Engine Light - Replace #1 Fuel Injector twice and possibly 3rd time within 3months

chris_j11

P0263 #1 Cylinder Contribution/Balance
- Canadian Tire (Car Repair Store) replaced - #1 Fuel Injector (AK#98749)
- 1 month after, another Engine light
- Tried Kia Dealer - they found the exact same code (and recommend to replace the #1 Fuel Injector)
- I went back to Canadian Tire and they replace with another new Fuel Injector
- Now after a month - i get another engine light- I suspect it's the same problem
- Help, any advice?
I uploaded the Dealer and Canadian Tire Diagnostic
-- Kia Rio 2013 - Canada

thecardoc3

I took some time to look through what the code actually means. Here is what it says in service information.

"ECM sets P0263 when the compensated value of #1 injector calculated with amount of air is higher or lower than threshold."

Then service information gives the technicians the onboard testing conditions.



DTC Strategy Air fuel ratio out of range
Detecting Condition 1. Poor connection 2. Injector

Enable Conditions
• 140°F ＜ ECT ＜ 221°F
• 1520rpm ＜ Engine speed ＜ 3000rpm
• 33% ＜ Engine load ＜ 60%
• Fuel system status : Closed loop

Threshold Value
• the compensated value of injector calculated with amount of air >10% or ＜ -10%

Diagnostic Time • -

MIL ON Condition • 2 driving cycle

What this means:
What the problem is happening the cylinder's injector pulse width is requiring more than a 10% correction to achieve the correct air/fuel ratio. This also has to happen two drive trips in a row to turn the lamp on.

Do you feel a misfire from time to time when driving with the engine warm, likely lightly accelerating or pulling a hill ? According to your post there was about a month between the times that the lamp came on, but that doesn't mean it isn't happening more frequently. The first part of diagnosing this is identifying the exact conditions when the problem happens. Then once that is known, connecting diagnostic tools such as low amps current probe and digital oscilloscope along with a scan tool will be required to prove why the code is setting. Service information even includes a known good oscilloscope waveform of an injector command to help the technician prove what is going on. Tests like checking the wiring, such as resistance checks only work when the problem is there 100% of the time. With a month between occurrences its obvious that it isn't there 100% of the time so there usually will be nothing to find. There really isn't any other way to do this. It's very labor intensive for the technician with the likelihood that he/she won't be making any progress towards a solution each time they go out the door to try and get it to happen. (Got to love the Diagnostic time listed as "-")