Intermittent miss-fire and stalling when at stops

[John L]

I am wondering if anyone has dealt with the problem themselves. What is happening is when I am at cruising speed 2500-3000+ rpm every now and then I can feel a sudden loss of power, which will last but a moment, then the car resumes running as if nothing had happened. But when at idle at a stop the engine will just suddenly die without warning. The rpm's are somewhere around 700 or so when it happens. I have been able to restart immediately but the last couple of times it doesn't want to start and just cranks over then starts. I have just recently replaced the plugs, wires cap and rotor. Within the last six months I replaced the distributor and had it it timed since the timing belt had jumped some teeth. On the fuel side I have replaced the fuel pump and filter as well as the egr valve. Any suggestions are appreciated.

[FE3-323]

have you tested any other ecu's?

[John L]

I looking over the vacuum system I found that the vacuum line that goes to the Fuel Pressure Regulator has been severed, the problem is that for the life of me i can not find where it goes.....the other half of the hose seems to be missing. Where does it go? I looked at the vacuum diagram on the hood of the car and it shows it going to the TSV but I don't know what that is and the diagram shows two of these things. I am wondering if the other part of the hose and it'
s component fell off the car.

[FE3-323]

hrmm. well an open vacuum line would certainly cause idle issues

[John L]

I reconnected the fuel pressure regulator vacuum line and I replaced the O2 sensor, but the problem persists. I am in the middle of having to replace the radiator since it seems to have sprung a leak as well. The problem is currently this: The idle is fluctuating from near stalling and stalling, to surging to 2000 and then falling back down. While driving there are random losses of power for a second or two. And as of late when the car does stall there are times when the car doesn't want to start without stepping on the peddle.

[FE3-323]

low coolant can be an idle issue - replacing the radiator may help solve some if not the whole issue

[1Mazda323Fan]

Have you tried cleaning the idle air valve yet? Your current issue sounds like it could be clogged, or possibly dying. Keep looking for vacuum leaks as well; they cause similar issues. Just for funsies, swap out the fuel filter too. Probably needs to be done anyway.

[John L]

The radiator has been replaced. I have not cleaned the idle air valve yet, but I have replaced the fuel filter and the fuel pump within the last nine months. When I did the fuel filter the tank was pristine. When I ran the car to top off the radiator I let it just idle without ever stepping on the peddle and the idle never fluctuated until it was at operating temperature and once I stepped on the gas. I have yet to drive it properly today to see what happens. If there is a change for the better I will re-post, otherwise there is no change. I was wondering if perhaps it could be the throttle position sensor?

[progt91]

That's a possibility. Check the intake tube for cracks as we'll.