the TPS. You should be connecting both meter probes to the TPS
and not one to the TPS and the other to ground.
3. Always reset the computer whenever you adjust the TPS or clean/change any sensors.
I just pull the battery lead for 10 minutes.
4. Check the procedure for your year, on my 90 I have to turn the idle screw until it just
touches the tab, then insert a .010 feeler gauge and give it about one more turn. Then you
adjust the TPS voltage to .98v, reset the computer. Start it up, if the idle is to low then
turn the screw in until it is just right, then readjust the TPS voltage to .98v and reset the
computer and start it up. The key is to adjust the TPS voltage and reset the computer
whenever the idle screw is changed.
Check the black/white wire resistance. Connect one ohmmeter lead to the black/white wire
on the TPS and one lead to the negative post on the battery. You should see less than 1.5
ohm, more than that indicates a problem.
Always take resistance measurements with
the circuit powered off.
Clean the 10 pin salt & pepper shaker connectors.
.
See
http://fordfuelinjection.com/index.php?p=85 for more help
Code 35 EVR - EVP sensor signal is/was high – Bad sensor, or possible missing ground for
EVR circuit. With the power off, measure the resistance between the black/white wire and
battery ground. You should see less than 1 ohm. Check the same black /white wire on the
TPS and MAP sensor. More than 1.5 ohm there and the wire is probably broken in the
harness between the engine and the computer. The 10 pin connectors pass the
black/white wire back to the computer, and can cause problems.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host)
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
See
http://fordfuelinjection.com/index.php?p=6 for more wiring help & 10 pin connector diagrams
Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
Possible bad ECT sensor, or wiring. Possible missing signal ground –
black/wire wire broken or bad connection. With the power off, measure the
resistance between the black/white wire and battery ground. You should see
less than 1 ohm. Check the same black /white wire on the TPS and MAP
sensor. More than 1 ohm there and the wire is probably broken in the harness
between the engine and the computer. The 10 pin connectors pass the
black/white wire back to the computer, and can cause problems.
Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts
Voltages may be measured across the ECT by probing the connector from the rear.
Use care in doing it so that you don't damage the wiring or connector.
Here's the table :
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
Note that all resistance tests must be done with power off. Measuring resistance
with a circuit powered on will give false readings and possibly damage the meter.
Ohms measures at the computer with the computer disconnected, or at the sensor with
the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
With all these codes, they all have the same thing in common: missing signal ground on the
black/white wire, pin 46 on the computer.