Help With Dumping Code's 98 Koer +

88droptop5.0 · Mar 8, 2015

liljoe07 said:
You won't get a code 11 unless all codes are fixed. See if you have 5v between the two terminals on the ECT connector.

Ok, I just checked my volts between the two ECT terminal plug ends with key off its 0 with key on its 4.66v.
I also checked my canister purge silinoid connectio ( not hooked up to anything as it sits when I got it ). Thats .03 with key off, with key on its 10.97v.
I just picked up an ATC sensor, I need to fish out the harness which has no sensor plugged into it. I'll check my volts, can I plug the sensor in and lay it on my manifold for the time being?

liljoe07 · Mar 8, 2015

So everything seems fine wiring wise. Have you cleared the codes any?

88droptop5.0 · Mar 8, 2015

liljoe07 said:
So everything seems fine wiring wise. Have you cleared the codes any?

I am trying to get to my ATC sensor harness to at least plug in a sensor. It looks like there is nothing plugged into it.
How do I clear coads? Do you mean if I plug my code scanner in to see if some coded go away. Or is there a actual prosses for clearing coads?
Thanks..

liljoe07 · Mar 8, 2015

Unplug the battery for about 10 minutes. Should clear the codes. Then run the KOEO codes.

88droptop5.0 · Mar 8, 2015

liljoe07 said:
Unplug the battery for about 10 minutes. Should clear the codes. Then run the KOEO codes.

Ok. I'll unhook my battery and check in about 10/20 min..
I'll report back with what I find, thank you

88droptop5.0 · Mar 8, 2015

Ok I unhooked my battery for a while, hooked up my new ECT sensor. I fished out my empty ACT harness and plugged in a new sensor.
I ran a koeo test and got a 22, 67, 81, 85. In that order...followed by what I think was a 11.
What next...

liljoe07 · Mar 8, 2015

Code 22 is the issue. I may have forgotten. Is this a speed density car or mass air?

jrichker · Mar 8, 2015

MAP/BARO sensor operation and code 22

Revised 14-Nov-2014 to add wire colors for frequency & voltage testing and engine sensor wiring diagrams.

On a Speed Density car, the MAP/BARO sensor is connected to the intake manifold and acts to sense the manifold pressure. Lower vacuum inside the intake manifold when combined with more throttle opening measured by the TPS means more airflow through the engine. As airflow increases, fuel flow through the injectors needs to increase to keep the air/fuel ratio where it needs to be. When manifold vacuum increases, the engine is either decelerating or idling, and it needs to reduce the fuel flow through the injectors.

On a Mass Air car, the MAP/BARO sensor vents to open air and actually senses the barometric pressure due to changes in weather and altitude. Its purpose is to set a baseline for the computer to know the barometric pressure. As barometric pressure decreases, it leans out the fuel flow to compensate for less oxygen in the air. When the barometric pressure rises, it increases to add fuel since there is more oxygen in the air. The fuel requirements decrease as altitude increases, since the atmospheric pressure decreases.

Disconnecting the MAP or BARO sensor will set code 22.

Misconnecting the BARO sensor to vacuum on a Mass Air car will cause the computer to lean out the fuel mixture.

Code 22 or 126 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 a very few DVM’s with a price tag under $40 that will measure frequency, but there are some out there.

Map sensor wiring:
black/white - ground
orange/white or +5 volts power
white/red signal out.

Measure the +5 volt supply using the orange/white and black/white wires
Measure the signal using the black/white and white/red wires.

The MAP/BARO sensor is mounted on the firewall behind the upper manifold on 86-93 Mustangs.

Baro or MAP test using a real 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. And oscilloscope is very useful if you have access to one or know of someone who does. With an oscilloscope, you can see the waveform and amplitude.

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 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.

Diagrams courtesy of Tmoss & Stang&2birds

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs

88droptop5.0 · Mar 8, 2015

Ok, thanks guys. I believe its a speed density car. I'll give it a test.
Is this the part I'm looking for?

liljoe07 · Mar 8, 2015

Yes that is it.

88droptop5.0 · Mar 8, 2015

liljoe07 said:
Yes that is it.

Ok, thanks. I tested as mentioned above at the black/white and red/white (ming is orange/white) and got 5.02v at the harness. I don't have a oscallascop lol.
What's next? Replace the sensor, check vacume line.
Thanks, I wouldn't of gotten this far without your guys help...

liljoe07 · Mar 8, 2015

The odd part is that the code didn't show up in the KOER test. So that tells me that technically the signal wire( green wire) might be ok. I would probably check the resistance of that wire all the way to the computer. With both the sensor and computer unplugged.

If that checks out, then unless you want to spend the money on the correct tools to test it. I would just replace it. Generally, if the power to the sensor is good, and the signal wire is in good condition, there really isn't anything else it could be.

88droptop5.0 · Mar 8, 2015

liljoe07 said:
The odd part is that the code didn't show up in the KOER test. So that tells me that technically the signal wire( green wire) might be ok. I would probably check the resistance of that wire all the way to the computer. With both the sensor and computer unplugged.

If that checks out, then unless you want to spend the money on the correct tools to test it. I would just replace it. Generally, if the power to the sensor is good, and the signal wire is in good condition, there really isn't anything else it could be.

Ok, I'm testing the green wire from the map sensor to the computer plug connection, I'll report back with my findings.

88droptop5.0 · Mar 8, 2015

Also there is a gas smell and seems on the rich side, but I'm not sure if that had anything to do with it. I'm testing the green wire now

88droptop5.0 · Mar 8, 2015

I'm trying to get a reading but I am getting no resistance or really high resistance. Its pin # 45 on the computer harness right? And the green/black wire on my map harness, correct?

liljoe07 · Mar 8, 2015

That is correct. Make sure you are on the correct pin on the computer harness. Does that wire color match the wire on the map sensor?

88droptop5.0 · Mar 8, 2015

Yes it matches green/black stripe. I'm getting the overload Ol simble,no ohm reading at all from #45 and green/black wire with my Fluke . sometimes it would show a really hi reading but I may of been hooked up incorrectly. I'll try again

88droptop5.0 · Mar 8, 2015

I'm just getting the overload 0L symbol. No reading. It seems my green/black wire is at the end of my harness, by the bolt bottom . its green/black just like my map green black wire

88droptop5.0 · Mar 8, 2015

Its the one I have the pin pointing to be n the close-up pic

liljoe07 · Mar 8, 2015

It should be about 5 spots from the side of the eec connector.

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