idle varies

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Can anybody help me, i am fairly new to the driving game as i am only 22, and i dont know that much about the mechanical side of cars. i have a 1989 ford telstar and the idle on it varies about 250-500rpm when the vehicle is stationary. the car will get down that low that it starts to stall. what could the problem be? If anyone could help me it would be a great help. thank you very much. you can contact me at

Thanks again, Ben :banghead:

posted by  bennyjenkins99

Do you perform regular matinance on your car? Changing oil, transmission fluid, anti-freeze, spark plugs & sparkplug wires, oil filter, and air filter?

posted by  FordFromHell351

yes i do perform all the basic maintance stuff on the car like oil change, water, plugs and leads etc.... i know most of the basic stuff it's just this that i'm having trouble with.

CAn you help? :banghead:

posted by  bennyjenkins99

Idle bypass adjustment;
Idle up VSV,
TPS adjustment;
Dirty TB around choke plates;
Oxy sensor;
Loose, cracked vacuum hose;
water temp sensor;
air intake temp sensor.

posted by  Wally

Out of the things that Wally here just mentioned, I would reccomend checking your oxygen sensor first, then your water and air intake temp. sensors.

posted by  FordFromHell351

thanks for the help, but i have another question.
sorry for not being well informed, but what do the follwing mean.
1. vsv
2. tps
3. tb
4. maf

sorry i am only new at this car maintance stuff and havent worked out all the jargon and tech terms.
also can anyone tell me a site i could go to where i could learn more about cars in the way they generally work, how to maintain them (more than just the basics) and etc....

talk to ya soon. :clap:

posted by  bennyjenkins99

Vacuum switching valve: in this instance when you operate your air cond, head lights, etc the extra load on the engine requires some increased air/fuel so the VSV operates to allow more air and the ECU increases the injector duty cycle.

Throttle position sensor: this a either a switch or potentiometer (or combination of both) on the TB that tells the ecu what the position of the choke plate(s) is so that it can ascertain what the driver is asking for.

Throttle body: the thing that throttles the air going into the engine using a choke plate. In you car era it is also generally fitted with an idle bypass valve that provides minimal air around the choke plate for idle.

Mass air flow sensor: measures the air going into the engine so that the ECU (engine control unit) can prempt the amount of fuel required to maintain correct mixtures, in conjuction withe the TPS, O2 sensor, air intake temp, water temp, etc.

A faulty O2 sensor will cause some hunting, but generally the ECU reverts to a limp mode that over fuels just to make sure. The O2 sensor is more for idle and low load/revs feedback and gets knocked out of the equation in a lot of cars at higher revs or load. There's always exceptions to the rules.

As for a forum, join a Mazda 626 bulletin board.

posted by  Wally

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