I have been dealing with a random misfire, and the CEL typically goes away and comes back from time to time. Lately it has been staying on. (once in a great while blinking.)

It was a couple cylinders, then it seemed to be different cylinders, and the most recent is cylinder 1,2,3,4 misfire and the "random misfire" code


The car is totally drivable. Car is a 2001.
Mods: K&N FIPK, DC header, Berk test pipe (with CEL fix), Spoon single side exhaust

Compression test yielded:
210
218
235
235

So far within the last 500 miles or so, I have replaced (to try and fix the problem)

(4) New OEM coil packs (for a 2004)
(4) New OEM NGK spark plugs
MAP whack + zip tie fix (and tried my best to clean the MAP passage way in throttle body
Throttle body cleaned
IACV removed and cleaned
New valve cover gasket and spark plug tube gaskets,
* after a few weeks of driving I checked to make sure coil packs were dry to see if gaskets didn't rip during install, and they were dry,
I had this issue the last time I installed the gaskets, one of the spark plug gaskets ripped, allowing some oil to pass by to coil pack, so I thought thats what killed a coil pack, so i replaced them all.


On order as of today:
Map sensor
O2 Sensor (upstream) Denso
O2 Sensor (downstream) Denso

I figured I would start with all new sensors to remove some variables.
If that's not the case, my next step is valve adjustment... alternator... battery (even though they seem to test out ok, it may be a bad cell in the battery or the rectifier in the alternator...


I will keep this thread updated as I go to make things easier if you ever get one of these pesky misfires...


If you have any input it would be appreciated. Or if you were lucky enough to already deal with this chime in! Thanks


- Dev

 

i had this issue and did the same as you nothing would fix it, it was actually an ecu issue, do you have someone close by that you could swap ecus with? need there key also to hold next to yours to start it. shoot me a pm if your not sure what to do. i wish i could help and loan you mine but i have kpro now so kinda useless.

 

I have an '00 ECU sitting around looking to sell but you would need to program keys to it. If you can find someone with a Mugen or other ECU that the key security is bypassed.

 

You may want to try changing the cam position sensors at the rear corners of the valve cover. While you are at it, check the wiring and connectors back there.

Have you checked fuel (bad gas) or fuel pressure?

 

All good points, will try ECU at some point if it doesn't clear up.

Gas is always 93, and fuel up quite frequently.

Have not checked fuel pressure.

I also made sure the ground on the back of motor near firewall is solid.

 

can you get a freeze frame of the misfire notably what the STFT and LTFT are at please

 

I will get this info asap, maybe tomorrow. Thanks

 

Do you get a dash flicker? I did before the cel came on and it turned out to be a bad alternator?

 

I don't have bad dash flicker at all, but like a quick flicker SOMETIMES during acceleration and as revs go up (~ 4K RPM) it'll "flicker" i guess. More like flashes a bit brighter for a half second then back to normal. Everything is fine at idle.

 

If your dash light flickers, my bet is on the alternator.