Hesitating Engine

[diehard80's]

I have an '87 Ranger with a 2.9L that wants to die after starting up. It works fine during it's fast idle, but then wants to die (and usually does) once it goes down to regular idle, and then it will run fine after a few seconds. Whatever it is, I suspect it is the same problem that causes it to hesitate and sputter while trying to accelerate for a few seconds and then all of a sudden kicks in and works fine. All of this usually only happens when the motor has not completely warmed up yet. Would anyone know the source of this issue? Thanks!

 

[Mark_88]

Do you have the pipe coming up from the exhaust manifold to the breather inlet connected? This allows warm air in during warmup and then closes to allow cold air into the TB...but it is vacuum driven...and if the vac line is off or broken then you're getting cold air on warm up...which makes things rough for a few minutes...

Does the acceleration hesitation happen only during warmup also or is that constantly a problem? That would indicate something else entirely...or maybe a combination of two or three things...

 

[diehard80's]

Do you mean the EGR valve? That seems like it's hooked up fine, and I replaced it almost a year ago. This issue just started about two months ago. Actually the acceleration problem happens at random times, whether the engine is cold or hot. The way it fumbles for a few seconds and then all of a sudden jolts into working fine kind of makes me think it's an electrical problem of some sort... bad sensor somewhere perhaps?

 

[Mark_88]

Perhaps a bad sensor...

Not the EGR...but a sort of vent pipe coming up from the exhaust manifold and connecting to the air inlet for the throttle body...I've seen them on Fuel Injected engines (mostly carbed) and not even sure if the 2.9 had one...

Anyway, if it not only at warm up then sensors are more likely the cause...did you manage to check for codes? That would tell you more than a million dollars worth of guesses...

 

[diehard80's]

Hm... I'll double check that. Is it possible to check the diagnostic system for codes even if the check engine light isn't on?

 

[Psychopete]

the check engine light will never turn on, it doesn't have a functioning CEL. that is a good place to start, though.

 

[rebel167us]

Check your spark plugs and if they look anything but normal change em'. I had the same issue. I had changed the TPS, IAC and EGR. Still nothing. I had bad spark plugs. One was soaked in oil, Two were white and just nasty looking and the rest were normal. It seemed to cure the problem. Who'da' thought?

 

[rebel167us]

Turns out I'm Still having the Same problem you are. my CEL works, but doesn't stay on or anything. Someone told me it could be one of three things: MAP Sensor, EGR Valve Position Sensor or Fuel Pressure Regulator sensor. I'm betting on the MAP Sensor.

 

[Psychopete]

It's not impossible for the CEL bulb to burn out. It's easy to pull codes, I would start there for any hints. You have a greater chance of losing than winning when you make bets.