deftsound said:
well, it runs really really rich, i mean it makes my eyes burn, but the codes i pull (91 and 41 i think) say its running lean....?? which is wierd, i also pulled code 21 and 34, so i replaced the egr valve and egr position sensor, i also replaced the ect sensor, no luck, runs the same as it did before....and im still getting those same codes which is even more wierd. ...
With an eye to all the problems you are having, I would suspect some wiring problems. Here are the test paths for the codes you posted.
Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error.
The ACT & ECT have the same thermistor, so the table values are the same
ACT & ECT test data:
Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.
Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts
Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.
Voltages may be measured across the ECT/ACT by probing the connector from the rear. Use care in doing it so that you don't damage the wiring or connector.
Here's the table :
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
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.
Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
If the ECT is out of range, it can send a false cold engine reading to the computer, causing a rich condition.
Code 34 EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).
If the blow by test passes, and you have replaced the sensor, then you have electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1 ohm.
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.
This will affect idle quality by diluting the intake air charge
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.
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
"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 .4 volt. 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 .6 volt. 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."
Charles O. Probst, Ford fuel Injection & Electronic Engine control
The O2 sensors have a ground wire that come out of the harness near the throttle body. Make sure that it is connected. If it isn't grounded to the manifold or head, it will affect O2 sensor performance.
Since you pulled the manifold, it is possible that the 10 pin salt & pepper shaker electrical connectors may have some dirty or bad connections. Open up the connectors & look for dirty or damaged pins. Use electrical contact cleaner or non-flammable brake parts cleaner (same stuff as the contact cleaner in a bigger can, & cheaper too) to clean the contacts.
