Can't get this car going! Help, please!

[albireo]

I hope someone can help. I am a member here and am enjoying my new GT. I have a friend that has an 86' 5.0 that I've adored

through the years and was one of the big reasons I have my new one now. Last year he started having problems with his car and has

tried everything. He's never posted to a forum before so I offered to do it for him, telling him you guys are GREAT and can figure out anything! :



Please help if you can. Post suggestions and I'll them right to him.



Here is the text file he sent me about his problem.

Thanks everyone!



Joe



"1986 Ford Mustang GT 5.0 (5-speed manual transmission)
•original owner
•believed to be 1990 motor (though a motor serial number check failed to establish this) (original motor replaced after 200,000

miles)
•began reving high on start-up then would level out after warming up
•several months later began reving low/stalling at traffic lights/low RPM
[low idle-stalls on decel or quick stop]
•currently can't exceed 15mph/runs very rough (about 6-7 months ago)
•hard start-ups when cold, then runs better, then runs worse as Mustang computer cycles through it's phases
-
•EGR replaced
•EVP replaced
•Idle Air Control inspected and cleaned:10/23/04
•Throttle Position Sensor adjusted: 10/23/04 (tracing vacuum leak)
•clean idle bypass valve-
thoroughly clean the idle bypass valve with carb/choke cleaner (10/23/04)
•(recent: 10/11/04) tune-up did not resolve
*cap/rotor replacement: 10/14/04
*replace spark plug wires: 10/14/04
*time motor-ok: 10/23/04
*air filter replaced (9/26/04)
•diagnostic tester identified the following error codes (10-23-04): 4, 12 , 41, 91, 32, 13 (10-2-04?)
---other notes---
•vehicle had passed most recent smog test
•computer chip for automatic transmission "

 

[Strype]

Check the control module at autozone, and you might want to replace that distributor

 

[FORCED2DV8]

Is it getting enough fuel?? Does it have consistant good spark, or is iti irratic?? Check the spark at coil and spark plug, Need more info, check wiring connection for the dist.

 

[jrichker]

Code 12 -Idle Air Bypass motor not controlling idle properly (generally idle too low) - IAB dirty or not working. Take it off and clean it thoroughly with throttle body cleaner. Clean the electrical contacts with non flammable brake parts cleaner at the same time.

Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.

The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel. Many times the end result is an engine that runs pig rich and stinks of unburned fuel.

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

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 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.

Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer.

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. Do not attempt to measure the resistance of the O2 sensors, it may damage them.

The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

Code 32 - Code 32 – EGR voltage below closed limit

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied.

As vacuum is applied, the voltage on the slider increases (EVP). As the voltage increases, the computer knows the how much the EGR valve is opened and how much exhaust gas is being recirculated. It uses the load table to calculate the amount of exhaust gas required depending on RPM, Mass Air Flow, ACT, ECT & TPS. It then sends a signal to the Electronic Vacuum Regulator to hold, increase or decrease the vacuum being applied to the EGR valve.

Theory class is over now, let’s spin up our propeller head beanies and get with it… Go Gadget, Go…

Measure the resistance of the EGR sensor between the two end pins. You should see between 3500 to 5500 Ohms. With the sensor removed, measure the resistance again while pressing on the plunger. You should see the resistance drop from its high value to a low reading of 200-700 ohms depending on the sensor. No resistance readings, or values way out of range, the sensor is bad.
If the Orange white wire has Vref, (5 volts =/-.25 volt) then you have some wiring problems because the computer isn’t seeing the minimum voltage on the EVR pin. Ohm the wiring back to the computer. Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1 ohm. Repeat the process for the orange/white wire and pin 26. Do it again between the black/white wire and pin 46. In no case should you have more than 1 ohm. Remember that resistance checks are always done with the power off the circuit.


Voltage and resistance checks are good: Here’s an EGR test procedure I copied from cjones

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5 in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 RPM’s (remember snap the throttle don't hold it there).
did the vacuum gauge show about 5 in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM’s.
should read about 5 in vacuum
End of cjones's test.

If the test procedure fails to provide proper vacuum, check vacuum feed lines for cracks & damage. If the vacuum lines are good, check the electrical wiring to the EVR. If the EVR electrical wiring is good, look for 12 volts on the red wire for the EVR. If the 12 volts is good, look for a varying voltage on the dark green wire on the EVR. Case of last resort, replace the EVR and then the computer

 

[albireo]

Thanks for the quick and detailed replies!
My friend is really at a loss, and he's taken it to at least 5 different people/places - they just tell him it's "baffling."

I KNEW you guys would have some ideas, I wish I'd have thought of doing this a long time ago!!

Again, super job!

Joe

 

[bock]

Does it smell fuel at the exhaust?

maybe the 0² sensors...