P0300, p0421, p0090

[skwirl]

confirmation from my son he had power and the car was turning over but just sputtering and would not re-start, when i got to him about 5 minutes after it died, it started right up and ran fine.. starting to sound like fuel problem? how do you check fuel pressure? and is there a way to pull the newer plugs and tell if there is a injector problem?

[skwirl]

did some work on the car tonight, checked the ground wire from the body to the right hand motor mount, cleaned it up and changed the negative battery clamp. my also checked wires and vacuum lines under the hood. when he started the car it was idling fine and then he turned on the fan for heat and it started idling bad rough. then turned off the heat fan and it idled good. turned on the head lights and it idled bad turned off the headlights and it idled good. he then drove it for about 3 miles with out any power items on...fan, lights, radio. it ran like crap (rough) for 2 miles and the check engine light came on and started to flash. half a block later the flashing stopped and the CEL was solid and it ran great. I checked the trouble codes and it is now the same old P0300 random misfire and a new one
P0506 showing up. I also sprayed all over the engine with starting fluid while he was idling with no symptoms of a vacuum leak. I put the volt meter on the battery terminals when he got back and at idle with nothing on it is at 14.40 when he turns on something, (fan, lights...) it drops to 12.40 but comes right back up to 14.40 within 5 seconds

[1Mazda323Fan]

That's...odd. When you checked the voltage, as he was turning on different things, was it starting to run rough again, or did that mysteriously disappear again? It almost sounds like you have some wires touching somewhere. Check the belt tension too; it may have loosened up somehow. I doubt that's the issue, but it doesn't hurt to check. As to those codes, I wouldn't worry too much about them. My guess is they were thrown when the car started running rough, but they weren't the cause of it.

[skwirl]

at first cold start is when the idle would go way down then after warming it up it did not dile down as much or for as long. people are now telling me it still could be the large cat right off of the exhaust manifold? would this make sense? and would the condition come and go like it is? power loss, then good power, then power loss?

[1Mazda323Fan]

IT is possible the issue could be the precat off of the maifold. It's unusual for a cat to have intermittent issues, but not out of the realm of possibility. I'd still put that down on the list of possible causes for now. Did you replace the fuel filter when you were replacing everything else? Maybe clean out the EGR again? Do you notice any weird smells at any time, especially fuel and/or rotten eggs? Pull a couple of spark plugs, see how they look and smell. I know I'm recommending a lot of stuff to check; I'm just hesitant to say go ahead and buy the precat because of the expense there.

[skwirl]

yes i will try pulling the plugs and checking them, i will also pull the EGR off although it is in a hard to get to spot. i have not checked the fuel filter yet on this one it has a bag around the fuel pump, in the tank. the only reason i would suspect the pre cat is because before i rebuilt this engine, it had rings that were so bad it smoked so much you could even see anything out the rear view mirror

[1Mazda323Fan]

Whoops. I forgot the fuel filter was in-tank on these. If the rings were that bad, the I would definitely suspect the precat. That much oil going through it probably ruined it. I'd still check the plugs first to make sure there isn't some fuel issue still, but if they're good I'd go for the precat. Skip the EGR; I know it's in a bad spot (thanks Mazda!). I should have asked why you rebuilt the engine sooner. My apologies.

[skwirl]

The new Precat showed up. Before taking off the old one I started the car to get it on the ramps and it ran bad and the CEL was blinking again. I got it on the ramps and removed the old Precat. It was a empty can no guts in it and no plugs. During this time I had the battery disconnected . I I reconnected the battery started the car with the open Heasee. The check engine light never came back on I ran it for about 10 minutes . This could have been because of the battery disconnect and the computer reset . I also bought a new fuel pump and the filter that I'll put on this weekend

[FE3-323]

an exhaust header would have been a cheaper alternative. & added a bit of performance at the same time. either way if it fixes it - win win

[1Mazda323Fan]

Any updates? You didn't say if the cat ended up fixing the issue or not (unless I misread your last post).

[skwirl]

A header would have been nice but I am not sure on which one to go with because of a lot of bad reviews, any recommendations? Well

[skwirl]

The car seems to be fixed. Two tanks of gas and a week and a half later no check engine light no misfires. I ended up replacing the nega The car seems to be fixed. Two tanks of gas and a week and a half later no check engine light no misfires. I ended up tube battery cable end and the fuel pump and filter, so far so good

[skwirl]

Spell check... Replace fuel pump and fuel filter and also the negative battery cable end that hooks to the battery

[FE3-323]

glad to hear thats resolved!

im anxious to see how my fuel pump replacement will effect my own BJ. im hoping for a few extra mpg