code 14, 29 & 66 help!

[omy65efi]

Hello,

I recently installed a used 88 5.0 mass air and 5 speed into a 65 mustang. The motor has a BBK 76 mm mass air meter, 30lb injectors, E303 cam, 70 mm (i think, TB), SCT chip, frickin autozone A9L computer, MSD coil and cap with stock dist. I used a RJM harness with the install, new o2s, vss, new fuel system 255 lph pump.

I will start and run the car, it fires up and runs good but usually after it gets good and hot it just shuts off and usually only happens when sitting at a red light. It doesn't miss or stumble just shuts off but always fires right back up.

I took it back to the shop, cleared the codes and let it run for about 20 min. Once it gets warmed up (180 deg), every so often it shuts off or will stumble and not die but this happens intermittently and I get the 14, 29 & 66 code.

I checked the voltage at the mass air and its within range, I could see the pip being erratic once its hot if this was the only code but the vss error I don't get because the car is not even moving and the sensor and harness are new.

I noticed that when the motor is warm the four relays that power the harness get hot from the header heat. I shot them with a temp gun and got as high as 170 deg on the top. Could these codes be tied together through a main power issue due to relays tripping out. I jiggle the wires and sometimes can get the motor to die but not always.

Any help is much appreciated

 

[jrichker]

Code 14 - Ignition pickup (PIP) was erratic – the hall effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts.

The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. They are often heat sensitive, increasing the failure rate as the temperature increases.

The PIP sensor is mounted in the bottom of the distributor under the shutter wheel. In stock Ford distributors, you have to press the gear off the distributor shaft to get access to it to replace it. Most guys just end up replacing the distributor with a reman unit for about $75 exchange

If possible, put a sheet of aluminum over the top of the relays. Leave 1/2" air gap between the relays and the aluminum. This air gap will help keep the relays cooler.

Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.

There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.

The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).

Changes in RPM causes the airflow to increase or decease, changing the voltage output.. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer. Be sure to measure the sensor output by measuring across the pins and not between the pins and ground.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.

There should be a minimum of 10K ohms between either pin C or D on the MAF wiring connector and ground. Make your measurement with the MAF disconnected from the wiring harness.


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info

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

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

Computer,. actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

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

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

The VSS may be defective, if it still is under warranty, swap it out.
Code 29 - Vehicle Speed Sensor (VSS) is an electronic sender mounted on the speedo pickup gear on the trans. It works the cruse control for both 5 speed and auto trans cars. The VSS is used to tell the computer to speed up the idle as you slow to a stop. This helps keep the engine from stalling when you slow down for a stop sign or stop light.
Check to see if the electrical connector is plugged into it. Clean the connector & contacts with non flammable brake parts cleaner prior to replacing the sensor, as that may fix the problem. The sensor cost is under $30 and it is easy to replace.

 

[Mustang5L5]

The VSS code may have to do with why it shuts off. The VSS tells the computer when the car has stopped so it can maintain idle correctly at a stop. With a VSS not hooked up, the car doesn't know and may stall out at a stop. You also get a code 29

1988 only had Mass Air in california. Is that where your harness came from? Did you tie the VSS wiring into the computer? It's done through the BODY harness on the Mustang, and not the engine, so if you've wired the engine in only using the engine harness, you will need to add in the VSS wiring.

Pin 3 and Pin 6 on the EEC are where the VSS ties in. Not sure if it matters which wire to what location. Take a quick look at the computer and if these two spots are empty, then the VSS is not hooked up and needs to be

 

[omy65efi]

I grabbed a 20 dollar junk yard distributor and installed a heat shield for the relays and it chilled out the motor. As for the MAF and the VSS errors they seem to be gone, for now. This motor is a 88 California emission mass air and the harness has provisions for the VSS. I drove about 40 miles and NO CODES!!! This thing is awesome. First gen mustangs should've came from the factory this way, throttle response and overall power is unreal. Thanks for all of the advice. Here is a couple pictures of the car, THANKS AGAIN!

 

[Griswald]

That car is friggin awesome!

 

[jrichker]

The location of your air flilter isn't the best plan. Turbulent hot air from the fan will cause some problems with the airflow through the MAF, and could be the cause of your code 66.

Fox body Mustangs avoid this by drawing air from the fenderwell. The 2005 and later Mustangs have a plastic airbox around around the filter and draw cold air from the fenderwell or the front of the car. You may need to get creative and do something similar.

The 2005 and later S&B kit may give you some ideas

 

[omy65efi]

Thanks for the tip, I will surely make one this summer. She ran great all day today. Once again thanks for all of the help

 

[omy65efi]

Dang code 66 came back

I thought it was odd that all the codes went away just by changing the dist, hey this fuel injection stuff is easy, WRONG.

This car runs awesome until I come to a complete stop and wait about 30 seconds. Today if I sit at a light for longer than 30 seconds the rpms will slowly creep up from about 850 to just under a 1000 and then it immediately shuts off. It doesn't stumble or miss. From the initial moment of rpm increase to engine off is about two seconds. It always fires right back up and runs smooth but if you don't get going down the road it will eventually do it again.

I don't know if this would have anything to do with the problem but when the car was acting up the other day, I started it for the first time of the day(motor cold) it fired and immediately died, I cranked it again and it would start and run. When it was acting right it wouldn't do that, today first crank it started and immediately died. coincidence probably not.

Three weeks ago I cleaned the MAF sensor, checked for 12v between the black and red wire (12 volts), tested resistance between pins C & D (49k ohms), checked resistance between pin D and pin 50 (1 ohm), checked resistance between pin C and pin 9 (1 ohm) and checked voltage between pins C and D and I believe I got around .33v, which seems low but I can't remember exactly what I got.

I will re-check everything tomorrow but I feel confident that all of the wiring and connectors are good. I think that the MAF may heat up and trip out, similar to an ignition module. If I do decide to buy a new MAF sensor is anyone better than any other? I was thinking about buying a C & L with the interchangeable calibration tubes because I may down size to 24lb injectors this winter, what do you guys think?

Once again thanks for all of the help

 

[jrichker]

Fix the air intake for the MAF so that the filter is either in the fenderwell or has a shield or box that shields it from the hot turblent air in the engine compartment.