new parts and now not running right...
 

Ive recently replaced my engine, but sounded congested, and old mid pipe was glowing red around the O2 sensor, so I disconnected the exhaust from the mid pipe. and it ran fine excluding the obvious sound change. I replaced the whole mid pipe but the cat is still glowing red, it takes longer then the old one but it still happens. Its glowing bright enough to see it outside during daylight. As well as its burning richly on fuel and will not idle I have to keep my foot on the gas. It ran fine without the mid pipe connected so I assume something is wrong along the exhaust. Any advice is helpful at this point, as I am at wits end with this

As well after it starts and is running, oil pressure and engine temp is in normal operating range as well as there is NO CEL

Your cat is bad. If the cat is glowing red/smells then it is bad. I'd take it off and see if you have any of the honey comb packing left on the inside.


Search glowing red cat.

I did, the old one had pieces rattling around in it, so I bought and installed a new one, the new one takes alot longer to glow like that, and the engine doesnt sound congested now it just wont idle

Need more info than that. Completely explain what is happening in steps, you have to understand it's hard to diagnose with little information and without seeing it.

Again, check your cat because it may have been replaced with a bad one, if your engine runs fine without it on then horrible with it on i.e lack of flow etc - it's a huge clue to a bad cat AGAIN.

Sounds like your catback is clogged due to the first bad cat.

Ok, after I installed the new engine it started up, but the engine sounded strained and I noticed the glowing of the cat. After reading on here about it possibly being a bad cat, I disconnected the cat between the front and rear O2 sensors.

Then I started it up again without it connected. It ran and idled just fine but being as it had no exhaust connected it was much more louder then usual. So I ordered a new cat and put it on.

Once I got it started with the new cat on, it sounds just a slight bit different then the stock 8 but the engine does not sound congested any more. But same as the last cat, it started glowing red about 5-10 mins AFTER reaching running temp, as well it was burning fuel very rich, ie. being the white smoke and smell of gas coming for the exhaust tips. It doesnt constantly burn like that but it does it off and on in a non rhythmic pattern.

Due to the state that it is registered in I have to have the cat due to inspection passing that I have to do.

If there is any more details I should include let me know, thanks, any help is better then none at all, so I will do my best to describe as much as possible when needed

Hey man. I'm in your area. I'd be willing to try to help figure that out. Shoot me a Pm if you'd like.

That was one thing I considered, I saw it as if thats the problem then the cat back got clogged which made the mid get clogged, but if thats the case would I still be getting exhaust out the tips because I can feel the exhaust coming out the tips

You got a new Mazda OE cat or something else?

a different aftermarket one, walker brand to be exact, the best I could do for the time being, its a direct fit as well

A cat turning red does not necessarily mean it is bad. You could have an engine issue

do you know what kind of engine issue that would cause something like that?

Another question I have is about the sensors.....You guys know where the front and rear O2 sensors are...tied in with the REAR O2 sensor there are 4 other cables all just one pin each, on mine 2 are black and 2 are white, and if I recall correctly the 2 black ones go to the side of the transmission...these 4 wires are ran along the same cabling as the rear O2 sensor all the way back to the engine...anyone know what they are and what they are for?

Ok so today I am in the process of disconnecting the back end of the mid pipe from the cat back to either eliminate or identify the cat back as the problem, I am still open to any other suggestions that people here on the forum have to offer. I am also still looking to identify those 4 connectors, I can take a picture of what Im talking about if needed, just let me know

The black and white connectors are the transmission neutral position switch and reverse position switch. Does not matter which is plugged in where as long as black is to black and white is to white.

Im not trying to doubt your experience but are you 100% sure as long as it doesnt mater as long as its black to black and white to white

Alright so I did the test of disconnecting the mid pipe from the muffler, and besides the CEL and the sounding like a lawn mower on steroids, it ran and idled just fine. The cat did not heat up nothing, it was running like a dream with a little extra shake, but Im chalking that up to because the muffler wasnt connected, so it seems that I need to replace the muffler....unless anyone has any other ideas.

Before someone makes suggestions about what could be done, keep in mind that my car is plated in North Carolina, so I HAVE to pass emission standards

Yes I'm 100% sure.

ok thanks Easy thats one load off my back, I was wondering if maybe I got those mixed up, now i just got to replace my muffler it seems