Fuel Possible fuel issue.

Mar 21, 2019
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Warren Center, PA
Hello, I have an 87 Mustang 5.0 that has been converted over to Mass Air by the previous owner. I have checked the wiring and it appears to all be done correctly. When it’s cold it runs perfectly, after it’s up to temp for s bit it starts fluctuating in idle and I also start noticing a strange smell from time to time that I’m not sure if it is some sort of exhaust smell or burning too much fuel.

It has a cold air filter on it but it is positioned right by the engine so I’m wondering if it’s pulling hot air if that might be causing a problem? Idk what it has for injectors currently but could I be pumping too much/not enough fuel?

Any advice, tips, thoughts would be greatly appreciated. I am always open to learning something new.

Thank you...
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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This checklist will help you resolve your issues, just read the directions step by step.
Let us know if you get stuck on anything. Post some pics of your stang and include the engine compartment and future plans.
 

c's90GT

Member
Oct 30, 2018
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NEW YORK, NY
I had a similar issue on my 90 gt. I used this checklist and got a few codes. Its actually easier to do than I thought. I kind of cheated and bought the OBD1 scanner for around $20.
 
Mar 21, 2019
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Warren Center, PA
General karthief thank you for that information. I had seen that once a while back but I couldn't remember where and was having trouble finding it. It has a lot more information there than I remembered. I believe it will be quite helpful. I am actually planning on cleaning the car up a little tomorrow so I will try to get a couple pictures and post them after.

c's90GT I decided to do the same and ordered an OBD1 scanner. Hopefully with both that list and the scanner I will be able to get it all worked out and running smooth.
 
Mar 21, 2019
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Hello again. Here are a couple pictures of the car from over the weekend. Our town did our yearly fireman field days and the actual picture of the car was taken during the parade. The engine pictures were taken the day before when I was replacing the heater hoses that both cracked that day while I was driving home from town.

In the picture you can see where the air filter is located, which in the surging check list says do not do that with the mas air conversion. SO I thnk that is the first thing that I am going to change this week. I already had planned to do plugs, wires, cap, rotor and thermostat Wednesday this week so I will add that to the list of things to do. I found a factory airbox for it and also have the kit to make the hood functional for ram air. The kit basically replaces the cover for the air filter and puts the cone style k&n filter inside the box while getting the air directly from the hood vents. (not really trying to explain how the ram air works because im assuming you already know that just trying to say what I have and plan to do). My question here is do you think this will help get me back to getting cooler air rather than the hot air that I would assume its getting being right next to the engine at t he moment?...

Also I thought I would mention, other than the Mass Air conversion, it has had long tube headers put on it and I don't believe it has the Cats on it.

During the parade going at slow speeds for longer than I have ever had it at slow speeds like that, it was deffinatelt overloading on fuel. A coule times when the few of us mustangs that were in the parade would rev it up for the amusements of the interested kids (and some adults lol) It was quite noticeable that I was getting some black smoke out the tailpipe. My cousin who was watching the parade said a couple time it looked like I was driving a diesel. In the article with the check list it mentioned that could also be a bad fuel pressure regulator. so there's something else that I am going to have to look into from the look of it.

First thing I am going to do this week however is run the codes with that new code reader that I have. I didn't realize until I was reading the manual what its a 2 person operation unless you have the extension cord to hook it up and be able to do it yourself from inside the car. I ordered that and plan to have it Tuesday so I think Wednesday will be a busy day diagnosing some problems.

One last thing that I have been thinking about that I am curious if anyone would know. Another thing that the list says is that the speed sensor being bad can cause the surging also. I replaced the speed sensor about 2 months ago because my speedometer wasn't working so I replaced the speed sensor and gear. My speedometer worked for about 2 weeks and quit working again. Well once in a while it will work but only for a few mins and quits again. The old gear when I took it out was stripped on the inside where is goes on the shaft of the speed sensor. I am assuming that this gear that I installed is doing the same thing with the new speed sensoe making me think that the cable has an issue. Either way what I'm wondering is even if I have a good speed sensor but the gear is no good, would that cause the same effect?

Thanks again for any help and time...
 
Mar 21, 2019
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Warren Center, PA
Hello, I just ran the codes in my 87 Mustang Converible 5.0. The following are what I came up with and I am hoping someone knows what they mean and can help me understand them,

Key On Engine Off:

67 Neutral Pressure Switch (NPS) Circuit failure. Circuit open.

Manual Lever Position (MLP) Sensor Out Of Range; or A/C input High

19 Failure in EEC (PCM) Internal Voltage

Power Processor Check

82 Air Diverter Solenoid Fault, intake air control circuit fault.

Integrated relay control module.


Then I got a Continuous Memory Code:

15 Power Interruption to Computer Memory or EEC (PCM) Keep Alive Memory (KAM) test failed.


It sounds to me like they are all related, and that maybe I have a bad PCM? or maybe bad wiring to the PCM. I started out with all this trying to figure out what's causing the surging idle, where I was pointed in the direction of the surging idle checklist, so my first attempt to try was to run the codes and this is what I have so far. It has had the Mass Air Flow conversion done, and I traced the wires to the best of my knowledge and it appears to be wired correctly but if I am wrong and its not wired properly could that be causing these codes? I know that my air cleaner needs to be redone because from the checklist it says don't have the cold air filter right in the engine bay and the previous owner had put it there so that's something I need to do but I wouldn't think that would cause these codes would it?

Here is the link to the post that I started initially in case I forgot to mention something here:


Any help and advice what to do with these codes would be greatly appreciated.

Thank you,
 

Blown88GT

Founding Member
Nov 13, 1999
1,357
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Palm Beach Gardens, FL
Since you have an 87 Mustang 5.0 that has been converted over to Mass Air by the previous owner, let's focus on the conversion to verify the proper parts were used. Many times the conversion looks right but some mistakes are made. You have to make modifications to the existing MAP sensor.
These are the instructions for the original Ford conversion kit.
attachment.jpg



Manual or auto?
What is the ECU part number? A9L for manual xmission?
What is the MAF sensor & housing? The housing/sensor pic looks like the factory 55mm.
What size fuel injectors? Can't quite see them clearly but appear to be the factory stock 19 lb.
 

Blown88GT

Founding Member
Nov 13, 1999
1,357
205
104
Palm Beach Gardens, FL
The VSS (speed sensor) is independent of the speedometer. On the GT, it was used for the cruise control. On mass cars, it is also used to keep the engine from stalling when rolling to a stop. '87's & '88's were SD (speed density), except for California where '88's were mass air.
 

John Dirks Jr

5 Year Member
Jun 28, 2013
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Maryland
Ditch that filter, its junk. Put a factory air box on with a KN filter element in it. That might even help you solve your problems. Those factory MASS sensors were not designed to have a cone filter on the end of them. It can mess up the way the incoming air is measured
 
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Reactions: General karthief
Mar 21, 2019
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To I took the air filter off to have a look at the MAF. It looked a bit dirty in there so I used some MAF cleaner and now it looks nice and clean. I will get the air box and new filter setup tomorrow if possible but for today I put the old filter back on and it seemed to actually like it had better throttle response then it did before however still had some fluctuation. Not nearly as bad as before though. I will get that filter changed tomorrow as long as it’s not raining.
 
Mar 21, 2019
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Thank you for that information. From just what little I saw of the instructions i not believe anything was done with the MAP sensor. If I’m understanding that properly is what it’s saying is to remove the tube, cap the tube but leave the port on the sensor with nothing attached? If that’s the case then I believe the tube is still attached as it was originally.

I will get the numbers off everything tomorrow and post them. It is a manual transmission however I am not sure how to tell what injectors I have.

Thank you again for the help.
 
Mar 21, 2019
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Ok, just updating what my progress was today. I put the airbox in with a K&N filter inside the box. After looking at the instructions for the MAF convertion I noticed that the hose from the MAP sensor had not been taken off and plugged so I did that. I cleaned the Mass Air sensor a couple days ago. Started it up and took it for a ride. Very noticible increase in power and throttle response however still has a bit of fluctuation when idling. Still theres is a bit of improvemtn so far.

Got home and pulled the codes again. This time with Key On Engine Off I got Less codes. Only 19. and then the Continuous Memory Code of 15.

Started it up, and pulled the codes with the engine running. These are the codes I got:

42 & 92 - HEGO (HO2S) sensor voltage high / system rich

33 - EGR valve not opening properly

Sounds to me like I ma need O2 Sensors and GR Valve possibly? Let me know what you think of those codes.

The pictures I posted were because I decided to take a closer look and get some more info to try to answer some of the questions that were asked of me. I desided to get under and make sure the o2 sensors were installed on the long tube headers and they are hoever I realized that there are not cats installed. I tried to get a picture of the injectors to try to figure out what I have and I am assuming they are the original 19# injectors. I got the picture of the Mass Air numbers, but I don't know what they mean and haven't been having much luck finding much about it other than where to buy it. And finally I got a picture of the computer which I believe is the right one for my situation.

I am curious about the Cats though. I was thinking that I might get a pair of hi flow cats for it and when looking them up I see that they come with a spot to install the o2 sensors in them. If I install the hi flow cats, should the o2 sensors be in them rather than in the long tube headers?

Thank you again for all the help and advise, I fell like im finally getting some progress thanks to you guys.

Also one more thing just out of curiosity... I notice when the surging is going on that the battery gauge jumps up and down... is that normal
during the surging or is that a sign of another problem?
 

jrichker

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Code 19 - Engine off - No Vehicle Power (pins 37 + 57) or bad PCM VPWR Diagnosis. This is a wiring problem that is from a bad ECC power relay, bad connection, bad fuse link, bad ignition switch or a bad computer. The ECC relay is located on top of the computer under the passenger side kick panel. Pull the connector off any fuel injector and measure the voltage on the red wire: if its 12 volts or better, the ECC relay is OK. If the ECC relay is OK, pull the kick panel off and measure the voltage at pins 37 & 57. If it is 12 volts or more, then the computer's diagnostic firmware has taken a dump and is defective.

Engine running - Erratic idle during test (reset throttle & retest) - Idle Set Procedures .
See http://www.stangnet.com/mustang-forums/698148-help-me-create-surging-idle-checklist.html#post6855020 for the best way to set the mechanical base idle and cleaning procedure for the IAC/IAB.

For best results the O2 sensors need to be as close as possible to where the exhaust ports merge into the collector. They depend on being hot to work properly, so the further downstream they are from the exhaust valve, the less efficient and accurate they are.

Code 42 & 92 & 137 & 173 (engine running) System rich - Fuel control or (memory) System was rich for 15 seconds or more (no HO2S switching) - Fuel control. Look for leaking injectors, fuel pressure too high, cylinder(s) not firing due to bad ignition.

Code 42 passenger side sensor, as viewed from the driver's seat
Code 92 is the driver side sensor, as viewed from the driver's seat..

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Testing the O2 sensors 87-93 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear.


Backside view of the computer wiring connector:
a9x-series-computer-connector-wire-side-view-gif.gif


87-90 5.0 Mustangs:
Computer pin 43 Dark blue/Lt green – LH O2 sensor
Computer pin 29 Dark Green/Pink – RH O2 sensor
The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.

91-93 5.0 Mustangs:
Computer pin 43 Red/Black – LH O2 sensor
Computer pin 29 Gray/Lt blue – RH O2 sensor
The computer pins are 29 (LH O2 with a Gray/Lt blue wire) and 43 (RH O2 with a Red/Black wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


Testing the O2 sensors 94-95 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a red/black wire) and 27 (RH O2 with a gray/lt blue wire). Use pin 32 (gray/red wire) to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.



There is a fuse link for the O2 sensor heater power. According to Ranchero50, it is in the wiring near the passenger side hood hinge. Measuring the voltages will give a clue if it has shorted to the O2 sensor signal lead. The O2 sensor voltage should switch between .2-.9 volt at idle.
 
Mar 21, 2019
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Thank you for that information. I just printed everything that has been given to me so far for help and information to figure all of this out. Hopefully I will be able to get out in the garage either tonight or tomorrow and test all of this. I am glad that I posted here for help and information because i would have just been buying parts and hoping they worked. All of you that have replied to me have been a great help so far and I greatly appreciate it. I am learning a lot in the process as well... thank you.
 
Mar 21, 2019
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Warren Center, PA
Code 19 - Engine off - No Vehicle Power (pins 37 + 57) or bad PCM VPWR Diagnosis. This is a wiring problem that is from a bad ECC power relay, bad connection, bad fuse link, bad ignition switch or a bad computer. The ECC relay is located on top of the computer under the passenger side kick panel. Pull the connector off any fuel injector and measure the voltage on the red wire: if its 12 volts or better, the ECC relay is OK. If the ECC relay is OK, pull the kick panel off and measure the voltage at pins 37 & 57. If it is 12 volts or more, then the computer's diagnostic firmware has taken a dump and is defective.
thank you again jrichker, I was just working on this part of things. I checked the voltage at the injectors and I got 12.4v. From what you have here I assume that the ECC relay is good. I looked up the wiring color codes for the PCM to try to help me find the right wires and I came up with a question that may sound dumb but im hoping that you can help me understand what I'm looking at.
629671

it appears to me that the pins 37 & 57 are the same as the red wire I tested at the injector which would make me think that the voltage would be the same, however if I am looking for a lower voltage at 37 & 57, what makes the voltage higher at the injector? I have not checked the voltage at the pins yet but thought I would ask this before I do so I can understand better what it is that im looking at when I do.

Thank you again for your help.
 

jrichker

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Dublin GA
In perfect world, the red wire should have the same voltage in all parts of the circuit. There may be some small differences due to the resistance of the wiring and connections.

Voltage drop testing of connections and grounds.

Use a Digital Volt Meter (DVM) to measure the voltage drop across a connection or wire. Adding length to the test leads may be required, and does not affect the accuracy of the test. Use 16-18 gauge wire for the test leads if you have to lengthen them.

Voltage drop increases with the increase of current in a circuit and it also increases with heat. Put a maximum current load on a bad wire or connection and it gets hot and drops more voltage across the wire or connection. As it heats up, resistance increases which makes more heat. Round and round you go in a vicious circle until something catches fire or fails.

Voltage drop testing must be done while the usual load is on the circuit. If it is a starter, it has to be tested while cranking the starter. If it is lights, A/C or fan, they must be turned on high while testing. Fail to do this and you will not get accurate results

1.) Most grounds use the negative battery post as their starting point. Keep this in mind when checking grounds.
2.) The voltage will be small if the ground is good: less voltage drop = better connection.
3.) Be sure that the power to the circuit is on, and the circuit is being used in its normal manner. For instance, if it is a light circuit, the lights on that circuit should be powered on.
4.) To measure grounds, place one DVM lead on the battery negative post and the other on the wire or connector that goes to ground.
5.) 5.) Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch
100 mV Ground
0 mV to <50 mV Sensor Connections (sensors are low voltage devices and small drops can have a large effect on the devices dependent on sensor accuracy)
0.0V Connections
A voltage drop lower that spec is always acceptable.
6.)
See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .


 

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