Random Misfires, bad idle but drives fine

[belo]

have had a evap code for awhile. i believe it was from a leaking #2 injector. fixed the leak with new o-rings. then i started getting the stalling, bad idle and random misfire. coil packs were replaced ~7k ago and fixed it the first time, but not evap code.

had replaced coil packs in spring too, but got cheapos from rockauoto. mechanic said they were both dead. cleaned egr in summer and new wires too. plugs are probably 20k old. tried the easy stuff. seafoam, maf, throttle body cleaning. have an ebay intake on. i do hear a hissing sound from above the injectors but cannot pinpoint a vacuum leak. these all helped, but did not cure.

any thoughts would be great. i dont want to spend more money at the garage on my winter beater. for what its worth, my rear cat rusted and leaking. i have a new one but dont want to slap it on till the misfires stops.

tia.

 

[Crafty Panther]

It could be the intake manifold gasket, I had a severe vacuum leak from where the gasket blew around the #2 cylinder a few months ago. Shop labor+parts for replacing the gasket+diagnostics was about $700. If you're willing to try and swap it yourself, all the gaskets will run you considerably less then that.

Also, double check the vacuum lines connected to the pcv valve.

I have an ebay intake on as well, I'm starting to believe that maybe relocating the maf to where it requires you to is the catalyst for most of these problems.

 

[belo]

i bought the ebay intake to replace a broken stock tube, and this problem just started up after the intake had been on for a while. i dont know. I'm worried too that it might be the intake gasket. is there anyway i can diagnose this myself?

 

[Crafty Panther]

http://youtu.be/9CPqbaSgcok

I used the aerosol method to find my leak, it's a little tricky with the location of the manifold gasket, but its a noticeable idle change.

 

[Crafty Panther]

http://www.youtube.com/watch?v=zMok2y05jNE&feature=fvwrel

Also found this. Don't know if you smoke or not, but if I ever have another leak, I might try this method, lol.

 

[tweety2300]

If you have p0300 it's a miss fire when was the last time you changed plug wires I had the same code and it drove fine but every once in a while it would start missing for about 10 seconds and stop. Have you tried cleaning the egr valve that's the most common problem for bad idle. The only way I know of to check that gasket is to just replace it... Did you get the rubber tube from eBay or was it a short ram?

 

[belo]

i tried the carb cleaner trick. no luck but i'm not sure i check all the right spots. the egr is probably 40k old. it has been replaced once. cleaned about 10k ago. plug wires are also 10k. the intake tube is a short ram.

not sure if it matters, but when i seafoamed i saw no smoke other than the tail pipe.

i just feel that i must have done something while fixing the injector to try and cure the large evap leak code because it ran and idled fine until i pulled off the rail. i also did an oil change if that matters. pcv valve also pass the "blowing" test.

 

[Crafty Panther]

It could be a bad injector spray pattern, i've read there was a tsb with the 2.0l engine about that. Unfortunately I have no clue how to diagnose that

 

[belo]

http://www.youtube.com/watch?v=zMok2y05jNE&feature=fvwrel

Also found this. Don't know if you smoke or not, but if I ever have another leak, I might try this method, lol.

that's interesting. i might try that using the intake vac hose...

 

[big Lou]

does it start rough at all? How many miles on the car? Might be a fuel pressure regulator or fuel pump. I would say plugs but your getting an evap code... Have you also checked the evap canister to make sure it's flowing ok? It's located on the fire wall, it's black and round.

 

[belo]

the start isnt anything like my 09 pontiac G8GT haha but it starts. little slower than i would like. it has 140k on it. it should have honestly been canned a while ago as its rusting but i just started a job requiring a long commute and until we move i want to drive the mazda. it's in good mechanical shape really other than this problem haha.

i have not checked the canister. not sure where it is. i'll look it up. might have explained the p0455 large evap leak i guess? always figured it was the leaking injector.

 

[tweety2300]

Did you bleed the fuel system when you pulled the rail off? It could still have air in it some how. Long shot of course try pull the injectors out and see if they spray ok not sure if you can do that with these cars though. Did you put all the vacume lines on right and double check?

 

[belo]

i did not purge the line, as it was leaking already, but honestly it's all going to the engine (with air) anyhow and doesn't recirculate so it should just burn off and then be fine if there was air in there. i'm no mechanic, but that's just my thoughts. i did not pull any lines when doing the fuel rails.

 

[tweety2300]

If its leaking it could be your problem air bubbles can mess the spray pattern of the injectors up or get stuck in them and cause them not to spray at all

 

[belo]

shouldn't be leaking anymore. new o-rings and no fuel present like before.

 

[belo]

fixed. last night after tracing all vacuum lines i still found no issues. did see that the tube to the manifold from the air intake wasn't very tight so i clamped it, but no luck.

after some more time trying to find the hissing sound i was able to silence it by pushing down on the #1 injector. i pulled the rail again and noticed some small rocks and crud underneath the gasket. cleaned this up and rebolted her down. idle much better but not perfect. noticed a small hiss from #4 this time. rail off once more (i'm a pro at this now) and again more crud. cleaned her up and made sure to evenly torque the rail down and secure. no hiss, no idle issues, top end is back and so far 60 miles with no cel.

not holding my breath but let it be a lesson to anyone who removes their injectors to be extra careful. i'd recommend cleaning around them before hand as well to avoid crud dropping into your manifold.