Hey all,
Truck isn't feeling well again. 96 k1500 5.7L vortec. It's stalling on me again, especially if it's cold outside. Not only that, but the truck is shifting into gear around 3000 rpm for some reason or another. I am still having rough idle as well.

So for those who may not know, I recently had another issue with my truck when it was popping a p1406 engine code. I ended up cleaning out the EGR valve and housing and then replacing the EGR valve itself. The idle improved for awhile when I took it around town for a drive, but returned shortly afterwards.

I ended up taking it to the local auto parts store to get the engine code readings after the check engine light came on and I got these error codes:
p0171 and p0174 -- which most likely is from an intake leak or some sort?
p0300 -- which comes up because of misfiring issues in my truck.. but I had a 2001 lincoln that multiple misfirings and I dont feel ANYTHING CLOSE to what I experienced in that lincoln... Now I know this can also be tripped by an intake leak, but I would also like to point out (like in my other posts) I am not particularly hands-on and could be missing something.... I could change out the spark plugs as I don't see when or if the spark plugs were changed in the previous owner's records, but if that won't ultimately help the issues I'm facing now then I would rather wait till warmer weather to do that..
p0122 -- so this is from the throttle position sensor not getting a proper voltage.

SOOO it seems that I have some sort of intake leak and may need to replace my throttle position sensor? Any thoughts?

 

pretty sure theyre the same TPS for the tbi but if you read this you'll find how to test the TPS sensor. i would start there as it might effect how the trans shifts and engine performance

 

Thanks for the reply Alley so I decided to swap out the sensor without testing it first. I wanted to see if that clears up the p0122 code. For the record and for anyone who may have an issue with their TP sensor.. you can ABSOLUTELY access the sensor as it is sitting in the engine bay with the torx screw driver... you may just need to finagle it a bit. I want to take a picture and upload it on here incase there are visual learners like me out there who may have trouble finding it.

I also swapped out the spark plugs as well. I didnt re-gap them.. i have nothing to measure the gap size though so... I'm hoping the p0300 code will be resolved now (although, as I said I was not feeling a misfire problem when I was driving the truck)...

I pulled the positive terminal off the battery to allow the truck to reset and will drive it around town and see if I have any issues. Ill post back tomorrow.

Couple questions though... can the p0122 code (tp sensor) cause the p0171 and p0174 codes? if the throttle body wasnt working properly, there could be a less than ideal ratio of air to fuel.. causing the codes to trip.. right? I also ask because 1) i dont know and 2) i cannt seem to find a vacuum leak.. lol

thanks all

 

So I drove the truck around yesterday and the engine light came back on. The truck was still shifting late as well. Went to the auto part store on the way back and had them read the codes. Here are the results:

p0122 - tpi sensor again, so now I'm going to have to test the voltage to it
p1122 - same as above, although it could mean that the sensor is not adjusted? I don't think that's the case though, because i did disconnect the positive terminal to reset everything... and I'd like to think after driving 30+ miles around the PCM would have reset.
p0507 - either an issue with my throttle body (like it needs to be cleaned) or an intake leak (idt that's the case) or electrical tied into the throttle body, again

please, if you read this and I am wrong, please let me know lol.

I'll start doing my research and see what I can come up with for a game plan (although i'll be looking at the source alley gave me as well)

 

What little I know about those things is this, they are a reostat variable resistor. Voltage going into it should be 5 volts, it reads the value across the resistor as the position changes, and comes back. Only adjustment I know of is throttle closed, sensor in closed position. Could be dirty, or more likley a worn wiper in the resistor. You can look at the output voltage, watch it change with throttle movement. Should also be linear, full closed, half open, full open corresponding output voltage. I had to replace one because of a worn wiper, the output voltage was all over at certain positions.

 

i would also check all your ground connections. unbolt them even the neg battery cable and clean the contact and re connect them. if you notice any corrosion make your you clean that all off or replace the ground if you have to