2010 f150
Asked by ChrisO2311 Jan 07, 2018 at 11:05 AM about the 2010 Ford F-150 XLT SuperCrew LB 4WD
Question type: Maintenance & Repair
What would cause rpms to jump up and down when in
park?
Bad spark plugs?
Thanks
8 Answers
Unmetered air entering engine caused by a vacuum leak. Bad or dirty sensors like a MAF or MAP. Bad idle air control (IAC) valve. Try cleaning the throttle body first, spray down the MAF with a MAF-only cleaner (carb cleaner can destroy it). Clean PCV valve/elbow. Check PCV & EGR hoses aren't cracked letting unmetered air in. If this only happens when in park or at idle, without your foot depressing gas pedal then suspect the IAC.
ChrisO2311 answered 6 years ago
Awesome will do all of this. I was thinking maybe fuel pump starting to go not too sure tho
you'd feel loss of fuel pressure when accelerating most, and bad plugs would be giving you misfires, loss of power. A hunting idle is a sign the engine computer can't decide how much fuel to use to match incoming air, when there is unmetered air entering, and that's usually the fault of a vacuum leak or a bad sensor somewhere.
ChrisO2311 answered 6 years ago
I looked and it turns out that my MAS clip is broken the part that connects to the intake. Could this be the issue
I'd say so, otherwise the ECM has no way to determine amount of air flow, or the sensor is sending spurious input to it causing ECM to move idle up and down.
ChrisO2311 answered 6 years ago
Well I found out what the problem was. I tested in ohms the accelerator pedal and the throttle position sensor.. (not a fun thing to do) but the TPS is bad and my throttle body is filthy
ChrisO2311 answered 6 years ago
The other problem was a cold air intake. Thoughts I like the sound the engine makes with one. Any ideas