Jeep temp funny

KarlVP · Apr 11, 2006

I have my TJ (2.5L) and it is running funny (funny strange, not funny ha ha:redneck: ). Whenever I turn the blower (heat) on it seems to idle fine. But when I turn it off, it idles funny. (not bad just between 500 and 750 rpm.

Another thing is the temp gauge fluctuates. It never overheats but sometimes on the trail it gets a little warmer than normal when idling for long periods of time. It doesn't matter if the heat is on or off. In traffic, when idling, it seems to cool down, then when I go again, it runs up to normal operating temp.

Any ideas?

JOOP · Apr 11, 2006

Hey if it aint broke dont fix it. :redneck:

If your worried about through in a new Thermostat.

E-rock · Apr 12, 2006

JOOP said:
Hey if it aint broke dont fix it. :redneck: .

a men to that..... semms like everytime i try to fix or upgrade something that isnt really broke i end up fawking something up even more......:censored:

NotMatt · Apr 12, 2006

JOOP said:
Hey if it aint broke dont fix it. :redneck:

It is broke... it idles funny when the blower isn't on.

Here's my 2 cents. The blower motor draws a lot of current... I can see it affecting the idle when you turn it on due to the extra load on the alternator, but I would think it would go the opposite way... idle would go up when the blower's off, and down when it's on... however, I've been wrong before. If it really bugs you, you could see if adjusting the idle speed some would help. I have no clue how to do that on a 2.5L, or if there even is a way to do it "properly", so you'll have to research that yourself. 500 does seem a bit low though.

If your worried about through in a new Thermostat.

A new thermostat will not fix a temperature problem like that. If the thermostat is bad, it's either stuck closed and the rig will overheat very soon after you start it, or it's stuck open and the rig will never heat up. One or the other.

More than likely, if it gets warm while it's idling you have a "bad" or "loose" fan clutch, or possibly it's getting close to radiator time for the rig if it's a bit older. However, some temperature fluctuation is normal because sitting and idling DOES create heat... how much does the temp gauge move when it's idling for a while? Honestly, it sounds like pretty normal behavior... as long as it's not getting way out of hand temperature wise while idling for a while or driving, some movement in the needle is normal.

GaryTJ · Apr 12, 2006

Change the Thermostat and clean the throttle plate...

JOOP · Apr 12, 2006

Example of it's nto broke.

When I had my Corvette if I turned on the AC the idle acted funny. That doesn't mean its broke, it's just what happens when you put a load on the engine. But thats different from a Heater blower.

Your Idle seems a bit low, it shoudl idle around 750-850 rpms. There should be an idle screw on the throttle body. But honestly if its not stallingout or dieing I wouldn;t worry about it. Just my 2 cents.

GaryTJ · Apr 12, 2006

JOOP said:
Example of it's nto broke.

When I had my Corvette if I turned on the AC the idle acted funny. That doesn't mean its broke, it's just what happens when you put a load on the engine. But thats different from a Heater blower.

Your Idle seems a bit low, it shoudl idle around 750-850 rpms. There should be an idle screw on the throttle body. But honestly if its not stallingout or dieing I wouldn;t worry about it. Just my 2 cents.

Kids...........

It is broke, you just don't realize it...

Computer controls adjust the idle to compensate for added loads. If they cannot, there is a problem. Most of the time it is a simple one..

DO NOT ADJUST THE IDLE SCREW ON AN INJECTED VEHICLE unless you know exactly what you are doing. Find the problem and fix it.

KarlVP · Apr 12, 2006

New Tstat goes in today.

I just thought it strange, that when I take the electrical load off the motor, it idles strange. When I turn the blower on, it increases RPM but remains steady.

How about the 02 sensor. I have never replaced that. If it were bad would it throw a code? Or should I replace it anyway. Jeep has over 135,000 on it.

Jeepasaurusrex · Apr 12, 2006

Is the heater controls actuated by vacuum? If so, there may be a leak in the system that opens when the switch is turned off.

Just my .05 (adjusted for inflation) :redneck:

GaryTJ · Apr 13, 2006

KarlVP said:
New Tstat goes in today.

I just thought it strange, that when I take the electrical load off the motor, it idles strange. When I turn the blower on, it increases RPM but remains steady.

How about the 02 sensor. I have never replaced that. If it were bad would it throw a code? Or should I replace it anyway. Jeep has over 135,000 on it.

Trust me, clean the throttle plate..

As far as the O2, it is digital so if you have a scope you can watch the pattern. Or use an analog voltmeter and watch the needle. It show be ranging up and down rapidly. Looking for a square wave pattern of varying frequency on the scope.

I don't replace parts that are not verified bad. I don't have enough money for that.

Not Jobless · Apr 13, 2006

Jeepasaurusrex said:
Is the heater controls actuated by vacuum? If so, there may be a leak in the system that opens when the switch is turned off.

Just my .05 (adjusted for inflation) :redneck:

Don't know about the TJ's but the YJ's were vacuum controlled.

GaryTJ · Apr 13, 2006

Jobless said:
Don't know about the TJ's but the YJ's were vacuum controlled.

Would not matter anyway. The small hose that the heater would draw vacuum from would not be enough to effect Idle quality. Might raise the idle a bit, but the computer controlled IAC should be more than enough to compensate for that small of a leak.