Power loss?

KK4x4 · **Posted:** Sun Nov 18, 2012 2:52 pm

Hey everyone, another month another problem. I gotta weird one here (weird to me at least). Everyone obsvally knows about how engines could have power surges at idle...well...how about just sitting in the driveway with the engine all warmed up from driving and the heat on but instead of a power surge it was almost like a power loss. The rpms were just sitting around 1000 but then like every 30sec or so they would drop almost below 500. Every time it did this it almost stalled but then was brought back up to the normal idle. My mom was driving it and she told me it was only becaus the heat was on so she showed me and shut it off and the idle drop(?) stopped, then she turned it back on and the problem resumed. Could it be a problem with the battery or even the alternator? I've never seen or heard of anything like this before so I'm at a total road block here.

Gageraid · **Posted:** Sun Nov 18, 2012 3:08 pm

You can easily test your battery or alternator at a Napa for free if you don't have the tools.

lfhoward · **Posted:** Sun Nov 18, 2012 3:52 pm

Little bit of a hijack here, but can you test a car battery at home with a multimeter? If so, what reading should you get?

Back on track now... 1000 rpm idle when hot seems a little high. Shouldn't the hot idle for the 3.7 be something like 600 rpm?

Gageraid · **Posted:** Sun Nov 18, 2012 4:26 pm

I believe the readings should be on the battery itself. Yes, a multimeter will work. 1000 RPMS does sound very high, maybe it was just an estimate. I do believe the KK idles at our very close to 600 RPMS.

Ted15 · **Posted:** Sun Nov 18, 2012 4:46 pm

A multimeter will only tell if the voltage is there. You will need a load tester to see if the battery is any good.

KK4x4 · **Posted:** Sun Nov 18, 2012 5:19 pm

Yeah my bad its not 100 it's at 600 then drops to 400

Gageraid · **Posted:** Sun Nov 18, 2012 5:22 pm

KK4x4 wrote:

Yeah my bad its not 100 it's at 600 then drops to 400

That doesn't sound too extreme now. It might still be a good idea to do some testing. If it throws a code, then you'll know there's a real problem.

KK4x4 · **Posted:** Sun Nov 18, 2012 7:06 pm

*1000 not 100 lol I don't think it can run at 100. And yeah I'm gonna try and take it to autozone or something this week and get it tested.

tjkj2002 · **Posted:** Sun Nov 18, 2012 8:15 pm

Sounds like the AC compressor kicking on and dropping the rpm's,explain why it does it with the heat on and at even intervals(clutch kicking on/off).This is normal but the PCM should adjust the idle a little faster with the rpm drop.Might have a carboned up TB and upper plenum.

KK4x4 · **Posted:** Sun Nov 18, 2012 10:54 pm

You know what tjkj I thought it old be the ac compressor from the start but then I just started thinking about the battery and blew off the compressor possibably being a problem

Gageraid · **Posted:** Mon Nov 19, 2012 12:56 pm

tjkj2002 wrote:

Sounds like the AC compressor kicking on and dropping the rpm's,explain why it does it with the heat on and at even intervals(clutch kicking on/off).This is normal but the PCM should adjust the idle a little faster with the rpm drop.Might have a carboned up TB and upper plenum.

If your throttle body is carboned, it'll take you all of 3 minutes to clean and I would recommend doing it anyways.

KK4x4 · **Posted:** Thu Nov 22, 2012 2:18 pm

Just cleaned the throttle body and its still doing it so that's off the list. Although cleaning it was worth it seeing that it was filthy

TurboGoKart · **Posted:** Mon Nov 26, 2012 12:37 am

Ted15 wrote:

A multimeter will only tell if the voltage is there. You will need a load tester to see if the battery is any good.

Bingo. Need to drive it to Vatozone/Advanced/Napa/whateverotherstore to have the battery tested.

KK4x4, the a/c compressor has nothing to do with the heat. Those two are completely separate. Yeah the a/c compressor wheel spins when the engine is running, but it only pulls a load when you turn the a/c or defroster on (aka the clutch inside the compressor engages and the compressor "turns on" and pulls voltage).

TurboGoKart · **Posted:** Mon Nov 26, 2012 12:40 am

Do these Jeeps have an idle air control valve/motor (IACV)? If so, I'd take that off and hose it down well with brake cleaner and see if that changes anything. Oh and get the battery tested! That load measurement is important.

KK4x4 · **Posted:** Mon Nov 26, 2012 1:47 am

Thanks for the info TurboGoKart. Yeah that's what threw me off about it having to do with the ac compressor just the fact that its "A/C" lol I guess I couldn't fully get that. Im gonna try and get my battery tested tomorrow and just hope that's the problem so I could just get this thing fixed.

tjkj2002 · **Posted:** Mon Nov 26, 2012 7:33 am

TurboGoKart wrote:

Do these Jeeps have an idle air control valve/motor (IACV)? If so, I'd take that off and hose it down well with brake cleaner and see if that changes anything. Oh and get the battery tested! That load measurement is important.

Do not use brake cleaner on your TB,unless you want to a new on.Use only soap and water and a soft bristle tooth brush.

Ted15 · **Posted:** Mon Nov 26, 2012 7:47 am

tjkj2002 wrote:

TurboGoKart wrote:

Do these Jeeps have an idle air control valve/motor (IACV)? If so, I'd take that off and hose it down well with brake cleaner and see if that changes anything. Oh and get the battery tested! That load measurement is important.

Do not use brake cleaner on your TB,unless you want to a new on.Use only soap and water and a soft bristle tooth brush.

Plastic issues?

tjkj2002 · **Posted:** Mon Nov 26, 2012 8:01 am

Ted15 wrote:

tjkj2002 wrote:

TurboGoKart wrote:

Do these Jeeps have an idle air control valve/motor (IACV)? If so, I'd take that off and hose it down well with brake cleaner and see if that changes anything. Oh and get the battery tested! That load measurement is important.

Do not use brake cleaner on your TB,unless you want to a new on.Use only soap and water and a soft bristle tooth brush.

Plastic issues?

No special TB coating issue.Do some searching on other forums like Dodge forums where they get P0500 something codes and P3000 something codes that will not go away till the TB is replaced after using TB cleaner or brake cleaner to clean there TB's.

Ted15 · **Posted:** Mon Nov 26, 2012 9:01 am

Is that the same reason that seafoam isn't recommended?

KK4x4 · **Posted:** Mon Nov 26, 2012 5:01 pm

Battery's fine...now I'm just completely lost.

Power loss?

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