Ran codes, how do I fix this?

281pony · Jul 27, 2009

first off, i have a nasty surging idle/dying when the clutch is disengaged issue. as of today, it developed a bad "miss/cutting out" when i stabbed the throttle/wot, any rpm range over 2k. it even died once today, and wouldnt start for 30 seconds. i looked under the hood, and nothing was out of place. so i got back in and it fired right up.

with that said, here is the codes;

10, 33, 41, 85, 87, 91.

10- cant find it listed, what does that mean?
33- egr valve related, egr stuff is gone. is that anything to mend?
41- HEGO sensor signal out of range/always lean?
85- adaptive fuel limit reached- lean?
87- fuel pump primary circuit fault
91- same definition as 41.

so, obviously ive got some fuel issues. which leads me to my next questions. what do i start with/replace? pump, o2 sensor, fuel filter? i have 2 vacuum lines in question, pics below;

View attachment 250253
this vacuum line and plug. both going to nothing. this is the passenger side corner by firewall. where should these be going?

View attachment 250254
plastic vacuum line (suction) coming from upper intake, going to afpr, is this correct?

also in that pic, its real hard to see, my pcv is plugged off. there is a plastic fitting with a rubber cap on it. nothing leading out of it, does this need to be changed?

lots of stuff to take in.. please help me out. hood just flew up today also and im really frustrated

281pony · Jul 27, 2009

mods also;

trickflow intake, unknown aluminum heads (supposed to be t/f), 24# injectors, maf for 24# from summit, 70mm tb, 1.6 rr, stock cam, equal lengths, o/r h, flowmasters, manual trans, 89 original mass air car, bbk cai fendermount.

o2 sensors were supposed to be new. fuel pump size is unknown. stock rails, it has an afpr but no clue where the pressure is.

jrichker · Jul 27, 2009

The PCV needs to be functional. The PCV valve is less than $3 at the auto parts store.

You may need a PCV grommet (rubber thingy the PVC fits in), less than $9

There is no valid code 10. That is a phantom code from your reader.

The following code definitons are for key on, engine not running.

Code 33 - Insufficient EGR flow detected.
Look for vacuum leaks, cracked vacuum lines, failed EGR vacuum regulator. Check to see if you have 10” of vacuum at the EGR vacuum connection coming from the intake manifold. Look for electrical signal at the vacuum regulator solenoid valves located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal flickers. Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.
Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1.5 ohm.

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

EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.

connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

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 EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 2-5 in vacuum?
if not the EVR has failed

EGR test jig

The operation of the EGR vacuum regulator can be checked by using a test light applied across the wiring connector. Jumper the computer into self test mode and turn the key on but do not start the engine. You will hear all the actuators (including the EVR vacuum regulator) cycle. Watch for the light to flicker: that means the computer has signaled the EGR vacuum regulator successfully.

Code 41 or 91 Three digit code 172 or 176 - O2 sensor indicates system lean. Look for a vacuum leak or failing O2 sensor.

Revised 22-Jun-2009 to include 3 digit code and wiring for 94-95 5.0 Mustangs

Code 41 is a RH side sensor,
Code 91 is the LH side sensor.

Code 172 is the RH side sensor
Code 176 is the LH side 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

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. 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.

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.

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.

Testing the O2 sensor wiring harness
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.

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

Make sure you have the proper 3 wire O2 sensors. Only the 4 cylinder cars used a 4 wire sensor, which is not compatible with the V8 wiring harness.

Replace the O2 sensors in pairs if replacement is indicated. If one is weak or bad, the other one probably isn't far behind.

If you get only code 41 and have changed the sensor, look for vacuum leaks. This is especially true if you are having idle problems. The small plastic tubing is very brittle after many years of the heating it receives. Replace the tubing and check the PVC and the hoses connected to it.
A secondary problem with only a code 41 is for cars with an intact smog pump and cats. If the tube on the back of the heads clogs up the driver’s side, all the air from the smog pump gets dumped into one side. This excess air upsets the O2 sensor calibration and can set a false code 41. The cure is to remove the crossover tube and thoroughly clean the insides so that there is no carbon blocking the free flow of air to both heads.

Code 85 - CANP solenoid - The Carbon Canister solenoid is inoperative or missing. 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?

Purge valve solenoid:

Carbon Canister:

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.

Diagram of the fuel pump wiring for 86-90 cars

Diagram of the fuel pump wiring for 91-93 cars.

Some basic theory to clarify how things work is in order…

EGR System theory and testing

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold
route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.

Troubleshooting:
There should be no vacuum at the EGR valve when at idle. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)

The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt.

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid.

EGR test procedure courtesy of cjones

EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.

connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

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 EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 2-5 in vacuum?
if not the EVR has failed

EGR test jig

To test the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker.

Late Model Restoration has the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See * * * N/A * * * 86-93 SENSOR KIT, 5.0L EFI, INCLUDES EGR VALVE & SENSOR, COOLANT TEMP SENSOR, & AIR CHARGE TEMP SENSOR MUSTANG for
more details

Diagrams courtesy of Tmoss & Stang&2birds

281pony · Jul 27, 2009

thats alot to take in, ill go start looking for a vacuum leak now.

ill start by making a pcv setup.

281pony · Jul 27, 2009

i do have a pcv valve and rubber gromet, both valves on the pcv however, are capped. here is a pic of my capped pcv, and 2 capped lines on the firewall. do i run one/both lines to these 2 caps on the firewall off my pcv?

the vacuum chart i looked at, says pcv to manifold vacuum. no specific lines. man i got rusty with these cars quickly. well 3 years worth.

View attachment 250251

i also found 2 straps/grounds hanging behind the heads. one had an orange wire lead, the other is just the metal braided strap. i grounded both of them to the firewall since my cowl is broken from the hood flying up, made it much easier

281pony · Jul 27, 2009

so i grounded the braided strap, the orange ground wire, both to the same bolt on the firewall. i felt around some lines, looked for cracks, ect.

put my pcv back in, and ran a single line to the tb. i didnt have enough hose for the intake. the car idles a tiny bit smoother, doesnt surge as badly. then i ran the codes...

ignition on, car off.

the FIRST time before above changes, i got these codes, in this order; 85, 10, 33, 41, 87, 91, then repeat 85.

with the changes above; 85, 10, 96 then it stopped for over 60 seconds.

code 96 is fuel pump secondary circuit fault/high speed fuel pump relay open.

where does that put me now? just like that, it cut out all my o2 sensor/lean issues?

281pony · Jul 28, 2009

ok so i took it out tonight for a drive after the new codes were gone.

first crank.. fired, sat at 1k rpm for 2 seconds, flat died. same with the second start, third start i gave it some gas and it idled reasonably smooth. idled for 20 seconds while i backed out driveway.

drove for probably 20 minutes, push in clutch as im almost home to take a turn, it just flat dies. fired it up, and it would drop to roughly 600 rpm, then level back out at 800ish.

so it only died once. i do have another driveability issue. i get a surging/bucking feeling at real light throttle application. rpm does not matter. i did some downshifts and let the engine pull the car down from roughly 3k rpm's, im getting a hollow popping.

i took it around the corner sideways through third though and it felt great. doesn't seem to be lean as the codes did indicate, and it was cutting out earlier. im confused.. no more codes, shouldn't vacuum leaks throw some kind of code if they are this severe?

HISSIN50 · Jul 28, 2009

As JR noted, vac leaks can manifest as a lean O2 code (41/91).

I'd try to get the air-fuel issues straightened out (along with probable vac leaks) because the leaks can cause the idle to wander all over the place. That could be responsible for half of your issues right now.

Ran codes, how do I fix this?

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