Topic: Engine lean code?

[sharpxmen]

No lean code in open loop since the O2 sensor is not generating a voltage yet.
The newer 3 and 4 wire sensors with the built in heater go in closed loop fast.
Still open loop no voltage fluctuation, means not be able to generate a code

I think i might have not explain my question the best way, so i'll try and rephrase - open loop is not just when the engine is cold and O2 sensor is not at operating temp, it also occurs during load when the ECU is preprogrammed and not using the O2 sensor feedback - however the O2 sensor is still giving a voltage just not accurate since it is not a wideband, but enough to tell that is lean (that most likely means below 0.45v which is equivalent to a 14.7 AFR or a lambda of 1) - the fuel map at full load would most likely target around 13.5 or so. So what i don't know is will the ecu monitor the voltage during that time, not when engine just started, at operating temp when you're at WOT with the pedal to the floor and trying to see how fast it goes (ecu will not use the O2 output to alter the AFR in this case, just don't know if it will monitor it and report lean if the voltage is below a certain level).

[aw12345]

If you read most code descriptions as to the conditions needed to set a code.
For lean or rich codes that is during cruise speed.
I know at full throttle there is no feedback control in essence the ecm pretty much commands full fuel thats programmed into its fuel map.

[jcsanders79]

Ok lots of info there.  Since the TJ doesn't have a "servicable" fuel filter should I start at the rail?  I've got mustang injectors, should I get a rebuild kit for them?

[chrisfranklin]

I didn't see a way to disassemble the MAP sensor.  Looked like it could receive a vacuum line and a three prong connector, but otherwise looked like a sealed unit.  I must be missing something.   

[sharpxmen]

was the code this
51    A lean air/fuel mixture has been indicated by an abnormally rich correction factor

or this ('97 or later)
P1298   Lean Operation At wide Open Throttle

[sharpxmen]

Ok lots of info there.  Since the TJ doesn't have a "servicable" fuel filter should I start at the rail?  I've got mustang injectors, should I get a rebuild kit for them?

This is all for a YJ, you'll have to find out if your numbers are different, but the idea is the same
Check the fuel pressure at idle - for my YJ it is supposed to be 31psi if i remember correctly. Unplug the vacuum hose that goes to the fuel pressure regulator with the engine running at idle - the fuel pressure should jump to 39psi. Plug the vacuum hose back and turn off the engine, should hold pressure above 31psi.

if all this is good then go for a test drive, hwy and/or uphill preferably - floor the accelerator pedal and try to keep it there as much as possible (that's why a long uphill is preferred, we don't want you speeding or anything) - monitor the fuel pressure and make sure it stays put at 39psi, if you see it dropping then you don't have enough fuel flow. I would start by replacing the fuel filter and go from there. If it doesn't drop i'd say to reset the computer and see if the code comes back - if it does then it could be a few other things including injectors, i would check the fuel pressure first and go from there.

[jcsanders79]

I think it was this code?  I'll have check to make sure.

P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally rich correction factor.

[sharpxmen]

I think it was this code?  I'll have check to make sure.

P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally rich correction factor.

I guess is the same as 51 on earlier models based on description. Did you reset the computer and see if it throws the same code again? if it does you could also replace the injectors with your original ones to see if it happens again, if it doesn't then one of your ford ones might have a problem, if it does throw the same code look at the fuel pressure and flow (you could do it the other way around too, whatever is more convenient - for the fuel pressure you'll have to buy/borrow a hose with adapters/fittings for your fuel rail and pressure gauge, i assume you already have the old injectors). Could be as simple as the filter though, so if you did not change it in a long time you might want to go ahead and replace it since you have to do it at some point anyway.

[jcsanders79]

It did still throw the code after it was cleared.  I have the old injectors and will start there.  Thanks.

[jcsanders79]

if it does you could also replace the injectors with your original ones to see if it happens again, if it doesn't then one of your ford ones might have a problem, if it does throw the same code look at the fuel pressure and flow (you could do it the other way around too, whatever is more convenient - for the fuel pressure you'll have to buy/borrow a hose with adapters/fittings for your fuel rail and pressure gauge, i assume you already have the old injectors). Could be as simple as the filter though, so if you did not change it in a long time you might want to go ahead and replace it since you have to do it at some point anyway.

The fuel pump was swapped about a year ago under recall so I don't think that would be the problem.  I'm going to swap the injectors, then check the fuel rail.  Does anyone know the readings for the mustang injectors?  I not sure it will really matter since I can check them all and if there is an odd ball I'll know its bad.  Also any ideas on part numbers for the rebuild kits for the mustang injectors?  Water pump blew today as well as the O2 sensor I just put in so I'll be at the parts store this weekend anyways. Thanks for the info.

[sharpxmen]

there was another thread and the person having an issue with ford injectors (i think) and it turned out that they were lower flow that the stock - have you checked the flow rating on the stock and compare with the ones you have on? just occurred to me that if that would be the problem in your case it would totally explain the error code (unless is the O2 sensor you just mentioned which can also result in the same code if it sends wrong info to the computer).

[jcsanders79]

The injectors have been on for a while without any problems.  I think the other guy had a 2.4L and I have the 2.5L.  Maybe it is the O2 sensor, that would be nice.  I think I'll still get the rebuild kits for the injectors though.

[sharpxmen]

how do you rebuild them - aren't they sealed? not sure how that can be done but would be interesting to find out.

[jcsanders79]

I don't know if you would call it a rebuild but their is a picture of new o-rings and caps.
http://4bangerjp.com/forums/index.php/topic,3479.0.html

[sharpxmen]

that's not a rebuild, it will just insure that the fuel rail does not leak and that the intake is sealed around the injector cap and there is no vacuum leak there.
what fails on an injector in time is the ability to atomize the fuel properly and also to seal when closed (not powered) - that makes it leak and drops of fuel enter the intake. I have heard of ultrasound cleaning of injectors, seen that done on the old style (and i am not talking about the solenoid actuated ones but the old pressure based injectors) with some results but out of 10 you would probably get 2 or 3 that were good. The solenoid can also fail on these, not a common occurrence but it can happen. I would look for new or almost new ones to purchase, i got a set of 8 32 lb/hr Accel for $70 + shipping off eBay, they were installed and taken out as they did not fit the person's application so I'm pretty sure you can get a set of 4 rated for your setup at a decent price. Just my opinion though, i would be interested in other options so let me know what you find