I have a 99 Ram 1500 3.9L 4x2 that sometimes has an extreme loss of power at highway speeds. My first thought was a vacuum leak because when I would experience the lack of power the a/c would change to where it would blow out of the defrost dash vents. I completely disconnected the a/c from the intake and did not notice a difference. The best way I can describe the loss is that it seems like you are dragging a boat anchor behind you when it happens. Now what I mean by sometimes is just that... today it may drive fine in the morning but on the way home it may be dragging or it may go a few days and be fine. I have no trouble codes, no check engine light. It acts almost as if the timing is retarded to much so I was wondering if it could possibly be the crank sensor. Any thoughts?

Thanks!
Brent

 

Hi Brent. Welcome to DF.

Given the intermittent nature of your problem..... I would first check and see if your plenum wasn't blown. (see the stickied thread at the top of this forum for information on that topic.)

Next, I would have a look at tune up parts. (I don't think this is the root of your problem though.....) Cap, rotor, wires, plugs, PCV valve.

If your plenum is indeed blown, you may have a fouled O2 sensor, which could give the symptoms your describe.... and won't necessarily set a code.

Another thing to check, would be the TPS. Trouble is, you would need to check it while the problem was happening...... which can be fun.....

 

Ok I read the sticky and it kinda sounds like my problem but I have no oil usage at all. I thought it may be a catalytic convertor so I "fixed" it but it did not make a difference. I havent thought about the O2 sensor or the TPS. I will probably replace the TPS this weekend and inspect the O2 sensors this weekend.

Thanks for the food for thought!

Brent