Question about 2008 Jeep Cherokee Grand
Every single time idles high regardless of outside temp or the temp of the engine. I could drive 50 miles turn it off and restart it immediately and idles fast. tranny jerks into reverse sometimes going to drive. I cleand the air sensor and the airflap on the other side of the air intake canister
SOURCE: Heater blows cold air when idle
Sounds like you may have a partially plugged heater core. You could flush this out separately, from flushing radiator & engine block. Diconnect heater hoses going to your heater core and clamp off, so not to loose coolant from engine. Now hook up separate hose to one side of heater core pipe and flush out with typical garden hose. Repeat procedure on both heater core inlets. Reconnect original heater hoses and test difference. You may have to add an additional litre of antifreeze. If this don't work i suggest changing heater core. Good luck.........Ron.
Posted on Jan 03, 2009
i recommend cleaning the throttle plates. they are located unter the intake hose form the engine to the air filter housing. if you open them with the engine not runniong you will see they will be covered in carbon. use a good carb cleaner and a rag to wipe them clean
Posted on Jan 20, 2009
First, nothing you have done has anything to do with valve tappet noise. What is your oil pressure? Have you positively identified the noise as a lifter (tappet), OR COULD IT BE AN ENGINE BERARING OR WRISTPIN? Other than tearing it down and replacing lifters, rockers or pushrods or possibly even the cam, if oil pressure is good, change the oil and put a quart of Marvel oil in there. If that does not clear it up in a few days, you will have to go inside the engine. You likely have over 160k on that engine...consider using a replacement. Get an older tech to listen to it...it takes years to be able to differentiate between different component noises with any accuracy.
Personally, without hearing it myself, I'm betting it's a rod knock.
Posted on Feb 20, 2009
Being injected, the control system varies fuel quantity and does not directly regulate air flow. Therefore, having black soot on plugs tells you that there is too much fuel going into the engine. The O2 sensor tends to react to, more than control that. Missing can be the result of plug fouling. Backfire may be the result of a too rich fuel mix permitting unburned fuel to enter the hot exhaust where it re-ignites.
Where I would look first in your case is to the manifold air temp sending unit and the coolant temp sender as well. If either or both are out of range the computer may "think" it is running a cold engine and therefore adding additional fuel for cold start up,and not switching to normal run mode when the engine reaches operating temp. Once the plugs foul the engine will continue to run poorly regardless of other conditions. You can test each component individually using either chilton or haynes manual as a guide. You will need a decent digital multi-meter to do the tests.
You can also have a code test done at most major parts stores, but often if sensors are not bad enough to set a code but together are causing a problem, you may not see anything except the O2 sensor.
There are other possible causes such as worn out injectors, but most often that won't happen in all cylinders at the same time. Do testing first, correct whatever you find and then make sure plugs are clean. If after running, the O2 sensor continues to register a fault, then replace it.
Good luck...any further questions are welcome and don't forget to rate answers!!!
Posted on Feb 22, 2010
Testimonial: "Thanks. We will try it."
usually rough Idle is not noticable at high ildle. Once it is idles normally try Disconnecting one injector at a time. If the idle stays the same than that cylinder is the culprit. Remove that spark. If it is wet than do a compression test. Should read better than 100lbs of compression.If compression is good take a spark plug and hook it into the end of the plug wire.Lay it across the intake,start the car and watch for spark. If you have spark than you probably have a bad injector. A miss will cause the vehicle to idle high. The computer is trying to keep the car from dieing out. Hope this helps. No spark do a tune up.
Posted on Dec 05, 2010
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