P0300, p0421, p0090

[skwirl]

my 2003 protege5 just started with the blinking CEL and i am getting P0300, P0321, and P0090. i have replaced the down stream CAT, both coils new wires new NGK plugs, new fuel pressure regulator, new diaphram looking thing on the fuel line, both O2 sensors, cam positioning sensor, crank positioning sensor...anymore ideas? i checked the intake tube looks fine, i just cleaned the EGR about 6 months ago when i rebuilt the engine?

[1Mazda323Fan]

First off, do you have a P0321 or -421 code? You listed both, one in the title and one in the post itself. As to causes, was the MIL on before you changed all of those parts? First step is to make sure everything is plugged in properly (connectors, plug wires, things like that). I'm assuming the car is running rather poorly?

[skwirl]

I had all three codes before starting to replace everything P0300, P0421, and P0090. Yea not running good and dying, but then it clears up and runs perfect for a mile or so then back to poorly

[1Mazda323Fan]

Did you replace the FPR solenoid, or just the regulator? Are there any other issues, namely overheating or smoke coming from the exhaust? Check the wiring/connectors going to the PCM; if the wires are damaged or the connectors are corroded that could cause those issues.

[skwirl]

Thanks for your reply, I bought a fuel pressure regulator off of amazon and installed it. The part had 2 vacuum lines to it and 1 plug. Is this the FPR. One of the lines went to the intake and the other to the end of the fuel rail. The car was not running hot, no extra smoke. Where is the PCM located?

[1Mazda323Fan]

Yes, that's the FPR. I forgot that the solenoid is attached to it...stupid me. The PCM is located under the passenger side kick panel (in the footwell, under the dash). Here's a diagram for getting to it/removing it if you have to. Don't worry, it's not complicated.

http://www.unichip.us/system/uploads...structions.pdf

Just for fun, disconnect both battery cables, stand on the brake pedal for about 30 seconds, then let the car sit for 10 minutes before reconnecting the battery. Fire it up, let it idle for a few minutes, then drive it sanely for a short while. That should reset the settings the computer learned and may clear up the issue. Again, say while it's sitting, double and triple check all of the connectors, wiring, vacuum lines, anything you can see under the hood. Also, check all under hood and in car fuses.

[skwirl]

I disconnected the battery overnight and applied the brake for 30 seconds, after I reconnected it , the car started right up with no check engine light (it used to come back on within 10 seconds after resetting it with the OBDll). My son drove it for 2 miles and the CEL never came back on. He is going to drive it school today ( about 2 miles ) I will let you know if it did the trick. Just to clarify why wouldn't the OBDll reset like the battery disconnect?

[1Mazda323Fan]

Most OBD scan tools only clear the code information, not the other information stored in the computer. Some have the ability to clear other stored data, but you have to specifically tell the scan tool to do it.

By disconnecting the battery you're removing the power to the PCM's memory, wiping all of the values it had stored and forcing it to relearn everything. It's like a hard reset on your phone or PC.

[skwirl]

Thanks for your help, I will let you know how it ran. Also without resetting the PCM but fixing the problem would the PCM still might believe there is a problem with the engine, and run like crap? The reason I ask is because, before disconnecting the battery when I would start the car after clearing with my OBD2 the car still ran really rough. After the battery disconnect it started right up and was idling great

[1Mazda323Fan]

It is possible for the computer to still see an issue even after repairs. It doesn't happen all the time, but it does happen. I've seen it myself a few times. The computer will either hang on to the bad information it saw, or just be unable to readjust everything if the new parts skew the information it's getting too far in the other direction. Sometimes all it takes is wiping the memory.

[FE3-323]

my car had a CEL & no working speedo. pulling the power was the fix for it.
its not likely to cause another issue (unless there is an actual problem)
did you hear back results yet?

[skwirl]

So far all is good, my son has driven it to and from school and soccer practice without the return of the CEL so far. All trips have been under 2 miles however before the CEL would come on within just 15 seconds after starting. Thanks 1mazda323Fan

[1Mazda323Fan]

Welcome. Glad I could help. Try to put some miles on it soon, though, just to be sure it stays fixed this time. Some of the OBD flags take 15-20 miles of steady driving to set. I'm 99% certain the MIL won't be turning back on, but it never hurts to be thorough.

[skwirl]

well the symptoms are back, CEL yet but the car ran really rough at a cold start 2 times yesterday and then last night it died when my son was driving it home. he was not able to restart the car. he said it had no power at all, he said he had it floored and only would reach 20 MPH, then when it died he said the battery light came on (i think this is normal when it dies but not sure). he tried to restart it and nothing wouldn't even turn over. he was only about a mile away, so i went to go help him. when i got there he said he needed a jump because it wouldn't even turn over however when i pulled up he had the headlights on and flashers going, i turned the key and it started right up and drove fine the rest of the way home. he said when it was idling so rough when he first started it up the engine was shaking and almost dying so he popped the hood and it started idling better so he closed the hood and it started idling rough again.... still no CEL but i will check for pending codes when i get home from work today.

[skwirl]

my first sentence should have read "Well the symptoms are back, No CEL yet