Engine Surging w/ A/C on every 20 seconds?

[OVERKILL]

Originally Posted By: 01rangerxl
Originally Posted By: Rocko1
Didn't see the valve that looks familiar. Only saw these.

Any ideas?


Hmmm...the first one looks like it's just a sensor. Not sure what the thing in the second picture is.

It should be very close to the throttle body. On my truck, it is directly behind the throttle body.

It should look something like this...

#1 is the TPS
#2 is the DBW throttle motor assembly.

This engine has no IAC as the OP has now mentioned.

Has this only started happening since you changed the plugs?

 

[Rocko1]

Did it before the plug change. Was hoping that would help.

 

[OVERKILL]

Originally Posted By: Rocko1
Did it before the plug change. Was hoping that would help.


Gotcha.

Do you have a scanner or anything that you could log what's going on when this happens?

 

[Rocko1]

No I wish I did. I have a vacuum gauge not sure if that helps. Strange thing is while in neutral or park with a/c on this does not happen. Brake on or not doesn't effect it also.

 

[OVERKILL]

Originally Posted By: Rocko1
No I wish I did. I have a vacuum gauge not sure if that helps. Strange thing is while in neutral or park with a/c on this does not happen. Brake on or not doesn't effect it also.


So only when it has load on it.

Yeah, hook up the vacuum gauge for S&G's and see what it does while this is happening.

 

[Rocko1]

Did a bit more investigating. It is related to the a/c compressor coming on. Strange it never happened before.

Should my a/c compressor cycle every 20 seconds?

 

[01rangerxl]

My Fords have always cycled the compressor frequently at idle. Both Rangers and my Explorer did it with properly charged and functioning AC.

 

[OVERKILL]

Originally Posted By: Rocko1
Did a bit more investigating. It is related to the a/c compressor coming on. Strange it never happened before.

Should my a/c compressor cycle every 20 seconds?



How well does the AC work?

 

[Rocko1]

Originally Posted By: OVERK1LL
Originally Posted By: Rocko1
Did a bit more investigating. It is related to the a/c compressor coming on. Strange it never happened before.

Should my a/c compressor cycle every 20 seconds?



How well does the AC work?


Decent. As well as it always has. I just never felt that surge or dip in rpms before.

 

[OVERKILL]

Well, I'd pursue it with Ford if it gets worse. For now, I'd just live with it.

 

[yonyon]

Maybe your throttle body, MAF, and intake tract aren't as clean as they used to be. Consider cleaning all that out and doing a battery disconnect. If that doesn't help, maybe check with your Ford dealer to see if there's any software update to address the issue. If it were mine, I'd just be glad it does that. Some of my cars don't have clutch-cycling AC and I find it annoying. There's a certain comfort in the familiar feel and sound of the AC cycling normally at idle.

 

[Rocko1]

I will do that. Thanks for the replies.

 

[JosephHarmon]

Low refrigerant will cause excessive cycling of the compressor.

 

[Rocko1]

Ok, pulled the battery for 15 minutes, took apart the air intake and look around. Looks like the throttle body is pretty dirty.

Didn't feel the surge this morning, but will try it more when it warms up.

Is it best to clean this off the truck or? I have seen people spray liberal amounts of throttle body cleaner but couldn't than hydro-lock the motor?

 

[OVERKILL]

It really doesn't look that awful, but you could do what I do, and that is use some AC Delco combustion chamber cleaner and a tooth brush, that will clean it right up. Then wipe it out with a rag. You can do that without taking it off the truck.

 

[Rocko1]

Ok this weekend I am cleaning the throttle body. I cleaned the MAF sensor and it did not change anything. If the throttle body cleaning doesn't yield any results I am guessing from the hours spent reading it could be a vacuum leak I have yet to detect and the beginning of a COP failing. I will report back. Thanks for the input so far.

 

[Rocko1]

Minor update. Cleaned the throttle body. Was not too bad. Took about 40 minutes. Truck idled perfectly for about an hour then the idle jumped around a bit. Next test is throttle position sensor.

 

[JHZR2]

Originally Posted By: Miller88
Then again, the compressor in my Cherokee cycles every 20 seconds or so, blows ice cold air and has the correct amount of refrigerant.


IMO it is highly ambient temp related and system related. Some of mine cycle a lot, others not. All cool well.

I dont think that a permanent change in RPM is right, but some cars, depending upon how fast their ICVs are, do show a drop and then a correction.

 

[Rocko1]

Originally Posted By: JHZR2
Originally Posted By: Miller88
Then again, the compressor in my Cherokee cycles every 20 seconds or so, blows ice cold air and has the correct amount of refrigerant.


IMO it is highly ambient temp related and system related. Some of mine cycle a lot, others not. All cool well.

I dont think that a permanent change in RPM is right, but some cars, depending upon how fast their ICVs are, do show a drop and then a correction.



I agree. What's strange is this just started and is accompanied with a slight rougher idle-now even with no a/c on. The a/c might just be what is exacerbating the underlying issue. Not many things left. Fuel filter, air filter, spark plugs new, clean throttle body, MAF. I will see how the TPS does today(no IAC on this year).