HEGO problems

[(NW)Drake]

ok guys i keep getting code 41/91 on the koer test, its saying that they are lean and or their is no switching detected, i cant figure it out, ive looked into everything. please help its angering me

 

[Mustangcwo]

Here is a rundown of all the possible problems you may have:

• Check engine oil for fuel contamination. If there is fuel in the engine oil you probably have a leaking fuel inector.
• Check fuel pressure and make sure is it set at 36 psi with the vacuum line pulled.
• Engines general condition.
• Fuel injectors (leaky, stuck, dirty).
• PCV / Hose stuck or blocked.
• Vacuum leaks.
• Fuel Injector O-Rings.
• MAP/MAF sensor.
• Wiring harness general condition. Recently, one of the guys pinched these wires installing some parts requiring some sodering to correct.

 

[(NW)Drake]

lol i have that site in my phone ive been going thru it and ive come to the conclusion that its a vaccuum leak but idk which line, should i just start replacing the lines i prolly have about 100ft of line

 

[wickedstangs]

Drake you only have one pic of your car up??????? 89 FORD MUSTANG - LX

1st have you checked your 02 sensors or replaced them?

'86-'93 O2 sensors are 3-wire setups, 3-wire sensors DO NOT use a SIG RTN circuit....

41 - System Indicates Lean -passenger side(R), No O2 Sensor Switching Detected. always lean -passenger side(CM)
91 - System Indicates Lean -driver side(R), No O2 Sensor Switching Detected. always lean -driver side(CM)

Codes 41/91 (Lean Condition) specific tests:

For codes 41/91 (lean condition), it is always recommended to check the condition of the HEGO GND circuit (pin 49 at ECM connector), a bad/open ground circuit will cause lean readings from the O2 sensors. The HEGO GND is an Orange wire, with a ring connector, that goes bolted to the back of the driver side cylinder head. Identified as item #19 in the following harness diagram.

 

[Mustangcwo]

lol i have that site in my phone ive been going thru it and ive come to the conclusion that its a vaccuum leak but idk which line, should i just start replacing the lines i prolly have about 100ft of line

If the O2 sensors are good, then your problem is more than likely a wiring problem. You need to disconnect the O2 sensor from the wiring harness and check for continuity. If you use a multimeter on the harness between the ground wire and the other two wires you should read resistance. This is commonly called a continuity check. If you have an infinite amount of resistance, take the meter lead touching the ground wire and place it to the block. If the meter shows resistance, then the ground wire is bad.

If all the wiring checks out good, then it could be a vacuum leak, however it would have to be quite large. I would spray all the mating surfaces between the upper and lower intake and heads and listen for the engine to change idle speed. If the engine speeds up, you have found your vacuum leak. If it's a vacuum line, then it would have to be broken in half or burned through...should be obvious if you hand trace them all.

 

[(NW)Drake]

ok thank you gus for your help and yes i only have pic right now because its been bad weather up here, so as soon as it gets better i will get more, also i will check the circuits and let you guys know, thx again for your help. and if its that ill check the upper and lower as you said. ill keep you guys posted