I have a 02 ram 4.7l. It started doing a high idle. would rev to 2000 rpm every time I started it then go down. About three weeks ago while driving it started running real rough. Almost felt like the tranny was slipping. Only way I can think to describe it. It was also shifting hard. Also it burned about 3/4 of a tank of gas on a 120 mile trip. MIL cam on and gave the code "P0121 Throttle Position Sensor Circuit Insufficient Activity".

Took it into the shop. He said the computer was telling him it was something with the tps. Also said it reported that other sensors had negative voltage. He checked the tps and other sensors and they all checked out fine. When he test drove it the thing ran fine. Didn't charge me anything. Told me to drive it till it does it again and bring it back.

Well now it is starting again after about 600 miles. I start it it will rev to 2000 rpm then come down to 1500 for about 30 seconds. Then it drops a little below 1000 and fluctuate between 400 and 1000. Almost like if oyu kept tapping the gas pedal. And when I am driving now I can feel what is kinda like a surge and the rpms will shoot up. Also sitting at a stop light the rpms shot up from like 800 to 1500 and it felt like it wanted to jump forward if I didn't have my foot on the brake.

So what could this be. I thought about just having the tps replaced but not sure if I would just be wasting my money. Thanks for the help.

 

a few things would cause this. 1 a dirty throttle body, remove it abd clean all the carbon out. also a bad 02 sensor. my tps did go and it did the same thing your engine did, 106.00 to replace out of warrenty. try cleaning the throttle body first,

 

umm i dont know where they bought the 107 tps but go to advance. i paid 32 and changed it the same time i cleaned my throttle body. do it all at once. its only 30 bucks and it will same you a ton of time if you have to take the air box and all that jazz off again. simple fix. main thing is get about 2 cans of carb cleaner n clean your throttle body really good. and take off the two things (tps and something else) and clean them well. well not the tps cus you should replace that. should solve your problems, it did for me

 

i replaced a throttle sensor on a impala 69 bucks with life time warranty fixed the problem right up, it tells the computer about you a/f mix and makes it fluctuate and or cut off engine

 

Check your spark plugs and plug wires. If you're getting arcing anywhere, it'll cause the RPMs to surge on the 4.7

 

This guy has no spark plug wires. He has a coil on top of each plug. I'd keep checking codes. A code reader can be had for 60 or 70 bucks. Get one that doesn't just give the code but tells you what it means too.

Driving the truck with that kind of activity is very hard on the drive train. In case you don't know those of us with the early 4.7 have an engine that blows head gaskets far too often. I'm new to my truck too so am not sure if my 02 has a tranny that has too many issues. They put a new auto in the 02 so they may have fixed the problems but I'm not sure. Good maintenance will pay off.

 

He still has wires leading to the coil packs. I have the same engine in my truck, and had a similar issue. Arcing wires were the problem. It can foul the plugs as well, so you'll need to check them and replace if necessary.

 

I stand corrected. Also I appreciate the advice. I can see where those wires could be an issue.

 

so if I change the tps is there any adjustment that needs to be done. Or is it just mainly unplugging the old and putting the new one on

 

unplug, unbolt, rebolt, replug. no adjustments. just make sure you get your old o ring off and the new on on. and dont forget to clean your TB you will be surprised at how dirty it may be.