91 explorer idle problems..
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91 explorer idle problems..
i have a 91 explorer and its starting to run horrible. it appears to be running really rich and idles bad. it also is starting to drink the gas. the CEL comes on after about 10 mins or so and the only code i get is the o2 sensor is bad. would the o2 sensor cause all the problems?
Postmaster
Joined: Dec 2001
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From: UT
Possibly. Which O2 sensor code? Does the code agree with your assessment that the engine is running rich or is it a false lean code? If the code agrees with your assessment, then the sensor is probably fine. If the code is for a lean mixture, then maybe the sensor is bad.
Logistics Pro
Joined: Jun 2009
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From: Cedar Rapids, IA
I agree that you need to understand the code better. There is basically no such thing as a code that says the O2 sensor is bad. The codes realistically just say there is an issue that is being reported by the O2 sensor.
Do you happen to have a performance air filter in the Explorer? It's somewhat common for oiled air filters to coat the MAF sensor with a film that will cause a rich condition. This is especially common if the filter has been cleaned and re-oiled.
-Rod
Do you happen to have a performance air filter in the Explorer? It's somewhat common for oiled air filters to coat the MAF sensor with a film that will cause a rich condition. This is especially common if the filter has been cleaned and re-oiled.
-Rod
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Joined: Jan 2011
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From: Florida
remove the vacuum line to the fuel pressure regulator while idling (watch out for fuel spray in case it's bad) if fuel comes out of the regulator than replace it, if not, more info. is needed (DTC's)
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91 explorer rough idle
the o2 code was showing it was running too lean.. had the o2 changed, the MAF changed, the IAC changed and its still running bad.im gonna try to fuel pressure regulator and see what that will do. i replaced the fuel pump and sending unit. no i dont have a high preformance air filter.
Logistics Pro
Joined: Jun 2009
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From: Cedar Rapids, IA
Since the code suggests that the vehicle is running too lean, have you carefully checked all vacuum lines and the intake air tubing after the MAF sensor? You will also want to inspect any elbows for the PCV system. I'm not very familiar with the '91 to know if it has the common PCV elbow issues or intake manifold gasket issues like the newer Explorers.
-Rod
-Rod
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91 explorer idle problem
i have checked the pcv and it was ok and the hose from it was ok.. i've tried listening for vacuum leaks and even sprayed alot of the hoses and found nothing. i checked the fuel pressure regulator and had no gas leaking from it. i replaced the tps. i since then ran the codes again and the o2 is still showing lean but its still using too much gas. the catalytic convertor isnt plugged since i checked it and its punched out. it still idles erratically. i also replaced the air filter. what else am i missing. took it to the dealer and they stopped checking after the o2 code came up. this is only the 2nd ford truck/suv i've ever owned so im not that familiar with the engines and components on them..
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Postmaster
Joined: Dec 2001
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From: UT
If you are getting a lean code, but the engine is running rich, then I would still suspect something in the O2 sensor circuit. You say you've replaced the sensor itself, have you checked the rest of the wiring between the O2 sensor and the PCM? A lot of people find wires that fall across the exhaust or get pinched between the transmission and the engine.
Junior User
Joined: Jan 2005
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From: Titusville, FL
Here is some food for thought. My 94 Explorer had a bad case of codes (226,212) for over two years. I was getting poor idling and rich exhaust smell. The engine would cut out at various times, sometimes restart by itself and sometimes required a manual restart. I replaced everything involving ignition. Checked and rechecked all wires and connections. I replaced o2 sensors, fuel pump, fuel pressure regulator and everything to do with engine air/fuel delivery. I was proceeding on the advice that computers don't fail gradually, it must be something else. As a last resort I replaced the 16+ years old computer. The rebuilt computer from Autozone eliminated all symptoms and all my problems. The truck runs like new.
Logistics Pro
Joined: Jun 2009
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From: Cedar Rapids, IA
Do you happen to have a vacuum gauge that you could put on a manifold port and check manifold vacuum? What specific diagnostic code number is the truck throwing? If you don't have the code number the dealer pulled, you can pull it yourself (See the information here, scroll to the bottom).
-Rod
-Rod
