MP3 idle issue with good news too

V
2001 Mazda MP3
Well, I am happy to report that I got the car put back all together and for the first time in my life it started right up...immediately. I was pretty pleased with that. Doesn't even have a CEL right now. The only issue I have is something to do with the idle. I'm not going to describe it as rough, so much as "loping". Forum research brought up a lot of remmendations about IAC, EGR, and MAF; but it can't hurt to ask.

I'm guessing its one of the 3, but I saw somebody was asking another poster to idle it with the A/C on to check what happens. He mentioned that it would probably stall out. I figured it wouldn't hurt, so I gave it a shot. Much to my surprise, it actually smoothed out the idle. High beams and A/C made it even better.

The only other thing that might be pertinent is that I decided last minute to hollow out the first cat. The material was already cracked, I messed with it some just to check it out, made it worse, and decided "what the hey, hollow it out." I did honestly get everything out of it, so I'm not worried about that stuff; but I just thought that might have something to do with it.

Just to clarify the "loping"; the tach is hopping from 500-600 RPMs, but the car feels like it gets a solid rotation when the tach drops to 500, pushes back up to 600, but then at 600 its as if it totally drops, but catches itself back at 500 got another push. It goes through that whole sequence about 4 times a second. It reminds me of a V8 with modded cams a little. Runs nice and smooth if I give it some gas too.
 
V
2001 Mazda MP3
I guess one other thing might be pertinent. Its hasn't been running for over a month, and it was at 1/4 of a tank the whole time. It has been very hot some days here in Missouri, but the car has been in the garage the whole time. Could gas have to do with it? I just did't think it would go bad that fast though.
 
V
Protege5
It takes some run time for the PCM to adjust the idle after being reset. Give it some time, it may work itself out.

Otherwise, leaks anywhere in the intake tube after the MAF and vacuum leaks are common causes of idle oscillation.
 
V
2001 Mazda MP3
I had been gone on a short trip until today. When I got back, I ran the car for about 10 minutes. Eventually the CEL came on. It was throwing 2 codes at the time;
P0106(Generic) Manifold Absolute Pressure/BARO Sensor Range/Performance
P1250(Mazda) Fuel Pressure Regulator Control Solenoid

I cleared the codes, and took it on a 10 mile 2-lane highway loop to get gas. It ran fine the whole way, and no CEL until I pulled in to the gas station and idled a little bit. I drove it back home, and checked the codes again. I got the same 2, and one more.
P0140(Generic) 02 Circuit No Activity Detected (Bank 1, Sensor 2)

It is still oscillating at idle, but it did run well. I'm thinking the fuel pressure one might require something be replaced, but I'm not sure yet. The other two I figured are from me removing all the material in the 1st cat, but I just wanted to check everyone's thoughts.

None of those sound like catastrophic failures to me either, so I'm planning on driving the car to work unless someone warns me otherwise.
 

hornsfan10609

Certified Mazda Tech
V
2003.5 Mazdaspeed Protege x2
You need to put a spacer on the rear O2 sensor to get rid of the P0140 since you deleted the first cat. Your idle should be right at 750, you either have a vacuum leak, a dirty MAF, dirty or failing primary O2 or some of the sensors under the hood may be connected wrong or not connected at all. I would start with the MAP/boost sensor in the passenger side corner of the engine bay by the firewall since you have a code for that. FPR solenoid is usually a P0090 but it's the solenoid on the intake manifold near the throttle body with the brown plug, they fail over time.
 
V
2002 Mazda P5
I had been gone on a short trip until today. When I got back, I ran the car for about 10 minutes. Eventually the CEL came on. It was throwing 2 codes at the time;
P0106(Generic) Manifold Absolute Pressure/BARO Sensor Range/Performance
P1250(Mazda) Fuel Pressure Regulator Control Solenoid

I cleared the codes, and took it on a 10 mile 2-lane highway loop to get gas. It ran fine the whole way, and no CEL until I pulled in to the gas station and idled a little bit. I drove it back home, and checked the codes again. I got the same 2, and one more.
P0140(Generic) 02 Circuit No Activity Detected (Bank 1, Sensor 2)

It is still oscillating at idle, but it did run well. I'm thinking the fuel pressure one might require something be replaced, but I'm not sure yet. The other two I figured are from me removing all the material in the 1st cat, but I just wanted to check everyone's thoughts.

None of those sound like catastrophic failures to me either, so I'm planning on driving the car to work unless someone warns me otherwise.
I actually have the same exact codes currently. I was the one who posted that I had stalling issues with the AC. I changed to an ebay cheapy IAC Valve after getting all those errors and it smoothed out my idle, but I broke my connector and when connected it caused my RPM's to jump between 2500-3500 while running/driving. So currently the IAC is disconnected and it idles at 850 and 700-750 with AC on, but I still have all the errors. Not much help I know, but tagging along to see what you come up with.
 
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