Miss fire codes P0300 - P03003 car jerking

[edrocket]

2003 CVT 45K miles only. - ongoing issue + new one: no heat from heater!

P0300- Random Misfire detected
P0301- Misfire detected on cylinder 1
P0302- Misfire detected on cylinder 2
P0303- Misfire detected on cylinder 3


Put new plugs in, New EGR valve, cleaned the EGR plate (no buildup.) Still jerking. Seems to run great when cold, then when warm, the jerking starts. Also last night, no heat from the heater? related issue?
what to replace next? about to sell it, wife wants it gone due to issues. ;-(

[JohnVirginia]

All cylinders misfiring? Bad tank of gas, such as water in the fuel? Try a fuel additive that gets rid of moisture in the system? Can't see that causing the heater not to work though.

[gilbertguy]

Not sure about the "no heat" issue but it is probably related. I've seen a few heat related issues where the car (not just this one but multiple cars) will run good when cold but when things warm up things act up. Normally it is related to an electrical connection issue of some type. Seen a transmission computer have issues after warming up, wire connections have issues loosing connectivity when warm.

Now it could also be a sensor having issues when the car warms up but the fact that there is now a heat issue also leads me to think more along the lines of an electrical connector issue. These can be tough to find, follow the plug coil wires back to a common connector, unplug, inspect and replug all connectors for a start. Good luck and report back what you find.

[edrocket]

I'll spend some time & check connections.

[edrocket]

I put about 12 oz of additive in to pull any moisture out. No difference. thanks for tips

[Jivko57]

My heater is acting up from time to time too. To make it run I have to turn it to ice cold- till the end , then to hot to the end . That readjusts some valve(s) and once the hot air starts flowing i can reduce it to where I like it.

[JohnVirginia]

Assume you have/will check out Varak's "misfires out of nowhere" post of today?

[edrocket]

Turns out it was the #2 coil pack that went bad. Would work just enough at times to drive but not accelerate very well & to keep up w/ timing advance. Put a new one in & problem instantly gone!

[Willie Williford]

Thanks for the closure.

What did you do to determine the solution? (Or malfunction)


Willie

[edrocket]

The next step i was going to do was swap injectors and/or coil packs. Started to look at prices & decided to have diagnostics done to narrow it down. Coil pack was my next item to go down if diagnostics came back w/ a ?. Took it to the dealer & they ended up not charging me anyways!