Have 1990 Dakota 4x4 3.9. Starts and runs normaly for about a quater mi. Then speed drops off,about 15mi per hr.Power down when load is on engine,hills,passing,etc.Scan shows code 34.(does'nt have cruize) but replaced speed sensor anyway. After quater mi it seams line something just switches off and speed bleeds off while holding foot on gas,on reaching 55mi.help.hargar.

 

When the load is on engine...

Does this happen only when having a load on the truck.. because of hills, etc.. that sounds about right.

 

Yes and does'nt change until truck is parked for a while. Upon restart it begains again.Same deal,same way day after day.Odd thing is,if truck is parked for several days it takes a little longer for prob.to start,say a half mi.or so.Hard to get it up to freeway speed,70,and then keep it there except on level. If this was older non computer rig,i'd supect that my vacuum advance wasn't working.Haygar.

 

p.s. U don't want to enter traffic,unless u can can get a good running head start,downhill ramps,if u gotta do it from dead stop,or uphill deal,prepare for hairraising experience.hargar

 

Does the truck still have a catalytic converter?

If it does, I can almost guarantee that is the problem (stopped up) If it does and you suspect it, unbolt the exhaust from it and drive it and see how it does.

 

Thanks for the post.Truck has 185,000+mi on it.I got so rapped up in playing with new scan tool i fogot there are things,not directly under the hood,that can affect diriveability.hargar.

 

how about the coil.i have a nissan truck and my problem i just found could the coils(2).it would do good and then lose speed and i would pull over and turn it off for a few mins and i did replace the cat