1999 Ford Explorer 4.0 SOHC hesitates, bucks and dies.

[Ranxeroxlubna]

1999 Ford Explorer 4.0 SOHC Limited 197,800 miles.

Initially, the hesitation began just at the start up. Wait a second and it would smooth out and no problems.

2 days ago the following happened.

• Motor died on the road.
• Repeated attempts to start it resulted in a stuttering idle, bucking, and the motor stopped running.
• After restarting the motor, if you work the throttle and let the engine spool up, it would accelerate up smoothly to wide-open throttle.
  
• If you open the throttle all they way suddenly, you get backfires in the manifold and the hesitation and stuttering really go nuts.
• I drove it home after clearing out whatever was involved, it stuttered and hesitated all the way home, but it got there. I put it in neutral at the lights and revved it up to keep it going.

What I have done.

• I sprayed starter fluid on all the vacuum connections with no change to the idle.
• I pulled the spark plug cable off the coils, one at a time; the front row caused major changes to idle, the back row did not seem to have as much of an effect, less as moved from 3-2-1.
• I disconnected the MAF connector and it did have a very subtle effect.
• I disconnected the intake hose at the throttle body and it ran a bit better, although moving the throttle manually repeated the aforementioned problems.
• When I reconnected the intake hose to the throttle body, it just died.
• I get no codes.
• The computer seems to struggle to connect with the diagnostic device.
• I cleaned the MAF in late summer.

Not sure what to do.

 

[XLTrunner]

Check your fuel pressure. How long since the fuel filter's been changed? Original fuel pump?

 

[96eb96]

1. STFT B1% - 10.1
   LTFT B1% - 25.0
   STFT B2% - 13.2
   LTFT B2% - 25.0

1. Pressure still at 24-25 PSI when I checked upon return home.

Brand of fuel pump?

PCM with the those numbers looks like it is desperately trying to add fuel. Similar to a vac leak, but it seems like fuel starvation.

Try disconnecting the fuel pressure regulator vac line.

What is the baro pid reading (you may need forscan).

 

[Ranxeroxlubna]

1. 
   
   
   • STFT B1% - 10.1
     LTFT B1% - 25.0
     STFT B2% - 13.2
     LTFT B2% - 25.0

1. 
   
   
   • Pressure still at 24-25 PSI when I checked upon return home.

Brand of fuel pump?

PCM with the those numbers looks like it is desperately trying to add fuel. Similar to a vac leak, but it seems like fuel starvation.

Try disconnecting the fuel pressure regulator vac line.

What is the baro pid reading (you may need forscan).

Sorry I've been off, I caught the flu. Took me down for a few days.

I'll disconnect the vac line form the FPR tomorrow. Still not 100%.

NAPA fuel pump, their best one.

What is the baro pid reading?

 

[Tech By Trade]

If your due for an oil change, can I suggest pulling the pan and seeing how much metal and plastic is laying in the bottom of it?

 

[FF_RSQExplorer]

So did I read that right you did a cylinder balence test and obe whole bank of the engine had no effect? You have mechanical issues, timming, compression, valve train etc.

24psi at the rail? Whole different problem, 24 psi is too low for EFI

 

[Ranxeroxlubna]

1. 
   
   
   • STFT B1% - 10.1
     LTFT B1% - 25.0
     STFT B2% - 13.2
     LTFT B2% - 25.0

1. 
   
   
   • Pressure still at 24-25 PSI when I checked upon return home.

Brand of fuel pump?

PCM with the those numbers looks like it is desperately trying to add fuel. Similar to a vac leak, but it seems like fuel starvation.

Try disconnecting the fuel pressure regulator vac line.

What is the baro pid reading (you may need forscan).

I disconnected the vac line from the fuel pressure reg, no effect or change.
My Innova doesn't have the ability to check PID, .and the one at NAPA didn't either. I'll get one. What am I looking for?

 

[Ranxeroxlubna]

If your due for an oil change, can I suggest pulling the pan and seeing how much metal and plastic is laying in the bottom of it?

I cleaned the pan out 2 years ago when i replaced the timing chain and the runners. Why would that be an issue?

 

[Ranxeroxlubna]

So did I read that right you did a cylinder balence test and obe whole bank of the engine had no effect? You have mechanical issues, timming, compression, valve train etc.

24psi at the rail? Whole different problem, 24 psi is too low for EFI

I know 24 PSI is low. I'm wondering if the regulator is busted.

I'm not sure what you're referring to regarding the Balance Test. Sorry.

 

[Tech By Trade]

Thinking your timing may be out again. Maybe a gear slipped.