throttle response

[ernie c.]

i have a 1994 ranger 4x4 pickup with the 4.0l engine. it was running great until driving home and it seemed like I lost power momentarily, then the check engine light came on and then went off. when I got it home it started running terrible . idles really rough and no throttle response. i checked the tps and it is within the correct specs, replaced the crank position sensor, checked and replaced the maf sensor which seems to help the idle issue somewhat. fuel pressure is at around 38 psi. any suggestion would help on where to go next.

 

[alwaysFlOoReD]

Get any codes?

 

[rhekman]

i have a 1994 ranger 4x4 pickup with the 4.0l engine. it was running great until driving home and it seemed like I lost power momentarily, then the check engine light came on and then went off. when I got it home it started running terrible . idles really rough and no throttle response. i checked the tps and it is within the correct specs, replaced the crank position sensor, checked and replaced the maf sensor which seems to help the idle issue somewhat. fuel pressure is at around 38 psi. any suggestion would help on where to go next.

I had this happen on my '95 recently from running out of gas on a side hill and damaged (though didn't kill) the fuel pump. When I replaced the pump, I also replaced the fuel pressure regulator, and found a vacuum leak downstream of the EGR valve. It ran like crap when I put it back together before I realized the intake tube connection to the MAF housing was loose.

If your issue happened suddenly, I'd look for things that are physically broken - melted or broken vacuum lines, cracked intake piping, EGR leaks (if your truck has EGR), failed IAC, stuck EVAP solenoid, broken or melted O2 sensor wiring, etc.

If nothing is obvious, then usual diagnostics apply -
1. Check for codes https://www.therangerstation.com/tech_library/OBD_I.shtml
2. Do symptoms change cold vs. warm. Any changes immediately after startup (open loop vs. closed)?