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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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Old 09-15-2012
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Pinging and High Idle

Hello there,

So My truck just recently started having a problem with high idle and pinging.

The truck will ping under load, and idle will stick at 1500, sometimes the idle will eventually go down after like 20 secs or so.

So If I unplug the MAF the truck stops the pinging, however the idle still sticks.

With the IAC unplugged the Truck idles fines, just super low, sometimes it dies when its cold.


I have been driving it with both Unplugged and its been running decent this way.

Today I tried replacing the TPS sensor, Because it was fairly cheap, and it made sense that the TPS could cause this problem as well, since it interacts with the other two in the same system. Problem is still there.


The truck has a produced a MAF Code, However.. .I have been getting this code for a year or two now. Engine light will flicker on once in a blue moon, but the truck always ran fine. I just never messed with it.

The MAF would be my next guess, but only a guess.

Something that I have always wanted to know, that maybe someone can answer....

When you unplug the MAF, the book says that this will put the computer into a limp home mode, Now what I never know is, does this disable the MAF or several sensors in the system? Not knowing which this is, makes it difficult to diagnose the problem.

I was reading that these could be symptoms of a vaccum leak, however, The fact that it idles fine with out the IAC plugged in should rule this possibility out, and it has to be a sensor somewhere.
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Old 09-22-2012
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The problem has been resolved.

Engine got hot and blew a head gasket. Gauge never Indicate a hot condition. Upon dissassembly we found that the temp sensor had come unplugged. Engine is put back together with fresh gaskets and it runs fine again. Idles and timing is fine.

I always read that the temp sensor could cause all kinds of problems. Amazing what one unplugged wire can do.

Oh and the Engine got hot because the Top radiator hose was leaking, it was only dripping water onto the top of the intake, Not significant enough to cause to blow, or be too noticeable, but apparently enough to empty the system over time, causing the head gaskets to fail, and due to the temp sensor being uplugged, by the time we realized it was hot it was too late.
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