So, I've had the P0122 code for a few weeks now. It's on a 97 SCREW 4X4 with the 5.4. I've replaced the TPS sensor, as I thought that might be the $35 fix. I also replaced the PCM (I had broken the connector bolt off in it about a year ago, and it was sitting tie wrapped in my engine bay-so I figured that it had succumbed to the desert heat. No dice. I then checked the wiring, thinking that I had a loose wire or short or something, and all of that appears good. At the sensor, with key off, engine off, I read a solid 5.07 VDC at the supply, and the reference is .986 VDC. at WOT the voltage reads 4.66 VDC, and it cycles smoothly in between.

I've had the truck for almost 2 years now. It has 113,000 miles on it. I've been meticulous on the maintenance, as I was driving it from Vegas to Los Angeles area every 2 weeks for work for the first year that I had it. I've replaced all the plugs and coil packs within the last year (10K miles). I'd hate to think that I'm having problems with one of those. I've also replaced both O2 sensors before the cats, along with cleaning the airflow meter.

The symptoms that it's giving me is hard shifts, and choppy running (feels like bad plug/coil) under light load. WOT does not feel choppy, but there is an inherent lack of power. I'm guessing at about 15-20% throttle is where the problems start.

When I use my scan tool to clear the code, the truck seems to shift well for a few minutes until the code pops back up. Before I got the code, the truck was running fine.

Any information would help. I've searched several different forums, and I don't seem to get any more information about what to do than what has already been done. I'm at the point where I'd even entertain changing out the plugs again-but I'd rather have a simple solution (It's hot as hell outside).

Thanks for the help.


Josh

 

Use your scan tool in Mode 06 to monitor the TPS voltage as sensed by the PCM and see if it matches up with the throttle plate position.

You might have an intermittent Vref feed to the TPS sensor, an intermittent short between Vref and Sig Gnd, or an intermittent output signal to the PCM.

 

Thanks for the input. The answer came to me last night as I was driving home from the Legion. The infamous code 308. I pulled off the cop and the plug and found the original motorcraft plug in place-not the denso iridium that was supposed to be there. damn shady mechanics. I still have to look at #4 and see if the guy did the same thing. #7 and #6 were both the iridium plugs. I changed the COP and the plug today-just to be on the safe side, and everything is back to "normal"-I think I have to change the ATF as well, been getting the "jerk" while I am driving.

 

Well, I cannot think of any mechanism by with a bad COP/plug would give that TPS fault code, but, WTH, if it's working, okay. It would, however, explain the mild misfire you described.

I'd be surprised if the TPS code didn't come back eventually. I think you've actually been experiencing two simultaneous problems and you've identified one of them so far.

 

I was actually hoping that the new pcm would fix the "studder" that the truck had before the blown plug. But the funny thing is that the code 0122 went away and the only thing I got after that was 0308. weird. Hopefully it holds up another month, as I'm shipping the truck with me to Hawaii.

 

Now you're reporting a blown plug????

 

Yeah weird huh? I replaced the plug and the cop, and it does seem to run better. I have to make time (probably next weekend) and pull out the rest. Apparently the alleged friend of a friend that I paid to do the job didn't fully come through. The "blown" plug was an original motorcraft plug, not the Iridium's that I bought to replace them (was planning on running a s/c-but not anymore). I'm suspecting to find at least #4 as an o.g. plug. I pulled the cop's off of #6&7, and they were the iridiums (can tell by the top of plug). I'm probably just gonna pull all 8 out and replace with motorcrafts, and get rid of the GMS cops, and go with OEM. But for now, it just needs to run for another 22 days-so I can get it on a slow boat to Hawaii.