95 JGClimited Idle Problems

When starting up my jeep, it idles fine. After a minute or two of warming up, the idle speed drops to 4-500 or so. :eek7: When the AC kicks on, it goes up to 7-8 for a few seconds , then down again. Once I turn the AC off, it bottoms out for a split second, 100-200 rpm, and then back up to 500 or so. I've usually idled around 750 or so. I've change the IAC and the TPS, and even put new spark plugs, and distributor cap. If I hold the throttle at 1000 or so, steadily, the engine still drops my rpms down a few seconds later. :banghead: I have noticed a crackling, clinging sound coming from the area of my alternator and AC compressor went cranking from a cold start, but the AC blow great. If I watch the clutch on the ac, the idle is fine when it is engaged , but once the clutch stops , the idle speed drops, and it seems to be slowing the engine. Could the AC be going out and causing strain on the engine? I've tried everything I know of. :banghead: Any help would be greatly appreciated. :biggrin: I've taken very good car of this vehicle, and never had this problem before. :frown: It is a 6cyl automatic.

A couple of things you can try 1 is to check the fuel pressure you fuel pump might be going out and causing idle problems . 2 unplug the AC or take out the fude and see if this helps your problem.Also make sure you Alternator is putting out enough voltage should be around 14 volts. One other thing is the Throttle position sensor hard to check without a scan tool or DVOM. Does your check engine light come on?

Should be hook up to scanner to check out properly. But with volt meter check vio/wht wire for 5 volts. Then check org/dkblu wire...(.2 volts at idle.....4.8 volts wot )

No, the light never came on. I have replaced the iac, tps, new plugs, rotor cap, cleaned throttle body, new tb gasket, new fuel filter. Still idles low after a few minutes of warming up. It is as if something is telling the engine to slow down when it gets warmed up. I'm totally lost on this one. I know the engine starts pretty well. I hear the fuel pump whirring when i turn the key. Seem to be working.

It seems that the problems revolve around the A/C. You might check the clutch on the condenser. Mine went two summers ago and caused a whole bunch of problems, including blowing out the power steering pump. That was a very expensive summer.

Thats what I was thinking. The AC acts weird, its hard to say why. How would it affect the power steering though? Should I be concerned over that also?

My clutch froze, which ended up putting too much friction on my steering pump - I think. It was two years ago. Rereading your first post, I wonder if it's not a problem in the condenser. You might try a cold start with the A/C off, then after a few minutes of idle, turn it on. If your rpms drop when you turn it on, you know there's a problem with it - probably in the condenser. If you still have the problem with the A/C off, you know that it's something different.

I've noticed that sometimes if I'm turning , the rpms drop, and almost stalls completely. Is this the power steering pump going? Or does the voltage regulator usually keep idle high when load is on engine? I think its either the condensor, power steering or alternator. I may just change all three if I can afford it, this is aggravating.

That seems odd to me. Even if your power steering pump was going, it shouldn't cause the rpms to drop like that only when you're turning. Because the pump is hooked up to the engine via the serpentine belt, it's always providing pressure when the engine is running. Obviously then, the pressure in the power steering system goes up with rpms. To prevent the pressure from building to dangerous levels, there is a pressure relief valve that usually consists of a spring with a ball bearing at the end. The spring pushes the ball bearing against a seal near the output of the pump. If the pressure gets to high, the force of the fluid overcomes the force of the spring against the seal, allowing fluid to go past the ball bearing and back into the reservoir, bypassing the rest of the system. For the power steering system to be causing your problems, in my opinon, several very unlikley things would have to happen. First, there would have to be a problem with the working end of the system - perhaps a valve stuck further down the line which allows too much pressure to build up. Also, the pressure relief valve would have to fail at the very instant you're turning. And, all of the lines would have to stay attached and intact. If that happens, it's possible that the resistance against the pump is great enough to slow the serpentine belt down, which then would affect the engine rpms. One problem with that, though. The engine has so much torque relative to the pressure the pump would provide against the serpentine belt that you would probably hear squealing before the engine slowed. Actually, after thinking about it, I would think that if it was a problem with the clutch on the A/C, you'd probably hear the squealing before the engine slowed. It still seems, though, that the problem revolves around the A/C. So, if it's not mechanical, then, I think, it's got to be electrical. Which would really suck. I don't know much of anything about the electrical systems of cars - other than that they're a real headache. If the throttle is controlled electronicaly as opposed to mechanicaly (I have no idea if it is or not), it (I think) could be possible that there's some sort of electrical problem. I can't think of another reason for the symptoms you're describing. Why would two separate systems cause a drop in rpms? The only things they have in common is the serpentine belt and the electrical system.

I'm gonna throw something out here, but it may be completly wrong - my ignorance of electrical systems is so great that I really don't know if this is even possible. Could it be that there's some sort of drain on the system from the A/C and/or power steering that the alternator can't overcome? If that's the case, would that cause a drop in rpms? My gut says that it would have to be a pretty big drain on the system to cause the rpms to drop so low the engine almost stalls. If this is feasible, it still is odd to me that you don't lose power all the time when you turn. Maybe it's a combination of you turning while the A/C cycles on. You could test that by watching when the A/C cycles on, and then having someone turn the steering wheel both when the A/C is on, and off. If it only happens when the A/C is on then it's got to be a combination of the power steering and the A/C. Whether it's mechanical or electrical, I'm afraid I don't know.

I'm rambeling a bit, ok, a lot, but ideas keep coming to me. What about your O2 sensor? Do you know when it was last replaced? Again, I'm not sure if this is right. Is it possible that after the O2 sensor warms up, it senses that the fuel to air ratio is off, decreases the amount of fuel being fed to the engine resulting in a drop in rpms?

I don't know if any of these ideas are possible, much less the cause of your problem. If they're not the answer, I hope they jumpstarted someone elses mind. Good luck! I'm anxious to find out what the problem really is.

You've got a point. I don't believe the O2sensor has ever been changed, and if so, then its got to be around 10years old. I really hope its not the power steering pump or AC. My money has summer fever... :shakehead but I will go ahead and replace the O2 sensor this weekend. The bad part about the whole problem is, I could drive the jeep across the country and not worry about it, except when I stop. It runs great except when idling. It has run great until about a month or so ago. I have noticed that when accellerating , the transmission goes to second gear and quickly, briefly jumps into overdrive, and back again. Weird. I'll post the results when I get it installed . Thanks to all for the input. :grinyes:

I have a '94 Jeep Grand Cherokee Limited, and I had the exact same problem. My issue was my idle accuator. Cost me about $120 for parts and labor if I remember correctly. Got it done about summer of '04, and fixed all the issues. I had my Timing Belt pulley replaced at same time because that was giving me grief as well, and I believe that also helped, as I had that do first, and the idle 2 weeks later. Hope this helps! :)

I've thought about the timing and whether or not that could be the problem. I hope it isn't. Do these jeeps have belts or Chains? However, I changed the oxygen sensor, and nothing. What exactly is the idle actuator? Is that the tube thing thats near the battery with the cable running to the throttle body and a vacuum tube hooked to it? That would make sense since the engine is fine, just something keep dropping the idle. Its as if the engine computer is just lazy or something... :rolleyes: . I took the throttle body off and turned the little idle screw below the throttle up and now it seems to NOT bog down when stopping, just still idles low. I think the thing is possessed :evillol: or something. I recently bought a 3000gt and have been spending alot of time with it, I think the jeeps jealous. I really never had problems with it until I bought a new vehicle. Thats wierd. :eek7: