Cylinder 1 Misfire - P0103 and P1399

I have a '00 4cyl, SE. I was driving home and noticed all of the sudden that the car started idling rough at stop lights, CEL flashing, and it didn't seem like the car wanted to keep running. Luckily made it back to my apartment which was about a mile from where it started happening.

I have a bluetooth OBDII scanner I use with my phone to pull the codes. P0301 is a cylinder 1 misfire, but I'm not sure what the P1399 is for. Seems from what I've read fixing the misfire will fix both.

I checked the ignition system. Distributor looks okay, as well as wires and plugs. I tried switching around wires and plugs (kept firing order same) to check...misfire stayed on cylinder 1.

Could it be the EGR? As far as I know it's never been cleaned. 332k miles on the car.

Dirty injector? Would that really only happen on a single cylinder?

One thing I did notice when troubleshooting it tonight was that it misfires MUCH more consistently when the engine is warm and when I press on the throttle.

Any help would be very appreciated!! I'm trying to avoid spending about half of what the car is worth for a mechanic to diagnose and fix...

It could be EGR. Also, definitely check into the condition of the spark plug. How old are the plugs? Id verify spark on cylinder 1. If spark is poor or non-existent, change the rotor behind the distributor cap.

Alright, I think I'm going to attempt cleaning the EGR this weekend. Any tips I should know? Is there a DIY here?

I'm fairly certain it's not the plugs or wires. I switched plugs between cylinders 1 and 2, and also checked the spark on cylinder 1 by pulling the wire off of the plug while it was running - there was spark there. Cylinder 2 never complained with the plug that was in cylinder 1 originally.

I'm really hoping it's not a compression problem....

did you pull the cap on the distributor?

Do you know how to test an injector?

No, didn't remove the cap on distributor. Should I do that? What do I look for?

I've never done it, but I've done some research and it seems I can use a multimeter to check them. Will that work?

Behind the cap, you will find a rotor that turns with the camshaft. As it turns, it sends spark to the corresponding point on the cap that is sent to the spark plug.



Here, the rotor I'm referring to is part #3, and the cap, #2.

Remove cap and inspect condition. Bad? Replace. We know the distributor is okay due to the fact that all other cylinders fire fine.

Compression is good seemingly considering this is an in and out issue. This problem is gonna come down to injector, or cap/rotor most likely.

sorta a voltmeter helps. Usually a problem is electrical, and you would have a code for this.

ok, got a fuel pressure gauge?

-ONLY- worry about this if the cap is fine, that is much more likely, this test just get's harder!

Replacing the distributor cap and ignition rotor right now..

Here what they looked like...

Looks like some of that oily grime could be the culprit

And the rotor..

Still getting a misfire with the new cap and rotor
Maybe I should check the wires again?

I don't have a fuel pressure gauge either...any ideas?

ok, check compression

he reason for fuel pressure check how fast it drops with the key off, then *power* the injector and it drops faster. You know it works electrically, or you'd have a code, this is to see if it works mechanically.

You said you don't have a fuel pressure gauge, so the alternate option is to pull the fuel rail up ~2" and leave the lines on it, leave the injectors in it, run the pump to get pressure, and see the injector sprays when powered.