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weird idle,gas smell,and code 41

thor1701

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fresno ca
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96 EB
91 explorer eb edition, it was running allright till a week or so ago, when i would be at a stoplight it would be fine at first, then the idle would go down to 900 rpms and it would shake and act like it was gonna stall, the voltage meeter also goes way down, lights dim and whatnot, it drives fine, just has issues with stoped, i've checked vacume leakes, didnt see any, i also get code 41 sometimes while driving, and there's useualy a gas smell when i get out of the truck, do i need to replace my o2 sensor? any help would be great
 


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Opera House

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O2 sensors do next to nothing, just a little fine tune. If it does a severe death rattle at idle and then starts running right, I would suspect the fuel pressure regulator. Some wear only to one side and then the valve slips open and gets stuck. This happens at idle when vacuum is the highest and the widest.
 




MrShorty

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92 XLT and '87 Bronco II
A little more information would help.

KOER/CM 41 is for an O2 sensor that indicates lean. A gas smell might indicate a rich condition. Can you verify the rich condition in other ways (black, sooty exhaust; overheating cat; fouled plugs)? If you can verify the rich condition where the O2 sensor is indicating lean, that strongly suggests a fault in the O2 sensor or in the wiring between the O2 sensor and the PCM.
 




thor1701

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A little more information would help.

KOER/CM 41 is for an O2 sensor that indicates lean. A gas smell might indicate a rich condition. Can you verify the rich condition in other ways (black, sooty exhaust; overheating cat; fouled plugs)? If you can verify the rich condition where the O2 sensor is indicating lean, that strongly suggests a fault in the O2 sensor or in the wiring between the O2 sensor and the PCM.

i do the test with it key on engine off, tho the gas smell useualy comes from where the tank is, never in the engine, no blaco soot or weird exhaust, just had a smog at the end of november, and it was fine, tho i had just replaced the sparks cuz one of them was fouled
the CEL doesnt come on till after i've been driving alittle bit
when the idle goes to 1000 or 900 and i have the foot on the break, it acts like it surges ever so slightly, the rpms bounce around between like 1000 and 1200
also, when i bought this truck 4 years or so ago, the idle was around 500 or 600 with no weirdness, but now standerd idle is like around 1500
is that normal?
 








MrShorty

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Diagnosing these lean codes is sometimes farily difficult.

By the book, the first test for most O2 sensor codes is to check fuel pressure. I doubt it is an issue here. Other quick first checks are: vacuum/intake leak or exhaust leak.

How long has it been since the O2 sensor was last changed? Some like to treat O2 sensors as a maintenance item, and when they get a lean code like that, start by replacing the O2 sensor if it is old.

I might put a voltmeter on the O2 sensor signal wire and see if it ever does anything. It's been a long time since I've read it, but it seems that the O2 sensor signal is supposed go from rich to lean (or from lean to rich, can't remember which) over the course of the KOER test. If the O2 sensor signal is stuck at 0, I would suspect a bad O2 sensor, or a break in the wiring between the sensor and the PCM.

Somewhere on the net, I once looked up a way to bench test O2 sensors. It's pretty simple: hook up a voltmeter to the signal wire, then heat the sensor end with a torch. The sensor should jump to about 1 V in the high temp/low O2 flame environment.
 




thor1701

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i plan on changing the 02 sensor soon, its only a few years old, 3 i think i cant remember now, i've cleaned out the IAC, cleaned the MAF took the sparks out and cleaned them, only one had any kind of oil deposits on it, i've also used one of thoes fuel injector cleaners on my last tank, also poured some stuff into the oil thats supposed to help with compression and sealing stuff back up, i could not find any vac leaks anyware, still getting the lean code, still smells like gas, still surging at idle every so often, tho its a VERY slight surge, and it does shake alittle at idle when the rpms get down to 1000-900
voltage gaudge likes to go down when it does it too, it doesnt always do it when i stop at a light, sometimes it will be fine, and then it will like make a drop like say im at 1400 rpms and then it will drop suddenly to 1000, like its switching gears, best way i can describe it
i have no way of testing the fuel pressure, i did replace the regulator a few years ago, i just wish i could remember why lol
 




specialized7

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99 SPORT
This is the same issues i was having except i got a misfire code, pulled the plugs and they were bosch +4's believe it or not one of the electrodes was broken off and just wiggling around in the end of the plug.
replaced plugs and no rough idle
 




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