86 Ranger bucks/jerks

[fordfam]

Hey guys I have an 1986 ranger with a 2.9L that bucks and jerks under med. to heavy throttle. I bought it knowing overdrive was out and thought it was causing the problem. Tranny is now rebuilt and still is doing it. Timing is on and someone had turned idle screw way in. I backed it out so truck would idle around 850 This problem is when truck is under a load in park engine revs fine no miss. Got any ideas.


Thanks

 

[RustedRanger]

Reset the "idle" screw. It is not for setting the idle it is for setting the TPS(throttle postition sensor) You can do a search here and find out how to do it. The computer uses the IAC(idle air control valve) to adjust idle.

 

[IMenriched]

may want to check for proper tension/slack on the throttle cable as to if it able to down shift correctly and or tranny linkage

 

[holyford86]

Pull codes, Replace your fuel filter, Reset your TPS baseline. backprobe the center pin of the connector and set the voltage to ~.84 volts. start the truck and run it at 2000 rpm for a minute, check your idle, it should be around 800 for an auto and 850 for a manual, if it isn't shut the truck off and unplug the IAC, Restart it and run it at 2000 rpm with the IAC unplugged for about 30 seconds, then let off, the idle should be right around 700 rpm, adjust accordingly if necessary then shut off the truck and restart it with the IAC still unplugged , run it for about 30 seconds again then confirm that the truck is running at 700 rpm, if it is, shut the truck off and reconnect the IAC. Keep in mind that this procedure requires a properly functioning IAC that isn't stuck open, as well as a properly functioning EEC system with no codes.

 

[RangerAndrew1989]

could be the torque converter was it replaced when you had the trans rebuilt

 

[fordfam]

New torque converter, shift pionts were high reajusted and also checked tps have .81 for volts with a good idle. After that drove it seems a little better. To ajust baseline do I turn the tps or what. Will be checking codes this afternoon.

 

[holyford86]

you turn the screw on the side of the TB opposite the TPS

 

[fordfam]

Got codes spout connector and knock sensor. Can clear them drive around block and they come back.

 

[fordfam]

fuel psi at 31 driving down the road it all of a sudden drops to 20-21

 

[Area 52]

Fuel filter

 

[jvs8864]

Fuel filter

agreed. my 86 2.9 had the sameee problem
i changed my fuel filter after everyone on here said to, and it worked.