I have a '98 Protege LX with the 1.5 liter engine. It currently has 151K miles on it.
I recently had taken my vehicle to a local Sears to have the battery in the car
replaced because it completely shut down on me without warning. I took the vehicle
to Sears because I had a warranty on the battery. After the battery was replaced, I noticed that
the car drove fine, but whenever I stopped at a red light or stop sign the engine idle speed
drops all the way down as if it is about to die.

I took the vehicle to a local mechanic to have a tune up done. The spark plugs, wires, gas cap, and
rotors were replaced, in addition too, having an oil change, fuel injector system cleaning, and the
air filter replaced. A total of $450 of work done!!! After leaving the mechanic I noticed that the problem
was still there. I took the car back and it was then that they suggested that my IAC motor
need replacing. They mentioned that they couldnt replace the part because they were out of stock
and they didnt have the special tool to remove it, but recommended that I take it to the dealer.

The check engine light is on and the tech at Advance mentioned that the code
that was being pulled from there scanner was a p0120 code and another relating to the catalyic converter.

I realize the vehicle is 10 years old, and parts are expensive, expecially if I go to the dealer.
This vehicle is my only mode of transportation. Could someone please recommend the best ideal approach here.
I want to have the car fixed so that the check engine light goes out and it drives like a champ.

All recommendations/suggestions are greatly appreciated.

 

Can someone help me, please....

 

Engine Idle Relearn; Having the battery disconnected erases the computer's memory. You'll have to reprogram the presets on the radio and reset the clock. Years ago, I had the same expereince and had to take the car to have the engine idle function reprogramed. Unfortunately, you got ripped off by that local mechanic; did you tell him that the batter had been recently changed? It's funny that he jumped to IAC the second time around. My IAC was messed up and I took it to a local dealer. They did all this work to the AC system and all and charged me some rediculous amont of money for it....all for nothing. Being that it was my first car, I was somewhat at their mercy.

 

agree with 93.. when the battery is off for a few minutes the computer will reset.. i reset my computer once a month.. no reason for it just something i do .. but i never heard of having to getthe idle reprogrammed. it does it on its own if you let it run for at least two to three minutes after replacing batt. cables.. anyway. if the code your mechanic read to you was in fact the cat. converter then that is a costly repair to go with a oem replacment.. i would check out the web for an aftermarket one .. or if you live in my state where there is no emisions law.. well .. we just cut ours off or gut them.. lol..... 1.5?? are you sure? didnt know they made a 1.5 i thought there was only 1.6, 1.8, 2.0, and then the 2.3..

 

Hi Angeldi,

OK, first thing, the PO120 code is a throttle position sensor error. If your PCM does not get a good TPS signal, it will throw a catalyst error also. A new Throttle Position Sensor is going to run you about $150.00 plus 1.5 hours labor. SINCE THE 1.5L MOTOR IS THE MOST COMMON MOTOR MAZDA EVER PRODUCED. 65% OF ALL MAZDA VEHICLES CAME OUT WITH THE 1.5L MOTOR, do not be afraid to check the junkyard for one. You'll save yourself $100. If you even need it. Most times if you cleanup the plugs on a car this old, the sensor will work again. Once you clear up this error, Then check for the catalyst error. It will probably disappear.

Check my profile, and email me if you need the shop manual page on how to troubleshoot the TPS.

As for the rough idle, before you go for the Idle air control valve, check for a leak in the intake manifold. The way to test this is to spray brake cleaner around the intake while the motor is running. If it starts to rev higher when you spray at a certain point, more than likely the intake gasket is leaking, which is a cheaper fix. The Idle Air control valve is a $600 item, so if you do end up needing it, again check the junkyard first.

There is no IDLE relearn procedure on any vehicle equipped with an OBD II PCM (1995 and higher in the US)

As for who can get the car going right again, check your local mazda dealer. The question to ask if they have any techs that have been there more than ten years. These are great cars, but they are a bit of a finicky animal. If you don't have experience going after the strange things that are unique to the generation 2 protege, they are just going to **** away your cash.