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Anonymous Posted on Nov 19, 2011
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My xj runs well at speed, but when idling in traffic, the idle speed races and the engine temperature rises.

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  • Posted on Jan 07, 2012
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Joined: Jan 07, 2012
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Check your cooling system - ESPECIALLY if you are driving a 4.0 L6...
Your engine's life is in the cooling system. If this engine overheats, you will crack the head or worst.
I would suggest (if you are mechanically inclined) that you check your coolant level - if you have added any recently, you have a problem.
Check the radiator for leaks, rusty spots, etc. I would also suggest that you open the draincock for the radiator (with a hose attached) and check the condition of the coolant. IF nothing comes out or anything other than green coolant comes out - you will need to flush the cooling system, and replace the coolant.
Now, it if was mine...(I own a 1993 ZJ, and previously owned a 1990 XJ)
I would purchase a new radiator - I bought my last one at 1-800 Radiator for the ZJ - it was $130 dollars with tax. New 192 degree Thermostat from NAPA or other reputable parts house. And the $4 thermostat gasket from the Jeep Dealer. The gasket is Daimler-Benz designed, and prevents galvanic corrosion (aka "my thermostat house was eaten by zombies"). This is the only gasket available that prevents this, and is worth the trip to the dealer.
Disconnect the battery, flush the cooling system, and drain. Replace the radiator with your new one, remove the thermostat housing, CLEAN everything and blow out with air, replace thermostat, Check all your hoses (inside of hose, more than the outside), and replace as needed. I would probably replace all of them at this point, but...
Refill with 50/50 Coolant/Distilled Water, and you should be good.
Now, what the H*^& does the idle have to do with speed racing and engine temp???
Jeeps, especially in the past twenty years, have used lower fuel/higher air ratios to reach fuel economy and emission goals. These cause higher engine temperature. IF the cooling system is great, not a problem. But if a problem exist with the cooling system, all that extra heat causes higher idle (due to premature ignition of fuel/air) and higher temperature (due to lack of cooling ability).
Hope this helps...

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2001 echo engine races when idling why
Engine idle speed is limited by reducing the amount of air entering the engine. When an accelerator pedal is pressed, it pulls a cable which opens a throttle plate which then allows more air to enter causing engine RPMs to increase. At an idle, the throttle plate should be closed as to not increase the RPM. There's also a part called the idle air control (IAC) valve which controls how much air bypasses the closed throttle plate at an idle. Lastly, air could enter the engine via an intake gasket or vacuum hose leak; the same rules apply, the split hose or gasket allows air to enter the engine and RPMs will rise. To summarize, a throttle plate not closing, and IAC valve stuck open, or a split intake gasket or vacuum hose could all cause a higher than normal idle condition. You can read more about how to troubleshoot high idle conditions here: https://www.yourmechanic.com/article/how-to-troubleshoot-a-car-idling-at-a-high-speed-by-tim-charlet
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I have just recently purchased a 2012 mitsubishi colt clear tech , and the slow idle speed sits at a shade under 1000rpm , is this too high and if so is it adjustable ?
Normal idle speeds on modern cars are usually between 600 and 1000 rpm so the idle does not seem too fast. Most modern cars now use electronically controlled throttle bodies instead of carburettors and most throttle bodies are not adjustable.
The idle speed can run higher when the engine is cold as more fuel is added until it reaches working temperature. Let the car warm up to it's working temperature, usually about 10 minutes at idle.
Keep your feet off the pedals and check the idle speed. Listen to the engine. Does it sound like it is 'racing' like your using the accelerator pedal or is it struggling and almost stalling? If it is an even steady idle it is probably set correctly. Get a good mechanic to look at it if your worried.
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Mitsubishi Lancer 2006 cooling / rough idle issue
Sensors do not always throw codes if they are close to normal parameters, needs to be checked with a scan tool and thermometer.

There is usually a high and a low speed fan relay, as well as a separate A/C fan relay (also high) Your High speed fan relay could be bad, or the fuse for it.

Engine idle surging usually means the coolant is boiling and there is no longer liquid in the throttlebody causing it to go to a high idle because it thinks the engine is cold. Warm coolant closes a valve lowering the idle on most Japanese makes of that year.

Also, sometimes Thermostats stick half open and do not allow enough flow. AND sometimes in neglected cooling systems Water pump Vains are eroded by electralosis causing low coolant flow as well. And a Clogged radiator can also cause this, as by the time the fans run on high it's to late.
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Gas pedal gets stuck and keeps the car going cant stop without turning the car off
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Hot and cold engine or BOTH>?
1995 Tracker, no tranny , no 4wd , on engine options stated.
Exact high RPM in neutral, not stated...... 1500 is normal cold.
keeps going in Neutral. (nah , you have 5 ways to stop any car.
key, hand brake, foot brake and neutral. and with 4wd, 1 more neutral.
keep that in mind driving any car.
this car has up to 3 throttle cables that can stick. and more!

1: floor mats hit the pedal>? ala. Toyota style (lawsuits)
2: the three cables are, throttle. , cruise and A/T transmission kick down cable. if car is M/T and no cruise it has 1 cable.
so disconnect it, throttle fixed? (disconn,. 1 by 1, bingo?

no cure?, then its not the pedal , you meant just high idle.
yes, replace the cable or bad parts three.
ok say its not the cables.. (tests proved that)
the 95 came with 2 engines, 8valves and 16valves,
they work differently (8v love so race, 16v loves to stall)

1: ISC Stuck open, common.
2: 8v, any air leaks at all , will cause super high idle speeds.
3: throttle valve in the throttle body is stuckopen (gunk) or the return spring broken (very very rare the latter,in fact never heard of one breaking)
4: IAC (thermal idle control stuck open ,(my 97 was). and lots more.
5: on the 16v it takes 2 failures. to make high idle.
gross rich running engine (cold engine its normal) and any air leak
once hot the engine can not race unless there is huge overfueling
and an air leak.
6: the 8v has this device on the side of the throttle body.
called a dash pot. its just a fast idle vacuum servo.
if stuck open the engine will scream full time....
7: ECU stuck in limphome, can cause too high idle speeds.

we need to know which engine
http://www.fixkick.com/find-parts.html
8v or 16v first.
then does the idle race hot or cold or both (engine temperatures)
if it races , then how fast?, RPM the dash tachometer tells you that.

it can be as simple as a 50cent hose cracked.
to a dead ISC. (idle speed control) IAC is thermal idle air controller.
the IAC must be closed on a hot engine,
if the the engine never gets hot,it will scream full time.
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Water temperature is low cost oil is certainly the easiest way is with a hard shell to block part of the warming effect of the radiator well as for how much you want to try to stop. Idle temperatures will rise up relatively low. What is the pull speed? Not run fast but continues to run uninterrupted some time. Usually two hours can be. Is to allow the engine to reach full swell purpose. Such a shift is to be based on the vehicle speed and the reference engine speed. Not based on the engine speed. Driving is probably the single 30 towards third gear, fourth gear towards forty, fifty five-speed ahead. Many people on the car ahead of change. As long as the engine sounds smooth, no trailer can be.
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Mar 07, 2011 • 2002 Mitsubishi Galant
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When idling my jeep overheats. The cooling fan is running and it speeds up when temperature goes up. The temperature gets close to 260 degrees and the engine tries to stall. when I start moving it cools...
At idling speed an engine does build up a lot of heat and the cooling fan will kick in. In slow moving traffic or traffic jams the temperature gauge can touch the red - particularly on hot days. The reason it cools down when you start moving is because of the air flow through the radiator.

Presumably there are no leaks from the cooling system otherwise you would have mentioned it. In normal circumstances the fan will not be running as you are driving at speed, as the air-flow through the radiator is sufficient to cool things. The fan only kicks in to get rid of excess heat - and this usually occurs at idling speed or after you have parked the car.

If the fan is running all the time as you drive, this points to either a fault in the fan switch, or the car is running too hot. presumably in normal driving the fan isn't running and the temperature gauge reads normal?

It is common - in stationary traffic many cars overheat (particularly big engined models) try to stall and 'cut out'. Restarting can be difficult until the engine cools down.

Is your car overheating in normal driving conditions or just at idle speed? Overheating in normal driving conditions can be caused by things like a failing water pump, blocked radiator, collapsed hose, faulty thermostat or, in the worst case scenario, cylinder head problems.

Overheating at idling speed is 'common'. Check your coolant level. If your car isn't using/losing coolant then there probably is no major problem. You can flush out the cooling system and refill with new coolant - and also check your radiator. Are the cooling fins crumbling with age? Or maybe they're partly clogged with insects and debris from the road? A blast with a hosepipe wil sort that out ..

The question is how much does your car overheat in normal driving? If it doesn't .. it appears as though you have nothing to worry about as such. Most cars have 2 speed fans... the 2nd faster stage kicks in at some point dependant on engine temperature. Perfectly normal.

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