Hey everyone:
'07 Ranger-4.0L-4x4-52,000 miles:

I have noticed a thumping noise when I have the A/C engaged. I know for sure the noise is not from the A/C clutch engaging/disengaging. It only makes noise with aftermarket high flow air filters. When I put the OEM filter in the air box I don't get the thumping noise. I was wondering if my truck is not creating enough vacuum because of how easy it is breathing with the AFE Dry Flow filter. Any suggestions about how to get the noise to stop? Advance the timing; is it possible and how? Programmer? Thanks in advance

Hella 4.0

 

Well the obvious answer is to reinstall & run the OEM air filter, it isn't meaningfully restrictive at any reasonable rpm we usually turn anyway.

But I suppose you want to run the new filter you've paid big bucks for!!!!

SO, Is the thumping noise you hear with the A/C on, inside the cabin, or under hood????

 

Under the hood. When I have the A/C on and I place my hand on the "vacuum ball" (I'm sorry I do not know the proper name) It's located below the air box on the passenger side, mounted on the splash guard, two vacuum lines are running to it: I can feel the thump when the A/C engages and disengages. A knowledgeable co-worker of mine mentioned that I may have a vacuum valve sticking; there is an in-line vacuum valve in one of the lines from the "ball." Thank you pawpaw for understanding, that yes I would like to use the new air filter. Also thank you again for the help!



4.0

 

When you install the OEM filter, do you "feel" the same thump at the same place, when the AC cycles on????

Have you modified the OEM air box????

On the timing question, the computer adjusts the spark & fuel injector timing on our engines, depending on the PID inputs it gets from a number of sensors & what we are asking the engine to do with the go pedal & tranny.

Yes the timing & auto tranny shift points can be messed with via a performance chip, or programmer, but the folks making the chip, or using the programmer had better know what they're doing.
Messing with all that could void any warranty you might have.

 

I hope this isn't too confusing...

No modifications to the OEM air box. With the stock air filter: I only feel or hear the thumping upon the initial engagement of the A/C. I turn it on, I hear the compressor cycle on and then 5-8 seconds after the compressor cycles on, a loud thump; like someone punched the front side of my truck. Regardless of which filter I have installed, I will get that initial thump when I first turn on the A/C, Cold or Hot weather. Took it in while I was under warranty and the dealership said it was normal. I told them they are crazy if they think I'm going to believe that and I left. Another dealership said same thing! It is not normal, I've been around a truck or two and please trust me. It is similar to when you are chewing gum and you pop a bubble in your mouth, with your mouth closed. You get that pop with a bit of bass, but that is just the initial engagement of the A/C, I don't get that loud thump each time, only smaller ones each time the compressor disengages. My RPM's are not stable when the compressor disengages, they bounce between 800 and 600, when idling in Drive at at stop or in Park, then level out around 800. No thumping at normal driving speeds.

Modifications:
I have installed a JET Mass air flow sensor, AFE Pro Dry S Air Intake, Throttle body spacer and Cherry bomb glass pack exhaust. I am no longer covered under warranty. (52,000 miles)

I sincerely hope this helps. Thank you again!



4.0

 

Not sure whats going on with the thump/pop when the A/C engages.

The mods you've made might be affecting the idle stability, as could an acting out IAC.

There have been so many changes made I'm not sure how together they may be affecting the computers PID inputs.

Did the thumping/pop & or idle instability begin after any particular mod????

 

The sound was happening before any of the modifications. The unsteady idle, after compressor disengages, happened when I added the AFE intake. Just sucks that the filter works great and I get this unsteady idle thank you pawpaw for your diligence!


4.0

 

When you added the intake, did you eliminate, or move any of the OEM sensors????

The air intake system, including the air filter, needs to provide a smooth, uncorrupted laminar air flow through the MAF sensor, if not, it's likely to feed the computer corrupt air flow info.

Don't know anything about the brand MAF sensor your using, but if it's PID to the computer is outside the computer programs expected output from a Ford MAF sensor, that could confuse the computer about true airflow into the engine.

If any intake sensors have been moved, or eliminated, jumpered, or otherwise messed with in order to try getting around the computer, it's likely to just end up confusing the computer.

The A/C clutch solenoid makes a click/clunk sorta sound when it actuates on & off.

 

Everything is still the same, no modifications to any sensors, other than mentioned upgrades. I unplugged the Idle air control valve tonight and I got a steady idle and no thumping sound.... I'll be taking my truck to a shop to have them run a diagnostic test on it to see what's going on. Thank you "pawpaw" your knowledge is insurmountable.


Fellow Ranger Owner,

William Keene.

 

OK, good idea on disconnecting the IAC to test idle quality.

Before spending the money for diagnostics, you might try removing the IAC & cleaning it inside with a plastc safe cleaner like CRC MAF spray cleaner & see if that'll make a postive difference in idle quality.

If so, you'll know what to replace if/when the problem returns, as cleaning the IAC often doesn't last, as it didn't for me, but it was a good, easy to do & inexpensive diagnostic step.

 

Well, I think I may have harmed the IAC when I removed it in the past for cleaning. I was a bit naive to plastic safe cleaners and I might have used something I shouldn't have. I've cleaned it twice in the past, once with Throttle Body Cleaner and once with MAF cleaner... stupid me. Well good thing I work for NAPA Auto Parts, I'll put that discount to good use for a new IAC! Thanks again pawpaw!




4.0

 

Sounds like plan to me, let us know how it goes.

Well Ford recommends replacement, as cleaning the IAC, even with a safe product, often doesn't last.
But I think it's a good, easy to do & inexpensive diagnostic/trouble shooting step, before we lay out our gold for a replacement!!!!

 

Ranger 2007 4.0L 53,300 miles:

Short and sweet/sour guys....

Engine idling, I raise RPM's to ~1200-1300, I get the "Thump" sound and the RPM's shoot up to ~2100-2200; I do not move the throttle at all after I reach the ~1200 RPM mark. Once I release the throttle the engine slowly winds down to the ~1200 RPM mark and I get the "Thump" again, and then the engine returns to normal idle of ~800-900 RPM's.

I installed a New IAC, no change. Plugged in a Code Scout, no detection of codes.

Some knowledgeable guys are thinking a Vacuum issue, but where? Others think a sticky valve in my head(s). How do i find out if I have a sticky valve?


Thanks everybody, I like to learn and I want to be a better Ranger owner!

 

Well lets think about this some more.

You posted above that when you disconnected the old IAC, you got a steady idle & no thumping, is that still the case with the new part????

What happens when you turn the in cabin Heater/AC **** to the OFF position????

After you installed the new IAC, did you pull the battey B- cable for at least 15 min, to wipe the computers memory & then go through the cold & warm idle relearn proceedure, so it could relearn it's cold & warm idle strategy with the new IAC in place????

Edit: You also posted earlier this year, that you had a "thump" that was associated with a high perfomance air filter you had installed, but you didn't get it with the stock air filter in the air box, so is the stock filter now in place????

 

Hey PawPaw,

Sorry it has taken me so long to get back to this...

I returned everything back to stock, everything. I went through the re-learning process for the idle and so forth. I am still using the old IAC because I returned the new one. I did not try this with the IAC unplugged because I am not sure if it is that anymore. I do not get the thump sound anymore, but the RPM issue is still occuring. When I bring the RPM's up to 1200 and hold the throttle steady, they shoot up to 1800-2000*. Then I let off, and the RPM's slowly come back down to 1200 and then drop suddenly to 800 RPM. The result is the same every time, right at 1200 and up to 1800-2000 and right back down to 1200 again with the sudden drop as soon as it hits 1200. 1200 is where i was getting the thump before, just now I cannot hear the sound.

* = correction of noted RPM from previous posts.