ok so I had a misfire problem last year but I thought I had it fixed. it seems to be outside temperature related.. the weather here has gotten into the 80's the past few days and after my car warms up and I drive it when it goes back to idle it will miss, but it doesnt miss while im driving. its got good plugs and wires just replaced all the oil seals, (lower rocker arm, upper tubes, valve cover, all the ones associated with timing belt change as well), and the timing is good. so...what could it be???

 

My guess would be an ignitor issue.... The reason bosch plugs suck is because the resistance is improper and so the ignitor overheats and that causes problems, given the fact that your issue is during warm weather that would be my first guess if you have a new cap/rotor, if you've never changed the cap/rotor I'd start there...

 

Ive got a new cap/rotor on there as well. I just put a new set of Denso plugs in 3 days ago.m should I try some iridium plugs? maybe that could help?

 

If you were to replace the plugs I'd probably suggest just going with standard NGK's.... iridium plugs are ok but you're not going to get much for the extra cash they will cost you...

 

the miss starts after the engine warms up?
Check valves for a tight clearance maybe?

 

valves are something I havent checked...although I dont have any tools or experience in valve checking. but yea it starts after the engine is warm and after its been driven. im stumped, the only things I havent done are changed injectors, ignition coil, and now that dude mentioned it the valves....

 

there is a full writeup in the DIY section on valve adjustment.... it's a cheap/easy thing to check/adjust and should be done periodically anyway.... why not? just get a go/no go guage and a new valve cover gasket and do it....

 

could I have a bad injector? or bad o-ring in the injector?

 

Maybe.

Probably not.
A bad O-ring where the injector fits into the fuel rail will leak fuel.
A bad O-ring where the injector fits into the manifold will be a vacuum leak.
You'renot a newbie in the engine department, youshould be able torecognize either of those issues for what they are.

 

does it misfire only on 1 cylinder ?? or across the board.. do a cylinder balance,, remove the spark plug wire off 1 at a time while engine is running and see if 1 cylinder rpm will not drop or drop a lot less than the other 3 ,,

if so.. yes it could be a bad injector,, get a screwdriver and put it on the injector and on your ear , make sure that they all click the same pattern ,, if 1 clicks too low or does not click you got a bad injector ..
as adviced ,, do a valve adjustment real easy to do,, if it still misses do a compression test , no need for iridium plugs stock plugs will do just fine ,,

OOOOOOPS i see i forgot to include wire . it is been corrected