Newbie here...

I have a '95 Milly S with the 2.3 Miller Cycle. Just got it this last spring (good deal) for a good run around car. Has like 115K miles on the car, but engine was rebuilt about 15K ago. Car ran like a raped ape. We even decided to take it California on trip, and again, ran super!!

About two weeks after returning home, I was going to take a short road trip, and while going up a pretty good hill I noticed it was suddenly running very sluggish. Plus, I looked down and noticed it was hotter than usual and pulled over, etc. Coolant wasn't low, let it cool down and limped it back to town (never has heated up again). While on my way home, it continued to run sluggish on accel and CEL began blinking for a while and then stayed on. I later found out this to be a "random misfire" code after hooking it up to scanner (I don't recall the code #). Took it to a technician, he found #6 to be the problem, replaced plug and still ran sluggish on acceleration, but no light coming on. Upon more review, he decides the front cat needs replaced...so, I did that thinking that was surely the problem. I did notice also that indeed the #6 was were the misfire was happening as evidenced by fuel around the gaskets and port of manifold. Go for a test drive...same thing!!! No better. Again, after driving for a while, the CEL begins to blink and then stay on again. So, I know the Mazda tech. who rebuilt the motor (unfortunately he is not close) and I call and he says to replace the coil on #6 and he sends me one (used, but sure it is good). I replace it, check the plug, and go for drive and same thing, except I didn't push it until the CEL came on this time. I could tell it wasn't right, and was running the same sluggish way. Kind of feels like missing when you step on it some.

Any suggestions???

 

The random missfire is a P0300. If your light was flashing it not only means you have a missfire but a potential catalytic converter damaging missfire. Coils have been a bit of a problem with Millenia S since 95 so good place to start along with a new spark plug. Doubt front cat had any effect unless it is plugged up. You made mention of fuel around the gaskets and port of manifold. This sounds very unusual. Where exactly was this fuel seen and how much? Fuel should not be getting anywhere that you should be able to see it. Is you CEL still coming on or flashing and if so what code is being set. A cylinder six miss would be a P0306.

 

Yes, the first code I got was a P0300, random misfire. Then, when I took it to the mechanic, he somehow came up with #6 misfiring, so I am assuming that he must have then got a P0306 code while he was test driving, etc.

The fuel sign I spoke of was when I replaced the front cat. I saw that the exhaust manifold gaskets were wet looking from around where the #6 port is, compared to #2 and #4 which were dry. Also a little wet looking inside the exhaust manifold at #6. I will drive again tomorrow, and see if CEL comes on and get the code and let you know.

What do you think about fuel pump? Bad gas??...I have always used premium gas, but who knows?? Supercharger?

I will try and get a fuel pressure reading tomorrow too, and also hook up a vaccuum gauge and see what it says...

Stumped for now

 

Fuel sign around where you are looking was not normal place that one would see. If damp around exhaust port areas then would say you probably do have a miss in the #6 cylinder. What other things have been checked in relation to the #6 cylinder? If a new spark plug and coil have already been replaced then is maybe time to head away from spark and look at compression or vacuum leaks or fuel injector. Better still , move the plug and coil to #2 spot and see if miss follows. Limit driving the car as like I said the flashing MIL means a catalyst damaging missfire and I am sure that you do no not want to pay for or replace that converter again.

 

Here's the latest: I have a P0301, which is on the #1 and completely on the other bank. I have the Data info. and freeze frame info., but don't remember where I put it. I will post and check back when I get it.

Could a bad battery cause misfires?

later

 

i had a similar problem on the black 99. random misfire. this happened right after we fueled up, and i suspected bad gas. i ran some dri gas thru, and it got a lot better, then i got bad coils codes. i got tired of going to autozone, so i bought my own scanner. i just replaced all 6 coils, my wife drives the black car, and i dont want her stuck on the side of the road. after coil replacement, it has been fine. i also see that in removing some of the coils, i broke off the little catch on the coil, and it looks like if the catch aint on there, the connector can back off. when i remove the connectors now, i push them in, then press down on the release.