Not your normal power loss from AC

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dgl6y6
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Joined: Wed Jul 22, 2009 8:56 am
Location: St. Louis

Not your normal power loss from AC

Postby dgl6y6 » Mon Jun 03, 2013 8:34 am

Ok you guys Im really stumped on this on. As its just starting to get warm enough here to run the AC, I just now noticed the problem. I know the AC always causes a noticeable power loss but this is crazy. If Im on the highway and i flip on the AC it looses a little power like normal. but after about 15 min of using the ac the power loss is so bad its like im driving with the E -brake on. I can barely get to 50 MPH on level ground. even after i switch off the AC the power loss continues for a while. I replaced the AC pump with a Motorcraft reman about 3 years ago. I have no CEL or memory codes. The ECT and ACT both test out. also the engine normally runs a little cool, about 40% of the way through the normal range. but when ive been running the AC, it gets up right to the middle and goes about 10% over for about 30 seconds when i come to a stop. even when its doing this it still idles smooth but revs slower.

does anybody know at what temperature the computer kicks over to closed loop mode and starts taking data from the O2 sensor? Im wondering if maybe I am stuck in warm-up mode and i need a hotter thermostat to let the engine warm up all the way.

when the fan clutch engages and you hear that roaring noise, could the fan itself cause this much of a drag on the engine?

kirkland2887
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Joined: Sun Jan 29, 2012 6:00 pm
Location: Albion, Idaho

Re: Not your normal power loss from AC

Postby kirkland2887 » Sun Jun 16, 2013 4:52 pm

i have seen compressors completly kill the motor. the fuel trims go into closed loop when the o2 sensors reach a certain temperature and actually start reading. the temperature of the motor does not affect open and closed loop.

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tekatlarge
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Re: Not your normal power loss from AC

Postby tekatlarge » Mon Jun 17, 2013 8:49 pm

Sounds to me like the HVAC compressor is going going going gone
The Tek @ Large
Kent,Worshington
I was borne under a rock. So what's your excuse?

dgl6y6
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Joined: Wed Jul 22, 2009 8:56 am
Location: St. Louis

Re: Not your normal power loss from AC

Postby dgl6y6 » Tue Jun 18, 2013 6:50 am

But why would the power loss continue after the AC is switched off?
and I need to clarify what I put in the description.
The problem is worse if it idles for a while with the AC on and then start driving. or if its on and I stop at a light. If I turn it on while driving on the highway and dont make any stops its not so bad.

dgl6y6
Posts: 84
Joined: Wed Jul 22, 2009 8:56 am
Location: St. Louis

Re: Not your normal power loss from AC

Postby dgl6y6 » Tue Jul 16, 2013 4:59 am

I had an idea about this in the middle of the night. Yesterday I argued with some d-bag about the dubious claims of power gains from a cold air intake. 7.3 diesel sized intake on a honda 4banger. what a moron.
anyway I was remembering about how the previous owner (my old man) had drilled a bunch of 1 in holes in the side of the airbox for better air flow up to the filter. Im wondering if its not the AC at all but just the hot air on the days I run the AC getting sucked into the engine? Im sure that running the AC just makes that even hotter thereby worsening the problem. It was pretty cool this morning so I ran the AC all the way to work and no significant power loss.

BTW I also had my TFI go out last week and changed that out. It runs better than it has in a while but as of yesterday it was still having unusual power loss when running the AC

kirkland2887
Posts: 86
Joined: Sun Jan 29, 2012 6:00 pm
Location: Albion, Idaho

Re: Not your normal power loss from AC

Postby kirkland2887 » Thu Jul 18, 2013 5:43 pm

pull the drve belt off and spin the pulleys. see if any are going bad

dgl6y6
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Joined: Wed Jul 22, 2009 8:56 am
Location: St. Louis

Re: Not your normal power loss from AC

Postby dgl6y6 » Fri Jul 19, 2013 4:31 am

So I blocked off the holes and Problem gone. It was 97 here yesterday and I drove about 10 miles on the highway with the AC cranked. I'm working on a derivative of Occam's Razor, Dave's Razor : It's not the simplest solution but the one you immediately disregarded as "That can't possibly be it". (Dave is me)

drofman
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Re: Not your normal power loss from AC

Postby drofman » Fri Jul 19, 2013 4:22 pm

What Holes?

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tekatlarge
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Location: Kent, Worshington

Re: Not your normal power loss from AC

Postby tekatlarge » Fri Jul 19, 2013 5:24 pm

Hey Drofman,

He said his dad did it long ago when he (The father and previous owner owned the rig.. Sounds like a misguide way to get more air in the engine.

Yeah, I have no doubt at 97 OAT the under hood temp is probably about a billion degrees. Try running an engine like that and it is a wonder it even ran..

Hey dgl6y6,

If ya have some metalized foam tape try covering the box in that reflectorized stuff that will help keep intake temperatures lower. I bought mine for just a couple of bucks and the local Home Depot. Look in plumbing..
The Tek @ Large
Kent,Worshington
I was borne under a rock. So what's your excuse?

dgl6y6
Posts: 84
Joined: Wed Jul 22, 2009 8:56 am
Location: St. Louis

Re: Not your normal power loss from AC

Postby dgl6y6 » Mon Jul 22, 2013 4:10 am

tekatlarge wrote:Hey Drofman,

He said his dad did it long ago when he (The father and previous owner owned the rig.. Sounds like a misguide way to get more air in the engine.

Yeah, I have no doubt at 97 OAT the under hood temp is probably about a billion degrees. Try running an engine like that and it is a wonder it even ran..

Hey dgl6y6,

If ya have some metalized foam tape try covering the box in that reflectorized stuff that will help keep intake temperatures lower. I bought mine for just a couple of bucks and the local Home Depot. Look in plumbing..


That's a great idea, Thanks!!


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