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

Question about a "surge" on the air intake...

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Old Mar 18, 2008
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WowMike2001's Avatar
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From: Stevenson, WA
Question about a "surge" on the air intake...

Not sure if its common or whatnot, it isn't too bothering but I need to know if anyone has any issues on when your going a steady speed, say 25mph in town.. and every now and then you can hear the intake suck in a little more air then normal and sort of pulses for just a second then goes back to normal. The engine RPM's pulse with the intake rising as well, I can feel it pull forward ever so slightly...

I have a K&N FIPK II CAI installed on my truck.. I cleaned the MAF sensor just to see if it would do anything, still pulses ever so slightly from time to time. Not worried about it that much, just seems odd.. wouldnt mind having an engine that runs 100%, but let me know if you have any ideas!
 
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Old Mar 18, 2008
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From: Boring, Oregon
Mine does the same thing......sorta sucks in more air for a few seconds, them goes back to normal. I'm cuious as to the reason as well.
 
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Old Mar 18, 2008
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From: Stevenson, WA
I read up a teeny bit.. searched and dug for a very broad range of searching, Someone recommended something about changing the fuel filter.. I might go ahead and do that down the line perhaps.

All the way up to it being a surge in the air compressor, supposedly somewhat "normal" in certain circumstances.


Any other recommendations or things to take a peek at may help as well too :-)
 
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Old Mar 18, 2008
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The A/C compressor clutch may be cycling normally. Depending on the ambient temperature, the compressor can run in every HVAC mode except OFF, FLOOR ONLY and VENT ONLY. Try switching the control to OFF and see if it stops surging.

Another idea - In addition to its idle function, the IAC valve is also active during cruise conditions. The PCM prepositions the IAC partially open to reduce the high vacuum that occurs during decelerations and manual gear changes. (Sudden vacuum increases cause condensed fuel in the intake runners/plenum to flash to vapor which may cause hydrocarbon spikes on the emission test.) You may be hearing the normal function of the IAC that is just more noticeable with the unsilenced FIPK. Or the IAC could be sticking slightly before jumping to the correct position.
 
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Old Mar 18, 2008
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From: Stevenson, WA
Hmm, good information indeed... Its not very bothering at all liek I mentioned above.. I'm jsut more curious as to what it is... thanks for a heads up on that, I can test it out switching the compressor to off for a bit.


Thanks rwenzing!!
 
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Old Mar 18, 2008
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Holy crap! I completely forgot about the AC clutch...duh. I knew that...but forgot. Bob, as always, your'e the best.
 
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