I'm having some issues, not too serious (I hope) with my 98 Dakota 4x4. It's an automatic.

Issue One
Almost predictably, when the truck is in park with the engine on idling for a while, eventually it will rev up to about 5 or 6k rpms then slowly go back down to idle. At first I thought it was my foot somehow touching the peddle, but it's not. What the hell is causing this and how do I fix it?

Issue Two
Especially when it's really cold, but sometimes when it's not, the truck seems like it's having a hard time finding second gear (automatic). For instance, pulling out from a red light, it may pause between gears, then hit 2nd hard and chirp the tires a little. I understand a transmission may act strange when it's cold, but not like this. Once the car is good and warm, it this problem rarely happens. Again, what the hell is causing that and how do I fix it?

 

I have a 99 5sp v6 4x4, and although yours is an automatic i seem to be having slightly the same problems. When I start it up and it is idling, it sometimes jumps up and then back down without me touching the gas at all. Once it warms up it hardly ever does this. Also when its cold out, I have a hard time shifting gears, and almost every time i try to shift from first to second, it doesnt allow me to. (For some reason these trucks wont let you downshift into too low of a gear for the speed the truck is going.) Once it warms up however, it shifts better but not perfect. I am just learning to deal with both of these, i dont have money to bring it in anywhere to have them fix it.

Also, ever since i put Bosch Platinum plugs with new napa wires, i have noticed a dramatic decrease in MPG. I averaged around 13 up here at school (all city driving on a LOT of hills, and it is generally higher up and colder then my home town where i would average about 17 half highway half city during the summer). I now get a little over 10 MPG and wish i would have never switched plugs. Is there any other contributing factors to loss in MPG?
Could it just be the fact that these plugs are not good for our motors, it has gotten a lot colder, and winter gas is less efficient then summer gas? Or is there an O2 sensor going? I have no way of doing anything on it myself so i was hoping someone could give me some opinions. I am planning on switching plugs as soon as it gets nice out again, which might be a couple months.

 

Toss the plugs, i use to use the same kind, they blow. Go with some Autolite 3923's or Champions, both are the best ones you can use for the engine, they are cheap to you can get them at any local part store for about 10-12 bucks, the o2 sensors could be going bad those are easy to take out and clean if you have a socket wrench. lol.. or any type of tools at that, best time to get gas is in the monring before the sun comes up in the summer. the gas is more dense.

 

Can i mess anything up by cleaning my O2 sensor? Someone once told me that replacing them is unnecessary and I should just clean them. Also, I had never replaced plugs or wires before and when I did, I did it alone without my Chiltons. Is there anything that I could have screwed up while replacing them that would make my engine work less efficiently? I put on the stuff to keep the threads greased and a small amount of the stuff used to help connectivity, could i have messed this up? Also, I dont hear any misfiring but when i was checking to make sure wires were all tight on the plugs, it seemed like a couple of them were actually connected, (when i push it in more it feels like it catches the plug and then when i let go it goes back out) Thanks a lot guys, i know a lot of people have already helped with this, but I am just trying to figure out the cheapest easiest way for me to take care of this.

 

You can always clean the outside of the O2 sensor, but what about the inside there are little slits that let the carbon build up inside. I found mine on E bay for 20 bucks a piece, they're Borg Warners and they work great. I was able to notice a big change when I put the new ones in. They're right about the plugs, get some champions, like others I went out and bought really good Bosch platinum 4, just to find that they suck w/our trucks. Plug change is very simple, just make sure you gap them to the specifications. On the plug wires, they feel like they're loose sometimes but they're not, unless they are very worn out. If it was misfiring you'd know. Try cleaning the TPS sensor on the driver's side of the throttle body, mine went out a while back and it ran me about 35 at O'Rielly's. Best of luck

 

Thanks a lot. As soon as the weather gets better and I get back home I will change out my O2 sensors and plugs. But for now I am stuck with under 11 MPG and not a lot of power...at least i dont have to drive anywhere but school and work usually.