misfire code

[jckevns]

this is not a neon issue so mods if you need to move the thread feel free, I posted here to get more traffic

This issue is my 2001 mr2 spyder
about a month ago i got a check engine light, ran the code it was a cylinder 4 misfire so i changed the spark plugs and cleared the code.

about a month later no codes and then today check engine light comes on so i run the codes and its showing random misfire in cylinder 1 and 4, this came up 4 times. then a random misfire in cylinder 3 came up once.

so i'm thinking its time to replace the coil packs (its a pack on plug setup) but this will cost $100 per cylinder.

it seems strange to me that all the cylinders threw a misfire code on the same day all at once

the guys on the spyder forum are pricks so i came here for some neon love

any suggestions or thoughts?

edit: forgot some general background info, the car has 111,000 miles. I store it for the winter so this may when i got it out for the season i put some fuel injector cleaner stuff in the gas tank. the car is not running rough, not idling rough, not having trouble starting, no smoke coming out of the exhaust. the mpgs are terrible right now but this happens anytime i get a check engine light

[BlackRoseRacing]

clear the codes and swap the suspect coil to a different cylinder. if the CEL comes back on and it followed the coil, then make sure the boot is not cracked and arcing. If thats good, then its probably the coil. if you get the oe specs on Ohms across the terminals of the coil you can bench test it for internal faults.
If the misfired cylinder stayed the same, pull the spark plug and check the tip for a color pattern. you can google search what spark plug tips are support to look like to help identify a problem.
If the coil and plug are good, you either have a bad injector or plugged injector, or at worst...carbon build up causing a valve to hang....

[jckevns]

Update
The car is now idling rough n the engine light comes back as soon as its cleared, it flashes as well.

I had a shop look at it they told me cylender 2 so I changed the coil for cylender 2 no change. I took the new coil n tried it in all the cylenders no change.
Checked the plugs they all look good.

So im thinking fuel injectors, just need to figure out which cylender i have misfire codes in all cylenders at the moment.

Any suggestions

[stdlystdmufn]

if it is only 1 cylinder that is misfiring then swap the bad with one of the others. so for p0302 swap #2 injector with #4
it sounds more like a multiple cyl mis. and it is pretty uncommon for all injectors to go out (even intermittently) at the same time. I would think something more along the lines of fuel delivery, or ignition timing, or mechanical timing. i don't know the mr2 very well and i don't feel like googling info about them but here is some generic info. keep in mind, only fuel, spark, and compression can cause misfire issues.

do these spyders use a fuel pressure regulator?
-if the FPR allows too much pressure it can bleed past the injectors. too little and the computer will not be able to up the injector ms enough to keep from lean misfires

fuel pumps can cause misfires for the same reason as FPR.

I have also seen fuel filter cause some problems

ignition timing is probably not programmable in your situation, but if your cam or crank sensor are not reading properly the computer may be sending spark at the wrong time.

and mechanical timing from worn belts or sloppy tensioners can cause odd misfire issues. you can spot one of these problems with a vacuum gauge normally but if the misfire is bad enough it may corrupt the results of the test.

[Dillmiester]

Recently I had the injectors off to clean and noticed the orings were very deteriorated, I replaced them after managing to drop one on the ground and break the pintle cap had to get a whole new injector from a LKQ salvage cause nobody has them, after I replaced the orings I put them back on the rail then ran xylene I got from work through them using an air compressor and 12v from the battery, my dad helped with firing the air while I opened and closed the injectors. I noticed a decent improvement in spray pattern cant say if it ran much better because of other issues.

[jckevns]

I should add currently getting random misfires for all cylenders.
Car has timing chain, so im thinking most likely not the issue

[timmyw28]

Don't over look them chains I had a f150 start stumbling because the chain guide was worn and had some slack in the chain

[jckevns]

Another update

Compression test cylender 1 & 3 130 &150
Cylender 2 & 4 50 & 50

Leak test shows 1 & 4 leaking on the exhuast side of the head

Geuss its time for a rebuild