Tech Help - Fixed - 1994 YJ - Jerky, Sputtering Mess After Warm
** FIXED! YAY! **
Dirty or Loose Wire Coupler from Power Distribution Center to Fuel Rail.
My Jeep has not been happy since the CK run. On the way home from it, right before I got to the highway it started acting up. It would sputter and buck when accelerating. At first it would only do it a little bit. But then after a while on the Highway it would do it more. If I stayed a constant speed it was fine. If I accelerated very slow through the gears it was fine. And I mean very slowly. If I tried to accelerate normally it would sputter and buck but would be fine once I got to whatever speed I chose to stay at.
I made it home ok but It continues to do this. But only after I have driven it for a while. the hotter it is outside the faster it seems to happen. I can make it to work in the morning without it doing it much. I can make it home but it does it more. I have a very short drive to work, about 1-2 miles or so.
1994 Jeep Wrangler
about 100k miles on it.
New Parts in Last 6 Months or less:
Fuel Pump, Fuel Filter, Battery, Spark Plugs Wires Rotor and Cap. Catalytic converter.
Sputters and Bucks Under Heavy Load. Like Acceleration or using a higher gear then would be ideal. Like trying to re-accelerate from 4th gear after slowing down to like 20 MPH or so.
Does not exhibit symptoms when engine is cold and has been sitting overnight.
Exhibits symptoms much less after sitting in covered parking all day and Driving home.
Testing Done So Far
Visual Inspected Everything. Found nothing disconnected. Nothing broken.
Replaced Fuel Filter
Performed Fuel Pressure Test with engine off. 32 PSI - Normal
Performed Fuel Pressure Test with engine running at idle. 32 PSI - Normal
Performed Fuel Pressure Test with fuel pressure regulator vacuum line disconnected. 38 PSI - Normal
Checked Resistance on all fuel injectors. All within the normal range of 14.5-15.5 ohms.
Disconnected Oxygen Sensor - No change
Disconnected MAP (Manifold Absolute Pressure) Sensor - Jeep Ran Worse.
Checked Rotor and Cap. Its good. (6 months old or so.)
Checked all spark plug wires and spark plugs. They are good (6 months old or so.)
Air intake is not obstructed. Air filter is not new but is not overly dirty.
No Codes on OBD1 System. (Except normal 55 code)
Engine Runs Fine at Idle.
When its hot I can give it a little gas at idle and get it to do it but it goes away quickly as I give it more gas.
Things I Plan To Do Still
I've been told to test the MAP (Manifold Absolute Pressure) Sensor, TPS (Throttle Position Sensor), and Oxygen Sensor. But I have not had time yet.
Things I'm Assuming / Know Based on Testing
Fuel Filter is Good.
Fuel Pump is Good.
If anyone has any other ideas for me to try It would be greatly appreciated. Thanks for reading.
Last edited by SkepticalChymst; 08-25-2011 at 04:57 PM..