2000 Sportage - Losing power & understandig codes

I'm trying to help a friend with a 2000 Sportage 4x4 with 60K miles. It had been stalling fairly regularly while driving, especially when tank is below 1/2 empty. Did not show any codes at first.

We put injector cleaner in tank and have seen an improvement with only one stall in last tank of fuel. Two days ago, check engine came on. I reset it and it hasn't come back on.

Checked at Autozone and got codes P0300 (Random multicylinder missfire) & P0303 (Cylinder 3 misfire detected). Counterman at Autozone said it sounded like fuel injectors may be going bad.

What do you think? Could injector cleaner have loosened up debris and caused check engine light?

Your help is appreciated.

I think the tank level is only a coincidence. MIsfire is electrical, not fuel related. Problems with firing are VERY frequently related to the CRANK position sensor: http://www.geocities.com/lmp4203/kiasport/cam_crank_sensors.jpg
easy to replace, and keep as a spare is it does not solve the problem. CPS failure is not an IF question, but a "when" so having one on hand is just OK and not expensive.
Once this is ruled out, always time to look for complications.

I think the tank level is only a coincidence. MIsfire is electrical, not fuel related. Problems with firing are VERY frequently related to the CRANK position sensor: http://www.geocities.com/lmp4203/kiasport/cam_crank_sensors.jpg
easy to replace, and keep as a spare is it does not solve the problem. CPS failure is not an IF question, but a "when" so having one on hand is just OK and not expensive.
Once this is ruled out, always time to look for complications.



:2cents: Before you get carried away, when was the last time the spark plugs where changed and the ignition modules/wiring looked at? The codes that you mention can be generated from several sources with the spark plugs the first thing to check. Misfire can be anything that interferes with the combustion in the cylinder, if there is a fuel related problem and the mixture is is extemely lean, you will get a misfire from too high a temperature in the cylinder. Start with the plugs first.

Indeed crank position sensor error has codes of its own (336,335,340,341,342) that should be present if this is the failure mode,and spark plugs/ignition modules/cables are the first "natural" to look at except their odd position in that engine makes one hope it is something else and prefers looking somewhere else...just like the 3 far side spark plugs in e-w V-6's that are out of reach in most cases.

BTW, I'd like to have temperature sensors in my cylinders too. (..have that in aircraft piston engine at the exhaust valves and the real time displays for this are a real freak)

You were on the right track (This of course depends on your freeze frame data stored before you erased the misfire code. Depends on the fuel trims.). Check the fuel filter for rust. If rust is present, go to the sock in the fuel tank to check for being plugged. (Rust or water in fuel tank?)

Those other Kia friends were just trying to be helpful, which is always appreciated. (I own 5 KIAs!? They are GREAT cars for the money!)

JP

Thanks for the tips. I'm going to start with the simple stuff and keep going until I figure out what is going on.