The engine starts and runs beautifully. When you first shift it into gear, forward or reverse, it hesitates then shudders and goes. After you get up to highway speed, it runs great until you ease more gas to it, then it shudders like something is loose or out of balance. My husband is a mechanic, he thinks it may be the torque converter either coming loose or going out. I think it may be something else, like a timing problem, vacuum leak or dirty injectors, but that may be wishful thinking. Does anyone have any ideas? Repair manual does not have what you could call a helpful troubleshooting guide!
You should be able to duplicate the issue with the truck parked. If it is something causing a miss in the engine you should find the exhaust tailpipe "puffing" as if you have a burnt valve or dead cylinder. A vac gauge would also show the loss of power on some cylinders.
If it is the transmission you should be able to feel a great deal of vibration coming from it rather than the engine.
SOURCE: I think i have a vacuum leak and some OBD codes to figure out
A P0303 P0204 code means that the the car's computer has detected that two of the engine's cylinders is not firing properly. In this case it's cylinder #3 and #4.
Symptoms may include:
The engine may be harder to start
The engine may stumble / stumble, and/or hesitate
Other symptoms may also be present
A code P0300's may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter
Running out of fuel
Poor compression
Defective computer
Things to look for:
Check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule.
I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
A code P0125 means that the engine coolant temperature (ECT) sensor indicates that the engine has not reached the required temperature level to enter closed-loop operation within a specified amount of time after starting the engine.
The simplest thing to do is to reset the code and see if it comes back.
If the code comes back, the problem is likely going to be the result of a (faulty thermostat, faulty coolant sensor, or a low coolant level).
P0705 mean's the Transmission Range Sensor Circuit malfunction (PRNDL Input) It is what looks like an old backup light/neutral safety switch and is attached to the transmission where the shift lever goes in.
Some vehicles may exhibit a Malfunction Indicator Lamp (MIL) illuminated with Diagnostic Trouble Codes (DTCs) P0442, P0455, P0456, P0457 or P1442 or a "Check Fuel Cap" Lamp illuminated with DTC P0457 for the Evaporatetive Emission System. This may be caused by loose or leaking hoses, loose or broken fuel cap, a leak at the top of the fuel filler pipe neck, a faulty purge valve, FTP sensor and etc. Has the vehicle been back up or bottomed out over something that tagged the vapor canister? I believe that the vapor canister sets under the vehicle just behind the fuel tank.
P0455 means a large vacuum leak or no vacuum in your EVAP system.
Good luck and hope this helps.
SOURCE: 99 ford expedition 4.6 misses / egr? vacuum?
it's getting to much egr the egr has gone bad and needs replaced.
the diaphragm in the egr is leaking, and default position for air is defrost.so when you hit 3000 rpm you don't have enough vacuum.
SOURCE: stalls when put into gear
Its possible it could be other things causing the problem, but seeing as you've checked most of the likely causes, it is most likely your Torque-Converter. The lockup clutch in your Stator-Fan located inside the Torque-Converter could be siezed, causing the car to stall.
SOURCE: engine cuts out or bogs down when accelerating
if the engine light is flashing, it means you have a misfire in one or more cylinders. it is most likely plugs or coil wires.
mine started doing this a few weeks ago. finally got around to changing the plugs today. the cylinder order on fords is easy, passenger side from front to back is 1234, driver side front to back is 5678. my number 4 cylinder had a plug that was collapsed. the metal piece was crushed into the contact, not allowing any spark.
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Thaks for the quick responses. They give us a few more things to check out before running it into the scrapyard!
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