2.5L ('98-'01) 2000 2.5L Auto Pulsing Vibration at All Speeds.

[HighMileage93]

Dad's Ranger started acting strange all of a sudden last night. Pulsing vibration at all speeds, downshifting different than before, stopped at light and idle dropped way down and rough, oil pressure guage dropped with needle wag, light turned green and could barely get it to take off. When it finally did take throttle again it was abrupt and spun the tires. Did this the rest of the way home. This morning, started and idle went high and took a good while to come down some but not to normal. Seems like delayed shifts too. WTH? No check engine light and no stored codes.

 

[Uncle Gump]

I moved this to the correct engine forum.

Most times when you have unstable idle it can be related to a vacuum leak. Depending on where it is... other symptoms can also be noted.

I would pop the hood and take a long visual inspection of all vacuum hoses first.

 

[HighMileage93]

Okay, it just now threw a trouble code.
P1132 - Lack of Upstream Heated Oxygen Sensor Switch, Sensor Indicates Rich Bank 1.

 

[Uncle Gump]

Doesn't mean the HEGO is bad...

Could mean a vacuum leak making the sensor trigger the code.

 

[HighMileage93]

Truck has new plugs, wires and a new upstream O2 Sensor. Going to check vacuum lines for sure.

 

[SenorNoob]

Rich for a vacuum leak? First thing I'd check is the vacuum line to the fuel pressure regulator if 2000 still has one on the engine.

 

[scotts90ranger]

That went away in '98 I think but there sounds like some type of issue, might be worth checking the fuel pressure...

Running rich would explain some things, could be the MAF reading high airflow which is usually backwards of what happens but it's also backwards of what a bad O2 sensor normally does or even a vacuum leak so I'm not too sure.

 

[RobWigglezz]

This is when looking at the live data though a scanner can really help. But no throttle response leaving a stop light and then it returning quickly is curious. . Floods itself at idle and pressing the throttle takes a few seconds for it to clear up.

 

[scotts90ranger]

Yeah, sounds like one of those super fun to diagnose intermittent issues... almost sounds like a shorted wire on the MAF tricking it to think there's more airflow than there is but that would take some very specific things to happen wrong...

 

[RobWigglezz]

There's a TSB for 2000 and 2001 might experience rough idle, delayed or harsh shifting transmission, erratic or inop speedo if connector under drives seat gets corroded from water intrusion. Other half of connector is underneath the vehicle

 

[HighMileage93]

My trusted mechanic put the scanner to it. Lots of misfiring on cylinder 3 but not throwing a 303 code.