QuestionI have a 97 Land Rover Discovery that continues not to idle correctly. It will crank but not hold enough idle to keep the engine running.I have changed all the wires and plugs, replaced the fuel filter, checked and replaced a few vaccum hoses. What else can I check or replace. Any ideas?
AnswerHi Eddie,
your GEMS engine does not give you very many options when it comes to adjusting the idle speed or timing. I have an older engine system but maybe the following can help you out...
You may have a fault with various sensors, fuel temperature, oil temperature, throttle speed sensor, O2 sensors. It may be the amplifier module, your coil pack, maybe even the fuel pump.
Do you have CHECK ENGINE appear on your dash? This would give you a possible starting point.
You can spray a very fine mist of water around your electrical wires to see if there is any arcing.
So far, you've replaced what should be done when troubleshooting this type of problem. Now, check the timing.
I'd then remove the air intake hose and inspect the throttle plate and housing for dirt and carbon and clean it with an air intake and throttle housing cleaner.
Next, remove the idle air control valve and housing located at the right rear of the intake plenum. Remove the valve from the housing and clean the openings on the housing. Careful attention should be placed to the seating area for the idle air control valve and the plunger. Replace all gaskets.
To check the base idle, this must be performed on a fully warmed engine:
Turn off all electrical accessory loads and connect a tachometer.
Clamp off the hose between the throttle housing and the idle speed control housing. The speed should be 525 + or - 25rpm. If not, remove the plug on the throttle housing and adjust the bypass screw until correct speed is attained.
Replace the plug.
That's about all I can suggest and this is based on my older '95 Disco.
Best of luck,
JohnMc
