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Hello everyone, I hope you are doing well. I'm new to the forums and was hoping you could help me with a vexing vehicular mystery I've been trying to solve.
I just bought a 2005 4.0 V6 manual 4x4 Ford Ranger with an unknown service history, and multiple check engine light codes. About 20-30 seconds after starting up, it goes into a strange surging idle. After an initial RPM of about 1500, the RPM drops to about 400 (and sounds like it's about to stall) before revving itself up to nearly 2000 RPM. It pulses back and forth like this for several minutes, but the problem usually resolves after driving for a bit.
My OBD2 initially read codes for MAF sensor out of range, O2 sensor circuit malfunction, misfires, EVAP issues, and EGR system issues. So I changed the spark plugs, coils, spark plug wires, MAF sensor, cleaned the idle air control (IAC), and swapped the upstream O2 sensors - but the OBD2 still reads all the same codes and the surging idle hasn't changed at all.
I'm confused as to what the issue is. Could the problem be a vacuum leak, or with the engine control computer itself? Any ideas, help, or input that you can offer would be greatly appreciated!
My OBD2 initially read codes for MAF sensor out of range, O2 sensor circuit malfunction, misfires, EVAP issues, and EGR system issues. So I changed the spark plugs, coils, spark plug wires, MAF sensor, cleaned the idle air control (IAC), and swapped the upstream O2 sensors - but the OBD2 still reads all the same codes and the surging idle hasn't changed at all.
Did you do a reset then run truck again to see what codes you have?
You've been busy on this puppy & good idea to have scanned for trouble code clues to begin a trouble shoot. I agree with toolman60, it would be helpful if you'd post All trouble code Numbers you initially found.
Also, the ones remaining, or any new ones that have turned up after the parts were installed, as they can help focus a trouble shoot.
Don't toss out any of the old parts as they may be ok to keep as spares after inspection or bench testing.
Might be helpful if you'd post the mileage on this puppy & were the replaced parts OEM, or lowest cost parts store items!!!!
Resist the urge to toss any more parts at the problem until you post the code Numbers to see if the forums collective mind can assist in getting your trouble shoot in better focus.
More thoughts for consideration, let us know the code Numbers.
I recently was gifted a 2004 Ranger V6 4X4 Edge from my 91 yr old FIL with only 55k original miles on it. It had a very slight stumble at idle. I installed a new air filter, cleaned the MAF, ran a bottle of Techtron through it and also changed out the EGR. I bought a new EGR from NAPA they actually had one on the shelf in stock. This really smoothed out the idle to my satisfaction. It purrs now. I hope this helps!
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