so I have been having idling issues with my 98 Dakota 3.9 l 2 wheel drive ever since I bought it. price was right 900$ anyway. changed TPS, MAP, cap rotor, plugs wires, IAC cleaned throttle body checked vacuume for plenume leaks. new battery and rebuilt alternator. so was about to swap out ECM right after I changed water pump. Changed water pump and truck has never run better never seen it before but what a difference. Any ideas why it would make a difference I'm stumped but pleased with the results

 

Are you sure it was ONLY after the water pump? or did you do everything listed before you tried to crank her up and try her out?

 

If I were to bet... The tensioner was sticking. When you pulled the belt off to replace the water pump it freed it up a little bit... wont last but id start there...just a guess

 

Idk, when the bearings went in my water pump my truck squealed till at op temp and had a noticeable more load then when replaced. The truck picked up 2mpg. Just dont do what I did and ever wait till the thing coats your engine bay in coolant, my k&n knockoff from autozone is stil green 9 months later

 

no changed everything before water pump didn't seem to make a difference until after water pump was changed

 

Guess those bearings were just fried. Would you be so kind to post the exact descriptions of any problems you had other than just "Running Rough"

What did you hear/feel ? What all did it do prior to fixing it; so others searching can try and match symptoms to problems. Thanks man!

 

well the running rough was just what it sounds like felt like a slight miss at idle speed and disappeared during acceleration and cruising speed. I had changed spark plugs, wires, TPS sensor, map sensor, iac, cleaned intake and checked manifold vacuum for leak on belly pan all checked out good. coolant temp sensor was also changed and cleaned intake air temp sensor. Checked real time data on O2's all within specs. the only noise was coming from front of engine which was the bad bering inside had a lot of play in it but was not leaking. the noise was a low clunking mostly at idle or acceleration. hope that helps

 

did you feel any jerk or shake at idle, or when you let off the brake and creep? Anything like that?

 

no not really I know usually when you have a misfire you get that jerkyness when you let off the breaks but no kind of a shake at idle you could see the engine move side to side