Hey guys, I've posted this before but I'm still getting a 41 code in both KOEO and KOER. I have replaced the O2 sensor and reset the codes. I can't understand why I'd still be getting that. Please help as I'm getting pretty bad mileage and worried about doing damage.

Thanks

Mike

 

Sorry guys, I have an 88 with a 302. The truck has 220000 (or so) and the engine has been rebuilt once and I did a head job about 3 years ago, probably 30000 miles or so, I have the numbers just not off the top of my head. Please help as I'm about ten minutes from using the truck as target practice and I'll never forgive myself for that.

Thanks

Mike

 

If you cleared the original Code 41 by disconnecting the battery for ten minutes and it has returned, check the wiring especially at the connector for the sensor. Code 41 is most often received when there is something adversely affecting the air-fuel ratio. These problems can range from simple vacuum leaks to fuel pressure problems to poor spark. While the latter is least common, vacuum leaks and fuel pressure issues are probable. For starters, check the voltage change at the O2 sensor by prodding through the insulation of the DARK GREEN/PURPLE wire and the ground (BLACK) wire with the test leads from a meter or straight pins. Using the meter (BLACK lead to BLACK wire) check the voltage. Start the engine and run @ 2000 rpm for about two minutes. Keep an eye on the meter. After the first couple minutes, the voltage should shift from below 0.45 volts DC to just above 0.45 Volts DC. If it doesn't change, You can "fool" the O2 sensor by removing the intake hoses to the throttle body and slowly opening the unlit end of a propane torch in the throttle body bores while the engine is running. If the voltage still does not shift check fuel pressure, ignition components, EGR system, and for vacuum leaks. The problem lies somewhere in these systems and not the O2 sensor. If by some miracle nothing else appears to be amiss, you may have gotten a bad O2 sensor right out of the box.

 

I haven't checked anything yet but now I'm leaking coolant from somewhere and after driving when I put it in park the idle drops and the car stalls or revs a few times. I don't know if that rings any bells but its pissin' me off. I'll probably get on it this weekend or take it to my mechanic Friday. Tell him what I think and see what he thinks.

Thanks Greystreak for this info and I'll be keeping all this in mind.

Mike

 

The stalling/reving sounds like IAC issues. There is a method for checking to see if its functioning properly too. Let me know if you want the particulars.

 

Joe I've changed that thing four times or so since I've had the truck. I'm going to look at my records to see when the last time I bought a new one was.

I would like the particulars. It seems like I have a busy weekend ahead of me.

Thanks

Mike

 

To test the IAC for proper operation you will need to warm the truck to normal operating temperature. Shut it off. Disconnect the connector at the IAC solenoid. Start the truck. The engine should run briefly (very briefly) and then fall flat on its face (die). If it does this, turn the key off and disconnect the battery for about ten minutes. Reconnect the IAC and the battery and restart the truck. Run a KOER test and see if anything ELSE pops up 'cause the IAC ain't the problem.

If, on the other hand, the engine does NOT die very quickly with the IAC solenoid disconnected, the solenoid and or the valve itself may be stuck open making it impossible for the ECM to control idle functions OR the solenoid has failed. Either way, the effect is the same... little or no idle control. Since you haven't mentioned getting an IAC-related code I'd be willing to bet that the problem is crud keeping it from moving properly IF there is anything wrong at all.

 

had the same problem thought it was only 1 O2 sensor, but there are 4 on mine. had to change all before the O2 light would reset.

 

My truck only has the one. Though I'm not sure it always did. My mechanic thinks its one of two things at this point.

The valve covers are leaking and 1357 are leaking down the motor and there is some oil on the sensor. He said its possible that the oil is getting into the connector and acting as a conductor.

The other possibility is (which may or may not answer some other questions) is the number 8 cylinder has blown twice, and the possibility exists that the cylinder running lean because of a bad injector could be both overheating the cylinder and giving the lean condition.

Anyone have any ideas on that?

Mike

 

bgblktruk,

Oil will act as an insulator rather than a conductor unless its got a LOT of metal shavings in it... but then your problems are only just beginning. And even if it is acting as an insulator, it would still screw with the sensor's ability to send correct information back to the computer. And your truck always had just the one sensor.

The number 8 cylinder fouling plugs is a known problem with the 302 and 351 because the EGR distribution sends more to this cylinder than others and it gets worse as the engine ages. A good cleaning of the EGR valve and the related hardware might not hurt since EGR also contributes to changes in the fuel/air ratio.

whreq,

FOUR O2 sensors, thats news to me. I didn't know any Bronco had more than three O2 sensors. 1996 models and some 95's had three becasue of the OBD-II dignostics and computer system.