Anyone wanna try to make sense of some engine codes?

PrimerdFury said:

If anyone has any input that would be great. I have been having idle problems and annoying bucking/stalling. First time I have ever pulled engine codes and they were as follows:

Engine Running
41 - HEGO sensor circuit indicates system lean (right side)
91 - HEGO sensor circuit indicates system lean (left side)

KOEO
67 - Nuetral safety circuit failure
95 - Fuel Pump secondary circuit failure EEC to ground (Relay resistance)

Continuous Memory
14 - PIP circuit failure
29 - Insufficient input from vehicle speed sensor
41 - No HEGO switching detected always lean (right)
91 - No HEGO switching detected always lean (left side)
95 - Fuel Pump secondary circuit failure EEC to ground(Relay resistance)

I have no clue what the PIP circuit or HEGO circuit are? Any input regarding any of the codes will help. Thanks.

Click to expand...

ill try to take a retarded stab at it.

41 and 91 are the o2's. the o2's have a wire for the heating thing (im not up to snuff on it). i believe the ground for the heated part is on the back of the lower intake - it is often not bolted down. might check that. but it looks like you have a lean condition. need to do more troubleshooting. it could be your fuel pump on the way out or too low a fuel pressure. but if both O2 sensors are real old, they could be shot, i suppose. IIRC, the range is about 0.1 to 1.0 volt. lower voltage is lean, higher is rich.

67 is probably that you did not have the car in neutral (if stick) or the switch is bad on your aod.

im not sure about the relay resistance. the puter sends ground to the FP relay. i wonder if the relay has gotten old and has built up resistance. ill leave that to the experts.

this is just my ramblings - im not real sure about it. good luck.

PS, has stangnet been really slow to load for anyone in the last 12 hours or so?

Code 14 - Ignition pickup (PIP) was erratic – the hall effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts. You have to press the distributor gear off the shaft to replace the sensor. The pip signal is used for ignition timing and fuel injector timing.

Fix code 14 first.

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.

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. 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 ground is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

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. On auto trans cars, it tells the computer to speed up the idle slightly as you slow down to a stop to keep the engine from stalling. Check to see if the electrical connector is plugged into it. Cost is under $30 and it is easy to replace.

Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto). Possible neutral safety switch or wiring problem. You can generally ignore this code, since it has no effect on engine performance.

To help troubleshoot the 95 code , follow this link for a wiring diagram http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump is the likely culprit since it is getting power. No voltage there, check the Orange/lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

Every 85 startup cycles the codes are erased if they do not re-occur.