Saturday, March 10, 2012

Rough idle,staling and Erratic shifting?

Multiple Problems on Mercury Cougar.
There are many possibilities that can cause this.

First of all inspect the EGR valve and head gasket.

A worn out EGR valve and cracked leaking Head Gasket can cause such problem.


You might have an air or a vacuum leak. This is very common! Open the hood and listen for a hissing sound when the engine is running.
Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow.
If it is hard to pinpoint take some brake cleaner or starting fluid around the intake manifold and vacuum lines and see if the engine stumbles or if the idle is affected. Be extremely careful when doing this.

Also, your throttle body may be carboned up and need to be cleaned. This can cause all sorts of idle and hesitation problems. This is caused by the throttle plate not seating properly. The First thing to do is clean out the throttle body with some throttle plate and intake cleaner and a small brush. Another common cause would be the Idle Air Control motor. This is very common on older cars. The IAC motor gets lazy and cant keep up with the fast idle changes. Also when the IAC motor is out, its recommended to check the passages for carbon build up. If they are plugged they need to be cleaned out.


Check for the following conditions:-----
Poor connection at PCM or IAC motor. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
Damaged harness. Inspect the wiring harness for damage.
Restricted air intake system. Check for a possible collapsed air intake duct, restricted air filter element, or foreign objects blocking the air intake system.
Throttle body. Check for objects blocking the IAC passage or throttle bore, excessive deposits in the IAC passage and on the IAC pintle, and excessive deposits in the throttle bore and on the throttle plate. Check for a sticking throttle plate. Also inspect the IAC passage for deposits or objects which will not allow the IAC pintle to fully extend.
Vacuum leak. Check for a condition that causes a vacuum leak, such as disconnected or damaged hoses, leaks at EGR valve and EGR pipe to intake manifold, leaks at throttle body, faulty or incorrectly installed PCV valve, leaks at intake manifold brake booster hose disconnected, oil filler cap, oil level indicator loose or missing, etc..


Possible Causes 
Check for air leaks in the Air Induction system (e.g., in the intake manifold)
Check for air leaks in the PCV system and in its related hoses and/or valve
Idle air inlet passage or throttle bore is dirty or full of deposits
IAC valve has failed
MAF sensor is dirty, "skewed" or installed improperly
Throttle plate, throttle shaft or linkage is damaged or sticking
TP sensor is out-of-range or "skewed" high.

One more thing if the transmission uses engine vacuum, then chances are the shifting is related to the engine performance... Chances are you just have a vacuum leak and it is affecting everything else. Do not use the old EGR valve back in. Perform a smoke test to the intake for vacuum leaks or maybe use some carb cleaner to find a leak. Of course.. be very careful. Also, check engine vacuum with a gauge at idle.

Another possibility is that,you might just have a bad pickup inside the distributor, lazy IAC motor, mass air flow sensor or even engine coolant temp sensor. You could check ignition timing and even the distributor signal while the engine is running. Obviously, just be sure the fuel pressure and the tune up parts check out ok.

If any engine noise is heard while Accelerating then,you could replace the o2 sensor that might have been contaminated.. that would be a good start.

IF the engine is making noise on accelerating, it could be lots of things. IF you are confident that it is the timing chain, then yes.. you could replace it.
Again, just be sure that the ignition timing is ok as well as the tune up parts. I would stick with the oil that is recommend by the manufacture in your owners manual.

This details will help.
Thanks.

See below latest solved car problems:-----

Bad miss at idle?
http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html


Engine stumbles coming off idle when warm?
http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

Erratic idle on car?
http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

Low idle when cold out side?
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

GMC Idle Air Control (IAC) Valve Replacing?
http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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http://repairhelpcenter.blogspot.com/2011/10/1996-camry-intermittent-engine-failure.html

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http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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http://schematicsdiagram.blogspot.in/2012/02/engine-overheated-then-car-will-not.html

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http://technoanswers.blogspot.in/2012/02/no-heatblower-blows-only-cold.html

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http://howtobyme.blogspot.com/2011/12/cylinder-6-misfire.html

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http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html

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http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html

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http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html


For more help go to:----

Car repair guide?

http://technoanswers.blogspot.in/2012/03/car-repair-guide.html