Engine Codes "again"

50gt1988 said:

Ok first I know everyone posts these but I'm stumped....
I just installed a completely new engine harnes in my MAF converted 1988. I'm getting the same codes as with the old harness. These codes are with a key on engine off test. The car won't test with the engine on, sputters out and dies with the tester connected.

51
22
53
54
35
67
85

Car runs great, no problems. 92 ECU, with a Ford mass air conversion harness. Thanks for you help.

Click to expand...

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 and 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.

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


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 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.

Use Pin 46 on the computer for ground for both ECT & ACT
to get most accurate readings.

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

Code 54 – ACT sensor out of range. Broken or damaged
wiring, bad ACT sensor. Note that that if the outside air
temp is below 50 degrees F that the test for the ACT can
be in error.

Check the resistance of the black/white wire to battery
ground. If it is less than 1.5 ohm, it is good. If it is more
than 1.5 ohm, the black/white wire has bad connections or
a broken wire. Always take resistance measurements with
the circuit powered off.

Then check the resistance of the ACT sender located in the
#5 intake runner on most 5.0 stangs.

ACT & ECT test data:

The ACT & ECT have the same thermistor, so the table
values are the same

Pin 7 on the computer - ECT signal in. at 176 degrees F it
should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it
should be 3.5 volts. It is a good number if the ACT is
mounted in the inlet airbox. If it is mounted in the lower
intake manifold, the voltage readings will be lower because
of the heat transfer. 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

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

Code 53 Throttle Position sensor too high – TPS. Set the
TPS according to the following tech tip.
Try this... Currently there is some dispute about setting it
at .99 volts being worth the effort, but anything less is
probably OK. All you need is less than 1.0 volt at idle and
more than 4.25 at Wide Open Throttle (WOT). You'll need a
Digital Voltmeter (DVM) to do the job.

The Orange/White wire is the VREF 5 volts from the
computer. You use the Dark Green/Lt green wire (TPS
signal) and the Black/White wire (TPS ground) to set the
TPS

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.

(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.

Clear the codes by disconnecting the scanner while it is
turned on or remove the jumper once the computer starts
to dump the codes. Or disconnect the battery for 10-20
minutes.

Once you have cleared the codes, retest for them. If you
still get a code 53, then check the resistance between the
black/white wire and the negative battery terminal.
Disconnect the battery before making any resistance
measurements. You should see less than1.5 ohms between
the black/white wire and the negative battery terminal.
More that that means wiring problems or bad connections.

Code 67 - clutch not depressed (5 speed) or car not in
neutral or park (auto) or A/C in On position when codes
where dumped. Possible neutral safety switch or wiring
problem. This code may prevent you from running the Key
On Engine On tests. You can generally ignore this code,
since it has no effect on engine performance.

Code 85 - CANP solenoid - The Carbon Canister solenoid is
inoperative. Check vacuum lines for leaks and cracks.
Check electrical wiring for loose connections, damaged
wiring and insulation. Check solenoid valve operation by
grounding the gray/yellow wire to the solenoid and
blowing through it.

The computer provides the ground for the solenoid. The
red wire to the solenoid is always energized any time the
ignition switch is in the run position.

Since you have several codes that involve signals out of
range or too high, I would suspect a defective signal
ground wire. The black/white signal ground wire runs from
pin 46 on the computer to all the sensors listed in the
above code descriptions.

Go back and read the code 35 tech note. It tells you where & how to use an ohmeter to measure the resistance.

The computer wires pin 46 to pins 40 & 60 internally. Sometimes it fries the connection inside the computer. Remove the wiring connector from the computer by loosening the 10 MM bolt until you can pull the connector out of the computer. Use the ohmmeter to measure the resistance between pins 46 and 40 & 60 on the computer. It should be less than 1.5 ohms. If it is a lot more than 1.5 ohms, the copper trace on the computer circuit board has burned up.