Ok, first off, long time lurker, finally created an account to post this question because I can't seem to figure it out and my opinion changes every other day on what the cause is. Have a three day weekend from a hectic work schedule so hoping to finally get to work on my TJ.
First the basics:
2000 4.0L TJ Sport Auto, just hit 150K miles.
Recent work done last three to four months (1being oldest work, 5 being most recent).
1. Replaced front axel u joints
2. Replaced water pump
3. Replaced power steering pump
4. Cleaned out IAC valve (more on that later)
5. Replaced blower motor resistor.
So beginning about two months ago, I started experiencing a drastic decrease in RPM's at idle, to the point where i would have to rev slightly at red lights to avoid a stall, this also coincided with a loud whistle/squeel/screech at idle as well. Go to the forums and it becomes clear it is the IAC Valve. So I cleaned that out by following the how to's, etc. as made by these esteemed forum members, and thought i fixed that problem. No longer a drastic drop in RPM's, no problems with a jeep stalling. About a week later, the screech/whistle appears again.
The sound that I am hearing occurs in the following scenarios.
Going from 40ish-55ish mpg decelerating to a red light/stop sign after about 10-15 minutes, then at the tail end, the sound appears, which decreases as soon as the foot touches the throttle and upon accelerating, whistle ceases. It continuously whistle/squeel/screeches if going from that 40-55 mph range, stop, then being in a 25mph area, when idling then that whistle/screech/squeel is there. I swear that when adjusting the ventilation, such as going from blowing on face to blowing on feet and defrost, it assists in stopping the whistle. After doing this and driving for about five-10 more minutes or so, it seems the whistle goes away.
One note is that this jeep rarely is driven more than 30 minutes at one time, no extended trips. Also, haven't taken it off the beaten path in quite some time, which leads me, at least, to think its not a crack in the intake/exhaust manifold.
I've never once gotten a code or check engine light. Any help will be hugely appreciated and i'm looking forward to tackling this head on. Thanks.
First the basics:
2000 4.0L TJ Sport Auto, just hit 150K miles.
Recent work done last three to four months (1being oldest work, 5 being most recent).
1. Replaced front axel u joints
2. Replaced water pump
3. Replaced power steering pump
4. Cleaned out IAC valve (more on that later)
5. Replaced blower motor resistor.
So beginning about two months ago, I started experiencing a drastic decrease in RPM's at idle, to the point where i would have to rev slightly at red lights to avoid a stall, this also coincided with a loud whistle/squeel/screech at idle as well. Go to the forums and it becomes clear it is the IAC Valve. So I cleaned that out by following the how to's, etc. as made by these esteemed forum members, and thought i fixed that problem. No longer a drastic drop in RPM's, no problems with a jeep stalling. About a week later, the screech/whistle appears again.
The sound that I am hearing occurs in the following scenarios.
Going from 40ish-55ish mpg decelerating to a red light/stop sign after about 10-15 minutes, then at the tail end, the sound appears, which decreases as soon as the foot touches the throttle and upon accelerating, whistle ceases. It continuously whistle/squeel/screeches if going from that 40-55 mph range, stop, then being in a 25mph area, when idling then that whistle/screech/squeel is there. I swear that when adjusting the ventilation, such as going from blowing on face to blowing on feet and defrost, it assists in stopping the whistle. After doing this and driving for about five-10 more minutes or so, it seems the whistle goes away.
One note is that this jeep rarely is driven more than 30 minutes at one time, no extended trips. Also, haven't taken it off the beaten path in quite some time, which leads me, at least, to think its not a crack in the intake/exhaust manifold.
I've never once gotten a code or check engine light. Any help will be hugely appreciated and i'm looking forward to tackling this head on. Thanks.
