So, off and on my car will have the check engine light on. Sometimes it will be on when it starts, other times not. Whenever i try to get the codes, the key is turned to on, the light is on for 3 seconds and the CLICK from the dash and it goes away... So today i checked when the light was off and got the codes
2..1 for ignition circuit : could explain why when i turn the key sometimes the starter doesn't turn (2 month old starter)
3..4 for knock sensor: replaced 2 weeks ago...

Those were the NOT the codes I was expecting, because last week when I turned my car on, it was misfiring hecka. It sounded like a V8 Diesel, then when i drove it a block it went back to normal... It did that to me off and on for a few days and now it isnt doing it lately. So, could a knock sensor misinstallation on my part cause all of this? (except ignition circuit) Or do I need to unplug coils? Because when it did do the misfire, I unplugged one coil, replugged and it fixed itself, and then restarted it (it was misfiring) and did unplugged again and them misfire got worse, so it couldnt have been that and the first time must have been a coincidence... I do think if it is though then its a rear coil... Also does that mean that the Upper Manifold has to come off? Because while im checking coils I might as well put in new plugs. So... any advice/help/suggestions would be amazing.
Thanks!

 

Since there haven't been guesses, i'll jump in. First, track your ignition problem. It prob isn't involved in the misfire, but best to get it clear. Then, test your coils properly, one by one. You haven't given much information, just need to test things, not guess. The coils are likely, but it culd also be a fuel problem, so test the coils first.

 

might need a new ignition switch. Spray MAF with MAF Cleaner. clean TB too

 

Is it misfiring or stalling once it cranks?

 

Misfire. It has never stalled, I dont know if it can since its an auto, iv only seen my moms suburban do that...(Belt Seized, then AC exploded.)

 

did you drop the knock sensor before you installed it? that will ruin it!

 

No. I was very careful with it.

 

Is your light STAYING on after starting it? Its supposed to illuminate for a short period at every start-up.

 

a bad knock sensor will not cause mis-firing, it only retards the ignition timing. Also the knock sensor code will pop up with other problems and many times is a false code, you focus on and fix the other code. Its possible you could have failing coil packs or failing/dirty fuel injectors.

 

The knock sensor has nothing to do with engine stalling, stumbling, or misfiring.
It is purely just to see what type of gas you gave it, and how much timing advance the engine can run with out pinging.

 

But it will throw a KS code if you have misfiring/stumbling/stalling.

I had a KS code when I brought my car... Also a nasty misfire @ WOT, changed my spark plugs and cleaned out some stuff and it went away... Along w/ the KS code.

Edit: Just incase ppl got confused, I'm saying it's NOT the KS, but other things can throw a KS code.

 

Its NOT the knock sensor...

 

So, to replace/check rear coils, does the Upper Intake have to come off? Because I have searched and some say yes and others say no.

 

Occasionally after I start it the light stays on, (meaning another code then the ones at the top). But can I turn the screw and count the flashes with the car running? Or do I need a DIAG tool?