So I have a s40 volvo 2.4i non turbo . I was driving and all of a sudden my car starts shaking and idling hard then I shut it off . I started it back up still idling hard now it shut off . I don't know whats going on so I go to autozone they scan my car it comes back random misfire . Po300 code) now they tell me it is my ignition coils are my spark plugs so I'll go to AutoZone get n g k spark plugs and ignition coils 5 brand new ones. I changed them out the fire spark plugs and the 5 ignition coils in my car is still not working and it's still saying it's misfiring random so can somebody please help me please

 

Number one - whoever suggested that FIVE coils and/or plugs could all fail simultaneously needs to be taken out back and slapped around a little.

You probably have a fuel pressure / deliver problem, or possibly a bad vacuum leak.

Are you absolutely sure that those are the only codes the car was throwing? Obviously, the AZ guy who helped you wasn't exactly a rocket scientist.

My advice - buy a cheap OBD reader / eraser and learn how to use it yourself so you aren't at the mercy of the three-whisker kid at the local big-box parts place. ;-)

 

I don't even know how to check all of that. I have been online looking for ways to help without going to volvo. I do have a obd scanner its an innova 5610 . It only show po300 far as codes but I do have the freeze screen I don't know if I can download it but maybe you could help me with that . How do I check fuel pressure??? I really don't know what I'm doing as you can tell.

 

I'm kinda jealous of that scan tool. I'm pretty sure it should allow you to monitor engine vacuum and fuel pressure. See if you can figure out how to do that... I suspect it will shed some light on the issues.

 

Welcome to VF Rashan

It would be best if you took the time to learn to use your scanner. If you don't have a manual you can find it here - - > https://www.innova.com/Support/Downl...10/CarScan-Pro

There are also a number of youtube videos on the 5610 that might be helpful as well. If it was me I'd put the old coils in and return the new ones as defective since you have the same problem.
Sometimes going to a dealer and paying to have it done for you is cheaper than doing it yourself.
A random misfire means the computer isn't seeing any one cylinder misfiring. Normally what will happen is one coil will start to cause a problem and you'd get a code for that cylinder. As stated above it's almost impossible to have two or more coils fail at the same time unless you were doing something with the wiring and really zapped them, maybe reverse current ??
I'm not sure exactly how the ignition system on your vehicle works but it might be something with the trigger sensor on the crankshaft or even a bad wire shorting out.
It could also be caused by low fuel pressure like a fuel pump getting ready to fail or a fuel pressure regulator that too isn't holding the proper pressure. It could even be the fuel injectors starting to clog up.
The cheapest thing to try would be to toss in a bottle of Lucas Fuel Injector cleaner and let it run for half an hour or drive it if possible.
Then there is a chance something after the throttle body is leaking air. Might try cleaning the IAC, idle air control valve.
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