Hey my 4.0 single overhead cam 2001 Ranger. It starts right up and idles okay. Completely bogs down when you give it gas. I have changed the throttle position sensor and the fuel filter. This has made no difference. Computer is calling for an oxygen sensor. However it was calling her that before this issue started. Also says it has a vacuum leak.
it was running fine and then the transmission let go on the freeway. Transmission has been rebuilt. I need to know what I should be looking for. I'm sure someone has had this problem before. Thank you.

 

Clean the MAF sensor, dirty MAF sensor is the most common problem for bogging symptom, should be cleaned once a year, easy to do

O2 sensors need to be changed every 100k miles or so, they use a chemical reaction to detect oxygen levels in the exhaust and the chemicals get used up, this causes engine to run richer than needed, so costs you $$$ in MPG, new O2 sensors pay for themselves 4 times over in MPG savings for the next 100k miles

Easy test for vacuum leak
Warm up engine fully, let it idle
Open hood and unplug the 2 wire connector on the IAC Valve
IAC Valve will close and Idle RPMs should drop to 500 or engine may even stall, either is good, no vacuum leaks
If idle stays high then there are vacuum leaks

You can unplug vacuum hoses and put finger over the intake port, if RPMs drop you found the hose/system with the vacuum leak

 

Thanks, I'll give these things a try.

 

Okay I've cleaned the maf sensor. Absolutely no change in the way it runs still bogs down. Is it possible that MAF sensor is bad but for some reason I'm not getting a code for it?

 

Sure it can just like any other sensor, MAF sensor issue would throw Lean codes though, not MAF sensor codes unless it fail completely

What about the O2s, how many miles on them?

These need to be changed every 100k anyway so not throwing away money on a new sensor when old one was fine, and if you got an O2 code???
And you would need working O2 sensors to get Lean codes if MAF was the issue, lol

 

Well the truck has about a hundred and twenty thousand on it. I got it when it had a hundred and nine. So I don't really know about the O2 I assume they've not been changed. Will they make it run this badly? It was running fine, then the transmission letting go on the freeway. It hasn't run worth a damn since then. Transmission has been rebuilt

 

I am getting an O2 sensor code. Bank 1 sensor number 2. Trying to figure out which side is bank 1. Pretty sure sensor number 2 is the downstream of the cat on that side

 

Yes, sensor 2 is down stream, you may only have the one unless you have a Dual exhaust system

Bank 1 is passenger side
Bank 2 is drivers side

Yes, over time O2 sensors will make the engine run richer and richer, as they run out of chemicals, and most people wouldn't notice unless they monitored MPG
But eventually it will effect operation
The computer has no idea of how the engine is running, it knows if its running lean or rich from O2 sensor feedback and thats about it
It doesn't know what bogging is or stalling, or hiccups

I have no idea what is causing your symptoms, but I also know no one else does either, lol, until the cause or causes are found

 

Well, I climbed under there and the damn Bank One sensor number 2 is unplugged. I guess maybe when they put the rebuilt transmission in they never plugged it back in. I've got a replacement for that one and I'm going to put it in there tomorrow and plug it in. It was calling for an O2 sensor before so since it's not calling for two of them I'm going to assume the one that was unplugged was the malfunctioning one. I'll be back at it tomorrow evening. Likely I'm going to have more questions LOL. Thank you I really appreciate your input.