When the vehicle comes to a stop (stop light or sign) after being driven/warmed-up, it will (stumble) drop rpm abruptly, then return to normal idle. The symptom is sporadic, but happening more frequently and severely. The last time I drove the car and this happened, the car lurched forward and died. It will restart with out problems and runs fine otherwise. Again, this only happens occasionally.

There are no engine codes or "check engine" light.

Any ideas?

 

Something is making the idle air control valve/motor really nervous. I have '98 protege and the idle used to go really low and then recovered. I had to work through a whole bunch of things to clear a check engine light. Once I had that accomplished the idle did not drop like that anymore.
The keys were to eliminate vacuum leaks and opening a plugged vacuum nipple at the back of the intake manifold. This nipple is for the vacuum signal to the EGR boost sensor. I opened it up with a piece of stiff wire.
Next was cleaning the EGR valve from deposits, cleaning the throttle body and opening plugged EGR port holes. I also cleaned the MAF sensor.

I hope this will work for you too. Please report back.

 

Thanks for the reply. I will be working onthe Mazda this week and will get back to you.

 

Finally got to work on this vehicle. Replaced the air intake hose because it was cracked in a number of ribs and the vacuum line from the small valve fixed to the topside of the intake hose was disconnected at the rear of the throttlebody. I am not sure whether I dislodged the line during removal from the intake hose or not, but the car seems to be running fine now.

 

There you go: vacuum leaks, again. That's a Mazda disease, but easy to remedy.

 

Just replaced the exact same hose on my wife's '03 for the same reason. I had cracked it when replacing the air filter.

 

Happy New Year. Hope this finds you'all well.

I have a 1998 Protege 1.8L manual 5 speed. I love the car and it still gets 30 - 32 mpg after 216,000. My problem started shortly after I turned the ignition on and off 5 times, to test the alarm's valet mode; but I don't think that had anything to do with it.

As mentioned in this thread, I am also getting engine sputtering (I call it), but not necessarily just at idle. I will drive the car 5 miles or so from cold and it will miss. The CEL will come on if it dies too much but not otherwise. An additional mile or two crusing down the road (about 2500 rpm) and it will stop firing intermittantly (sputtering). The oddities are:

1) If I stomp on the gas, after a bit of hesitation, it will pick up and go;
2) With the clutch in and a rev of the gas, there is no hesitation;
2) If I press the clutch in and allow it to coast, it will go to idle (not stall);
3) If while moving with the clutch in, I rev the engine to ~2500 rpm, it will oscillate between 2000 and 2500 rpm;
4) If I come to a stop with the clutch in or take it out of gear and allow it to sit running, the idle goes from 1200 rpm to 750 rpm (no more than 10 secs) and the problem goes away. And it will not come back for the rest of the trip (sometimes 150 miles).

It took a while to isolate because there are lots of traffic lights where I live. Most of the time sitting at a light cleared the problem (see #4) without it showing up. And letting it idle for 7 minutes in the morning had the same effect.

A friend of mine is a car enthusiast and started by cleaning things out. We added HEET for fuel tank water and used Sea Foam on the air flow sensor and the intake. Lots of smoke but the problem is still there.

There are no codes and no freeze frame data, even with the OBD scanner continuously connected; just a CEL flash on the occasion the rpm gets too low.

I've been waiting for it to get bad enough (consistancy that is) to take it to the garage, since I cannot remember when it had its last tuneup. Idea being that if it is inconsistant, then it won't do it for him.

Should we check the same things noted before (vacuum, EGR, MAP sensor) or am I looking at a different issue.

Take care and thanks for your advice in advance.

Rich

 

When's the last time you changed plugs/coilpacks/wires? Have you tested the coilpacks/wires to see if they fall out of spec? What code is the CEL giving you?

 

Yes, Rich you should look at the same things as listed before.

 

Thanks to both of you for your responses. For TristanP, there were no codes and a tune up with a coil/wire/plug review will be next. For tanprotege, I will be printing this thread for reference and let you know what is found.

Take care and have a good day.

Rich