After a few month, I finally got my 87 f150 back on the road. See post: https://www.f150forum.com/f10/can-no...r-55-a-450588/

The only two error codes I am getting know is 41 (O2/HO2 Sensor) and 25 (Knock Sensor) and can not find their locations.

For the O2 Sensor, I know it is located on the passenger side, but looks like it has been removed along with the CAT. Converters, just a muffler now. I do see a place on the exhaust manifold where it looks like it goes, but can not find the plug or where to plug in the new one O2 Sensor.

From what I found online, looks like the Knock Sensor might be on the passenger side also. Also can not find a plug for it...


Thanks in advance...

 

Codes do NOT mean to replace parts - they only suggest where to BEGIN DIAGNOSIS. Don't pick words or part names out of code definitions - read (and post) the COMPLETE definition for each one. Click this & read the whole caption a few times:

(phone app link)

 

If a sensor is missing I would address that before worrying about any codes.Code 41 in most cases is a lean code set by an O2 sensor doing its job. Vacuum leaks, low fuel pressure are far more likely to set a 41. Appears to set a 41 when you say the O2 sensor is AWOL. It sounds as if someone has tried to re-engineer your truck. If parts are missing and your engine is not detonating, I would not worry about codes unless you plan on putting it back together again as it was originally designed. Who knows what else has been messed with?

 

The codes are

41R HEGO (HO2S) sensor voltage low / system lean
41C HEGO (HO2S) sensor signal out of range
41C No HO2S switching detected

I know that codes are a starting point, but it looks like the HO2S sensor is not there and trying to find the plug (wiring) that the sensor plugs into. As I mentioned "CAT. Converters, just a muffler now", so it looks like one of the previous owners removed it, including where it screws into the exhaust system, (did not mention that, my fault).

25 R Knock not sensed during Dynamic Response Test (operator error)

Can live with this one for now, until my OCD makes me not able to.....

 

I did a vacuum test and that looks good, and double check the connections to make sure they are in the right place.

Yes it looks like the HO2S (O2) sensor has been removed, including where is screws into the exhaust. I do want to get the HO2s sensor back on to see if it helps on some running issues and see if it help milage. Plus make my OCD stop about it...

 

That's 1 code. That you posted 3 definitions for it suggests that you don't understand what you're posting. That caption is very technical, so you can't expect to comprehend it all after only one read.This also suggests that you didn't read that whole caption, even once.

Yes, I read your first post. But since you didn't post any pics, I can't confirm that anything is missing, so I haven't addressed that issue yet.
http://www.supermotors.net/forums/th...-and-or-videos

This shows the factory exhaust:

(phone app link)