Quote:
Originally Posted by jrichker
Are you experiencing surging with the IAC disconnected? If so, you have mechanical problems that need to be fixed.
funkytrunk92 said:
What type of mechanical problems would you suspect with this issue.
Once again, from the "Help me create the Surging Idle Checklist"
Vacuum leaks are the #1 suspect in this case. An extreme cam can make the 600 RPM set point difficult to set. Contact your cam supplier or manufacturer to get information on idle speed and quality. Improperly adjusted valves are another possibility. A vacuum gauge will help pinpoint both vacuum leaks and improperly adjusted valves. A sticking valve or one adjusted too tight will cause low vacuum and a 5"-8" sweep every time the bad cylinder comes up on compression stroke.
Vacuum readings can run from 14.5"-18" at 650-725 RPM, at 1000 RPM, look for 18"-21" of vacuum.
Your code 66 may be from disconnecting the MAF while the key was in the run position. I would recommend that you clear the codes by disconnecting the test dump jumper when the codes start to dump. Then run the engine or drive the car and see if the code 66 comes back.
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).
The MAF output varies with RPM which causes the airflow to increase or decease. 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.
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 and ground.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
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.
Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel.
It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?
Code 87 – fuel pump primary circuit failure. The fuel pump lost power while the engine was running. Check fuel pump relay, check inertia switch, wiring to/from inertia switch, red wire going to inertia switch for +12volts. Check the other side of inertia switch for +12 volts.
To help troubleshoot the 87 code, follow this link for a wiring diagram for 89-93 cars
http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp
For 79-88 cars use,
http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp
Code 96 – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump circuit lost power at one time or another.
Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the Mass Air Meter on Fox bodied stangs built after 91. On earlier model cars is under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly. See
http://www.stangnet.com/tech/maf/massairconversion.html
To help troubleshoot the 96 code for 91-93 models see
http://www.autozone.com/images/cds/gif/large/0900823d80195960.gif
Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.
for a description of the test connector.. No voltage when jumpered, check the fuel pump relay and fuse links.
Power feed: Look for 12 volts at the pink/black wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring, or connections. Remember that on 92 or later models the fuel pump relay is located under the Mass Air meter. Watch out for the WOT A/C control relay on these cars, as it is located in the same place and can easily be mistaken for the fuel pump relay.
Relay: Turn on the key and jumper the ECC test connector as previously described. Look for 12 volts at the dark green\yellow wire (relay controlled power for the fuel pump). No voltage there means that the relay has failed, or there is a broken wire in the relay control circuit.
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