I have a 90 F250 7.5l 460 2wd. I get random code 41 error.. What I have done.

Went thru and replaced
o2 sensor (bosch)
cap/rotor (MSD)
New plugs (Bosch)
New Wires
New filters fuel, Oil and tranny along with fluids
New air filter and breather filter
New PVC
checked voltage from O2 vehicle side for the heater ~12v
Vehicle Side O2 ground <5ohms
Checked all vac lines. All in good condition. Found 1 with slight crack and fixed it.
Fuel Pressure kind on the low side but within spec. 31 running 35-36 KOEO.
Timing 10' btdc with spout disconnected

no exhaust leaks Prior to o2 sensor as verified by myself and the Exhaust shop. Cat was removed and Smog lines just hanging out in the area open. Damn previous owner!!! Havent had the $$$ to replace the cat yet.

I can drive for some time >10 mile trip and not get the code and then all of a sudden it comes on. Other times I can take a short <10 mile trip and when backing in to the driveway i get the code. It seems to most happen when backing off the gas. At freeway speeds it seems just fine.

Get this in both KOEO CM code and KOER code 41. Only codes I am getting and its bothersome as I would like to be pretty safe knowing if a different code comes up instead of assuming its just the bothersome code 41.

Any ideas or suggestions that I have not thought of? I am getting ready for a long 400+ mile trip and would like this taken care of before I head out. The local Ford dealership is several weeks out before they can even get to it.

Thanks again,
James

 

Ok Replaced Fuel Injectors with new 24lb injectors. Also replaced the missing Cat with a magnaflow Direct fit cat.

Still getting code 41 hego lean or not switching.. Also getting Code 56 TOT below -40f... Anyone with any suggestions... I pulled the entire wire harness from the O2 sensor and Tranny and checked resistance between every pin.. All reading quite a bit less than 5ohm.

Please help before I am forced to take this thing to the Dealership and pay a ton of money for them to diagnose this... Also the dealership says that more than likely anything wrong they can no longer get parts for. About the only thing left I can think of that is left is the ECU module

PLEASE HELP..

Thanks again,
James

 

Did you check the ACT and ECT sensors?

Consult ford fuel injection on how to test the two sensor, Air charge temperature, and Engine coolant temperture. You can acquire both sensors aftermarket.

The Transmission oil Temperture sensor, from an old post in the superduty section a recommendation was to simply check your trans harness to make sure that corossion or dirt wasnt in the harness connectors.

https://www.ford-trucks.com/forums/1...ot-sensor.html

 

That's a problem, are these lines still open after you have replaced the cat? Can you confirm there are no leaks in the plumbing attached to this system? Any fresh air entering the the exhaust upstream of the O2 sensor will throw the engine fuel mixture out of whack.

 

yes there is absolutely no exhaust leaks as confirmed by myself as well as a well known exhaust place. The cat was replaced and all air lines attached.

Rechecked all wires running in the harness from the tranny and the o2 sensor.. All check good. Ground wire to tranny was 11ohm though. Going to replace the battery terminals now in hopes that the terminals arent providing a good ground. All other ground points check out good.

My guess is the Computer. ACT and ECT test good. It makes me think the ECU is bad as both the TOT -40 (open) and the hego switching (code 41) are both happening... Tranny is definetly up to temp ~160f as per inline temp gauge. Any other suggestions before I go and order a new ECU at the tune of ~$150.00?

James

 

Take the harness off the ECU and check for corrosion in the ECU harness or if water got inside the ECU. If you can try a similar ECU and see if you still get the same code would help as well.

Just as a thought, have you just disconnected the AIR valves to make sure the air injection is dumping to the atmosphere at all times. Then just run the motor to see if the code goes away? Like Conanski said, if there is air being forced into the motor upstream of the o2 sensor, it will think the engine is lean when it actually isnt. If the diverter valves are not operating correctly, you could get air into the exhaust ports at the head thus causing the lean condition.

 

Harness has all been checked...

Have not checked the AIR valves.. I do know I can feel it venting to the Outside when running...

James

 

Maybe just unplug the air line(s) running back to the exhaust and heads and capping them closed for a short time. I am not sure how the system is set up on the 90 460, as ford used a couple different routings of the AIR system on these trucks.

 

well I went thur my alldata pinpoint tests for code 41 and it came up being the Computer... Unplugged vacumm line from Map sensor.. Apply 10-14 in hg vacumm pressure and plug line that was going to map sensor.. Code 41 still happens replace ECM. I could tell ya the truck was not running lean like this... I could smell it really rich.

Had a buddy order me up a new ECM for the truck for pretty cheap ~80.00 and it should be here in a few days or so...

Hopefully that takes care of the issue..

James

 

Well New computer arrived and still same issue... Code 41 and nothing seems to fix it.. All the wiring is good... This is driving me absoltuely insane...

Any other suggestions???

James

 

I think temporarially removing the air injection tubing from the up stream side of the exhaust would help rule out the possiblity that it was a contributor to the lean code. If the code goes away with the AIR ports at the manifold or heads is disconnected then a possiblity exists for a leaky diverter switch. If not then either the O2 sensor was bum from the start, or low fuel flow is a factor even if pressure is acceptable.

 

Well I went ahead and made sure the Air injection stuff was all working and everything is there... Out of curiosity I decided to pull out my old O2 sensor and strip the wires some to get a better reading with my meter.. At the O2 sensor I am getting between .8 and .9v which would indicate that it was actually running rich... My guess is somehow the computer is not getting this reading... I have tested both the Gr/Lb and O wires from harness to harness and havent found any issues... No shorts or anything that my FLuke meter is showing.

My thought clip Grey/l-blue wire at the O2 vehicle side plug and the Orange wire at the vhicle side plug and run new ones directly to the harness as a troubleshooting method but thats a lot of work to do just for testing purposes... I tested pin 29 on the ECU harness to the Grey/L-blue wire and read less than 2ohms... Really stumping me here... New ECU so I know thats working just fine...

James

 

SON OF A B#@$@#$ I finally fixed it... Seems as though in the 1990 Ford used both a 3 wire o2 sensor on the earlier builds and a 4 wire on the later builds... Well Napa gave me a 4 wire o2 sensor... Exchange the 4 wire for 3 wire sensor and code is gone. All this money thrown at it and it was truely the O2 sensor. I found out by grounding the 4th wire (orange wire) and code went away... Traced the orange wire after ripping the wire harness apart and found it was just a dead wire and went no where... Checked on an 89 model and they used a 3 wire sensor.

Exchanged Sensor and codes are 100% gone. 1 ecu $102.00, set of injectors $135.00,
Replaced Cat and air tubes (missing prior to troubleshooting) $300.00, Bosch 4 wire o2 sensor $30.00... all becuase the truck used an 89 o2 sensor at $34.00

Cat was going to be replaced anyways. Anyone else having this issue Make sure you have the right o2 sensor... Granted the Injectors were not all that good anyways but the ECu was absolutely a waste of $$$ because of AllDatas pinpoint tests lead the path of bad ECU.

James