- Joined
- Sep 21, 2026
- Messages
- 1
- Points
- 1
- City
- North Chesterfield
- State - Country
- VA - USA
- Vehicle Year
- 1997
- Vehicle
- Ford Ranger
- Drive
- 4WD
- Engine
- 4.0L
- Transmission
- Automatic
- Total Lift
- 0
- Total Drop
- 0
Hey guys, I could use a hand diagnosing this issue I'm having with a 1997 Ranger, has the 4.0L engine. After getting warmed up a little bit, when you blip the throttle the engine will stumble to like 300 RPMs or just stall out entirely. After the blip, if it doesn't stall, the engine RPMs stay very low and occasionally it will die from running so slowly. It has a new Delphi MAF sensor in it, and has a new-ish IAC valve. The IAC valve seems to be operating normally, what I've found by watching the data on the scan tool is that when the engine is idling low the IAC valve is commanding a very small opening value, like it's being told by the PCM to be nearly closed. I have also found that when you blip the throttle, the MAF data will shoot up to like 25 grams per second when the engine is falling flat on it's face.
I guess I'm looking for suggestions on what to check? I don't seem to have any vacuum leaks, my MAF is reading 5 GPS when the idle is good (which is a little high, but definitely doesn't indicate any intake leaks). My TPS sweep data seems to be normal on the scan tool. I don't have a PID for the crankshaft reluctor wave, but this doesn't feel like that kind of issue to me anyways. Am I wrong about that? I do have good fuel pressure although it seems to spike on tip-in which feels counterintuitive to me.
Any help that can be provided would be extremely helpful. Thank you!
I guess I'm looking for suggestions on what to check? I don't seem to have any vacuum leaks, my MAF is reading 5 GPS when the idle is good (which is a little high, but definitely doesn't indicate any intake leaks). My TPS sweep data seems to be normal on the scan tool. I don't have a PID for the crankshaft reluctor wave, but this doesn't feel like that kind of issue to me anyways. Am I wrong about that? I do have good fuel pressure although it seems to spike on tip-in which feels counterintuitive to me.
Any help that can be provided would be extremely helpful. Thank you!
