Codes I'm getting...

[NoSlo]

Now it's time to diagnose like a pro, after some distraction, using recommended procedures. Be aware that a lean condition trouble code can expand to numerous faults:

Description

The HEGO Sensor is monitored for switching. The code will set when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.​

Possible Causes

Electrical:

•Short to VPWR or VREF in harness or HO2S
•HO2S circuit shorted to Ground
•Water in harness connector
•Open circuit
•Corrosion or poor mating terminals and wiring
•Damaged HO2S
•Damaged PCM (other DTCs should be present)

Fuel System:

•Excessive fuel pressure (stuck fuel pressure regulator, restricted fuel return lines, etc.)
•Leaking/contaminated fuel injectors or fuel pressure regulator
•Low fuel pressure or running out of fuel (fuel pump concern, fuel supply line restrictions, low fuel level, etc.)
•Vapor recovery system (stuck VMV, etc.)

Induction System:

•MAF contamination
•Air leaks between MAF and throttle plate
•PCV system / Other vacuum leaks
•Improperly seated engine oil dipstick

EGR System:

•Leaking gasket
•Stuck EGR valve / Leaking diaphragm or EVR

Base Engine:

•Oil overfill
•Incorrect cylinder compression
•Exhaust leaks before or near the HO2S
•Secondary air stuck on​

Now to start diagnosing in a systematic manner...

Go here: http://www.diesel-dave.com/vehic/manual/vra/leftside=vras6al.htm&rightside=vras6ar.htm
You are in Section 6A. On the left panel, select the intro link for Pinpoint test H: Fuel control

(Yes, that is from a partial 1994 Ford Powertrain Control/Emissions Diagnosis Manual (PCED) in HTML. You might find missing pages if you fully explore the links.)

Read the intro page, reminding you of the many possible faults outside the scope of this pinpoint test, and then click on the upper right link. Proceed systematically through the pinpoint test procedures. Some of these will be assisted by having wiring diagram pinouts, and familiarity with electrical concepts.

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And from that same manual, which also has extensive information about not just diagnosing DTCs, but how to get them - to put a nail in FastCADs code-reading advice:



"Do not disconnect battery to clear codes" indicates it works, but it should not be your method to do only that.

 

[rubydist]

One correction to the stuff posted in the last several posts:

There is no "idle re-learn procedure" - that is an urban myth.

Yes, it will take a bit for the engine to learn how to idle properly in some cases. This is because the iac is far off from the nominal, but there is no short-cut to getting this re-learned quicker - if you have one of these iac units, it will take a while for it to idle right.

 

[NoSlo]

One correction to the stuff posted in the last several posts:

There is no "idle re-learn procedure" - that is an urban myth.

Yes, it will take a bit for the engine to learn how to idle properly in some cases. This is because the iac is far off from the nominal, but there is no short-cut to getting this re-learned quicker - if you have one of these iac units, it will take a while for it to idle right.

One correction to the stuff posted in the last post:






"If you do not let the engine relearn its idle before you drive your vehicle, the idle quality of your vehicle may be adversely affected until the idle is re-learned" - evidenced just a week ago.

 

[rubydist]

Don't know where you found that, but its not in the service manual, so no service tech ever did that. Just saying...

 

[NoSlo]

Don't know where you found that, but its not in the service manual, so no service tech ever did that. Just saying...

In my glove box...

 

[SHOYAY]

Well I've had 3 different sho's over the years, other two gen 2 atx...each one was different for relearns ...when I'd either store for winter or whatever and battery was unhooked for months, and then start for the summer, my 95 atx didn't care, always ran idle great from the start, white 94 was more temperamental and had to do relearn or it surged idling for a week or so...my current 92 needs relearn it seems or idle surges for few days.