My Discovery1,v8,3.9efi 1998. Idle keeps shaking up and down up and down, the exhaust gas is black. Fuel(gasoline)33liter/100km. The mass air flow,idle speed motor, ignition coil, solar term door position sensor and the spark plug are all new, what's the problem with my car? The land rover service center has no solution to my problem. My e-mail add:[email protected]
Black exhaust = over fueling
so there is an injector problem either in the seals under the injectors or in an over pressure problem
The sensor that controls the air / fuel mixtures is the heated oxygen (HO2S) that is in the exhaust manifold before the cat converter and that often fails and so the ECM cannot control the injector operation
have the fault codes run before you waste any more money replacing items not connected to the problem
SOURCE: car will not start when
hi there, when air flow unplugged, ecu goes into limp home mode ,a back up if something dies whilst driving. it sounds as if your used mass air flow sensor is faulty , they are more fragile than they look, one knock and these early fine wire models are gone. i replaced many when i worked at a volvo dealership a few years ago. hope this helps, and good luck.
SOURCE: car runs rough at idle
clean out ur throttle body, just follow the hose from the air filter to the throttle body. Need 2 people to do this. Don't remove the hose completely from the throttle body. Just enuff to be able to spray ur intake cleaner into the throttle body. Do this especially if its worse when the motor is hot, as this would confirm the problem.
SOURCE: 1998 Pontiac Sunfire won't accelerate
I assume that you do not have a "check engine" light?
The next thing I would do is check the pressure from the fuel pump. You can have this done at your preferred garage, or by purchasing a fuel pressure gauge from any parts store.
Vent the fuel tank vapors by loosening the fuel cap. Remove the electric fuel pump fuse and start the engine. Allow the engine to run until it runs out of fuel and stalls. After spinning the engine over for a period of 3 to 5 seconds, turn off the ignition switch and install the electric fuel pump fuse. Next, install a fuel pressure gauge in the fuel rail supply line, and secure the fuel tank cap. With the ignition key in the on position, verify that no leaks are present and start the engine. Visually verify the PSI reading on the gauge. The pressure for your vehicle should be 41-47 PSI (Pounds per Square Inch). Hope this helps and good luck!
SOURCE: 1992 Pontiac Grand PrixPower loss,erratic idle
spark plug gaps are very critical on computerised cars!! [some wont even start!]
distributor module may be breeaking down as temp rises they fail!
otherwise do compression check as it may have valve problems
also check plug leads & injectors aswell as the fuel pump pressure [ could bestarving for fuel]
Here is the common cause of surges, cold stalls, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours.
To correct this problem Buy a can of throttle valve cleaner (it is made by CRC) from the local auto parts store, NEVER USE CARB CLEANING SPRAY, IT DESTROYS THE ANTI-STICK TEFLON COATING, spray it into the air intake through the throttle body of the engine until you have used about half the can, you will need to hold the idle up while you do this, it will try to stall, after this shut the engine down and disconnect the Negative (-) battery cable for 5 minutes. The intake is now clean, if you continue to have the idle speed control problems you may need to seek the help of a professional.
60 views
Usually answered in minutes!
×