Engine won't run after trying to fix misfire - Need Help

[Schwamm]

Two weeks ago my car (137,000 miles) very suddenly started to run rough and then the third cylinder started misfiring consistently, making the car barely drivable. I tried swapping coil packs, plugs, and wires but nothing changed. I then tried to swap the third and fourth fuel injectors to see if the misfire moved to cylinder 4, but I broke an O-ring and decided to go ahead and purchase a set of used injectors cheap on the forum. Shipping was slow and I had to wait two weeks, and when they arrived I swapped out the injector originally on cylinder 3 with a replacement. When I then tried to start the car after letting the fuel pump build up pressure it would not start. It tries to turn over slowly and makes a clunking noise, almost like a knock. It doesn't sound close to correct. Even with the misfire before, the engine would still start and run.

I don't know if this could be related, but I have been burning oil for a while (blue smoke when I start the car). I assume the valve seals are bad but I haven't gotten around to fixing them. Could letting the car sit for two weeks have let too much oil drip into the engine or caused some other problem? I also noticed oil around the intake manifold and on the back of the engine, including puddles behind the intake manifold gasket. Could I have a more serious problem now? I'm trying to figure out why it won't even start today, when it started with a misfire two weeks ago.

I know this is an odd mix of symptoms & problems, but any advice, even just what else to test, is greatly appreciated. I am stumped.

 

[hornsfan10609]

So the car will crank but not start? I still think it's ignition related, check the harness for damage or use a voltmeter if you have one.

 

[gangstagangsta]

Did you replace all the injectors?

The resistance on the injectors should be 14.2Ohms -14.8Ohms around 70*f (if memory serves). Its funny that I remember that from my testing but I cant remember what time it is after looking at my watch 2 sec prior.

 

[Schwamm]

I only tried swapping out one injector, the one originally on the third cylinder. I'll definitely check the resistance. I swapped out spark plugs when I was debugging. I suppose it's possible one of my spares is now fouled. If I have a bad plug in one cylinder and a different problem in another I suppose it would barely run or not run at all. I'll give it a shot tomorrow and report back

 

[Schwamm]

So the car will crank but not start? I still think it's ignition related, check the harness for damage or use a voltmeter if you have one.

To clarify, it does crank and just about starts sometimes. If I let it turn over and leave it it will die within about 10 seconds. It does try to run, but at a very low RPM and it isn't sustainable

 

[hornsfan10609]

It would likely still run if you didn't but what type of plugs and did you gap them? Have you checked for a massive vacuum leak?

 

[Schwamm]

I am currently using NGK Iridium plugs but I swapped them out for an older (still functional) set of Bosch platinums when debugging. I didn't gap them (somewhere I read not to with those), but I probably have 15,000 miles on them without issue so I think they're OK.

I'm pretty sure all the vacuum hoses are plugged in correctly. It would take a massive leak to cause this, as I've had small leaks before and it will still run. I have a mechanic looking at it this afternoon so I will see what I find out. Thanks for the help

 

[Schwamm]

Turns out it just really wasn't getting enough gas, even after following Mazda's directions to short the fuel pump to build pressure. I got it started with starter fluid in the intake. I still have a misfire issue and it seems to be valve related, but the car cranks and runs now