ok ive just about got my car tuned to the best of my ability. It runs great when im not runnin into things(the 2 times ive driven it in the rain). But anyway my surging problem is just about gone. I replaced the tps, and instead of jumping from .6 to 1.02 volts like the old one did it just sits right at .96 volts with the car running. When the car is warm an i start it up, it surges for about 2-4 seconds then its fine. I've put two new IAC valves on, along with the ford idle air adjuster, and cleaned the hell outta my intake and throttle body when i had it off to polish them. I havent been able to drive it so i cant see if it still does it at like a stop light/sign an die like it did before. My next guess would be the 02's cause i ran the codes an got one for 02 signal but it didnt say which bank it was for(stupid haynes manual). would the 02's cause this slight surging???? I didnt think they were suppose to work right as soon as you start up the car, but thats the only time (right now) that it surges....... Any help would be appreciated!!!
does unhooking 02's send the computer into limp mode???
- Thread starter noslow5_0
- Start date
Yes, disconnecting the O2 sensors will put the computerinto limp mode.
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 Ouote.
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 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 Ouote.
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
makarov
New Member
Yes, they can. In closed loop, (below 2500rpm), the computer constantly checks the maf voltage and 02's voltage to maintain as near a perfect air/fuel mixture that it can. In open loop, above 2500rpm, it doesn't check air/fuel at all (or very little), but consults pre-programmed "look up tables" to determine fuel and spark settings.
If you are surging at startup or below 2500rpm, the 02(s) could be the problem as the computer is probably being confused. If the battery has been disconnected, the computer will revert to the newest sensor readings, and the old ones stored in the computer's "keep alive memory" are forgotten. The "keep alive memory" was designed to compansate for hosed 02's and other sensors, and will normally get you home or to a shop for repair, thus the "check engine light" and codes. But when the battery is disconnected, it picks up on what's happening right now and has no old "good" readings in storage. Hope that helps you out.
If you are surging at startup or below 2500rpm, the 02(s) could be the problem as the computer is probably being confused. If the battery has been disconnected, the computer will revert to the newest sensor readings, and the old ones stored in the computer's "keep alive memory" are forgotten. The "keep alive memory" was designed to compansate for hosed 02's and other sensors, and will normally get you home or to a shop for repair, thus the "check engine light" and codes. But when the battery is disconnected, it picks up on what's happening right now and has no old "good" readings in storage. Hope that helps you out.
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