Fox 89 Mustang Convertable Lx 5.0 Conversion Appraisal

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The code 1 is a spacer code that signals that the computer is beginning to dump codes.

MAP/BARO sensor operation and code 22

Revised 19-Jul-2011 to add functional descriptions for MAP and BARO operation.

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.Be sure to clear the computer codes by disconnecting the code dump test jumper or pressing the clear button on the scanner once the codes start to dump.

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.

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.



Code 98 - basic computer internal tests not passed before it started processing the request to dump codes. Do a Key On Engine Off test before starting the engine. Wait until you see the 11 flash before pressing any buttons if you have a hand operated scanner. The computer is operating in Limp mode, so fix any codes it dumps prior to doing anything else. In your case, it is set because of the code 22.
 
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And you have the MAP sensor plumbed into the intake manifold correct?
This is the MAP, correct?

If so I would expect that line to go to the intake like you said. However, it connects to the tree and then go's up into the driver's side fender well and disappears from sight in the upper rear corner of the fender.

If the quality of the picture isn't good enough when I upload it I'll upload it to my live.com account for the original size.
DSCF0003.JPG
 
Well, from the factory, the MAP sensor (which is what you are pointed to) connects to the intake manifold. Technically on speed density it's referred to as a MAP sensor (manifold air pressure sensor)

However, connecting it to the tree shouldn't make a difference. When i installed my Cobra intake, there was no provision for it so I direct connected it to the vac tree and it's been fine.

However, the second part confuses me. What line runs up into the fender? The MAP just has 1 port on it and 1 vac line connects it to the source. Beyond that, i'm confused as to what line is running into the fender.

You sure you haven't mixed up the windshield washer fluid line which crosses right in front of it?

I confused my terms

Speed Density = MAP = Manifold pressure
Mass Air = BAP = barometric pressure
 
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The code 1 is a spacer code that signals that the computer is beginning to dump codes.

MAP/BARO sensor operation and code 22

Revised 19-Jul-2011 to add functional descriptions for MAP and BARO operation.

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.Be sure to clear the computer codes by disconnecting the code dump test jumper or pressing the clear button on the scanner once the codes start to dump.

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.

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.



Code 98 - basic computer internal tests not passed before it started processing the request to dump codes. Do a Key On Engine Off test before starting the engine. Wait until you see the 11 flash before pressing any buttons if you have a hand operated scanner. The computer is operating in Limp mode, so fix any codes it dumps prior to doing anything else. In your case, it is set because of the code 22.

Thanks for posting that, I may well need it before this is over! great information there.
Well, from the factory, the MAP sensor (which is what you are pointed to) connects to the intake manifold. Technically on speed density it's referred to as a BAP sensor (barometric air pressure sensor)

However, connecting it to the tree shouldn't make a difference. When i installed my Cobra intake, there was no provision for it so I direct connected it to the vac tree and it's been fine.

However, the second part confuses me. What line runs up into the fender? The BAP just has 1 port on it and 1 vac line connects it to the source. Beyond that, i'm confused as to what line is running into the fender.

You sure you haven't mixed up the windshield washer fluid line which crosses right in front of it?

I'm going out now to double check but I'm 98% sure there is a T fitting right under that larger hose. If that is the case I guess I'll have to take the wheel off and see if I can figure out where that line is going.

Be back in a few...Thanks for the help fellas.
 
The MAP line does go to a T which then go's to to the vacuum tree with the other side going to what appears to be a vacuum canister tucked about as far back and up as you can get in the drivers fender well.

This seems like a plausible explanation here:
http://www.allfordmustangs.com/foru...t-round-canister-under-driverside-fender.html

If that information is relevant it would make that canister part of the cruise control setup. I'm guessing the 4cyl that came with the car had it and the 88 5.0 that was swapped does not.

Two questions to ask I guess are, does that seem right? if so what should I do about it/how could it be affecting the MAP sensor's function. I guess it is still possible the problem is just that the map sensor is bad itself from an electrical standpoint.
 
I think for the sake of elimination, i would change that around to closer to what factory setup would be.

There's a port under the intake manifold on the backside that the MAP connects to. I'd run some vac line there. You'll need ot unbolt the upper intake to get to it though, but I think it's worth ot to have the MAP see direct manifold pressure vs indirect.

For the sake of speed, you can directly connect the MAP to the tree. It should still work, but this isn;'t the proper, factory setup for that vac line

The port marked S/C on the tree is usually reserved for speed control on the 5.0. If you don't have cruise, you can prob eliminate that canister if you want.
 
I just unplugged the S/C hose to the T and plugged the MAP directly into it's spot on the tree. Came back with the same codes, same conditions, and this time it stalled where it usually had a brief stumble at the end of the KOER test.

The physical symptoms are that it stumbles around 1700-2300rpms(roughly) and is fine below or above that.

Going to do the diagnostic tests that jrichker mentioned. If everything comes back clean I'll get to your suggestion 5l5 of removing the intake and inspecting/ plugging the MAP into a port back there.

It is kind of curious if the MAP isn't plugged in back there then what is or isn't plugged into it's spot.

p.s...sorry for the link up there. can't seem to edit it back out
 
I tested the wires to the MAP and got 1.8ohms from the black/white wire to the battery neg terminal and 5 volts from the orange wire.

As I was just about to take the intake off I noticed a 3/8 hose sticking out the back with a bolt in it so I plugged that into the MAP and still have the same issue.

I'm clearing the codes now to see if the MAP code comes back now that it's plugged into the intake manifold. It doesn't seem like there is much left but to test the MAP itself and/or try a new one.

I have a NAPA PRO diagnostic DVM which I believe can test the MAP sensor. Is the following information still applicable for the 40ish degrees we have here in Massachusetts today? I do live very close to sea level.

"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."

I would be testing for 154hz with the DVM I'm guessing set to 320hz? Which wires are used for testing this?

The following is the exact same DVM I own:
http://miami.craigslist.org/brw/eld/4744519520.html
NAPA PRO Diagnostics 700-2603
 
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At this point, i might be considering replacing the MAP sensor. Rockauto.com has 1 motorcraft sensor in stock for $47 (MOTORCRAFT Part # DY532) plus there are discount codes available. I might get ready to just pull the trigger on a new one if troubleshooting comes up empty.


But, befor you buy, this might be helpful (although i'm sure you prob saw it)

http://sbftech.com/index.php/topic,19336.0.html


One last ditch thing i'd do. Plug the TPS in and verify the voltage is between 0.6 - 1.1 volt at idle. You don't need to hit .999999v, that's a huge myth. Anywhere in the specified range is fine. Then, erase all the codes.

Go for a drive a bit, let the car run, and then redo all the codes again. See if oyu still get code 22 (which seems ot be your biggest issue)

Also, did you perform the cylinder balance test and get a 9 (all cylinders OK)
 
At this point, i might be considering replacing the MAP sensor. Rockauto.com has 1 motorcraft sensor in stock for $47 (MOTORCRAFT Part # DY532) plus there are discount codes available. I might get ready to just pull the trigger on a new one if troubleshooting comes up empty.


But, befor you buy, this might be helpful (although i'm sure you prob saw it)

http://sbftech.com/index.php/topic,19336.0.html


One last ditch thing i'd do. Plug the TPS in and verify the voltage is between 0.6 - 1.1 volt at idle. You don't need to hit .999999v, that's a huge myth. Anywhere in the specified range is fine. Then, erase all the codes.

Go for a drive a bit, let the car run, and then redo all the codes again. See if oyu still get code 22 (which seems ot be your biggest issue)

Also, did you perform the cylinder balance test and get a 9 (all cylinders OK)

I think you may be on to something with the MAP sensor being bad. I went out and set the DVM to 324hz and it was reading around -.01 or something like that with no change at all using my lungs to move air through the hose.
I just ran the TPS sensor test again and it's saying 1.8v and 5.2v :/

For the cylinder balance test I kept getting code 98(Repeat test sequence) before it kicked off. Someone mentioned that was most likely because the code 22 is present.
 
Map sensor wiring:
black/white - ground
orange/white +5 volts power
white/red signal out.

Measure the signal using the black/white and white/red wires.

Diagrams courtesy of Tmoss & Stang&2birds

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs -it says Mass Air, but the MAP/Baro sensor wiring is the same for both mass air and speed density.

88-91_5.0_EEC_Wiring_Diagram.gif


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/ Everyone should bookmark this site.

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

T5 Cutaway showing T5 internal parts
http://www.veryuseful.com/mustang/tech/engine/images/5_Speed_Cutaway_Illustrated.jpg

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg
 

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

Measure the signal using the black/white and white/red wires.

Diagrams courtesy of Tmoss & Stang&2birds

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs -it says Mass Air, but the MAP/Baro sensor wiring is the same for both mass air and speed density.

88-91_5.0_EEC_Wiring_Diagram.gif


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/ Everyone should bookmark this site.

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

T5 Cutaway showing T5 internal parts
http://www.veryuseful.com/mustang/tech/engine/images/5_Speed_Cutaway_Illustrated.jpg

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg
Roger, thanks again. I'll try that out tomorrow morning. God it gets dark early now.
 

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At this point I'm suspecting the TPS, MAP, and dimmer to be bad.

I also suspect the voltage regulator may be bad because the volts on the gauge go up wildly with RPM increase.

Is it possible a bad voltage regulator could be causing these other electrical parts to fail? I'm also trying to locate the voltage regulator, I've seen very contradictory information. My best guess so far is the black box screwed to the alternator?
 
Yes, but put a meter on the battery and have someone rev, see if the voltage fluctuates.

Should be around 12V at idle and 14V just above idle and to redline.


There's a small circuit board on backside of the gauge cluster. I "think" that may have to do with your issue. I'd research this a bit more though first.
 
I would make trade mustangs are better then maximas Junk. The mustang looks really clean I like what they did with interior, looks like they put a lot of money into it. But yeah for sure A LX exhaust better look.
 
Yes, but put a meter on the battery and have someone rev, see if the voltage fluctuates.

Should be around 12V at idle and 14V just above idle and to redline.


There's a small circuit board on backside of the gauge cluster. I "think" that may have to do with your issue. I'd research this a bit more though first.

I have a TPS and MAP sensor on the way. I couldn't get the TPS to give me the same reading or even near the same reading twice in a row. The MAP sensor, upon putting back in the car after testing I noticed had a big crack in the top of it with a smaller one running down one edge toward the bottom. The only thing I can think of is it was smashed putting the engine in.

For the cluster illumination I unplugged the dimmer and jumped the brown and blue/red wires. I could immediately see through the bottom of the cluster housing it was lit up back there. I'm not sure if I'm goign to permanently jump them or play the lottery with a used switch. Definitely not spending $100 on a new one.

Assuming all that takes care of the other problems - the only thing I have left is the temprature control knob won't turn all the way to the cold side. It functions fine on the heat side to about 10-15% into the cold side then just stops dead short. I see some things to check from reading online, I just though I'd run that one by you guys in case this is something common to the Fox.

Thanks again for all the help. Attached is a picture of the MAP sensor.

P.S. finding that plug for the heater was a mother...
 

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