joefnh
Well-Known Member
- Joined
- April 30, 2005
- Messages
- 223
- Reaction score
- 0
- City, State
- New Hampshire
- Year, Model & Trim Level
- 03 XLT
- Callsign
- KA1DGB
I have a 2003 Explorer 4.0L XLT 4WD with 301,000 miles.
Has a rough starting process that the RPM’s jump up to maybe 1500 and then dip and sometimes stall, it does this RPM cycling a few times but after about 30 seconds, it idles fine and will be fine throughout the day as long as the engine is modestly warmed up. The confusing part is that there is a real time limit for this behavior of about 30 seconds and then runs and drives fine. First thing in the morning the engine will not have warmed up in 30 seconds from a cold start, but this time issue is repeatable each time. I can drive to the store and be there for an hour come out and it starts and idles fine. If the car sits overnight it will start rough again and after this roughly 30 seconds then runs and drives fine
So here’s a list of what I know and have done:
- No codes displayed or are pending, checked several times
- I have cleaned the MAF sensor 2 times including the connectors with MAF cleaner
- Replaced the IAC
- Re-seated all plug and coil wires.
- I have used the old starting fluid check to see if there are any vacuum leaks. Sprayed around the intake manifold base and the throttle body. I have not measured the vacuum level yet. With the very real time factor Involved where the problem goes away with either time or being warmed up, it doesn’t sound like a chronic vacuum leak issue
With the issue of the engine being slightly warmed up and the short time where the problem stops, this seems like some type of sensor issue and the computer causing the rough start. This is a very high mileage vehicle but it runs great, does not burn a drop of oil and still gets about 18 - 19 MPG (mixed driving) The engine has no knocks or ticks. I have meticulously maintained the vehidle.
Any ideas??
Thanks
-Joe
Has a rough starting process that the RPM’s jump up to maybe 1500 and then dip and sometimes stall, it does this RPM cycling a few times but after about 30 seconds, it idles fine and will be fine throughout the day as long as the engine is modestly warmed up. The confusing part is that there is a real time limit for this behavior of about 30 seconds and then runs and drives fine. First thing in the morning the engine will not have warmed up in 30 seconds from a cold start, but this time issue is repeatable each time. I can drive to the store and be there for an hour come out and it starts and idles fine. If the car sits overnight it will start rough again and after this roughly 30 seconds then runs and drives fine
So here’s a list of what I know and have done:
- No codes displayed or are pending, checked several times
- I have cleaned the MAF sensor 2 times including the connectors with MAF cleaner
- Replaced the IAC
- Re-seated all plug and coil wires.
- I have used the old starting fluid check to see if there are any vacuum leaks. Sprayed around the intake manifold base and the throttle body. I have not measured the vacuum level yet. With the very real time factor Involved where the problem goes away with either time or being warmed up, it doesn’t sound like a chronic vacuum leak issue
With the issue of the engine being slightly warmed up and the short time where the problem stops, this seems like some type of sensor issue and the computer causing the rough start. This is a very high mileage vehicle but it runs great, does not burn a drop of oil and still gets about 18 - 19 MPG (mixed driving) The engine has no knocks or ticks. I have meticulously maintained the vehidle.
Any ideas??
Thanks
-Joe