2008 ford ranger 2.5, what could be the problem if engine starts normal but after second the engine fluctuate?
Bleeding the fuel system is typically only needed on high pressure systems like GDI and Diesel vehicles, and only to get them to start if they run dry once.
If your engine keeps running but the idle speed moves up and down there are many things that can cause that. More information is always helpful. Does it always do it whenever the car is running? Or does it only do it conditionally (IE Only when 1st started in the morning, only after warmed up or getting off the dreeway, only with AC on or at night...describe as much as you can.)
Most newer cars have computer controlled idle strategy that wants to idle the car cold around 1000-1500 rpm (After an initial higher rev called a FLARE) and then bring it down in 3 or 4 minutes to 700ish rpm. If it CANNOT bring it down by normal means, then many resort to something called FUEL CUT IDLE where it actually turns off the fuel momentarily and the RPM will drop because the car is stalling and running out of gas...then back on and it starts to rev back up and when it gets too hiugh it turns back off. Cars that do this can have annoying surges from 500-2000 back and forth at idle forever.
a vacuum leak or MAF meter problem can cause rough idle. ALmost any engine code that turns on CHECK ENGINE lamp may be suspect, does it have any current fault codes?
As well, consider Sticking manifold runners, EGR systems, and temperature sensors all can cause surging, so can a defective Oxygen sensor, slightly jumped timing, and dirty throttle plates the ECM wants to close more but they wont due to dirt. If its not something fairly obvious, it may require deeper checking.
Jan 29, 2015 |
2008 Ford Ranger 2.5